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National Strength and Conditioning Association 2016 Japan Abstracts

Journal of Strength and Conditioning Research: January 2017 - Volume 31 - Issue 1 - p e8-e60
doi: 10.1519/JSC.0000000000001704

In the January 2017 issue of the in the “National Strength and Conditioning Association 2016 Japan Abstracts”, the following corrections should be noted:

In the abstract “Eucalyptus Smell Can Assist In Delaying Of Exhaustion”, the author group should appear as follows: Kyoka Kurii, Kento Oku, and Yasuto Nakanishi. Their affiliation should be listed as “Osaka Aoyama University, Minoh, Japan”.

The first of two abstracts called, “The Possibility of Slow Training As A Method To Improve Locomotive Syndrome”, should have been listed as “The Relationship Between Jumping, Acceleration, Agility Skills, And 1RM Of Back Squat And Dead Lift In Collegiate Male Volleyball Athletes”. The authors of this abstract should be listed as “Junpei Shiba and Rieko Kuramochi”, and their affiliations as “Graduate School of Health and Sport Sciences, Chukyo University, Aichi, Japan; and School of Health and Sport Sciences, Chukyo University, Aichi, Japan”.

The abstract “The Impact Affected By Hyperextended Knees On Underwater Dolphin Kicking” should be listed as “The Effect Of The Genu Recurvetum In The Performance Of Underwater Dolphin Kicking”

The Journal of Strength & Conditioning Research. 31(3):e67, March 2017.

The Effect of Moving From the Center of the Body Controlled by Trunk Muscles With Focusing Center of Gravity on Dynamic Vision, Whole-Body Reaction Time, Dynamic Balance, Muscle Strength and Psychological State

Noboru Saito

Total Fitness Support Inc, Tochigi, Japan

Purpose: In a training to enhance athlete's performance, focusing on the center of gravity (COG) and using core musculature to control the position of the COG to initiate movement from the COG (COG initiation) have been the parts of our training program. This is coming from the idea of that COG initiation can positively affect the ability to enhance performance. However, this idea is rather empirical and has not been proven scientifically. In this study it is purposed to examine the effects of COG initiation on performance parameters such as dynamic vision, whole-body reaction time, dynamic balance, muscle strength and psychological state. Methods: Nineteen subjects (15 males and 4 females, age 34.8 ± 16.4) involved in this study are athletes including the ones with disabilities (2 athletes) from 19 sports consisted of track and field, swimming, shooting, power sports, field sports, winter sports and motor sports. Same subject had COG initiation trial and control trial and had been assessed for dynamic vision, whole-body reaction time, dynamic balance, muscle strength and psychological state. Dynamic vision was assessed with subjective scaling of 3 non-contact thrusts to the face of subject. Whole body reaction time has been measured with the time to leave floor from position with lightly flexed hip at the visual signal. The trial was recorded with video camera and time was calculated using the frames (24 fps). Dynamic balance assessment used body weight forward lunge and measured time from full contact of stepping foot to whole body stabilization at the bottom position of lunge. Time had been calculated using video camera, the same way as whole body reaction time. Muscle strength was measured using Smedley grip dynamometer. Psychological state was assessed by walking in 3 different COG position (normal, high, and low) which subject changes the vertical diameter of abdominal cavity by voluntarily controlling transverse abdominal muscle and diaphragm. Then subject answers the 24 questionnaires to assess the changes in psychological state. Results: Dynamic vision was measured using subjective scaling (1: looked slow, 3: looked fast, 5: looked very fast) and COG initiation trial (2.53 ± 0.77) has stated that the thrusts looked slower than control trial (3.63 ± 0.67) (p ≤ 0.05). For whole body reaction time, COG initiation trial (460 ± 130 ms) was significantly shorter than control trial (550 ± 170 ms) (p ≤ 0.05). In dynamic balance, COG initiation trial (right: 620 ± 290 ms, left: 610 ± 190 ms) had used significantly shorter time to stabilize the body then control trial (right: 780 ± 320 ms, left: 1,150 ± 570 ms) (p ≤ 0.05). For muscle strength, COG initiation trial (right: 42.18 ± 8.16 kg, left: 41.39 ± 7.64 kg) showed significantly higher number than control trial (right: 40.29 ± 8.73 kg, left: 38.81 ± 6.79 kg) (p ≤ 0.05). For psychological state, all subjects selected different answer for each COG position. At normal position “well-controlled,” at high position “walking on air” and at low position “heavy-footed” are the most chosen phrases to express each position. Discussion: From the results, it can be stated that by using COG initiation, dynamic vision, whole-body reaction time, dynamic balance and muscle strength can be enhanced and psychological state can also be altered. Followings could have been affected by COG initiation. For dynamic vision, by focusing on COG, one tends not to stare at object and rather use peripheral visions. For whole body reaction time, by initiating movement from COG, core and hip joint muscles are first activated and thus proximal to distal movement chain happens. This results in higher muscle power output. Counter movement that happens at the beginning of the jump will be reduced. Another factor is that reaction force can be effectively earned since one can apply force onto the floor more precisely to the directly opposite of the COG direction. In dynamic balance, controlling the position of COG with core musculature, one can suppress the fluctuation of COG during movement. Lumbar spine and pelvis can be stabilized by core muscles. Also affecting is that by initiating from COG, motor control becomes feed forward and thus the movements are carried out smoothly. For muscle strength, it can be thought that when body is stabilized, the postural muscle activity is reduced thus grip strength can be more effectively carried out. For psychological state, different COG position can alter the sole-pressure sensation and such change may affect one's psychological state. Practical Application: By including COG initiation into athlete's training, his performance can be enhanced. Before starting exercising, by using COG initiation on top of basic exercise technique, training becomes more specific and thus performance enhancing effect is anticipated. COG initiation utilizes COG focus during movement and therefore timing of installing COG initiation should automated stage, where athlete can perform exercise without conscious control, after acquiring the exercise technique. For future study, to make it more practical information, it is required to scientifically investigate COG initiation mechanism.

High-Intensity Interval Training in College Hockey Players Using the 30-15 Intermittent Fitness Test

Toshiki Kanto1and Masatoshi Nakamura2

1Department of Students Sports Support, Doshisha University, Kyoto, Japan; and2Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan

Introduction: Soccer and rugby, as with most competitive team sports, have repeated high-intensity movements interspersed with periods of low-intensity activity. Thus, endurance training is important in these sports. Although most teams cannot spend a lot of time on endurance training, strength and conditioning coaches are required to improve their players' endurance capacities efficiently in a limited time. In recent years, high-intensity interval training (HIIT) is gathering attention as an effective form of endurance training. In the field, however, it is difficult to individualize the optimal training load of HIIT. Thus, we focused on the 30-15 intermittent fitness test (30-15 IFT). 30-15 IFT not only evaluates aerobic capacity but also uses individualized training prescription. Previous studies have reported that HIIT improves aerobic capacity in a relatively short period (2–6 weeks). In Japan, however, few studies have elevated the aerobic capacity by field running tests (such as 30-15 IFT) and have used training prescription following HIIT. The present report evaluated a running HIIT program based on 30-15 IFT in college hockey players during pre-season. Methods: Ten male college hockey players (19.8 ± 1.0 years; 174 ± 4.7 cm; 63.9 ± 6.8 kg) performed the 30-15 IFT before and after a pre-season HIIT intervention. The primary outcome measure was participant performance, and the final stage reached in the 30-15 IFT was reported as 30-15 IFT maximum velocity (VIFT). The HIIT intervention was implemented over an 8-week period from February to April, and each session consisted of 17–21 minutes of intermittent running for 15 seconds (95–105% VIFT) interspersed with 15 seconds of passive recovery. Shuttle length was 40 m and running distances were determined by individual VIFT by using the spreadsheet created by Buchheit. The pre- and post-test and all running HIIT were performed on a clay field with similar temperature. Results: All players completed more than 6 weeks of training, and the attendance was 92.5%. After training, VIFT improved (+4.5%; p < 0.01; effect size: 1.5). Although weight did not change, body fat percentage was decreased (−1.8%; p = 0.03; effect size: 0.4). Discussion: In this study, VIFT improved by 4.5%, which was less than the 5–9% improvements in handball players (Buchheit et al.), probably because the previous study had 2 sessions per week as a general rule and this study had only one session. However, our results show that only one session per week can elicit an improvement of VIFT in all players, and it is remarkable that individualized training prescription was realistically achieved. In addition, Scott et al. (2015) suggested a change of 1 stage (0.5 km·h−1) can be interpreted as a real change in performance. Hence, one HIIT session per week improved aerobic capacity in college hockey players during pre-season. Also, because HIIT session proceeds could increase aerobic energy delivery, it is likely that the increase in using fats was contributed the decrease in body fat percentage. Practical Applications: Properly programmed pre-season HIIT is effective in improving players' aerobic capacity even with only one training session per week. In particular, it is meaningful to college athletes in Japan where the training volume is considerably decreased in the so-called off-season. In the presentation, we will refer to devises and problems in practical applications.

Functional Movements in Japanese Mini-Basketball Players

Kenji Kuzuhara,1,2Masashi Shibata,3Junta Iguchi,4and Ryo Uchida2

1Department of Human Health, Faculty of Human Studies, Aichi Toho University, Nagoya, Japan;2Graduate School of Education and Human Development, Nagoya University, Nagoya, Japan;3College of Nursing Art and Science, University of Hyogo, Hyogo, Japan; and4Department of Health and Sports Sciences, Faculty of Health and Medical Sciences, Kyoto Gakuen University, Kyoto, Japan

Introduction: Functional Movement Screen (FMS) has been used to establish normative data and determine potential injury risk for young adults and athletes, but there are few data in elementary school-age children. The purpose of this study was to establish normative values for the FMS in a population of mini-basketball players. Secondary purposes were to examine relations between functional movement patterns and age, peak height velocity (PHV), and body mass index (BMI), and to compare functional movement patterns between boys and girls and between individuals with and without a history of injury. Methods: Seventy-one players (47 boys, 24 girls) in 5 community-based club teams of mini-basketball participated in this study. The participants were elementary school third grade (9 year old) to sixth grade (12 year old) students, and their mean age, height, body weight, and BMI were 11.09 ± 0.8 years, 145.2 ± 9.7 cm, 36.0 ± 7.8 kg, and 16.9 ± 2.2 kg·m−2, respectively. PHV and PHV age were predicted using age, body weight, height, and sitting height. Functional movement was assessed using the FMS which consists of 7 tests (deep squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, trunk stability push-up and rotary stability). Relations between composite FMS score and age, BMI, PHV and PHV age were analyzed using Spearman's rank order correlation. Mann-Whitney U test was used for gender difference in FMS and previous injury history analysis, and gender difference for individual FMS scores was analyzed by Mantel-extension test. Significant level was set at P ≤ 0.05. Results: Mean composite FMS score was 16.5 ± 2.2 (16.5 ± 2.4 for boys, 16.5 ± 1.7 for girls). Composite FMS score was significantly positively correlated with age (r = 0.312, P = 0.008) and negatively correlated with BMI (r = −0.371, P = 0.002), but not significantly correlated with PHV or with PHV age. The FMS score was not significantly different between boys and girls (P = 0.922) and between those with and without a history of injury (P = 0.423). There was a significant difference between boys and girls for the trunk stability push-up (P < 0.001) and rotary stability (P = 0.033). Discussion: This study demonstrated that composite FMS score was significantly and positively related to age in mini-basketball players. The result suggested that fundamental movement patterns may be influenced by age and maturation. We demonstrated that composite FMS score was negatively related to BMI, with functional movement being poorer in mini-basketball players with higher BMI. In this study, there was no significant difference in composite FMS score between boys and girls, but there were significant gender differences on 2 individual FMS tests. The results suggested that boys in this age category have stronger upper-body and better trunk muscular control than girls of the same age. Practical Application: Using FMS to detect musculoskeletal alterations in children would allow clinicians to identify elementary school-age players who would benefit from individualized neuromuscular training programs to prevent future injuries. Moreover, for those coaching elementary school-age players in mini-basketball, the FMS is a very useful tool to provide each player with appropriate individual physical conditioning.

Response of Skeletal Muscle Injured by Eccentric Contractions to Training

Ryo Takagi,1Riki Ogasawara,2Jyunya Takegaki,1Arata Tsutaki,3Koichi Nakazato,3and Naokata Ishii1

1The University of Tokyo, Tokyo, Japan;2Nagoya Institute of Technology, Aichi, Japan; and3Nippon Sport Science University, Tokyo, Japan

Purpose: It is necessary to overload to a certain degree to gain training effect (Overload principle). However, the risk of injuries increases if the load is too much. Especially, it is reported that muscle injury by eccentric contractions induce lowered contractile protein and decreased strength from physical muscle damage. Lowered contractile protein during late recovery stage from the damage is thought to be the main reason for decreased strength and thus training can expedite the recovery process from decreased muscular strength. Recently, we discovered that muscle protein synthesis (MPS) after a single bout of resistance exercise (RE) in injured muscle is enhanced compared to intact muscle. However, that mechanism has not been discovered. As a change after injury, we reported that fiber type composition is altered: lower IIb type fibers ratio and higher IIa type fibers ratio. The purpose of this study is to discover the fiber type-specific response to RE to clarify influence of fiber type conversion on the enhanced anabolic response. Methods: Muscle damage intervention and MPS measurement by surface sensing of translation method are required thus animal study is conducted. Right gastrocnemius muscle of Wistar rat is used in the study. Rats are divided into exercise (E) group which only performs RE and injury-exercise (I-E) group which performs RE after injury. Injury and exercise both utilize tetanus and isokinetic dorsiflexion motion by electric stimulation and an interval between injury and exercise is determined to 4 weeks when maximum planter flexion isometric contraction torque is recovered. Targeted muscle fiber is extracted pre and 6 hours post exercise at week 14 from both groups and histological and biochemical analysis was conducted. Results: I-E group has significant increase myosin heavy chain (MHC) IIa ratio and decrease IIb ratio than E group. In the phospho-rpS6 and MPS response, intensity of whole cross section showed same significant differences as the result by western blotting. In I-E group, the phospho-rpS6 response showed the following manner: IIb and IIx < IIa and I. Additionally, type IIb showed higher MPS response than other types, and type IIx showed higher value than IIa. Furthermore, the phospho-rpS6 response of all fiber types except type IIb in I-E group showed higher value than in E group. On the other hand, MPS response of all fiber types except type IIa in I-E group showed higher value than in E group. Discussion: In this study, fiber type-specific anabolic response to RE was investigated in intact and injured muscle. Past muscle injury increased MHC IIa ratio and decreased IIb ratio, and type IIa in injured muscle showed higher phospho-rpS6 response and lower MPS response than IIb. The findings suggest that altered MHC composition may partially contribute to the enhanced phospho-rpS6 response in whole muscle, but not to the MPS response. In the differences between intact and injured muscle, phospho-rpS6 response of type IIx, IIa, and I and MPS response of type IIb, IIx, and I in injured muscle were higher than in intact muscle, indicating that past muscle injury increases phospho-rpS6 response of fiber types except type IIb and MPS response of fiber types except type IIa. As for the non-increased response, we previously reported that collagen deposition occurs in the part of gastrocnemius muscle where filled with type IIb and IIx fibers, and heat shock protein 72 (HSP72) is upregulated in the part where type I and IIa are the majority. It is reported that increased attachment of muscle fibers to extracellular matrix decreases mTORC1 activation after exercise, and HSP72 upregulation by heat stress suppress increase of protein content after overload, thus the alteration may relate to the non-increased response. In conclusion, the enhanced anabolic response in whole muscle after injury may be induced by altered MHC composition and increased response of type IIx, IIa, and I in phospho-rpS6, and increased response of type IIb, IIx, and I in MPS. For future study, it is required to carefully examine different response between phospho-rpS6 and MPS, and the mechanism in upregulated anabolic response in muscle fibers. Practical Application: The fact that training effect after injury is different from muscle that is not injured is thought to affect the whole body performance. It is necessary to appropriately prescribe exercise program considering the altered muscle characteristics to resolve such unexpected training effect.

Effects of Circuit Functional High-Intensity Training on Physical Fitness in Sedentary Overweight or Obese Women

Alexios Batrakoulis, Dimitrios Draganidis, Kalliopi Georgakouli, Konstantinos Papanikolaou, Athanasios Jamurtas, and Ioannis Fatouros

University of Thessaly, Trikala, Greece

Introduction: The body weight training, high-intensity interval training (HIIT), functional fitness, and circuit training, are widely some of the most attractive and promising worldwide trends in the commercial, corporate, clinical, and community landscapes within the health and fitness industry. In addition, adult obesity and physical inactivity rates have grown immensely worldwide. This study investigated the effectiveness of a circuit functional high-intensity training program on physical fitness components in sedentary overweight or obese women. Methods: Sixty-five healthy, sedentary, premenopausal overweight or obese women (n = 65; 36.5 ± 4.5 years; 165.0 ± 0.1 cm; 79.4 ± 9.3 kg; 29.0 ± 2.8 kg·m−2) volunteered to participated and were randomly assigned to either the control (n = 32) or experimental group (n = 33). The training program was structured as a circuit functional high-intensity workout with progressively increasing intensity and volume. The exercise protocol was conducted thrice weekly in non-consecutive days using exclusively full-body functional exercises for a period of 16 weeks. Participants in both groups were tested before and after the intervention period in body composition {dual-energy X-ray absorptiometry (DXA), muscular strength (6RM in chest press, lat pulldown, leg press), muscular endurance (push-up, curl-up, parallel bodyweight squat), cardiorespiratory endurance (maximal treadmill graded exercise test [V̇o2peak]), flexibility (modified sit and reach), static balance (Sharpened Romberg)}. Results: Significant improvements were observed in all measurements. Body fat declined (p < 0.01) by 6.4% while fat-free mass, muscular strength and endurance, V̇o2peak, flexibility and static balance increased (p < 0.01) by 2.8%, 20.8% (6RM-chest), 14% (6RM-legs), 12% (6RM-back), 39% (torso), 62,1% (upper body), 48,6% (lower body), 19.4, 21.8, and 41.8%, respectively. Discussion: No study so far has examined the effects of an exercise modality that combines the circuit training, HIIT, and functional fitness on health and skill-related physical fitness components in sedentary, premenopausal overweight or obese women. The results of present study suggest that a circuit functional high-intensity training program, which uses body weight exercises and functional fitness training tools may improves many different components of physical fitness in sedentary, premenopausal overweight or obese women. These results may be attributed to a hybrid training workout and efficient exercise programming through full-body movements and high-intensity routines. Practical Applications: Since the prevalence of physical inactivity and obesity are higher than never at global level, exercise professionals may have to provide a full-body routine that combines HIIT, functional fitness, and circuit training. Thus, a functional hybrid training workout seems as a time-effective and evidence-based exercise modality that induces significant improvements on physical fitness parameters.

Conditioning of Adolescent Baseball Players With Lumbar Spine Stress Fracture

Takashi Fukushima,1Kenzo Kawasaki,2,3Shigeo Yamashita,1and Koichi Sugiyama2

1Yokohama General Hospital Department of Rehabilitation, Yokohama, Japan;2Yokohama General Hospital Department of Sports Orthopedics, Yokohama, Japan; and3Toin Yokohama University Department of Faculty of Culture and Sport Policy, Yokohama, Japan

Introduction: Low back pain (LBP) is a common complaint among young baseball athletes requiring repetitive spinal flexion (forward bending)/extension (backward bending), especially during periods of rapid growth. Two types of LBP were assessed: LBP on forward and backward bending. The present case report aimed to describe both types of LBP in adolescent baseball players with lumbar spine stress fractures. Methods: Case 1: A 16-year-old, high school baseball player (catcher, hereafter called player A) was diagnosed with a stress fracture of the fourth lumbar vertebrae. He had been feeling LBP when playing defense 5 days before starting treatment. His pain increased when bending forward. Case 2: A 17-year-old high school baseball player (pitcher, hereafter called player B) was diagnosed with a stress fracture of the fourth lumbar vertebrae. He had been feeling LBP during the warm-up run 5 days before starting treatment. His pain increased when bending backward. We assessed the Numerical Rating Scale (NRS) while player A bended forward and player B bended backward. Furthermore, we assessed the finger-floor distance (FFD), heel-buttock distance (HBD), straight leg raise (SLR), and passive internal and external hip rotation range of motion (ROM) of both players in the sitting (90° IR and 90° ER) and prone (0° IR and 0° ER) positions. We instructed player A to stretch the hamstring and gluteus maximus muscles and player B to stretch the iliopsoas and rectus femoris muscles, subsequently evaluating both players at treatment initiation and 2 weeks later. Results: At treatment initiation, player A had 7/10 NRS, 0.5 cm FFD, 8.0/8.5 (Right/Left, unit:cm) HBD, (Right/Left, unit:degrees) ROM, 70/70 SLR, 50/45 90° ER, 25/30 90° IR, 60/50 0° ER, and 45/50 0° IR. Two weeks later, the NRS was 3/10 with 8 cm FFD, 0/6 HBD, 85/75 SLR, 60/60 90° ER, 50/50 90° IR, 55/55 0° ER, and 50/50 0° IR. At treatment initiation, player B had 8/10 NRS, 3 cm FFD, 9.0/9.5 HBD, 70/70 SLR, 60/60 90° ER, 40/45 90° IR, 30/40 0° ER, and 25/30 0° I/R. Two weeks later, the NRS was 1/10 with 1 cm FFD, 0/4 HBD, 70/75 SLR, 40/40 90° ER, 40/40 90° IR, 60/50 0° ER, and 40/35 0° IR. Discussion: The hip rotation ROM of Player A with LBP on forward bending was limited because the hamstring and gluteus maximus muscles were tight, which increased the internal pressure of the intervertebral disc due to trick movements of the lumbar spine and caused pain. The hip rotation ROM of Player B with LBP on forward bending was limited because the iliopsoas and rectus femoris muscles were tight, which burdened his facet joint due to excessive movement. Taimela et al. reported that LBP is a relatively common complaint among adolescents. These results suggest that adolescent baseball players at risk for LBP must stretch before exercising. Practical Applications: Adolescent baseball players at risk for LBP on forward bending must stretch the hamstring and gluteus maximus muscles and those at risk for LBP on backward bending must stretch the iliopsoas and rectus femoris muscles to prevent LBP.

Examinations the Injury Risk for Female Wrestlers by Investigating the Relationship of Static and Dynamic Alignment

Kiwa Sakae1,2and Kaori Mitsuoka3

1Graduate School of Sigakkan University, Aichi, Japan;2JTEKT Corporation, Aichi, Japan; and3Department of Sports and Fitness, Faculty of Wellness, Shigakkan University, Aichi, Japan

Introduction: For sports injury prevention, it is important to evaluate the alignment of the body. Alignment can be divided as static alignment and dynamic alignment. As a combat sport, wrestling involves intense movement and thus abnormal alignment may lead to sports injury. However, no study was done using wrestlers. This study is purposed to examine the injury risk for wrestlers by investigating the relationship of static and dynamic alignment. Methods: Fifteen female collegiate wrestlers (age 20 ± 2, height 156 ± 5.6 cm, body weight 58.8 ± 8.0 kg) participated as subjects. Survey for injury history was obtained. For static alignment, horizontal angles for shoulders and pelvis and vertical angles for cervical and lumbar spine were obtained from static picture and then total angle was used as whole body distortion. Subjects were then divided into big distortion group (8 subjects) and small distortion group (7 subjects) using mean as standard. For dynamic alignment, subjects were instructed to perform squat movement on a wrestling mat and video recorded. Using Myer's back squat evaluation method (2015), 10 faulty movement patterns were scored (more faulty—2 points, less faulty—1 point) and injury risk was calculated. T-test was used for group difference. Results: Injury history for big distortion group includes shoulder dislocation and ligament injury, ACL and MCL tear, ankle sprain, foot fracture and cervical sprain. Also included was the pain around scapular. For small distortion group, burner syndrome, hand and finger ligament injury and herniated disc at lumbar spine are reported. For static alignment distortion, big distortion group was 21.8 ± 3.9° and small distortion group was 10.5 ± 3.2° and distortion was statistically bigger in big distortion group (p < 0.001). Also, distortion was statistically bigger in big distortion group at shoulder, pelvis, cervical and lumbar spine (P < 0.001). For dynamic alignment, big distortion group was 6.3 ± 1.1 points and significantly bigger than small distortion group (3.1 ± 0.6 points, P < 0.001). Discussion: As a result of alignment evaluation of female wrestlers, big distortion group's dynamic alignment score was twofolds of small distortion group. This suggests that static alignment is relevant to dynamic alignment. Also, big distortion group has more major ligament injury histories. It is reported that after lower body ligament injury, injured side tends to bear less weight than healthier side. By injuring ligament, static alignment abnormality can be triggered and then increases dynamic alignment distortion thus increases the risk of sport injuries. Wrestling mat is less stable than hard floor and therefore the risk of ligament injury may increase. In sports like wrestling, it is supposed to prevent injuries by evaluating and correcting static and dynamic alignment as well as sports movement. Practical Applications: Myer's back squat evaluation method is designed for the people with less skill. For athletes who have better squat technique and experience, it is difficult to apply this method. Therefore by using much softer surface like wrestling mat used in present study or tumbling mat rather than hard floor, it is possible to examine the injury risk related to athletes' dynamic alignment.

Effects of Lower-Body Positive Pressure Treadmill on Oxygen Uptake Using Multiple Regression Analysis

Kojiro Ishii, Tomohiro Oba, Yuya Kikuchi, and Kanta Hamaguchi

Doshisha University, Kyo-Tanabe, Japan

Introduction: The Lower Body Positive Pressure Treadmill (LBPPT) is a training device that enables body-weight supported running and walking exercises. Previous studies have mostly focused on changes in oxygen uptake levels due to differing body weight support (BWS) during exercise performed using the LBPPT. The purpose of the study was to estimate the necessary running speed (RS) and body-weight support percentage (%BWS) needed for maintaining equal oxygen uptake regardless of RS, %BWS, physique, or sex, using multiple regression analysis. Methods: Eight male university-level medium- and long distance runners (age: 20.3 ± 0.9; height: 170.9 ± 3.3 cm; weight: 57.0 ± 2.6 kg; body mass index [BMI]: 19.5 ± 0.9) and 5 female university-level middle- and long distance runners participated in this study. After taking measurements for 5 minutes while standing at rest on the LBPPT (DREAM HUNTER, Showa Denki, Osaka, Japan), we conducted a running test with gradual increases in the running speed. The speed was set to 10 km·h−1, 12 km·h−1, 15 km·h−1, and 18 km·h−1; each running test lasted for 5 minutes. The female runners did not participate in the 18 km·h−1 running test. Furthermore, the order of the 6% BWS (0, 10, 20, 30, 40, 50%), at which the subjects performed the exercise tests, were varied to avoid bias. Measurements were taken by using the breath by the breath method and a respiratory gas analyzer (AE-310S; Minato Medical Science, Osaka, Japan). The data on respiratory metabolism were analyzed and assessed. The oxygen uptake per body weight (V̇o2/W; ml·kg−1·min−1) was set as the dependent variable, and RS (km·h−1), %BWS, BMI (kg·m−2), and sex (M = 0, F = 1) were set as the independent variables; a forced entry multiple regression analysis was conducted. Results: The oxygen uptake rate was analyzed using 2 analysis: the gross value (V̇o2/W = −2.934 + 2.285 × RS − 0.22 × %BWS + 0.583 × BMI − 0.825 sex) and the net value (V̇o2/W = −10.354 + 2.287 × RS − 0.22 × %BWS + 0.663 × BMI − 0.523 sex), which was calculated by subtracting oxygen uptake during the standing rest. The adjusted R-squared of the gross value was slightly greater (0.780 vs. 0.769). RS had a larger influence on oxygen uptake when compared to the standard partial regression coefficient of the multiple regression analysis, followed by %BWS, BMI, and sex. Discussion: We created 2 multiple regression equations using the gross value and the net value. However, based on the values of their adjusted R-squared, the gross value was deemed sufficient. Using the multiple regression analysis for the gross value, we calculated that if a man with a BMI of 20 who was running at a speed of 10 km·h−1 with 0% BWS used the same amount of oxygen as with 50% BWS, he would be running approximately at a speed of 14.8 km·h−1. Therefore, by using the multiple regression analysis, it is possible to calculate the speed and %BWS necessary for maintaining equal levels of oxygen uptake individually. Practical Applications: A study by Raffalt et al. (2013) showed that BWS reduces the ground reaction force while maintaining equal oxygen intake. Therefore, LBPPT may be an effective rehabilitation training device because it provides an efficient exercise for the cardiovascular system while reducing burden on the musculoskeletal system.

Comparison of Muscle Strength of Lower Leg Among Rugby, Athletics and Soccer to Characterize Their Muscle Strength with Z-Score

Seita Kuki1and Satoru Tanigawa2

1University of Tsukuba, Ibaraki, Japan; and2University of Tsukuba, Ibaraki, Japan

Introduction: Muscle strength is divided into maximum strength, power and explosive strength from the force-velocity relationship. It's well known that there are sports specific features of muscle strength, but a few researches argued that the differences among the muscle features in several sports players. Therefore, the purpose of this study was to characterize the muscle strength of lower leg in sports players with comparing among their muscle strengths. Methods: Sixteen collegiate rugby union players, 15 collegiate athletic players (sprinters and jumpers) and 21 collegiate soccer players volunteered to participate in present study. Subjects performed Isometric Mid Thigh clean Pull (IMTP), Counter Movement Jump with holding 10 kg dumbbells in each hand (CMJ 20 kg) and Counter Movement Jump without arm action (CMJ). The data was converted to z-score by following formula: z-score = (subject's score − average)/standard deviation. Unpaired 1-way repeated measures analysis of variance (ANOVA) was used to analyze the trials with an alpha level of p ≤ 0.05. Results: The peak force in IMTP, the height in CMJ 20 kg and the height in CMJ were measured. The ANOVA indicated that there were significant differences among rugby, athletics and soccer at IMTP (rugby > athletics > soccer; p ≤ 0.05), and at CMJ (athletics > rugby > soccer; p ≤ 0.05). Moreover, the averages of these trials were converted to z-score, respectively (IMTP, CMJ 20 kg, CMJ, rugby: 1.0 ± 0.80, 0.4 ± 0.85, 0.1 ± 0.71, athletics: −0.4 ± 1.07, 0.6 ± 0.93, 0.9 ± 1.05, soccer: −0.5 ± 0.65 to 0.7 ± 0.61 to 0.7 ± 0.45). There were no significant differences in each sport events, but rugby union players were good at IMTP and athletic players were good at CMJ. The z-score of these strength in soccer players have no difference. Discussion: The primary purpose of this study was to characterize the muscle strength of lower leg in rugby, athletics and soccer. The results indicated that rugby union players are excellent at maximum strength, and athletics are excellent at explosive strength. This means that players have each sport-specific strength features. While they repeat the sport-specific movements in most of training, the specific strength is enhanced in each sport events. Therefore, they should decide the priority of exercises to improve the performance in consideration of their sport-specific strength features. Practical Applications: In this study, we characterized the sport-specific strength features, and the z-score might be useful method to assess the sport-specific strength features of players. However, every player has his own strength feature in each event, so coaches have to make the training plan for individual players.

Five Weeks of Hypoxic Exposure in a Top Japanese 800 Metre Runner: A Case Study on Changes in Physiological Variables During the Pre-Competitive Season

Fumiya Tanji,1Masato Yokota,2,3Wataru Shimazu,1Toshiki Tsuji,1Yasushi Enomoto,1and Yoshiharu Nabekura1

1University of Tsukuba, Tsukuba, Japan;2Fujitsu Limited Corporation, Kawasaki, Japan; and3Asia United Bank Corporation, Tokyo, Japan

Introduction: Living or training in hypoxic conditions increases aerobic and/or anaerobic energy capacities, which are important for performance in the 800-m run. This implies that acclimatization to hypoxia increases these capacities and improves performance. Here we investigated physiological changes in a top Japanese runner following 5 weeks of acclimatization to hypoxia. Methods: A top Japanese 800 m runner (age, 28 years; height, 178.1 cm; body weight, 64.1 kg; personal best time, 1′46″16) took part in this study. The experiment lasted for 11 weeks during which the subject lived for 5 weeks in a hypoxic environment (altitude: 2,000–3,000 m; 4 weeks in the hypoxia +10 days in the normoxia +1 week in the hypoxia) for 8 hours per day. Maximal oxygen uptake (V̇o2max), running economy (RE), and maximal accumulated oxygen deficit (MAOD) were determined at 3 and 7 weeks after beginning and 4 weeks after ending (11 weeks) hypoxic conditioning. Hemoglobin mass (Hbmass) was determined within 3 days before or after determining the other variables. The subject participated in an 800-m competition 1 week (8 weeks) and 3 weeks (10 weeks) after hypoxic conditioning. Results: There was a 15% increase in V̇o2max (61.4–70.6 ml·kg−1·min−1), no change in MAOD (52.6–52.4 mLO2·kg−1), and a 7.1% reduction in RE (0.99–1.06 kcal·kg−1·km−1) during weeks 3–7. Subsequently, there was a 3.3% reduction in V̇o2max (70.6–68.3 ml·kg−1·min−1), no change in MAOD (52.4–52.4 mLO2·kg−1), and a 4.7% increase in RE (1.06–1.01 kcal·kg−1·km−1) during weeks 7–11. Hbmass increased by 11.3% during weeks 0–3 (14.2–15.8 g·dl−1), did not change during weeks 3–7 (15.8–15.7 g·dl−1), and reduced by 8.3% during weeks 7–11 (15.7–14.4 g·dl−1). The performance in the 800-m run at 8 and 10 weeks were 1′48″82 and 1′47″81, respectively. Discussion: Hbmass increased by a short exposure (3 weeks) to hypoxic conditions, although this effect disappeared after a short period. However, V̇o2max increased delay than Hbmass, and the hypoxic effect for V̇o2max also disappeared delay than Hbmass. RE showed the opposite response to V̇o2max, suggesting an inverse relationship between the longitudinal changes in V̇o2max and RE. In contrast, MAOD remained unchanged, suggesting that exposure to hypoxia does not increase anaerobic energy capacity in middle-distance runners. We suggest that hypoxic effect on running performance were maintained for 3 weeks after hypoxic training because the performance of our runner was better at 10 weeks than at 8 weeks. Practical Applications: Hypoxic exposure should begin at 8 weeks and cease 1 week or later before the target competition. This acclimatization period leads to improvements in running performance.

The Role of Lower-Body Kinematics and Kinetics in Pitching Performance of Youth Baseball Players

Katsutoshi Nishino,1Hidetomo Suzuki,2Noriaki Yamamoto,3Masaei Tanaka,1Tomoharu Mochizuki,4Naoto Endo,4and Masaaki Arakawa

1Niigata Institute for Health and Sports Medicine, Niigata, Japan;2Niigata University of Management, Niigata, Japan;3Niigata Rehabilitation Hospital, Niigata, Japan; and4Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan

Introduction: Baseball pitching has a whole-body complex mechanics that the ball velocity is generated by the kinetic energy transformation from the stride movement of lower body to the throwing movement of upper extremities. The proper pitching mechanics can expect the effects of not only throwing injury prevention but also high pitching performance. Many studies of the pitching mechanics have focused on the kinematics and kinetics of shoulder and elbow joints, and however those of lower body have been little studied. The purpose of this study is to analyze the role of lower-body kinematics and kinetics in pitching performance of youth baseball players. Methods: The subject was 102 male high-school baseball pitchers (16.6 ± 0.6-year-old, 174.3 ± 5.4 cm, 68.7 ± 6.9 kg). Subject's fast-ball pitch was measured by the motion capture system, the 2 force plates and the speed gun. The pitching performance assessed the maximum swing velocity of wrist center of throwing side as throwing-arm velocity. The lower-body kinematics and kinetics evaluated as 4 parameters: pelvic rotational velocity, pelvic delivery velocity, stride length and ground reaction force (GRF) of the pivot and step legs. The leg anaerobic ability assessed as leg extension power on seat sitting by an isotonic apparatus (ANAEROPRESS3500, Combi Co., JPN). The relationships between pitching performance and lower-body parameters was analyzed using the multiple regression analysis (b = standard partial regression coefficient). Results: The ball and throwing-arm velocities were 114.2 ± 8.0 km·h−1 and 62.7 ± 4.7 km·h−1, respectively. Higher ball velocity was significantly correlated with higher throwing-arm velocity (R = 0.833, p < 0.000). Higher throwing-arm velocity was determined by larger GRF (b = 0.310, p = 0.002), higher pelvic rotational velocity (b = 0.307, p = 0.001) and longer stride length (b = 0.211, p = 0.040). Although larger GRF was significantly correlated with higher throwing-arm velocity (R = 0.489, p < 0.000) and higher leg extension power (R = 0.427, p < 0.000), about 20 subjects deviated from these correlations. Discussion: From the results of the multiple regression analysis, it was cleared that larger kinematics and kinetics of the pelvis and leg during the stride phase had an important role to generate higher throwing-arm velocity. Because higher leg extension power was related to obtain larger GRF during pitching, some anaerobic and strength trainings of lower-body are necessary to achieve high pitching performance. On the other hand, about 20 youth pitchers who deviated from the above tendencies were a potential to have the low-skilled pitching mechanics, and thus they must firstly learn the proper pitching mechanics than the anaerobic and strength trainings. Practical Applications: In order to achieve high pitching performance, following approaches seem to be effective for the youth pitchers: (a) improvement of mobility of the pelvis and hip joint to enhance the pelvic rotational velocity, (b) improvement of flexibility of the hip and knee joints to increase the stride length, (c) lower-body strength training to stably support the upper body and (d) plyometric training to obtain the anaerobic ability such as single-leg jump and bounding jump. The measurement of leg extension power is also effective for evaluating the pitching performance.

Assessments of Junior Rugby Players' Toe Muscle Strength and the Foot Shape

Hiroto Kato,1Toru Handa,2and Tsutomu Komino3

1Teikyo Heisei University, Tokyo, Japan;2Futaba Nutrition College, Tokyo, Japan; and3Komino Osteopathic Clinic, Tokyo, Japan

Purpose: In recent years, the importance of foot transformation or toe muscle strength has been reported in the studies using elderly and female subjects. However, no study is targeted for athletes. Even though measuring instrument for toe muscle strength had been developed and sold in the market, only the strength of big toe is measurable and instrument that is capable of measuring other toes is still underway. Therefore, in this study, we developed a device capable of measuring all toes then assessed junior rugby players' toe muscle strength as well as the foot shape. Methods: Twenty-two high school rugby players (age 16.6 ± 0.66 years, height 172 ± 5.28 cm, weight 76.6 ± 15.61 kg) participated in the study. They had been playing rugby for 2.6 ± 2.4 years. Foot-doc-print (Fukui Corp) was used to acquire the duplicate print of subject's feet, then length, width, hallux valgus angle and digitus minimus varus angle were measured. Toe muscle strength was measured with custom-made toe muscle strength system (Takei Scientific Instruments Co., Ltd.) and maximum isometric strength at anatomical position was measured. Results: Foot length and width for right foot were 24.6 ± 1.33 cm and 9.8 ± 0.68 cm, respectively and for left foot were 24.8 ± 1.35 cm and 9.9 ± 0.69 cm respectively. Hallux valgus angle and digitus minimus varus angle were 8.8 ± 4.2° and 16.4 ± 4.57° respectively for right foot and 9.7 ± 3.82° and 15.8 ± 4.34° respectively for left foot. Right toe muscle strength for first (big toe), second, third, fourth and fifth toe was 12.5 ± 4.55 kg, 4.8 ± 2.33 kg, 5.4 ± 2.24 kg, 5.1 ± 1.95 kg and 8.0 ± 3.17 kg respectively. For left foot, it was 11.7 ± 5.07 kg, 5.3 ± 2.07 kg, 5.6 ± 1.94 kg, 5.6 ± 2.42 kg and 6.5 ± 2.97 kg respectively. There were significant relationships between first toe and fifth toe muscle strength for both feet and body weight. Discussion: Hallux valgus angle for both feet were in the normal range, but digitus minimus varus angles for right and left foot were 16.4 ± 4.57° and 15.8 ± 4.34° respectively and this denotes light varus for digitus minimus. The shoes that are too narrow may cause this and thus it is suggested to switch to wider shoes. The correlations between body weight and first and fifth toe strength may denote the important role of those toes for supporting body weight. Body weight of human is distributed to first metatarsal head, fifth metatarsal head and calcaneus in 2:1:3 ratio respectively. Thus it is a logical outcome that there were relationships between first and fifth toe muscle strength and bodyweight. However, it may be important to strengthen such muscles during growth period to utilize bigger muscle groups as in quadriceps and hamstrings more efficiently. Practical Application: Tendency for light varus for digitus minimus suggest the necessity for wider shoes for rugby players in a growth period. Also, strengthening toe muscles as they grow may help them to develop an ability to “grab and hold the ground” and lead to effective utilization of lower body muscle groups.

Differences in Localized Muscle Reoxygenation Kinetics Between Endurance Athletes and Non-Athletes

Kaori Mitsuoka1and Sayaka Tomokane2

1Sigakkan University, Ohbu, Japan; and2Osaka University of Health and Sports Sciences, Sennan, Japan

Introduction: There have been many reports on muscle oxygenation kinetics during exercise measured using near-infrared spectroscopy (NIRS). Several studies evaluating aerobic capacity of skeletal muscle have also been conducted, based on the recovery kinetics of muscle oxygenation levels after exercise. It has been reported that reoxygenation time (Tr) after submaximal exercise in triathletes is shorter than that of sedentary subjects. The purpose of this study was to examine the difference in localized muscle reoxygenation kinetics between endurance athletes and non-athletes in the context of cardiopulmonary exercise testing (CPX). Methods: Seven healthy female middle- and long-distance runners (AT group: 20 ± 1.5 years, 160.3 ± 3.55 cm, 50.7 ± 4.35 kg) and 7 healthy female non-athletes (nAT group: 22 ± 0.5 years, 160.1 ± 4.44 cm, 52.1 ± 5.44 kg) participated in this study. Ramp protocols are used with a cycle ergometer until exhaustion, peak V̇o2 was measured using breath-by-breath gas analysis. Simultaneously, changes in muscle oxygenation were measured using NIRS, and muscle oxygen saturation (SmO2) was recorded at the right vastus lateralis. Tr after exercise was calculated as the time of reaching the half value from the lowest value and the highest value of the SmO2. Each value in both groups was compared by t-test. Results: The peak V̇o2 for the AT group was 42.3 ± 3.69 ml·kg−1·min−1, while that for the nAT group was 35.7 ± 2.67 ml·kg−1·min−1; a significant difference (p < 0.01) was found between both groups. The Tr for the AT group was 17.7 ± 4.80 seconds, while that for the nAT group was 23.7 ± 4.30 seconds; the Tr for the AT group was significantly shorter (p ≤ 0.05) than that for the nAT group. Discussion: Although the peak V̇o2 of the AT group was a little low for endurance athletes, it is thought that peak V̇o2 is about 20% lower when using the bicycle ergometer compared with the treadmill in long-distance runners. After exercise, oxygen consumption reduces rapidly and oxygen supply increases; SmO2 mainly reflects oxygen supply. Mitsuoka et al. (2013) reported that in a comparison of Tr on maximal short-term isometric knee extension exercise in an endurance trained (ET) group and non-trained (nET) group, the ET group data appears to show that Tr tends to be shorter in this group than in the nET group. In this study, we used incremental load on CPX, and because the vastus lateralis works as an agonist in the cycle ergometer exercise, it is suggested that high oxygen supply at the vastus lateralis is one of the factors of high peak V̇o2. Practical Applications: Another study indicated that based on a comparison between before and after 4 weeks of localized muscle training, local blood flow was higher after the training than before the training. It is thought that an increase in the blood flow by training promotes reoxygenation after exercise, and NIRS might be useful for evaluating muscle function of athletes during and after exercise.

Constructing Organizational Structure for a Holistic High Performance Support


Teikyo University Institute of Sports Science and Medicine, Tokyo, Japan

Introduction: Since the level of demand in high performance sports in the world has continued to grow, many non-traditional professionals enter the sport industry and it becomes much more complexed than ever before. So as a supporting system for high performance athletes, in the field of sports science and medicine has undergone drastic changes in a past decade. Many high performance institutes or organizations hire a variety of professionals to conjoin together for providing a holistic support for athletes. However, since a process to construct organizational goals, strategies, and organizational structure in order to provide a holistic support has not much discussed or researched, therefore; many professionals on site are facing many challenges. During this presentation, the author reports the process and results from 2 theories he applied (Competitive Advantage theory and Contingency Effectiveness Approach theory) in order to provide 3 divisional (medical, physical, science) holistic approach called, “Total Support,” at Teikyo University Institute of Sports Science and Medicine (TUISSM). Methods: TUISSM was established in 2011 and its philosophy is TUISSM to provide high level athletes all supports necessary in the field of sports medicine and science. TUISSM has 3 divisions (medical, physical, science) to cooperate together for sports medicine support, research, and development of medical professionals. Since its establishment, TUISSM has continued hiring nation top staff, except management staff. In 2013, the first management staff was hired and he brought fundamental changes into organization. He applied organizational theories and designs in order to reconstruct organizational goals, strategies, organizational structure. Results: In 2014, TUISSM restated its philosophy, mission, and vision. Also, in order to meet high demands from top performance athletes, TUISSM publically stated “Declaration of Top Athlete Support.” In the same time, TUISSM reconstruct organizational chart so that each leader was given specific duties and authorities in order to fasten decision making process, cross-divisional communication, and projects better. Discussion: Even though TUISSM operation has become dramatically effective and efficient, there are areas much needed to improve. One of areas is its evaluation process; TUISSM currently focuses on Internal Process Approach that ignore input and output of organization. Considering a field of sports are surrounded by diverse stakeholders, eventually TUISSM need evaluate its performance and effectiveness by Stakeholder Approach. Practical Applications: As a holistic support to high performance athletes becomes more complexed, and needed, the demands for organizational structure continue to grow. Cross-professional holistic approaches would explore new level of high performance support, yet much discussion needed in order to organize and operate its services. One thing for sure that it cannot be done as a side job. Every professional has his/her own background, believes, approaches for one single athletes. In order to organize and optimize the level of support with numerous professionals, the organization must have a full-time management staff who could theoretically construct its goals and strategies.

Efforts of Health Fitness Programmers in Short-Term Day-Care Rehabilitation and Their Effects

Michio Ito,1Mitsushiro Nagao,2and Takatugu Okamoto3

1HOUWA-Kai Health Development Center Will, Hiroshima, Japan;2Hyogo University College of Nursing Art and Science, Hyogo, Japan; and3HOUWA-Kai Nishi Hiroshima Rehabilitation Hospital, Hiroshima, Japan

Introduction: In 2009, the Nishi Hiroshima Rehabilitation Hospital (henceforth referred to as “our hospital”) first began offering short-term day-care rehabilitation in addition to conventional outpatient rehabilitation. The features of this program (henceforth referred to as “the program”) are as follows: (a) it is conducted in a fitness gym space in order to elicit the desire to exercise, (b) it has a high retention rate for self-directed training as health fitness programmers give one-on-one instructions on self-directed training, and (c) it promotes the use of the gym by patients' families (a system wherein primary caregivers are encouraged to use the fitness gym). This study was a comparative investigation of the effect of this program on the physical function and psychological state of in-home patients (henceforth referred to as “patients”) and their families, and on the feeling of caregiving burden experienced by the families. Methods: The subjects were 28 patients undergoing short-term day-care rehabilitation at our hospital and 18 primary caregivers. Physical function was evaluated using physical fitness measures. The psychological evaluation involved measuring serotonin levels, using a biochemical test. Furthermore, questionnaires were used to survey exercise habits, psychological changes, etc. Results: Overall, the physical function of the patients tended to show a trend of improvement, and walking speed in particular improved significantly. Furthermore, after the patients completed a 3-month program, there was a significant increase in their serotonin levels, a psychological evaluation indicator. According to the results of the questionnaire surveys, 75% of the patients and 87% of the primary caregivers reported a psychological change after starting the program. Discussion: The program served as a continuous individual rehabilitation intervention for patients, resulted in retention for self-directed training, and improved patients' physical functionality due to their participation in group calisthenics and also increased their independence. When primary caregivers exercised together with patients, it led to a better understanding of the patients' condition. Furthermore, there was increased awareness about health, rehabilitation, and exercise. Additionally, the program resulted in the formation of a community wherein patients and families could relieve stress through exercise and wherein families could discuss the worries and hardships they faced as a result of caregiving. This also had a positive effect on psychological variables, for example, it helped relieve the feeling of caregiving burden experienced by caregivers. Practical Applications: Family involvement was considered to be a significant factor in improving the physical function and psychological state of in-home patients. As a result, the approach adopted toward families is important, and it is necessary to build systems in which families are participants in rehabilitation.

Hamstrings Training Effect on Hip and Knee Joint Function and Muscle Morphology

Takashi Ono,1Michio Tojima,2and Norikazu Hirose2

1Kitasato University, Kanagawa, Japan; and2Waseda University, Saitama, Japan

Introduction: Hamstring muscles form a multi-articular muscle group that crosses the hip and knee joints, which include the biceps femoris short head (BFsh), biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM). These muscles work synergistically to produce hip extension and/or knee flexion torque and have an important role in football for sprinting or kicking. It has been said that the imbalance in the hamstrings:quadriceps strength ratio (H:Q ratio) due to weaker hamstring muscles results in an increased susceptibility to hamstring, especially BFlh, strain injuries. We have clarified that BFlh is more activated during hip extension exercise than knee flexion exercise, however, there is little information about the effect of hip extension training on H:Q ratio in hip and knee joint, and on the morphology of each hamstring muscle. The purpose of this study was to clarify the effect of hip extension training on H:Q ratio in hip and knee joint, and on the morphological adaptations of each hamstring muscle. Methods: Ten healthy collegiate sprinters (20 limbs) were recruited. Subjects joined the Single-leg Deadlift training program in twice a week for 3 months. Before (Pre) and 1 and 3 months after training period, isokinetic strength testing was conducted to measure flexion and extension torques in hip and knee joint, and MRI to determine the cross sectional area (CSA) of each hamstring muscle. Results: After the training of 3 months, significant increase of hip extension torque (+13.4 ± 0.06%) and H:Q ratios in the hip joint (1.41 ± 0.06 → 1.56 ± 0.07) were found, and significant increase of CSAs were found in BFlh (+13.1 ± 0.04%) and SM (+35.8 ± 0.04%) muscle (P ≤ 0.05). Discussion: Hip extension (Single-leg Deadlift) training appears to be effective for promoting hypertrophy in the common injured BFlh and SM muscles, and develop H:Q ratio in hip joint. These data may provide compelling evidence to warrant the further exploration of hip extension oriented exercises in hamstring strain injury prevention protocols. Practical Applications: Hip extension (Single-leg Deadlift) exercise training may be useful for preventing and rehabilitating from hamstring strain injury by stimulating hypertrophy in biceps femoris long head and semimembranosus muscle and promoting improvements in hip extensor strength and H:Q ratio in hip joint.

The Effect of Plyometric Training on Jumping Performance and Lower Body Eccentric Muscle Strength of Adolescent Female Volleyball Players

Yasunobu Suzuki,1Tomoki Tashiro,2Takahiro Adachi,3Tetsushi Moriguchi,4and Syogo Hayakawa5

1Physical Support, Fukuoka, Japan;2Kyushu Kyoritsu University, Fukuoka, Japan;3Kyushu Sangyo University, Fukuoka, Japan;4Fukuoka University, Fukuoka, Japan; and5Kogahigashi Junior High School, Fukuoka, Japan

Purpose: Plyometric training (PT) is widely acknowledged to improve athlete's jumping performance. PT uses stretch-shortening cycle (SSC) of muscle. Previous studies related to PT focus on concentric muscle actions and not many studies focus on eccentric muscle action. Furthermore, adults and adolescent males are targeted in majority of studies and not many studies use adolescent females as subjects. Thus this study is purposed to examine the effect of PT on jumping performance of adolescent female volleyball players as well as lower body eccentric muscle strength. Methods: Twenty-eight female junior-high volleyball players were recruited as subject. Subjects were divided into 2 groups. Fourteen players (age 14.5 ± 0.50 years, height 157.6 ± 5.26 cm and weight 49.3 ± 4.35 kg) performed plyometric training twice a week for 12 weeks (JUMP) and another 14 players (age 14.3 ± 0.45 years, height 157.3 ± 5.26 cm and weight 49.8 ± 4.35 kg) were in control group (CONT). Jump height was calculated by flight time of squat jump (SJ), counter-movement jump (CMJ) and spike jump (SP) using force plate before and after the intervention. Eccentric muscle strength of knee and hip extensors was measured using isokinetic dynamometer (Kincom 500H). Eccentric strength was measured at 60, 120 and 180 deg·s−1 and peak value was divided by body weight (Nm·kg−1). T-test was used to compare before and after values and p value was set at less than 5%. Results: Jump height of SJ, CMJ and SP from before and after the training was compared. In JUMP, all the jump height values significantly improved after training (p < 0.01), but CONT group showed no significant improvement in 3 jumps after 12 weeks. Then, eccentric extensor strength for knee and hip before and after the training was compared. In JUMP group, eccentric knee extensor strength at every speed had significantly improved (p < 0.01) but not in CONT group. Eccentric hip extensor strength was significantly improved at 120 and 180 deg·s−1 in JUMP but not in CONT at every speed. Discussion: PT has been popularized as a training means to improve jump performance and muscle power. As SJ, CMJ and SP performance improved in our study, PT is expected to be effective for adolescent female athletes. Furthermore, eccentric extensor strength of knee and hip can also be improved through PT. PT is a training method that utilizes SSC of muscle and improvement of eccentric lower body strength is expected to enhance concentric strength, thus jump performance is expected to be improved. Practical Application: For athlete, incorporating PT in adolescent is not only effective to improve jump performance but also effective for enhancing lower body eccentric strength, neuromuscular function, and acquisition of safe landing technique for injury prevention.

Maximal Oxygen Uptake, Ventilatory Threshold, and Running Economy During a Treadmill Running Test Predict Marathon Time in Recreational Runners

Fuminori Takayama, Atsushi Aoyagi,Wataru Shimazu, Toshiki Tsuji, and Yoshiharu Nabekura

University of Tsukuba, Ibaraki, Japan

Introduction: The number of recreational runners in Japan has increased over the last decade. From a physiological perspective, maximal oxygen uptake (V̇o2max), ventilatory threshold (VT), and running economy (RE) are considered the main determinants for performance in a marathon. The purpose of this study was to develop a predictive model for marathon time using a treadmill running test with recreational marathon runners. Methods: Fourteen recreational marathon runners (9 male and 5 female; 25 ± 5 years; range of recent marathon time: 151–295 minutes) performed a treadmill running test. The subjects completed a 2-part test that consisted of a 5-minutes RE test and a maximal incremental test. The velocity of the RE test was set below marathon race pace for each subject. RE is expressed as the oxygen cost (ml·kg−1·km−1). The maximal incremental test was performed to determine V̇o2max and VT. The initial velocity of the maximal incremental test was set at 140 m·min−1 and it was increased by 10 m·min−1 every 1 minute until volitional exhaustion. VT was defined as the point when respiratory exchange ratio is 1.0 or greater, and is expressed as a percentage of V̇o2max (%V̇o2max). The relationships between aerobic fitness variables and recent marathon time were determined using Pearson's product-moment correlation coefficient tests. Simultaneous multiple regression analysis was used to predict marathon time from a model that included V̇o2max, VT, and RE. Results:o2max was significantly correlated with marathon time (r = –0.827, p < 0.001), but VT (r = –0.211, p = 0.469) and RE (r = 0.446, p = 0.110) were not. Multiple regression analysis showed that 86% of marathon time was predicted by V̇o2max, VT, and RE (p < 0.001). In addition, all variables were strong predictors of marathon time (V̇o2max, p < 0.001; VT, p = 0.021; RE, p = 0.011). The following equation was used: marathon time (min) = 477.517 − 3.407 (V̇o2max, ml·kg−1·min−1) − 3.991 (VT, %V̇o2max) + 1.290 (RE, ml·kg−1·km−1). Discussion: It is well known that peak velocity and velocity at VT during a treadmill running test are good predictors of marathon time, but these variables cannot help runners interpret the trainability of their aerobic fitness. In this study, we conducted multiple regression analysis using only aerobic fitness variables (i.e., V̇o2max, VT, and RE) measured during a treadmill running test. As a result, it was found that marathon time can be predicted from this model. Practical Applications: Many recreational runners train hard to maximize their performance. The present findings indicate that all aerobic fitness variables are important for recreational runner performance in a marathon (race time: 2.5–5 hours). At present, many laboratories and sports facilities have expired gas analyzers and access to treadmill running tests has increased compared to the past. We thus recommend that runners perform the treadmill running test in order to evaluate the effects of their training and the trainability of their aerobic fitness. This model would also be useful for determining running pace before a marathon race.

The Effect of Conventional Cooling Vest Covered Neck Region on Cycling Time Trial Performance and Thermal Perception in the Heat

Keisuke Takeshima,1Atsushi Shiraishi,2Takatsugu Shimana,2and Hiroshi Hasegawa1

1Hiroshima University, Hiroshima, Japan; and2Mizuno Corporation, Osaka, Japan

Purpose: Body cooling before exercise has been attracting attention because it lowers skin temperature at the onset of exercise and thus improves thermal perception that leads to endurance performance improvement in the heat. Especially, cooling at neck region has shown better improvement of thermal sensory than other body parts. This study compared the new cooling vest that is capable of cooling neck region and conventional cooling vest that cools trunk region only and investigated their effect on time trial performance and thermal perception in the heat. Methods: Eight college male students who regularly exercise performed 30 minutes cycling time trial under heat (32° C, 50% Rh). Subjects had performed all 3 time trials, a controlled condition (CON), a conventional Cryovest condition (CRYO) and a condition with new cooling vest (NEW), in randomized order. Cooling vest were worn 15 minutes after warming up. Power output, rectal temperature, skin temperature, heart rate, ratings of perceived exertion, whole body thermal sensation and comfort were measured. Results: Average power output were higher in CRYO (182 ± 17 W, d = 0.29) and NEW (183 ± 16 W, d = 0.36) compared to CON (176 ± 21 W). At the onset of exercise, mean skin temperature was significantly lower in CRYO (34.03 ± 0.84° C) and NEW (33.80 ± 1.06° C) than CON (35.22 ± 0.57) (p ≤ 0.05). Skin temperature at neck region was significantly lower in NEW (32.54 ± 1.23° C) than CON (35.91 ± 0.29° C) and CRYO (35.44 ± 0.38° C) (p ≤ 0.05). Thermal sensation after cooling was lowest in NEW and was significantly lower than CRYO or CON. Thermal comfort was not significant but improved with cooling vest. There was no difference in rectal temperature and heart rate throughout any experimental conditions. Discussion: Cooling vest improved performance without increasing physiological strain. This improvement happened without the rectal temperature change thus indicates the importance of lowering skin temperature and improvement of thermal perception before exercise. Cooling vest that is capable of cooling neck region improves thermal perception much better than trunk only cooling vest. As a result of cooling of the carotid artery that lowers brain temperature, afferent signal has been sent to the sensorium and stimulated cooling sensation. However, there was no additional performance enhancement after such improvement. Practical Application: The thermal perception improvement that has been observed in this study is thought to be important to participate in competition in better psychological state. Also, this lets athletes train more comfortable and gain better training effect, thus improves their performance. For future study, it is suggested to examine these results in various sporting events using elite level athletes.

Single Session of Resistance Exercise Reduces Endurance-Adaptive Factors in Mouse Skeletal Muscle

Junya Takegaki,1Riki Ogasawara,2Ryo Takagi,1Takaya Kotani,1Arata Tsutaki,3Koichi Nakazato,3and Naokata Ishii1

1The University of Tokyo, Tokyo, Japan;2Nagoya Institute of Technology, Nagoya, Japan; and3Nippon Sport Science University, Tokyo, Japan

Introduction: Concurrent training, a combination of endurance and resistance exercises, is used widely for improving skeletal muscle strength and endurance. A number of studies have reported some inhibitory effects of endurance exercise on muscular hypertrophy. However, the influences of resistance exercise on endurance adaptation are unclear. In the present study, we investigated the changes in factors relating to the adaptation to endurance exercise after single session of resistance exercise. Methods: Male C57BL/6J mice (n = 24) were euthanized at 1, 3, 6, 12, 24, and 48 hours after single session of resistance exercise. The resistance exercise consisted of 50 repetitions of maximal isometric contraction of the gastrocnemius muscle. The right gastrocnemius muscle was subjected to exercise, and the left was used as internal control. The muscle contraction was induced by transcutaneous electrical stimulation. Muscle samples were kept frozen until analysis. Results: The phosphorylation of Akt (Ser473) reached a maximum 1 hour after the exercise, and immediately decreased within 6 hours after the exercise. The phosphorylation of rpS6 (Ser240/244) showed a peak 3 hours after the exercise, and decreased slowly for the period of 24 hours after the exercise. The protein expression of citrate synthase decreased slowly, and showed a significant change from the initial level 12 hours after the exercise. The expression of PGC-1α also decreased slowly with a significant change 6 hours after the exercise. Discussion: The phosphorylation of Akt and rpS6 indicates the activation of skeletal muscle protein synthesis. On the other hand, PGC-1α and citrate synthase decreased during the period of 6–12 hours after the resistance exercise. PGC-1α is a transcription factor for mitochondrial biogenesis, and citrate synthase is a rate-limiting enzyme for oxidative energy supply. Therefore, the present results suggest that after the resistance exercise, while protein synthesis is activated, the adaptability to endurance exercise is reduced. Practical Applications: This study suggests that keeping more than half a day after the resistance exercise is suitable for taking endurance exercise.

Correlation of Hip Functions With Ball Velocity in Japanese Collegiate Baseball Pitchers

Osamu Yanagisawa,1Kenta Wakamatsu,2Genki Futatsubashi,1and Hidenori Taniguchi1

1Jobu University, Isesaki, Japan; and2J.F. Oberlin University, Machida, Japan

Introduction: Baseball pitching is a total kinetic chain activity that requires efficient coordination of the legs, trunk, and arms for effective ball release. Hip functions can affect smooth energy transfer from the legs to the trunk during pitching; however, the relationships between hip functions and pitching performance have not been sufficiently investigated. Therefore, this study aimed at determining the effects of hip functions on ball velocity in collegiate baseball pitchers. Methods: Twenty-three overhanded Japanese collegiate baseball pitchers (mean age, 19.3 years) participated in this study. Passive hip range of motion (ROM) and isometric hip muscle strength were bilaterally measured in flexion, extension, abduction, adduction, external rotation, and internal rotation. Maximal ball velocity at the official pitching distance (18.44 m) was evaluated with a radar gun. Correlations between hip functions (joint ROM and muscle strength) and maximal ball velocity were evaluated for both legs. The statistical significance was set at P ≤ 0.05. Results: Maximal ball velocity (135.3 ± 4.1 km·h−1) had a significant correlation with the ROM of hip extension on the stride leg (r = −0.578, P < 0.01). Additionally, maximal ball velocity was significantly correlated with the strength of hip extension (r = 0.585, P < 0.01), flexion (r = 0.567, P < 0.01), abduction (r = 0.551, P < 0.01), and adduction (r = 0.551, P < 0.01) on the pivot leg, and the strength of hip flexion (r = 0.526, P < 0.01), abduction (r = 0.667, P < 0.01), and adduction (r = 0.458, P ≤ 0.05) on the stride leg. Discussion: The findings of this study suggest that the hip muscle strength acting on both legs is one of the important factors that contribute to ball velocity in baseball pitchers. Hip muscles are related to the stability and motion of the pelvis during pitching. Therefore, excellent hip muscle strength may contribute not only to smooth energy transfer from the pivot leg to the stride leg and then to the trunk, but may also be useful for forming a firm foundation that supports strenuous movement of the upper body during pitching. Practical Applications: Training to enhance the strength and power of hip muscles, particularly hip extension/flexion and abduction/adduction, may be effective for increasing the velocities of the balls thrown by baseball pitchers. Moreover, high-intensity intermittent training of the hip muscles may help to maintain pitchers' ball velocities at high levels during the games.

Cross-Sectional and Longitudinal Analyses on Development of Sprinting in Japanese Youth Soccer Players

Yoshihiro Hoshikawa1and Kentaro Chuman2

1Tokaigakuen University, Miyoshi, Japan; and2JUBILO CO.,LTD., Iwata, Japan

Introduction: How to train a player's sprint ability during adolescence is one of the key issues for coaches so as to make a successful soccer player. The average distance of sprinting in a soccer game is less than 20 m, so soccer players are required to strengthen this ability for very short distance. To achieve this, developmental changes in the ability should be monitored throughout the growth period; however, no systematic data covering the whole growth period which allows coaches to evaluate a player's development is available. The purpose of the study is twofold: the one is to measure 20 m sprint time of many high-level youth soccer players, and the other is to make an age-related evaluation chart based on the data. We also checked applicability of the chart using longitudinal data which followed selected players for 2 years. Methods: The participants were 870 high-level Japanese soccer players from 18 teams whose ages ranged from 10 to 18 years. In addition, 9 players at age of 12–13 (L1) and 24 players at age of 15–16 (L2) were followed longitudinally for 2 years to confirm developmental changes in ability. As a reference 120 senior professionals from 4 clubs were also measured. All the participants were out-field players. Sprinting times for 20 m were measured using infrared photocell sensors. The participants undertook the measurements on grassed fields wearing soccer boots. Using the averages and standard deviations an evaluation chart classifying the 20-m sprint time into 5 levels (fast, fairly fast, average, rather slow, and slow) was developed for each age group. In association with the chart the longitudinal changes for L1 and L2 were analyzed. Results: The average time for 20 m reduced from 3.79 seconds at the age of 10 to 3.02 seconds at age 17. The criteria value classified as “slow” reduced linearly with age from more than 3.89 seconds at the age of 10 to more than 3.15 seconds at age 17, whereas those as “fast” decreased linearly with age only under the age of 14. Over the age of 14 the value as “fast” appeared to reach a plateau, where the values were less than 2.93 and 2.89 at ages 14 and 18, respectively. The values classified as “slow” and “fast” for professionals are more than 3.11 seconds and less than 2.86 seconds, respectively. Although all the L1 players reduced 20 m time over the 2 years, 4 of 9 players changed their classification only by 1 level and the rest did not change classification. For L2 no significant changes occurred in 20 m time over the 2 years, and only 3 of 24 players classified as “average” at the first measurement improved their classification by 1 level. Discussion: The pattern of age-related reduction in 20 m time differed between criteria classified as “slow” and “fast.” The ability of youth players with higher sprinting for short distance may level off the ability earlier during adolescence compared with their lower counterpart. It is also suggested youth players with lower sprinting may drop out from the selection as they get older. Practical Applications: The evaluation chart presented in the study is useful to identify short-distance sprint ability of youth soccer players. However, sprint ability for very short distance is not easy to change at late adolescence for players who have already achieved higher ability.

Functional Fitness and Activity Levels of Community Dwelling Older Adults

B. Sue Graves,1Anthony Krahwinkel,1Chad Dolan,2Jacob Goldsmith,1and Michael Zourdos1

1Exercise Science and Health Promotion, Florida Atlantic University, Boca Raton, FL, United States; and2Health and Human Performance Department, University of Houston, Houston, TX, United States

Introduction: The strength and conditioning professional can provide applied ways to evaluate and implement training techniques when working with the older adult. Current evidence exists which indicates regular exercise tends to minimize the adverse effects of sedentary lifestyles. Purpose: This study evaluated the individual fitness levels of community-dwelling older adults using the Senior Fitness Test, which would indicate if they were meeting established guidelines for their age. By wearing a Fitlinxx Pebble, an all-day activity tracker, the step count was used to assess daily and weekly movement levels. Methods: Twenty-six independent living older adults, who considered themselves moderately active or higher, participated. Ten males (M) (79.4 ± 3.3 years, 173.5 ± 7.6 cm, 81.8 ± 3.8 kg) and 16 females (F) (80.8 ± 4.3 years, 164.3 ± 7.6 cm, 72.6 ± 5.8 kg) completed the study. All were evaluated using the Senior Fitness Test for functional strength, aerobic endurance, balance, agility, and flexibility measures. Each participant wore the Pebble on their shoe from the time they woke up until bedtime, which was during their normal daily activities accessing step counts and activity. Results: No significant differences were found between the BMIs, males (27.18 ± 3.1) and females (26.8 ± 4.0), p = 58 nor for the Senior Fitness Test, Chair Stand (seconds), M, 12.7 ± 3.87, F, 12.0 ± 2.44, p = 0.48; Arm Curls (n), M, 17.3 ± 3.55, F, 15.37 ± 3.17, p = 0.58; and 8-foot Up and Go (seconds), M, 6.41 ± 0.91, F, 7.72 ± 1.20, p = 0.78. However, significant differences were found for the 6 Minute Walk (seconds), M, 517.2 ± 67.27, F, 438.8 ± 54.9, p = 0.04; Back Scratch (in), M, −6.15 ± 2.55, F, −3.06 ± 1.48, p = 0.03; Sit and Reach (in), M, −3.15 ± 4.21, F, 1.53 ± 2.81, p = 0.043. Results for total steps were significant, also, F, 28,148 ± 1,257 and M, 23,210 ± 2,486, p = 0.37. Daily steps for the M were 3,762.9 ± 1,980 and F, 4,691.5 ± 2753, p = 0.24. Conclusions: The results of this research indicate that many of these community-dwelling older adults do score over the 50th percentile in several of the Senior Fitness Test assessments (chair stand, arm curls), but not in the 6-minute walk nor back scratch. Older adults may need to increase their step count per d·wk−1, plus may need continue to concentrate on their strength. In addition, a general recommendation of 10,000 steps per day may not be appropriate for this older population. Thus, we encourage older adults to exercise for health reasons and future research to continue to evaluate normative daily step values for this population.

Association Between Experience of Strength-Training Under Proper Supervision and the Knowledge of Single-Joint Exercise

Kazushige Oshita,1Takuya Matsuzaki,2Akihisa Hikita,1Ryo Miyazaki,3Goichi Hagiwara,4Tomoki Tashiro,1Tempei Tsuno,5Yukito Higuchi,1and Kyotaro Funatsu1

1Department of Sports Science, Kyushu Kyoritsu University, Kitakyushu, Japan;2Integrated Arts & Science, Kitakyushu National College of Technology, Kitakyushu, Japan;3Department of Sport and Health Sciences, University of East Asia, Shimonoseki, Japan;4Department of Sports Humanities and Applied Social Science, National Institute of Fitness and Sports, Kanoya, Japan; and5Graduate School of Physical Education, National Institute of Fitness and Sports, Kanoya, Japan

Introduction: Our previous study reported that persons with no experience in weight training under supervision made significantly fewer attempts to consciously train their gluteal and knee flexor muscles during back squats, compared to those with experience (Oshita et al., Int J Sport Health Sci, 2016). Therefore, to enhance the benefits of training, people should be shown the correct method of performing these exercises and be given the appropriate supervision. However, a back squat is a multi-joint exercise, recruiting several muscle groups and requiring a variety of movements. As a result, people have difficulty understanding precisely which muscle group(s) are trained with a multi-joint exercise. Therefore, the aim of the present study was to investigate the participant's understanding of training body part(s) with a single-joint exercise. A questionnaire-based survey was used to study the relationship between the participant's experience of strength training under appropriate supervision and knowledge of the leg extension exercise (Leg-EXT). Methods: A survey was conducted among young men and women (20 ± 1 year old, n = 850). Participants were shown a picture of the Leg-EXT, and were asked which body part(s) they felt was being trained in the picture. Participants were divided into those who had no experience of performing the Leg-EXT exercise (NO-EXERC group, n = 235) and those with experience performing the exercise. The participants who were experienced with the Leg-EXT were further divided into those that had strength training under appropriate supervision (INSTRUCT group, n = 294) and those that did not (NO-INST group, n = 321). Results: On seeing the picture, more than 70% of the participants in the NO-EXERC and NO-INST groups felt that the Leg-EXT was used to train not only their lower limb but also other body part(s). Only 8.5% of the NO-EXERC group felt that the Leg-EXT was used to train only their lower limb muscles. Further, 65% of the NO- EXERC and 82% of the NO-INST groups thought that the Leg-EXT was used to train their knee flexor muscles. Discussion: These results suggest that to perform exercises by referring to only a picture may result in the participants not properly understanding how the body part(s) should be trained during that exercise. Participants seemed to have an especially difficult time understanding the role of the flexor and extensor muscles. However, understanding of agonist and antagonist (i.e., flexor and extensor) muscles is important for designing exercise programs, particularly for those using a superset method, and improving the exercise movement to prevent muscle co-contraction. Practical Applications: These study results suggest that to enhance the benefits of training, individuals need to be instructed, under appropriate supervision, on correct technique as well as knowledge about the exercise, even single-joint exercises. Further, the results of the NO-EXERC group suggest that appropriate supervision is of even greater importance for strength training beginners who do not have experience of performing the exercise.

Effects of Stretching Positions on the Elongation of the Flexor Digitorum Longus

Junya Saeki,1,2Masatoshi Nakamura,3Masahide Yagi,1Toru Tamezawa,1and Noriaki Ichihashi1

1Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan;2Research Fellow of the Japan Society for the Promotion of Science, Tokyo, Japan; and3Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan

Purpose: Medial tibial stress syndrome (MTSS) is one of the most frequent running injuries. Previous studies have reported that elongational stress of the flexor digitorum longus (FDL) caused increased stress to the periosteum of the medial tibia. In addition, the FDL attaches to the posteromedial border of the tibia, which is the most common site of MTSS. Therefore, the promotion of FDL flexibility may be effective in preventing and treating MTSS. Regarding stretching of the FDL, the latter has a moment arm not only for toe flexion, but also for planter flexion and inversion. Therefore, it is assumed that this muscle could be stretched by dorsiflexion and eversion of the ankle. However, the mobility of the talus in the dorsiflexed position is small. Therefore, it is unclear whether the addition of eversion is effective for FDL stretching. The purpose of this study was to compare the elastic modulus, which is the index of muscle elongation, in the rest position and in 4 different stretching positions using shear wave elastography, and to determine the best position for FDL stretching. Methods: Ten healthy male adults (age: 24.3 ± 2.7 years, height: 173.4 ± 6.2 cm, and weight: 67.2 ± 7.2 kg) participated in the study. Ultrasonic shear wave elastography (Supersonic Imagine) was used to measure the shear elastic modulus at rest (with the ankle joint and toe at midpoint) and in 4 different FDL stretching positions. The 4 stretching positions were as follows: maximum eversion, maximum dorsiflexion, eversion at maximum dorsiflexion, and dorsiflexion at maximum eversion. In each stretching position, the toe was kept in maximal extension. The ankle dorsiflexion and eversion angle in each stretching position were recorded by taking an image of the ankle during stretching in the frontal and sagittal planes. The images were then analyzed with the ImageJ software. For statistical analysis, a one-way analysis of variance was used with Bonferroni's post-hoc test. Results: The shear elastic modulus of the FDL during stretching differed significantly between positions, ranking in the following order from highest to lowest: dorsiflexion at maximum eversion, eversion at maximum dorsiflexion, maximum dorsiflexion, and maximum eversion followed by resting position. The dorsiflexion angle during stretching was significantly higher during eversion at maximum dorsiflexion than during dorsiflexion at maximum eversion. On the other hand, the eversion angle was significantly higher during dorsiflexion at maximum eversion than during eversion at maximum dorsiflexion. Discussion: The results confirmed that during stretching, the FDL is elongated by ankle dorsiflexion and eversion as well as toe extension. Furthermore, the FDL was more elongated by dorsiflexion at maximum eversion than by eversion at maximum dorsiflexion in terms of stretching position of the ankle joint. A previous study reported that the inversion moment arm of the FDL is larger than its plantarflexion moment arm in the dorsiflexed and everted position. Therefore, the FDL can logically be stretched by moving the ankle into a dorsiflexed position while maintaining maximum eversion, which has a larger moment arm. Practical Application: This study found that regular stretching was an effective maneuver that could help increase the FDL flexibility, and perhaps prevent MTSS.

A Study of the Scoring Model and Its Calculation Method to Evaluate and Standardize Collected Test and Measurement Data of High School Baseball Clubs

Bukatsu physical club, Tokyo, Japan

Purpose: Test and measurement (T&M) is a one of strength and conditioning coach's tasks. Measured value and standardized standard will be a help for evaluation. Therefore, the purpose of this study is to discuss the scoring model and its calculation method to evaluate and standardize by collecting T&M data of high school baseball clubs. Methods: T&M data from April 2005 to February 2016 of K high school baseball players was collected. T&M was done in November and March, before and end of off season. Data from quat score (n = 1,153), squat weight divided by body weight (n = 1,153), vertical jump (n = 1,489), 5-star test (n = 805), 50m sprint (N = 1,435), and shuttle run (n = 1,022) were collected. From the mean (AV) and standard deviation (SD) were used to classify the collected data into 5 grade system. AV ± 0.5 SD was set for 3, from there to AV ± 1.5 SD was set for 2 and 4 in each direction and beyond that range were set for 1 and 5 respectively. To validate the mentioned classification, most recent 3-year data were collected and kurtosis and skewness of distribution were calculated. Results - Standardized score from mean and SD were as below;

  • Squat score: ⑤∼150 kg∼④∼130 kg∼③∼110 kg∼②∼90 kg∼①
  • Squat weight divided by body weight: ⑤∼2.10∼④∼1.84∼③∼1.59∼②∼1.34∼①
  • Vertical jump: ⑤∼70 cm∼④∼63 cm∼③∼56 cm∼②∼49 cm∼①
  • 5-star test: ⑤∼11″39∼④∼11″39∼③∼13″19∼②∼14″10∼①
  • 50m sprint: ⑤∼6″33∼④∼6″65∼③∼6″98∼②∼7″30∼①
  • Shuttle run: ⑤∼52″∼④∼54″∼③∼57″∼②∼60″∼①

Based on the standardized score above, distribution of data from most recent 3 years were 12% at 5, 26% at 4, 36% at 3, 21% at 2 and 5% at 1. Skewness was −0.001 and kurtosis was −0.617 and was not far away from normal distribution. Discussion: Represented by new fitness test by Ministry of Education, Culture, Sports, Science and Technology, creating scoring model of measured data is useful for evaluation. The purpose of this report is to collect T&M data of high school baseball team and discuss the calculation for scoring model. With past T&M data, mean and AD were calculated and as validity was tested using data from past 3 years, data was not far off from normal distribution. Therefore, the calculation method used in this report is one of the valid methods to score collected data. Practical Application: Using AV and SD are effective value that can be easily calculated using Microsoft Excel. Since the data from this report is from one team, calculation of standard for each team is suggested.

Self Conditioning and Health Literacy of in Collegiate Students Majoring Sports

Shinobu Tanaka,Fumiko Tsukuda, and Satoko Takeda

Biwako Seikei Sport College, Shiga, Japan

Purpose: To make competitive career more fulfilling, knowing own condition and self-management ability to improve own condition is necessary. In this study, the effect of continuing filling of self-check sheet of body and life style condition and conditioning instruction to information processing ability related to condition and health (health literacy) is investigated. Methods: Twelve female athletes in university were the subject of the study. From July to December of 2015, filling of self-check sheet (sheet) of body and life style was demanded. From October to December of 2015, conditioning instruction by specialized staff (JASA-AT) was performed once per month (intervention). Survey with 73 questionnaires (1 being least applicable and 6 being most applicable) was done before sheet, before intervention and after intervention. Of 12 subjects, 3 were regularly filling sheet and classified as record group and 9 with fragment record of sheet were classified as no-record group. Total of 4 factors derived from previous studies were used to compare the results of health literacy survey. Repeated 2-way ANOVA was used for statistical analysis and significance was set at 5% or less. Results: When points from survey were summed and compared between record and no-record groups, record group showed significantly higher score at after intervention than before sheet. Also, at after intervention, record group showed significantly higher score than no-record group. Factor for health information transmission was not different between groups or periods. On the other hand, points of factor for self-management of diet were significantly higher at after intervention than before sheet or before intervention in record group. Points from self-management of training factor were significantly higher at after intervention than before sheet or intervention in no-record group. Processing of self-information factor was significantly higher at after intervention than before sheet in record group and also higher in record group than no-record group at after intervention. Discussion: In this study, the influence of filling sheet and conditioning instruction to health literacy was investigated. Filling of sheet was voluntary and subjects' autonomy was respected. As a result, athletes who regularly filled were limited and were mainly from individual sports. Factors that constitute health literacy were higher at after intervention than before sheet in record group and this suggests that regular recording is effective in improvement of health literacy. However, there was no difference between before sheet and before intervention in record group, not only filling sheet was effective but conditioning instruction was also effective. Practical Application: Facing themselves and providing precise advice are possible opportunity to improve self-management ability of athletes. For female athletes, with female specific condition change, it is required to set a supporting environment that combines grasping the current condition and advising for improvement.

The Effect of the Different Tempo in Dynamic Stretching on Flexibility and Vertical Jump

Kohei Ariyoshi1and Kazushige Oshita2

1Osaka University of Health and Sport Sciences, Osaka, Japan; and2Kyushu Kyoritsu University, Fukuoka, Japan

Purpose: Dynamic stretching (DS) is used as a method expected to improve flexibility and exercise performance in a warm up before exercises. However, there was no stable opinion about its ideal procedure including repetition, tempo, or intensity. The purpose of this study was to investigate the effect of the different tempo of leg swing for flexibility and VJ. Methods: Subjects were healthy 10 students, and the purpose and procedure were explained to obtain their consents prior the study. This study was done as approved by Kyusyu Kyoritsu University's Standards of Official Conduct Committee. DS trials were 10 leg swings (hip joint flexion-extension movement on the sagittal plane with a single leg standing) of dominant leg with maximum range of motion, and a total of 4 trials consisted by DS with 3 different tempos, 34, 44, 54 b·min−1, and a minute of rest without DS (NS) were performed. The values of Straight-Leg-Raise range of motion (ROM) and VJ were compared between before and after each trial. The measurement was done once a week, and subjects were performed all trials in a random order. All data was shown as mean ± standard deviation. Paired t-test was used to analysis the significance to compare before and after each trial of ROM and VJ. (p ≤ 0.05) Results: ROM showed significant increase in the tempo of 44 b·min−1 (Pre = 85.5 ± 9.3°, Post = 92.5 ± 8.6°) and 54 b·min−1 (Pre = 82.5 ± 11.8°, Post = 89.0 ± 9.7°). No significant difference were shown in 34 bmp (Pre = 83.5 ± 8.8°, Post = 84.0 ± 9.4°) and NS (Pre = 85.5 ± 9.6°, Post = 87.5 ± 10.9°). VJ showed significant increase in the tempo of 44 b·min−1 (Pre = 28.7 ± 3.8 cm, Post = 30.9 ± 2.9 cm) and 54 b·min−1 (Pre = 29.3 ± 3.6 cm, Post = 32.1 ± 5.0 cm). It was significantly decreased in 34 bmp (Pre = 31.2 ± 3.8 cm, Post = 29.8 ± 3.7 cm). No significant difference were shown in NS (Pre = 29.4 ± 3.9 cm, Post = 28.9 ± 2.8 cm). Discussion: This study showed the performance of ROM and VJ was improved by DS performed with the tempo generally used (44 b·min−1) and faster tempo (54 b·min−1). In general, the increase of flexibility, the amount of muscle activities, and neuromuscular conduction speed and facilitation of circulation due to the increase of heart rate are the effects expected in warm up before exercises. In this study, it was considered that DS with faster tempo would be more suitable than that with slower tempo for the facilitation of the warm up effects in power and flexibility. Practical Application: The appropriate repetition or intensity of DS in warm up was often decided based on only experiences and not clear. This study is an information of the most suitable tempo of DS often performed as lower extremity DS and could be directly feedback to the sports field. Also, it may be helpful to establish the implementation method of DS.

The Effect of Strength Training on Swimmers of the Paralympic by Measurement of Performance in 4 Years

Tomohiro Noguchi,1Tetsuro Tanigawa,2Masanobu Tachi,3Yasushi Ikuta,4and Masahiro Terada5

1Nihon University, Tokyo, Japan;2Keio University, Kanagawa, Japan;3Nara University of Education, Nara, Japan;4Osaka University of Education, Osaka, Japan; and5Kobe City College of Technology, Hyogo, Japan

Purpose: To date, Noguchi (2013) investigated the strength training until London Paralympics of a swimmer, K.K., who was a blind (visual deficit: total blindness) Japanese Paralympian in London 2012 and won 2 medals, by stroke parameter calculated in that event in 2012. Also, Noguchi et al. (2014) and Noguchi et al. (2016) investigated the training program until the IPC World Championship in 2015 by stroke parameter of each major event. This is a report of the change of the strength training program from the IPC World Championship in 2015 to Rio de Janeiro Paralympics in 2016 as well as the investigation of that based on previous race analysis recorded at major events. Furthermore, it was aimed to find the training targets and strategy of the same swimmer for Tokyo Paralympics 2020. Methods: Subject was a blind Japanese Paralympian (26 year old, 171 cm, 69 kg). Regarding the strength training program, exercise names performed in each training term and a total loading weight (kg) of each training session were recorded in each category such as high load or high repetition. The results of each major event and swimming velocity as well as stroke parameter of each interval calculated by Japanese Para-Swimming Federation science staff in the race analysis were recorded and graphed in the Microsoft Excel 2010 to observe the yearly changes. Results: Swimming time at the starting and turning phase was shortened until Rio Paralympics Trial in March, 2016. Also, regarding stroke parameter, it was observed that the maximum load weight and the total work of the strength training the subject had done influenced the race result of breast stroke. In freestyle and butterfly, the training done with light loads with high repetitions and high velocity of muscle contraction as well as resistance training in water contributed to the improvement of swimming speed caused by maintained length of stroke and increased stroke frequency. However, breast stroke did not show that tendency. On the presentation day, the result at Rio de Janeiro Paralympics will be reported too. Discussion: From 2013 to 2016, there were both cases the strength training did and did not contribute to improve swimming performance. Specifically, only breast stroke did not clearly show the training effect of speed and power training. Breast stroke's swimming characteristics is a large passive resistance and the difference between acceleration and deceleration. Thus, the resistance generated by legs (feet) influence a lot to produce driving force in breast stroke. Therefore, it was considered that the legs' muscle strength was required only in breast stroke since the driving force and the endurance generated by legs were necessarily required. Also, there was a great improvement seen in the starting and turning velocities from 2015 to 2016. During that time, the load of topside deadlift was significantly increased, and high clean was introduced to increase instantaneous force. Those changes were considered to improve the performance. More specifically, from the season in 2015 to 2016, work of the strength training and muscle mass were greatly increased while the amount of training was increased, then the performance was significantly improved especially in butterfly, freestyle and individual medley. Considering how to overcome the instability of swimming which was unique to blind swimmers might be the cause behind the results. Blind swimmers swim repeating acceleration and deceleration due to the hit course rope during the race. Furthermore, even though the course distance was the same, they need to swim additional distance swimming from side to side within the course because they cannot stable the swimming direction. Also, it is impossible to avoid any contact with course rope or other swimmers of the next course. If they try to guide themselves rubbing their bodies to the course rope to swim straight, the force developed would not directly transfer to driving force due to the friction between course rope and their bodies. In conclusion, it was considered to be necessary for the performance improvement of blind top swimmers to train for “overcoming the contact with course rope or other swimmers” and “resisting friction or handling repeated acceleration and deceleration.” Energy production capacity is required more than we expected to maintain the speed in the latter half of the race. Thus, the increase of muscle mass is important for blind swimmers to “increase the energy tank” too. Practical Application: This report showed the training history of a top blind swimmer and considered its effect from the stroke parameters in the major events and the transit time in each phase. For Tokyo Paralympics 2020, this kind of research should be continued to find issues and improve performance. From now on, it will be fortunate if this report can help some training operations of coaches who work on the development of blind swimmers.

Eucalyptus Smell Can Assist in Delaying of Exhaustion

Junpei Shiba1and Rieko Kuramochi1,2

1Graduate School of Health and Sport Sciences, Chukyo University, Aichi, Japan; and2School of Health and Sport Sciences, Chukyo University, Aichi, Japan

Introduction: The sense of smell is a primal and primitive function for humans as well as animals. The limbic system, supporting emotions, behavioral motivation, and memory, in the brain receives coming odor before the sensory cortex. Therefore, it is possible that certain odor can affect motor performance due to smell-induced activity in the limbic system. The purpose of the present study was to examine influences of odor on exercise. Methods: Two aroma (peppermint, and eucalyptus), and no-aroma conditions were tested using 8 young healthy males (20.6 ± 5.7 year). Each subject first completed an aerobic capacity test using a bicycle ergometer to determine his 80% maximum workload level. In a temperature (25 ± 1° C) and humidity (50 ± 5%) controlled experimental room filled with a testing aroma, the subject rested for 4 minutes followed by 2 sets of pedaling and rest tasks to fully warm-up and acclimate the smell condition. The subject then performed 80% maximum workload until exhaustion. The order of tests was given randomly to each subject with more than 48 hours between tests. Heart rate and PRE were monitored throughout the test. Salivary amylase was measured before and after each test, and blood lactate was measured 30 seconds after the exhaustion test. One-way repeated measures ANOVA and Tukey post-hoc test were performed to identify the difference at 0.05 level of probability. Results: The mean duration to exhaustion was 169.1 ± 49.5 seconds for control condition, and 170.0 ± 42.6 seconds for the peppermint condition. The corresponding duration for the eucalyptus condition was 208.5 ± 49.2 seconds, which was significantly longer (p < 0.01) than the control and peppermint conditions. No condition difference was found in other variables Discussion: It is well known that Cineol, which is contained in eucalyptus, functions to activate sympathetic nerve. We thus assume that this was one of the reasons for increased exercise duration for the eucalyptus condition. However, there was no significant differences in other physiological parameters such as HR-max, blood lactate, and amylase secreted in saliva. So, increase of exercise duration cannot be accounted for solely by activation of nerve activity. We assume there might be other reasons such as, increase of hemoglobin dissociation in body tissues or activation of mitochondria as Shiota (2012) mentioned, which needs to be examined in the future study. Practical Applications: The findings of the present study can be applied to a new training method in order to improve aerobic capacity if we clarify the functions more. The findings will be more useful and practical if we can clarify the relationship between autonomic nerve activity and odor, and effects of certain odor on oxygen transport system.

The Possibility of Slow Training as a Method to Improve Locomotive Syndrome

Shunta Shimono,Makoto Fukuwaka, and Yasuto Nakanishi

Osaka Aoyama University, Osaka, Japan

Purpose: There are many studies about the relationship between one repetition maximum (1RM) or submaximal load of back squat (BSQ) or clean and vertical jump in volleyball players. However, volleyball requires not only jumping skills but also moving quickly to rally, block and dig, and it is considered that acceleration and agility are also important fitness aspects. Furthermore, there are few studies about dead lift (DL), which is one of the core lower extremity exercises like back squat, in volleyball players. Training facilities in Japan are not well equipped, and it may be beneficial to report the effect of DL which can be performed more easily than BSQ. Considering that, the purpose of this study is investigating the relationship between jumping, acceleration and agility skills, which are required for volleyball players, and 1RM of BSQ and DL. Methods: Subjects were 15 male collegiate volleyball players (height: 179.8 ± 8.9 cm, body weight: 71.1 ± 9.6 kg, age: 18.7 ± 0.6 year old) of Tokai University Volleyball Federation First League. Measurements were BSQ, DL, Vertical Jump (VJ), Squat Jump with Arm Swing (SQJ), 10 m Sprint, and T-test. A Yard Stick (Swift equipment) was used to measure VJ and SQJ. The highest values of VH and SQJ and the fastest time of 10 m Sprint and T-test were recorded. Also, 1RM was normalized with body weight (BW). Pearson product-moment correlation was used for statistical processing, and the level of significance was 5%. Results: BSQ/BW showed a significant correlation with VJ (r = 0.694, p < 0.01), SQJ (r = 0.607, p ≤ 0.05), and 10 m Sprint (r = 0.518, p ≤ 0.05), but there was no significant correlation with T-test (r = 0.391, N.S.). DL/BW showed a significant correlation with VJ (r = 0.631, p ≤ 0.05), SQJ (r = 0.723, p < 0.01), 10 m Sprint (r = 0.716, p < 0.01), and T-test (r = 0.655, p < 0.01). Discussion: Although both jumps were the same jumping movements toward vertical direction, BSQ/BW showed a stronger correlation with VJ than that with SQJ whereas DL/BW showed a stronger correlation with SQJ than that with VJ. These results might be influenced by the movement characteristics of BSQ, DL, and each jumping. BSQ and VJ begin with eccentric concentration and transfer to concentric concentration afterward. In volleyball, most movement patterns are required countermovement (CM) like VJ, but it also requires other movement patterns without CM like block jump. Thus, it may be beneficial to improve SQJ too. Ten meter Sprint and T-test showed a strong correlation with DL/BW. The role of hip extension muscles is important for acceleration and changing direction skills, and DL requires more muscle activity of hip extensors than BSQ. That might cause these results. Practical Application: From the results of this study, it was considered that the higher 1RM players showed in not only BSQ but also DL, the higher the skills required for volleyball were. In the coaching field in Japan, there are lots of training facilities which does or cannot install any expensive training equipment such as squat rack. However, DL can be performed with only barbells and plates which are more convenient than BSQ. Thus, when BSQ cannot be practiced, introducing DL effectively into the training program may be able to improve jump, acceleration and agility skills.

The Possibility of Slow Training as a Method to Improve Locomotive Syndrome

Shunta Shimono,Makoto Fukuwaka, and Yasuto Nakanishi

Osaka Aoyama University, Osaka, Japan

Purpose: Locomotive syndrome (LS) is defined as a condition in a high risk of nursing care level due to “locomotorium dysfunction” and it is also defined as one of life style related diseases or geriatric syndromes. It is said that one of its major causes is locomotorium dysfunction (i.e., decreasing muscle strength or flexibility) due to aging. It is well known that the function of muscle is improved by strength training, however, it is necessary to consider the types, frequencies and amount of activity well to obtain benefits from the training. In addition, it is not recommended for the elderly to do high intensity or load training from the point of safety. Thus, the purpose of the present study was to investigate the influence of slow training using relatively low intensity or load on the improvement of LS in order to find out a safe and effective training method. Methods: Four healthy young men and a woman (age 20.6 ± 0.5 year old, 165.7 ± 9.3 cm, body weight 55.3 ± 5.7 kg, body fat 18.0 ± 7.8%) served as subjects. All subjects have completed 8-week slow training session. The session required the subjects to practice 3 types of slow training (leg extension, both legs; leg press; lat pull down) twice a week. The screening tests (stand-up test, 2-step test) for a risk of LS, maximum strength and resting metabolic rate were measured before and after the training session. The obtained data were analyzed by repeated t-test. For all statistic measures, significance was established at the 0.05 level of probability. Results: After the 8-week training session, the resting metabolic rate, leg press, and lat pull down went up by 11.0, 10.8, and 7.8% (p ≤ 0.05), respectively. In addition, the screening test score of LS (stand-up) has improved 1.6 points (p ≤ 0.05), however, there was no change for leg extension and the screening test score of LS (2-step). Discussion: This study showed a significant improvement of the screening test score of LS (stand-up). The major muscles relates to standing-up movement are the gluteus maximus and the quadriceps femoris, and involvement of the gluteus maximus for the movement goes up as one squat deeper. The height of the chair used for the stand-up test was as low as 40 cm. To date, the improvement of the score is thought to be mainly caused by the improvement of leg press. There was no improvement of the 2-step test score in the present study. There are 2 main factors, which is thought to bring about the improvement of the 2-step score. One is the strength of lower extremity, and the other is flexibility of lower extremity. Thus, we assume that the present study could detect no improvement in the score, although there was an increase in lower extremity strength (leg press value). The present study also showed an improvement in resting metabolic rate after 8-week of training session. It is thought that the improvement of the metabolic rate is one of important factors to prevent offal fat, which relates to metabolic syndrome, from being stored and to decrease the fat. Therefore, slow training can be an effective training method not only to improve LS but also to prevent and/or improve metabolic syndrome, which highly relates to life style diseases. Practical Application: The results of the present study can offer an important information for designing exercises, which can serve to prevent LS and/or improve a risk of LS. In addition, the results can offer more useful information in the practical field by studying middle-aged and elderly subjects and investigating the combination effects with flexibility training of lower extremity.

Movement With Greater Trunk Acceleration During Badminton Games

Yasuharu Nagano,1Shogo Sasaki,2Ayako Higashihara,3and Ichikawa Hiroshi4

1Japan Womens College of Physical Education, Tokyo, Japan;2Tokyo Ariake University of Medical and Health Sciences, Tokyo, Japan;3The Japan Society for the Promotion of Science, Tokyo, Japan; and4Niigata University of Health and Welfare, Tokyo, Japan

Introduction: Evaluating movements during sports activities is essential for examining the physical load and risk of injury. Measurements using an accelerometer are comparatively simple, with the measured acceleration also reflecting the force applied to the segment. When an accelerometer is worn on the trunk, subjects hardly limited their sports movements. However, previous research studies that used an accelerometer were only conducted in the laboratory. If the trunk acceleration during real sports movement was clarified, high-risk movement in these sports would be identified. Details of trunk acceleration during real-sport movement are not known. We selected badminton as a sport where landing and cutting, which carry the risk of injury, are performed. The purpose of this study was to clarify movements that require greater trunk acceleration during badminton games. Methods: Six female high-school badminton players participated in this study. The subjects wore a triaxial accelerometer on the upper back. Acceleration was measured during 2 badminton games. Video data were also obtained that were synchronized with the acceleration data. The resultant acceleration was calculated, and the acceleration movements generating >4 G were identified. Results: There were 826 movements generated >4 G (8.3 ± 3.4 cases/min [mean ± SD]). The top 6 extracted movements were landing from an overhand stroke (187 cases, 22.6%, 1.9 ± 0.7 cases·min−1), cutting from a split step (147 cases, 17.8%, 1.5 ± 0.4 cases·min−1), lunging during an underhand stroke (134 cases, 16.2%, 1.3 ± 0.5 cases·min−1), takeoff before overhand stroke (64 cases, 7.7%, 0.7 ± 0.8 cases·min−1), stopping (43 cases, 5.2%, 0.4 ± 0.5 cases·min−1), and pre-split stepping (42 cases, 5.1%, 0.4 ± 0.3 cases·min−1). Landing from an overhand stroke was distinguished between the limb of the dominant-hand side (100 cases, 12.1%, 1.0 ± 0.2 cases·min−1) and that of the non-dominant-hand side (86 cases, 10.4%, 0.9 ± 0.6 cases·min−1). Discussion: Acceleration can be measured with few body restrictions. In the previous study, vertical trunk acceleration was greater in females than in males during cutting (Nagano et al., 2016) and landing (Sasaki et al., 2016). Trunk acceleration also had strong relationships with vertical ground reaction force (Nagano et al., 2016). Therefore, injury, including anterior cruciate ligament injury, might be caused by greater ground reaction force, and the high injury rate in females might be due to greater ground reaction force. The results of this study showed that movements with greater trunk acceleration during 2 badminton games occurred in high frequency. Landing from an overhand stroke, cutting from a split step, and lunging during an underhand stroke occurred frequently. Anterior cruciate ligament injury during badminton games occurred at the time of landing from an overhand stroke by the limb on the non-dominant-hand side and lunging during an underhand stroke (Kimura et al., 2010). These movements also occurred in high frequency during real badminton games. Practical Applications: To prevent injury and re-injury, enough training for movement with high trunk acceleration is essential. Preventive plans are required especially for athletes who frequently perform movements that require greater trunk acceleration.

The Relationship of the Step Stride and Pitch During Sprint Acceleration in Junior Soccer Players. Comparison Between Fast and Slow Sprinters

Sho Kozaki,1Yoshihiro Hoshikawa,1Masahiro Kurosu,1Masato Amano,2and Yuki Nakata3

1Department of Sport and Health Science, Tokaigakuen University, Aichi, Japan;2Trident College of Sports, Medical Care and Nursing, Aichi, Japan; and3Japan Nursery Service Inc., Aichi, Japan

Purpose: Sprint ability in a short distance is really important for soccer. Hoshikawa et al. (2012) indicated that high sprint ability should be gained during puberty for the later success as soccer players. However, shortened sprint time could be resulted from the growth spurt in height during the puberty. Therefore, it has been unclear where to focus on in training to improve sprint ability in puberty. This study aims to compare a high sprint ability group and low group collated each evaluation standard in the step stride and pitch from start to 10th step of sprint, and organize the characteristics of sprinters with high sprint ability in puberty. Methods: Subjects were 283 middle school students from first grade to third grade. They were participating soccer practice at least 3 times a week. One hundred twenty-one of them were players expected to become professional players in minor organization under a J-league club. The measurements were height, body mass and composition, vertical jump, and time, step stride (St) and pitch (P) during a 20-m sprint. Yardstick were used to measure vertical jump height. Light-gate method, and both OptoJump system and video were used to measure 20 m sprint time and St and P, respectively. Using the standard values from the previous study by Hoshikawa et al. as a reference, the faster group (F) and slower group (S) were classified by 20 m sprint time in each class. The subject number of first, second and third graders in the F group were 23, 13, and 6, respectively, and in the S group were 32, 34, and 29, respectively. Each measurement was compared between F and S groups. Results: Height of F group was significantly higher than that of S group in all grades, but the difference was less in the third grader, 3.8 cm, than first and second graders, approximately 9 cm. Similar to the result of the height, the F group showed greater body mass, BMI, and lean body mass than the S group, but the difference between groups was less in the third graders. Vertical jump height of the F group was more than 15 cm higher than that of the S group in the first and second graders and 12 cm more than that of the S group in the third graders. From start through 10th step, St of the F group was approximately 7–11% longer than that of the S group in the first and second graders. However, in the third graders, the F group showed 8% longer than the S group in the first 2 steps, but the difference between 2 groups got smaller as stepped further, and the F group was only 2% greater than the S group at 10th step. St-height ratio of the F group was approximately 3–5% greater than that of the S group in the first and second graders, but the difference between 2 groups was almost disappeared after fifth step in the third graders. Also, there were no intragroup differences of the St-height ratio in each grade. On the other hand, from start through 10th step, P of the F group was approximately 5–7% greater than that of the S group in the first and second graders, and its difference was greater at 10th step than in the first 2 steps after start. Furthermore, after fifth step, the F group showed approximately 9% greater P than the S group in the third graders. In both groups, P was increased over the first, second and the third grades. Discussion: The timing and tempo of maturation influenced the difference between the F and S groups in the first and second graders but less in the third graders in this study. The longer St and faster sprint time were seen as the grade went higher in both groups. However, in the third graders, there was almost no difference in the step St-height ratio after the fifth step between the F and S groups, and the difference of P mainly distinguished between the F and the S groups. In general, the development of sprint ability is resulted from the growth of the step stride along with the growth of length of the lower extremity. However, this study suggested the importance of acquiring high pitch during the puberty. In addition, in a few steps after starting, the F group showed greater step stride even in terms of a value normalized with height, and that was also considered as an important standpoint to gain high sprint ability in puberty. Practical Application: It is important to gain higher pitch without shortening step stride to improve spring ability in puberty. It is also important to develop the step stride over the height growth in a few steps right after starting.

The Yo-Yo Intermittent Recovery Level 2 Test on Japanese Elite Youth Soccer Players

Kentaro Chuman1and Yoshihiro Hoshikawa2

1JUBILO CO.,LTD., Iwata, Japan; and2Tokaigakuen University, Miyoshi, Japan

Introduction: The Yo-Yo intermittent tests developed by Jens Bangsbo were performed world-wide to evaluate intermittent endurance of soccer players during a game. There are 2 types of Yo-Yo intermittent tests: one is the Yo-Yo intermittent endurance test and the other is the Yo-Yo intermittent recovery test (YYIR). The YYIR has 2 levels, level 1 and 2 (YYIR2). The score of YYIR2 in which a higher running velocity than the level 1 is applied has been confirmed to predict a player's number of high intensity runs in professional games. Nowadays, the YYIR2 has come to be applied to youth players not only professional players, but there are still limited data on young stars. The purpose of the study is to report YYIR2 scores in elite Japanese youth players. Methods: A total of 168 players aged from 12 to 18 years (U-13 to U-18) participated in the study. The participants were academy trainee in a club belonging to the Japan Professional Football League Division 1. The participants consisted of only out-field players. They passed through the selection process to join the team and engaged in organized training 1.5–2 hours a day, 6 days a week. The study reports 4 results: (a) cross-sectional age-related changes of the YYIR2 score from U-13 to U-18, (b) longitudinal developmental changes of the score from U-13 to U-15, (c) the relation of the score with aerobic and anaerobic fitness during adolescence, and (d) the relation of the score with individual playing time in official matches over a season. Results: The average scores for the YYIR2 continued to increase gradually from 426 m at U-13–1196 m at U-18 without reaching a plateau throughout the period. The longitudinal changes of the scores from U-13 to U-15 were strongly influenced by the individual stage of maturation. Subjects in an early maturational group showed early developmental spurts of the scores at U-13, whereas subjects in a later counterpart showed later spurts around U-14. However, both groups achieved the same score level, 800 m, at U-15. No significant correlations were found between the score and the V̇o2max before U-15 after which the V̇o2max came to moderately affect the score. Before U-15 the Wingate anaerobic power had higher impact on the score. The U-18 players with higher YYIR2 scores had a tendency to be selected as starters in official matches, and showed longer playing time (76.0%) averaged through the season compared with players with lower YYIR2 scores (26.6%). Discussion: In general, fitness test scores of boys during growth reach a plateau around the age of 16–17. Contrary to this, youth players are suggested to continue to improve the YYIR2 after the age of 18. Because physical demands in a soccer game include acceleration, deceleration and turn, the YYIR2 applying a heavy load to both the aerobic and anaerobic systems of a player validly reflects soccer-specific intermittent endurance. It is also suggested that immature anaerobic development in early adolescence limit the test score and early-maturing players can perform better due to their early development of anaerobic power. Practical Applications: The YYIR2 scores increase gradually over the course from U-13 to U-18. The test is useful to evaluate intermittent endurance of youth players as well as seniors. However, caution should be paid when interpreting under U-15 players because early maturation works as a favor factor for the YYIR2.

The Relationship Between Trunk Acceleration and Ground Reaction Force in Landing Phase of Repeated Tuck Jump

Yui Shimada,1Sayaka Watanabe,1Takakuni Sakurai,1,2Yasuharu Nagano,3and Shogo Sasaki1,2

1Graduate School of Tokyo, Ariake University of Medical and Health Sciences, Tokyo, Japan;2Tokyo Ariake University of Medical and Health Sciences, Tokyo, Japan; and3Japan Women's College of Physical Education, Tokyo, Japan

Purpose: Recently, a screening program using tuck jumps for injury prevention in a practical field. The specialty of Tuck Jump Assessment is repeatedly jumping on the same spot for 10-second which is categorized as a high-intensity plyometric exercise. Although an “excess noise when landing” is considered as one of error patterns of the Tuck Jump Assessment, the error is often judged subjectively. On the other hand, it has been reported that the ground reaction force of single landing is correlated to the acceleration sensor applied on trunk. However, there was no report about the relationship between trunk acceleration of repeated jumps and ground reaction force. The purpose of this study was to investigate the relationship between trunk acceleration and ground reaction force in landing phase of the Tuck Jump Assessment. Methods: Subjects were high school female handball players (age 16.1 ± 0.9 year old, height 160.3 ± 6.7 cm, body weight 56.0 ± 6.1 kg, lean-body mass 45.0 ± 4.5 kg) who experienced playing at the national level. All subjects were applied a 3-axis acceleration sensor (Logical Product; 200 Hz) on their upper thoracic spines and performed Tuck Jump repeatedly for 10 seconds on the force plate (KISTLER; 1,000 Hz). Maximum values of vertical acceleration, resultant acceleration, and vertical ground reaction force were extracted from each landing of individual's 10-seconds Tuck Jumps. Then, mean scores of each variable were defined as trunk maximum vertical acceleration, maximum resultant acceleration and maximum vertical ground reaction force per body weight, respectively. The relationship between maximum vertical acceleration or maximum resultant acceleration and maximum vertical ground reaction force was analyzed by Pearson product-moment coefficients. The level of statistical significance was 5%. Results: Subjects completed 14.8 ± 0.9 times of Tuck Jumps in 10-second. Maximum trunk vertical acceleration was 7.6 ± 1.3 G, and maximum resultant acceleration was 11.3 ± 2.1 G. Also, maximum vertical ground reaction force per body weight was 66.6 ± 9.1 N·kg−1. Maximum vertical ground reaction force showed medium or higher correlation with trunk maximum vertical acceleration (r = 0.88, p < 0.001) and maximum resultant acceleration (r = 0.66, p < 0.001). Discussion: Previous study has reported that there was a strong correlation between ground reaction forces and trunk acceleration in a single trial of single leg landing, and the results of this study that used repeated and high-intensity Tuck Jump supported that previous study. Because extreme ground reaction force is a risk factor of knee anterior cruciate ligament (ACL) injuries, it was considered that screening high-risk athletes could be easily done with using the trunk acceleration measure. It is expected that the observation of the landing of Tuck Jump Assessment with an acceleration sensor will develop the screening of ACL injury risk in a practical field to more objective standard. Practical Application: Force plate is excellent to collect detail data in the lab-like space but requires enough space and time. On the other hand, an acceleration sensor can be used in any place. Furthermore, using multiple acceleration sensors allows to measure multiple subjects at the same time and save subjects' time. Because there was a correlation between trunk acceleration and ground reaction force in repeated Tuck Jump, screening ACL injury risk in actual sports fields will be done more easily and objectively.

The Correlation of Physical Activity Using the Pedometer With Accelerometer Between an Infant and the Father


Chiba University, Chiba, Japan

Introduction: In Japan, it was suggested that the higher frequency exercise with a father, there is much frequency, strength and continuous time for exercise of his child explored by a questionnaire survey. Exercise and sports play with the father is expected to be secured the appropriate physical active mass of the early childhood. And, the future issue is to need to research an investigation quantitatively. The purpose of this study was to investigate whether amount of physical activity in early childhood is connected with father's physical activities. Methods: Twenty-five pairs of infant who belong to the Kindergarten in Chiba, Japan (14 boys and 11 girls, 6.1 ± 0.3 years), and the father (42.2 ± 4.3 years) were participated in this study. To determine the number of steps and the amount time of physical activity on each intensive level per a day, a pedometer with 3-dimension accelerometer (Actimarker; Panasonic Electric Works, Osaka, Japan) was put on the waist of each participant between a week. The data were separated into weekdays and holidays and calculated. Pearson correlation coefficients (r) used to assess the significance of relationships between the infants and the fathers, and between weekdays and holidays. A significance level of 0.05 were used. Results: At weekdays, no significant correlations existed in the number of steps and the amount time of physical activity on each intensive level, between the infants and the fathers. At holidays, however, the amount time of physical activity more than 5.0 and 6.0 METs were significantly correlated between the infants and the fathers (r = 0.457, p ≤ 0.05; r = 0.485, p ≤ 0.05, respectively). In the infants, the amount time of physical activity more than 2.0, 3.0, 4.0, 5.0 and 6.0 METs were significantly correlated between holidays and weekdays (r = 0.430, p ≤ 0.05; r = 0.666, p < 0.001; r = 0.591, p < 0.01; r = 0.480, p ≤ 0.05; r = 0.446, p ≤ 0.05; r = 0.458, p ≤ 0.05, respectively). On the other hand, in the fathers, the amount time of physical activity more than 3.0 METs was only significantly correlated between holidays and weekdays (r = 0.461, p ≤ 0.05). Discussion: In the holidays, the reason why the correlation was observed 5.0 METs more might be caused to play the infants and the father together is considered likely to be selected exercise and sports play. The infants are similar features of weekdays and holidays of physical activity. The fathers are considered that the much activities of more than walking on holidays, is much on weekdays. Practical Applications: Physical activity that the infants and the father to play together on holidays affect physical activity of early childhood on weekdays, would be expected to form to exercise habits, may lead to the future of sports activities.

Consecutive Bouts of Resistance Exercise Cause Increase in Ribosomes in Rat Training Model


The University of Tokyo, Meguro-ku, Japan Juntendo University

Introduction: Resistance training (RT) causes hypertrophy in skeletal muscle with the rate of hypertrophy gradually decreasing during the period of exercise training. One of the possible causes for the attenuation of hypertrophic effect would be the acclimatization of mammalian target of rapamycin (mTOR) signaling pathway to the chronic stimulation of RT. On the other hand, it has recently been shown that ribosome biogenesis plays an important part in skeletal muscle hypertrophy. With a rat compensatory hypertrophy model, we have shown that the magnitude of muscle hypertrophy after synergist ablation is closely correlated with the increase of ribosome content (Nakada et al., 2016). However, little is known whether RT effectively causes ribosome biogenesis. Therefore, the present study aimed to investigate the changes of 18S + 28S ribosomal RNA (rRNA) content during the consecutive bouts of RT. Methods: Male Sprague-Dawley rats were randomly assigned into 4 groups: resistance-trained with 1 bout (1B), 3 bouts (3B), 6 bouts (6B) and 12 bouts (12B). The gastrocnemius muscle was subjected to resistance training protocol consisting of 50 reps of maximal isometric contractions evoked by direct electric stimulation. Groups other than 1B performed 3 bouts of exercise per week. The muscle samples were taken 48 hours after the last session of training, and analyzed for rRNA content. Results: The content of rRNA per tissue weight increased with increasing the consecutive volume of exercise, but no significant difference was seen between 6B and 12B. Discussion: The present results showed a close association between ribosome biogenesis and the volume of RT during early period of training. This suggests that ribosome biogenesis plays an important part in the muscle hypertrophy caused by RT, and it also limits the rate of protein synthesis during the later period of RT. Practical Applications: Up to present, activation of mTOR signaling pathway has been regarded as important in the effective prescriptions of RT. The present study showed a novel indicator for the effect of RT, i.e., ribosome biogenesis. This may lead to the development of more effective methodology of RT.

Performance Evaluation Using PUSH Band in Collegiate Football Athletes: the Relationship Between Training Load and Physical Performance

Takeshi Sakaguchi,1Shinto Kinoshita,1and Daichi Yamashita2

1Kobe University RAVENS, Hyogo, Japan; and2Japan Institute of Sports Sciences, Tokyo, Japan

Purpose: For sports that have seasons, it is important to understand athletes' condition through performance converted into numerical values. Monitoring devices have recently become very small and handy, and an individual is able to evaluate own performance of exercise. Especially, PUSH band can give feedback of jump height and velocity by 3-axis accelerometer and gyroscope, and a previous study showed its strong validity in elevating velocity of squat (Fernandez et al., JSCR, 2016). Thus, this presentation reports the relationship between training load and performance (vertical jump) of collegiate American football players as an example of performance evaluation using PUSH band. Methods: Subjects were 56 collegiate American football players played in Kansai Division 1 collegiate football team. Subjects performed 3 trials of each of vertical jump, rebound jump, and 40 kg bench press following a specific procedure using PUSH band (20 Hz, PUSH Inc.) during preseason from February to July, and the best score was recorded. Measurement was done before practice of a first half of the week (Monday through Wednesday) every week. Each individual's training load was quantified based on practice time and subjective exercise intensity. Results: Focusing on before and after week 13 that training load was temporary decreased for a pre-season match, individuals' training loads were decreased 6% between week 11 and week 12 and 35% between week 12 and week 13 in average, and week 13 was confirmed as a week that training load was decreased. Also, comparing between week 12 and week 13 and week 13 and week 14, jump height increased 1.6 and 5.9%, rebound jump index 3.1 and 16.2%, and maximum power of 40 kg bench press was 8.1 and 16.6%, respectively. Discussion: It was confirmed that performance a week after was improved when training load was decreased in previous week, and each event showed different characteristics. Because the injury risk gets higher due to increase of training load during the season (Gabbert, BJSM, 2004), quantifying and controlling training load have been tested. PUSH band may be able to monitor the change of performance in each body part or each power output characteristics because it can evaluate various exercises. Practical Application: Small and handy monitoring devices enable to monitor the change of various conditions that training load, which has been focused on in recent, may not evaluate by itself. In the future, the measurement for a prolong period will evaluate the improvement of the fitness.

The Relationship Between Body Size, Muscle Strength, Power, and Sprint Performance in Collegiate Rugby Athletes—Focusing on Power Snatch

Yoshihisa Kawanoand Jun Tanaka

International Pacific University, Okayama, Japan

Purpose: Rugby is a collision sport that consists of intermittent high intensity running and physical contact repeatedly for 40 minutes in each half with a 10-minute break, a total of 80 minutes. In detail, a ball starts from scrum, line-out, ruck and maul, and players score by moving a ball forward while running and tackling repeatedly or kicking a ball to gain ground strategically. Players are required to have not only aerobic capacity but also high anaerobic capacity, muscle strength, power, and speed. Also, considering the necessary of the momentum calculated by body weight and velocity in contact, body weight (especially lean body mass) is an important factor. This study is aimed to establish a reference for a training program designing by investigating college rugby players' characteristics of muscle strength, power, and sprint ability and relationships between each measurement. Methods: Subjects were 29 men's college rugby players (FW 15, BK 14) playing the China A League. Measurements were height (cm), body weight (kg), lean body mass (%), standing trunk forward flexion (cm), 40 m sprint with each 10 m lap (sec.), Pro-agility (sec.), standing broad jump (cm), standing triple jump (cm), standing broad jump/triple jump index (STJ index), counter-movement jump (cm), jump height of 5-repeated rebound jumps (cm), ground time (ms), RJ index, absolute and relative values of 1RM power snatch (kg), 1RM squat (kg), and 1RM bench press (kg), and pull-ups (rep). Then, correlation between each measurement was calculated (*p ≤ 0.05; **p < 0.01). Excel Statistics 2015 (Social Survey Research Information Co. Ltd), an add-in software of Microsoft Excel, was used for statistics analysis. Result: The average and standard deviations (SD) for each measurement is detailed on our poster presentation. All measurements were lined up in order of the number of significant correlation, and the relative values of 1RM power snatch (** = 3, * = 11) showed the most number of significant correlation followed by body weight (** = 9, * = 4) and Pro-agility (** = 3, * = 8) (others are shown on the poster). Discussion: This study's results suggested following 3 points would possibly influence to other measurements; (a) improving the load of power snatch relative to body weight, (b) increasing body weight, and (c) improving Pro-agility time. It was going to be one of the useful references for training program designing. Practical Application: As mentioned previously, it is important to design a training program utilizing power snatch as priority during muscle strengthening and power training. Also, it is known that improving power snatch record requires increasing squat load. How to arrange not only power snatch but also squat into the training program may be an important stand point.

The Effect of Physical and Fitness Factors in Bat Swing Speed

Tsubasa Yasuda,1Yoshiho Muraoka,2Rouichi Horikiri,3and Keiji Kaneko2

1Niigata University of Management, Niigata, Japan; 2Meisei University, Tokyo, Japan; and 3Hirayama Elementary School, Tokyo, Japan

Purpose: It has been reported that the amount of lean body mass is a factor which influences bat swing speed (SS) (Kasahara et al., 2012, Hisamura and Yamanaka, 2015). In practical field, squat is chosen for a training to increase lean body mass and maximum strength. However, there are few studies investigated the relationship between SS and squat, and results varies (Sawamura et al., 2006, Sato et al., 2013). Considering these issues, this study aims to clarify the physical and fitness factors which influence SS and offer a suggestion for an effective training method in a practical field. Method: Subjects were 28 collegiate baseball players of the M University (which had won the Metropolitan Collegiate Baseball League Division II Championship, Fall and Spring in 2015). SS of 5 swings without ball was measured, and the fastest speed was recorded (Multispeed Tester II, SSK). There were additional swings performed when trial was failed or subject desired. The relationship between the fastest SS measured and physical and fitness was studied. Height, arm span, body weight, body fat (InBody, Biospace), and lean body mass were recorded as physical values, and squat (maximum muscle strength), high-pull (maximum power), and rowing (high-speed power; D/PM3 Concept) were recorded as fitness values. To see the relationship between SS and each value, Pearson product-moment coefficient was calculated and the level of significance was set as 5% (p ≤ 0.05). All values were shown as mean ± standard deviation. Result and Discussion: Mean SS was 124.6 ± 8.0 km·h−1. There were significant positive correlations between SS and each following items; height (r = 0.55), arm span (r = 0.58), body weight (r = 0.50), lean body mass (r = 0.49). However, there was no significant correlation between SS and body fat. Higher height and longer arm span may increase radius of gyration of bat +α and possibly contribute to increase SS. Squat was 140.2 ± 16.9 kg (1.9 ± 0.3 times of body weight), high-pull was 80.4 ± 13.0 kg (1.1 ± 0.1 times of body weight), and rowing was 528.5 ± 94.2 W. There was a significant positive correlation between SS and rowing (r = 0.38). Neither squat nor high-pull showed no significant correlation with SS. Based on these results, improving dynamic, instead of isometric, muscle contraction speed and high-speed power development may be necessary to improve SS. Therefore, there is a possibility that SS depends on high-speed power like rowing more than maximum muscle strength and power like squat and high-pull. Practical Application: As seeing from a standpoint of talent identification, players who perform the higher SS may have more lean body mass which has been previously reported and longer arm span. Thus, it may be meaningful to measure arm span at selections or other events. Also, the result of this study suggested that training to improve high-speed power may be more effective than that of maximum muscle strength and power. In future study, movement patterns and load/intensity for high-speed power needs to be investigated.

The Relationship Between Body Type and Other Fitness Aspects for Performance in High School Baseball Athletes


Yokohama Commercial High School, Kanagawa, Japan

Body type is an important factor along with the technique of batting, throwing, and fielding to improve performance in high school baseball. High school students' bodies are in progress of development, and most of students are over PHV age that the increase of body weight may naturally occur too. It is common to do training for fitness to increase body weight during off season. For batting, it is considered that the more body weight players have, the longer distance they can hit. However, in the baseball fitness, high performance requires speed to sprint quickly and agility skill. Just gaining body weight does not work positively to speed or agility; rather, it may decrease the performance due to overweight. Thus, this study aims to clarify the influence of body type and other fitness aspects to speed and agility. Methods: Subjects were 1,591 high school baseball players of baseball clubs in Hokuriku area, and data was collected from 2006 to 2016. Measurements were height, body weight, BMI, body fat, SQ1RM, SQ-body weight rate, long-seated forward flexion, 50 m sprint, and T test. It was investigated how body type such as height and body weight influences speed or agility and the relationship between lower extremity strength or flexion and speed or agility. Results: There was no correlation among height, body weight, BMI and 50 m sprint. There was a correlation between SQ1RM and 50 m sprint. The body type showed no correlation with T test but SQ1RM. Also, SQ-body weight rate which can be an index of the muscle strength per body weight showed a correlation with 50 m sprint and T test but no significant difference with SQ1RM, which was absolute value. Discussion: This study showed that speed and agility would depend not body type such as height and body weight but lower extremity strength to appropriately control own body weight. Furthermore, the improvement degree of strength was not that large since the strength training periods might be too short, that caused no significant difference between SQ1RM and SQ-body weight rate. SQ-body weight rate may show stronger correlation as players continue training in collegiate, adult, and professional level. Practical Application: In the coaching field of baseball, it is common to train to increase of body weight during off season. However, just gaining body weight may not be suitable to improve speed or agility. Performing squats to improve lower extremity strength while increasing body weight may improve speed and agility and avoid a risk of overweight. Considering the characteristics of baseball, not only speed but also explosive power is required, and maximum strength will improve explosive power. Improving maximum strength will be an effective method as fitness for high school baseball players to improve performance.

The Standard Value for the Fitness Level in Elite Junior Tennis Players

Shogo Uota,1Taira Imanishi,2Satoshi Inaba,1Miki Nariai,3Akiyo Yoshida,4and Kaoru Umebayashi1

1Osaka university of health and sport sciences, Graduate school of sport and exercise science, Osaka, Japan;2Rikkyo University, Tokyo, Japan;3Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan; and4Osaka Sports College, Osaka, Japan

Purpose: Jump and sprint with changing direction are the field tests used to test the fitness level of elite junior tennis players. However, there was no clear fitness target (i.e., standard value, maximum value) for junior tennis players, and it has been difficult to give any objective feedback in practical fields. This study aims to set the standard value for the feedback in coaching tennis by testing categorized fitness level of elite junior tennis players selected for Japan Tennis Association, District Training Center (DTC). Method: Subjects were 274 junior elite tennis players (70 U-12 males and 73 U-12 females; 74 U-14 males and 57 U-14 females) who have participated in DTC from May, 2015 to May 2016. U-12 included players from 9 to 12 year old, and U-14 included players from 13 to 14 year old. Data collected were height (cm), body weight (kg), body fat (%), 3-minute shuttle stamina (m), standing broad jump (m), standing triple jump (m), medicine ball throw (m), 20-m sprint, Pro-agility with lateral step, 505 agility, 5-direction sprint, and time trial of hexagon (second) considering the sports characteristics of tennis. There were 2 types of surface of the court used for testing; 94 were tested on the hard court or gym floor, and 178 tested on the omni court. Standard values for each category were calculated by Microsoft Excel. The difference of mean values among categories and gender were statistically analyzed by t-test on SPSS. The level of significance was set as 5%. Result: This study established the mean and maximum values of the data in each category (i.e., U-12 and U-14), gender, and court surface, respectively (all data will be shown on the presentation day). U-14 showed significantly higher average values in almost all data than U-12 and so did male players' record comparing to that of female players (p ≤ 0.05). However, there was no significant difference in body weight between both genders' average values (p = 0.36). Discussion: The results of this study showed that U-14 was likely to have higher fitness than U-12 as Umebayashi et al. had reported (2011). Considering the result that males showed higher fitness than females, there was a general development aspect of this age group seen. This study was the largest investigation of the fitness targeting Japanese junior tennis players and was appropriate to set a standard value because subjects were selected nationally. Also, there were some new measurement items designed for this study considering the characteristics of tennis. These data will be used as an indicator of the feedback in various coaching fields because the standard of average and maximum values were set for each court surface. Practical Application: This study set the average and maximum values of the fitness level for Japanese junior tennis players. It will be useful for a standard of a fitness test as an objective standard.

A Study of Children's Lower Extremity Flexibility and Their Movement Pattern—Changes in 7 Months

Akane Saito1and Keisuke Koizumi2

1Chiba University Graduate School of Humanities and Social Sciences, Chiba, Japan; and2Chiba University College of Liberal Arts and Sciences, Chiba, Japan

Purpose: Whereas children's lower extremity flexibility is generally evaluated by testing long-seated forward flexion, there is few studies evaluated range of motion of each joint. Furthermore, there is no studies investigated whether long-seated forward flexion test is appropriate for children whose pelvic and spine mobility are in the age-specific development stage and soft tissues are premature although long-seated forward flexion test has been used for a part of the recent fitness test for school children. Thus, it is necessary to investigate the evaluation of flexibility to understand children's fitness level. Also, there is few investigation between lower extremity flexibility and movement pattern in this age group. This study aims to investigate children's lower extremity flexibility as well as movement pattern and exam the evaluation procedure of flexibility. Methods: There were 2 investigation terms, May and December in 2015, and subjects were healthy 14 children, both boys and girls, from 4 to 5 year old. Digital video camera was used to evaluate movement pattern, and basic movements such as running, jumping, rolling and throwing based on the new fitness test for children (MEXT, 2009) were categorized through quality assessment. Additionally, subjects were tested the ability to squat with keeping heels on the ground and stand on single leg for 5 seconds. To evaluate lower extremity flexibility, SLR angle and ankle dorsiflexion angle were measured by a goniometer (Tokyo University goniometer, large, S7010, Minato Medical Science, Osaka), and long-seated forward flexion was measured by digital long-seated forward flexion measure (T.K.K.5112, Takei Mechanics, Niigata). Results: There was a strong correlation between long-seated forward flexion and SLR (May r = 0.736, December r = 0.877). Although the correlation between long-seated forward flexion and ankle dorsiflexion angle was strong in May (r = 0.772), it became weak in 7 months (r = 0.279). The correlation between SLR and ankle dorsiflexion angle was medium in May (r = 0.512) but weak in December (r = 0.296). There was no significant difference between age in months and lower extremity flexibility in each investigation term. Also, there was no significant difference in the average value of range of motion categorized by the maturity of movement patterns and long-seated forward flexion in May and December, respectively. The rate of the height development between 2 investigation terms and the rate of the changes of SLR angles, ankle dorsiflexion angles and long-seated forward flexion showed a weak correlation (r = 0.232, r = 0.426, r = 0.317, respectively). Discussion: There was little relationship between children's lower extremity range of motion and age in months, height, and basic movement patterns. Also, considering an evaluation standard for lower extremity flexibility, long-seated forward flexion test was strongly correlated with 4-year old children's SLR angles which referred hip flexion angles with hip and knee extended. Thus, the alignment of children's spine may not influence the movement pattern of long-seated forward flexion. Also, ankle dorsiflexion angles may not be referred consistently. According to the results of 2 separated investigation terms, change of the maturity of movement patterns hardly influenced lower extremity flexibility, and it is necessary to evaluate lower extremity flexibility chronologically. Practical Application: It has been reported that decreased flexibility may be one of factors of the increased sports injuries and other injuries among school children in recent. Children's bodies are generally considered as well flexible. Based on the results of this study, it is considered that the factor of changing flexibility in this age group may simply be along with neither physical development or body shape nor development of movement patterns. Thus, flexibility should be focused and evaluated as well as physical development and movement patterns in not only school ages but also pre-school ages. Also, ankle dorsiflexion angle is strongly related to squatting movement, which is used as a part of movement tests for school children, it is recommended to carefully observe ankle flexibility in family and nursing fields in future.

The Validity of the Use of Smartphone Application to Measure Counter Movement Vertical Jump

Takenori Awatani,1,2Tatsuya Urata,3Akinori Nagata,1Junji Shinohara,1Yasutaka Tatsumi,1and Ikuhiro Morikita2

1Kyushu Kyoritsu University, Fukuoka, Japan;2Graduate School of Sport and Exercise Sciences, Osaka University of Health and Sport Sciences, Osaka, Japan; and3Kansai University, Osaka, Japan

Purpose: Counter movement vertical jump (CMJ) has been used as one of the fitness test. There are various equipment to measure CMJ, and the Smartphone application (APP) is a recent measuring equipment for CMJ. However, its validity has been not clear enough. The purpose of this study is investigating the validity of the use of APP to measure CMJ. Methods: Subjects were healthy 10 collegiate male volleyball players (age 19.7 ± 0.8 year old; height 173.9 ± 6.2 cm; body weight 70.4 ± 10.7 kg). Based on the Declaration of Helsinki, all subjects were explained about this investigation and confirmed the consent before the investigation. All subjects were instructed to land on the starting point and keep facing forward while performing CMJ. A total of 5 trials were performed with a minute of rest between each trial. A video camera for the video observation (VID) was set at 1.4 m high and 4 m apart from subject, and videos were recorded with 60 fps. The inter-rater reliability of VID was investigated, and the intraclass correlation coefficients was 0.99. Measurement of jump height was processed through Kinovea, video editing software (free software). Earhole was the point of measurement, and its vertical displacement was defined as the jumping height. An iPad Touch (Apple, Inc.) was set at 1.6 m high and 2.5 m apart from subject for APP measurement, and an iOS APP (JumpPower, App Store, 120 yen) was used for the measurement. JumpPower recognized person's face and calculated jump height from the flight duration during jumping. Each trial was recorded by both equipment simultaneously. Mean value of the 5 trials was the representative value, and mean value ± standard deviation for each measurement were calculated. Validity analysis was done by Person product-moment coefficients, systematic error analysis was done Bland-Altman analysis, and the absolute value was applied. Statistical analysis was done by R2.8.1 with the level of significance set as 5%. Result: Average VID was 58.7 ± 6.4 cm while average APP was 54.4 ± 4.4 cm. The correlation coefficients was r = 0.95 (0.81–0.99), and regression formula was y = 1.155 × −4.077 (R2 = 0.91). Systematic error showed fixed bias but proportional bias. Absolute difference was 4.4 cm (95% CI; 2.8–5.9). Discussion: APP measurement for CMJ showed a higher correlation with VID observation. However, there was an average of 4.4 cm difference as well as fixed bias. Thus, it was indicated that APP measurement would always show about 4 cm lower than that of VID. The difference between both equipment may occur because VID defines jump height by vertical displacement whereas APP calculates jump height with flight duration. In future study, investigating the validity using force platform is needed. Practical Application: JumpPower is a simple APP for a very reasonable price and showed high correlation with VID observation. However, there may be a problem with a simple comparison to VID or multi-party comparison because there is a fixed bias. Using regression formula enables to get a reliable measurement without any expensive equipment. Thus, it is considered that following the progression of individual's jump height with JumpPower is sufficiently possible.

Running Performance Evaluation by Global Positioning System in Elite Rugby Athletes

Hayato Yamamoto,1Masanori Takemura,1,2Takashi Toda,3Masatoshi Nakamura,4Miku Tachibana,1Junzo Tsujita,5and Tatsuya Hojo

1Doshisha University Graduate School of Health & Sports Science, Kyoto, Japan;2Ichihashi Clinic, Kobe, Japan;3NTT DOCOMO INC., Osaka, Japan;4Niigata University of Health & Welfare, Niigata, Japan; and Institute of Health & Sports Med. Sci., Osaka, Japan

Objective: Previous researches showed the data which analyzed the running performance during rugby games such as the moving distance and velocity with the spread of the Global Positioning System (GPS), but most of those analysis were insufficient because of the short of the recruited numbers of games and players. The finding resulting from the game analysis is fundamental information to build the training programs. Therefore, it is necessary to obtain the study which has enough number of players, more subdivided positions and the new analysis items in the relationship with more improved performance. And then, the purpose of this study is to assess the performance with analyzing all 10 positions instead of doing as a position group after adding of the analysis items connected with performance. Methods: This study recruited 15 starting members from each game in the rugby team which belongs to the Japan Rugby Top League and assessed their all 39 official games in 3 seasons (15 members times 39 games, 585 samples). All 10 positions were classified into PR, HO, LO, FL, No.8, SH, SO, CTB, WTB, FB and their data was analyzed. The date was collected by the GPS-HPU (GPSPORTS, Australia) and the Team AMS (GPSPORT, Australia) was utilized for the data analysis. The analysis items for the running performance included: (a) total moving distance, (b) moving distance upon the speed zone and (c) the impact values. The statistical analyses were performed using Analysis of variance and the multiple comparisons. Results: The total moving distance were observed as follows: the Forward (PR: 5,619.1 m, HO: 5,509.8 m, LO: 5,885.8 m, FL: 5,877.9 m, No.8: 5,359.6 m), and the Backs (SH: 7,014.3 m, SO: 6,419.6 m, CTB: 6,055.4 m, WTB: 6,243.9 m, FB: 7,166.9 m). As the result of the multiple comparisons, there are significantly superior values (p ≤ 0.05) in Backs relative to Forward except there was no significant difference between both LO and FL in Forward and CTB in Backs. Between Forwards, both LO and FL showed a significantly superior value compared to No.8 (p ≤ 0.05). In Backs, the following relationship was seen: SH = > FB > SO = WTB > CTB (but SO = CTB) (p ≤ 0.05). As the result of an F-test after adjusting the ratio of the moving distance upon the speed zone to the total moving distance, the SH (23%) showed the highest value and also a significantly higher value compared to positions but WTB and FB. Discussion: The result from the total moving distance proved significance differences between each position. This result also revealed the necessity to consider the characteristics of each position when building the training programs because it is believed that the characteristics of each position required during a game influence on it. In addition to that, it is necessary to assess the characteristics of each position by adding not only the result of the total moving distance but also that of the moving distance upon the speed zone and the impact value. Practical Application: This study revealed how items related to the performance were observed depending on each position. Supporting their performance improvement during a game is a part of roles by S&C coaches, and also the game analysis is important to predict the essential training tasks to improve their performance. The findings in this study could be considered as fundamental information to build a training program for rugby.

Fitness Testing in Regional Seleced Members in U-15 Femal Soccer Athletes—Comparison Between Teams and Keys for the future

Tatsuya Aritomo,Shuhei Ohashi, and Fumiaki Onishi

Ehime Football Association Performance Enhancement Committee, Ehime, Japan

Objective: The Japan Football Association (JFA) provides special training sessions as a part of its youth project in each category every year to enhance “Individual” athletic performance based upon the “Training Centre (TC) System.” The purpose of this study is to perform the physical measurement in U-15 TC members in Shikoku (selected members in Shikoku area and among players who were under 15 year old, Shikoku Training Centre [STC]) and then investigate items which should be focused to improve the training strategies of STC in the future by the comparison to the Japanese national team members in 2 categories and that in 4 prefectures. Methods: (a) Subjects The subjects were 51 female soccer players under 15 year old selected from the areas of Shikoku. They were composed of 14 (players) from Tokushima, 11 from Kochi, 12 from Kagawa and 14 from Ehime. (b) Measurement items This study utilized 10 m run, 40 m run, Bounding (BD) and Shuttle 50 (S50) for the measurement based on the format advocated by the JFA Physical Fitness Project. In addition to that, this study referred the official data of the Nadeshiko Japan (NJ) and the U-16 National TC (Japanese national selection members under 16 year old, U16). (c) Statistical analysis The one-way analysis of variance was performed by SPSS based on values from the measurement and then the multiple comparisons by the Turkey's test was used for the result which showed significant differences. Results: From the measured results, mean values in STC were as follows respectively: 10 m run: 2.10 ± 0.08 seconds (the fastest was Tokushima: 2.06 ± 0.06 seconds, the slowest in Kochi: 2.14 ± 0.08 seconds, same order in following values), 40 m run: 6.54 ± 0.26 seconds (Tokushima: 6.41 ± 0.16 seconds, Kochi: 6.69 ± 0.30 seconds), BD: 9.4 ± 0.6 m (Tokushima: 9.6 ± 0.6 m, Kochi: 9.1 ± 0.5 m) and S50: 12.77 ± 0.44 seconds (Ehime: 12.59 ± 0.45 seconds, Kochi: 13.00 ± 0.43 seconds). Analysis of variance showed a significant difference between groups of 10 m run and 40 m run (p ≤ 0.05) but the multiple comparisons produced a significant difference only in the group of 40 m run between Tokushima and Kochi (p ≤ 0.05). The results in NJ were recorded as follows: 10 m run (1.99 ± 0.08 seconds, 40 m run (6.10 ± 0.22 seconds), BD (10.6 ± 0.5 m) and S50 (11.79 ± 0.21 seconds), and the results in U16 showed as follows: 10 m run (2.05 ± 0.08 seconds), 40 m run (6.31 ± 0.24 seconds), BD (10.1 ± 0.4 m), S50 (12.52 ± 0.40 seconds). This study revealed no superior value of any item than both NJ and U16 was obtained. Discussion: In the point that the lowest value was recorded in Kochi by the comparison between prefectures when measuring the item regarding running in a straight line, it is considered there is a possibility regarding the rate occupied by the number of players who were born between January 1st and April 1st who tended to be under the unfair condition when they were younger because the period of maturity takes approximately one year at most (27.2% in Kochi, 13.7% of all). It is also observed that Ehime, established the performance enhancement committee focusing to develop the special footwork programs, performed the highest average within the groups of Shikoku even though Tokushima performed the best in other measurements, which showed some points that should be considered for the future program. Practical Applications: The result made a point that it is necessary to raise the general standard of the physical ability of the STC to make their players to be picked into the Japanese national selection even the age category at that time was slightly different. It is hoped to share the effective training program with TC staffs from each prefecture who are engaged in STC as considering the fact that there was a significant difference in each result of the comparison between prefectures. Especially in physical ability, it is wished that the performance enhancement committee in Ehime takes a lead role to work with coaches and their coaching fields in other prefectures to make a higher standard in Shikoku regarding both the speed, as basic skills, and the footwork which has been showing the result of their efforts.

Analysis of Physical Characteristics Among Different Positions in High School Rugby Football Players

Akira Kumazaki, Shimojo Hirofumi,Kikumoto Takanori, Ito Wataru, Nakamura Emi, and Nakamura Masatoshi

Niigata University of Health and Welfare, Niigata, Japan

Introduction: Rugby football is one of the sports that demand a component of physical strength such as muscle strength and muscle volume, and this component is different for each position (e.g., FW and BK). It is thought that an FW player should weight more, and that it is necessary for a BK player to have more strength in their lower limbs. The present study examined the physiological characteristics of high school rugby football players. Methods: Fifty-three male rugby football players participated in this study during the preseason. They were shared with 23 FW players and 18 BK players, and also classified into the first team (players with high performance: 21 players) and the secondary team (players with low performance: 20 players). Twelve players whose position is not clear (e.g., sophomore) were excluded. Body composition (body mass, lean, fat) was measured using an Inbody 370 (Biospace, Korea), and the lower-limb isokinetic muscle strength was measured using a Biodex system 4 (BIODEX, USA). The isokinetic strength variables that were most commonly used were the concentric/concentric mode of contraction at angular velocity of 60 and 180 deg·s−1. Results: Body mass and lean in the first team were significantly heavier than those in the secondary team (p < 0.01). There was a stronger correlation between body mass and fat in FW players (r = 0.89, p < 0.01) than in BK players (r = 0.62, p < 0.01). There were significantly correlation among isokinetic strength and body mass, lean in BK players (r = 0.62 and 0.63, p < 0.01, respectively) but not in FW players (r = −0.03 and −0.02, p > 0.05, respectively). Discussion: In rugby football, body mass and lean are important physiological components required to play the sport. In the present study, first team players had a heavier body mass and lean than secondary team players. However, there was a stronger relationship between body mass and fat but not lean in FW players. In addition, the body mass was not associated with lower-limb isokinetic strength in FW players. The results of this study indicate that high school rugby FW players leave a margin for improvement in strength and conditioning. Practical Applications: The results of this study indicate that the body constitution relates to the selection of a player in high school rugby football. However, there are differences between FW players and BK players.

The Effect of the Single Drop Sets Strength Training With Varieties of Load on the Muscle Hypertrophy, the Maximum Muscle Strength and the Muscle Endurance

Hayao Ozaki,1Atsushi Kubota,1Toshiharu Natsume,1Takashi Abe,2Shuichi Machida,1and Hisashi Naito1

1Juntendo University, Inzai, Japan; and2National Institute of Fitness and Sports in Kanoya, Kanoya, Japan

Objective: The purpose of this study is to investigate the effect of the single drop sets which is the strength training combined from the high load (80% of one-repetition maximum [1RM]) to the low load (30% of 1RM) for the muscular hypertrophy, the maximum muscle strength and the muscle endurance. Methods: Nine young participants who didn't have a strength training habit regularly (age: 26 ± 1 year old, height: 172.6 ± 2.4 cm, weight: 65.1 ± 3.1 kg) were assigned to 8 weeks dumbbell curl training program. Each one of arms of subjects was randomly assigned to 2 of 3 categories: (a) the high load condition (80% of 1RM: n = 6), (b) the low load condition (30% of 1RM: n = 6) and the single drop sets condition (80→30% of 1RM: n = 6). At conditions of the high load and low load, 3 sets of the training were performed until concentric failure. The high load condition had 3 minutes resting period between sets, and the low load condition set 90 seconds. On the other hand, the single drop sets condition performed a single high-load (80% 1RM) set and then 4 drop sets at 65, 50, 40 and 30% 1RM without recovery intervals between sets. A cross-sectional area of arm flexors examined by MRI and the 1RM were measured at baseline, 4 and 8 weeks. The maximum isometric strength and the maximum repetition number at 30% of 1RM (muscle endurance test) were also measured by BIODEX system 4 before and after the training. Results: This study showed that the total amount of the training (lifted weights times repetitions) during the entire period of the low load condition (15,365 ± 3,251 kg) was significantly larger (p ≤ 0.05) relative to both the high load condition (4,724 ± 354 kg) and the single drop sets condition (5,308 ± 408 kg). The mean value of each training time per a session included the resting time between sets was the shortest at single drop sets condition (2 minutes and 5 ± 8 seconds) followed by the high load condition (6 minutes and 50 ± 6 seconds) and the low load condition (11 minutes and 39 seconds ± 2 minutes and 17 seconds.). A cross-sectional area of arm flexors showed the effect of the time (p < 0.001) but there was no significant difference between 3 groups (the high load: 14.7%, the low load: 14.0% and the single drop sets: 14.8%). An interaction in 1RM muscle strength was observed (p ≤ 0.05), and the high load condition (22.4%) had the tendency to be the highest training effect while the low load condition (8.3%) tended to be lower. On the other hand, an interaction in the maximum isometric strength was also recorded (p ≤ 0.05) but no significant increase was observed in the low load condition (1.6%) while both high load (9.4%) and the single drop sets condition (10.0%) revealed an increase of the same level. In addition to that, an interaction in the maximum repetition number at 30% of 1RM was seen (p < 0.01) while the low load (91.3%) and the single drop setscondition (39.2%) showed a significant increase (p ≤ 0.05). Discussion: This study revealed the single drop sets strength training composed of the range from high load (80% 1RM) to the low load (30% 1RM) obtain the similar effectiveness for muscular hypertrophy with less training amount and time compared to only the high load or the low load training. Generally speaking, the high load training causes an increased maximum muscle strength and the low load training is effective to improve the muscular endurance in addition to muscular hypertrophy but the single drop sets strength training utilized in the study showed increased both the maximum muscle strength and muscle endurance. As a conclusion, it is assumed that the single drop sets strength training composed from the high load (80% 1RM) through the low load (30% 1RM) increase the maximum muscle strength and muscle endurance in addition to muscular hypertrophy. Practical Applications: The single drop sets strength training is time effective because it doesn't need to take resting time between sets. And also, performing the training with this protocol could improve not only the muscular hypertrophy but also the maximum muscle strength and muscular endurance simultaneously. It is thought that the protocol in this study could be an effective way for athletes and the enthusiasts who have limited time for training.

Differences in Cardiorespiratory Responses Body Mass-Based Squat Exercise Between Boys and Adult Men

Miki Haramura, Yohei Takai,Masayoshi Yamamoto, and Hiroaki Kanehisa

National Institute of Fitness and Sports in Kanoya, Kanoya, Japan

Introduction: Body mass-based exercise can produce favorable stimulus for improving neuromuscular and cardiorespiratory functions, and metabolic profiles in men and women with a wide range of age (Takai et al., 2013; Haramura et al., 2015). Children show unique metabolic responses (Armstrong and Welsman., 1994) and ventilatory regulation (Springer et al., 1988) to exercises, compared with adults. Considering these aspects, cardiorespiratory responses during body mass-based exercises in children may be different from those in adults. For children, however, there is little information concerning this subject. Therefore, this study aimed to clarify the differences in cardiorespiratory response during the body mass-based squat exercise between children and adults. Methods: Eleven boys (10.6 ± 0.5 years) and 15 adult men (24.2 ± 4.8 years) continuously performed 200 times body mass-based parallel squat exercise with a tempo of 45 rpm. During the exercise, oxygen uptake (V̇o2) and heart rate (HR) were measured. V̇o2 was expressed the value relative to body mass (V̇o2/BM), and was normalized to maximal V̇o2 (V̇o2max) obtained from an incremental load test (%V̇o2max). Electromyograms from the vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM), biceps femoris (BF) muscles were determined. EMG amplitudes during the exercise were normalized to those during maximal voluntary contraction, and expressed as relative value (% EMGmax). All data were averaged over every 1 minute. Results: After first minute from exercise onset, V̇o2/BM, %V̇o2max, HR in children was higher than those in adults, but there were no significant age-related differences in the corresponding variables at other time points. There were no significant age-related differences in the %EMGmax of VL, RF and VM. The %EMGmax of BF was higher in boys than adults. The exercise time that cardiorespiratory parameters became stable was faster in boys than in adults when V̇o2/BM reached to steady state, the relative loads of cardiorespiratory parameters and muscular activity levels of the knee extensors did not differ between boys and adults men. V̇o2max/BM was negatively related to %V̇o2max during the body-mass squat exercise (r = −0.617 for boys, r = −0.561 for adults, p ≤ 0.05). Time courses of V̇o2/BM and HR differed between boys and adult men. Discussion: The faster appearance of stable condition in boys compared to adults agrees with earlier findings. Similarity between boys and adults in the relative loads of cardiorespiratory parameters and muscular activity levels of the knee extensors under steady state condition indicates that relative physiological requirements during body mass-based squat exercise may be independent of age. Practical Applications: The present findings can be useful to design training program consisting of body-mass based exercise for children and adults.

Effects of Aerobic Arm or Leg Exercise Following Resistance Training on Blood Flow of the Brachial Artery and Femoral Artery


Nippon Sport Science University, Tokyo, Japan

Introduction: Previous studies suggest that concurrent endurance training (ET) and resistance training (RT) interfere with the effects of RT, such as strength gains and muscle hypertrophy. Local interference with lower-body strength or muscle gain has reportedly occurred when RT and ET were performed concurrently in the lower extremities. Although systemic interference, also termed the transfer effect, has been reported, its mechanisms have not been examined. We hypothesized that blood flow plays a pivotal role in systemic interference. The purpose of this study was to examine the effects of lower-body or upper-body ET following RT on blood flow in the brachial artery (BA) and femoral artery (FA). Methods: Fourteen healthy young men (age: 20.1 ± 1.5 years, height: 170.9 ± 4.1 cm, weight: 62.4 ± 6.4 kg) were divided into exercise and control groups. The 2 exercise groups consisted of aerobic arm exercise following whole-body RT (AT) and aerobic leg exercise following whole-body RT (LT). Seven subjects crossed over to a different exercise group. The control group was comprised of 7 subjects (age: 20.0 ± 1.4 years, height: 167.0 ± 4.2 cm, weight: 57.6 ± 1.4 kg) who underwent whole-body RT alone. All subjects performed whole-body RT (free weight bench press and squat exercises) consisting of 3 sets of 10 exercises at 75% of 1 repetition maximum. Subjects in the exercise groups performed aerobic arm or leg exercise at 65–75% of their maximal heart rate for 30 minutes immediately after each RT session. Blood flow was measured before and immediately after RT, immediately after ET, and 15 and 30 minutes after each training session. Pulse wave velocity (PWV) was measured before and 30 minutes after ET. Results: FA blood flow in the LT group was higher at all time points compared with baseline. FA blood flow in the AT group was higher after RT, compared with baseline. BA blood flow in the LT and AT group was higher immediately after RT and immediately after ET compared with baseline. Additionally, it was significantly increased in the AT group at 15 minutes after ET. Discussion: An increase in blood flow due to RT was maintained in both the upper and lower body following ET at the site of exercise. Moreover, ET of the lower extremities improved blood flow in the upper limbs that did not undergo ET. Lower-body ET performed after lower-body RT and upper-body and lower-body ET performed after upper-body RT seemed to contribute to the interference mechanism. In conclusion, we found that blood flow after RT differed according to the ET site. Practical Applications: Concurrent ET and RT adaptation and interference may be affected by the exercise mode, such as upper-body or lower-body exercise.

The Effectiveness of the Training Program of the Former Decathlon Athlete in Track and Field Who Aims to Become a Keirin Athlete—Two Months Training

Miyuki Moriand Maki Akiyama

International Budo University, Chiba, Japan

Objective: People who want to be a keirin athlete have to pass the national board exam as known as the keirin athlete certificate exam. The people also have to enter the Japan Keirin School for taking the training program for approximately one year to pass the certificate exam. The people who have not experienced a keirin race before need to take the qualification exam to enter the school and the first-stage exam includes the measurement of both the height of vertical jump and the back muscle strength. As the second-stage exam of the qualification exam, the momentary maximum speed, the maximum revolutions per minute and the total workload with utilizing bicycle pedaling are measured 2 months after passing the first-stage exam. The purpose of this study is to report both the effectiveness and contents of 2 months training of the former decathlon athlete in track and field who aims to become a keirin athlete. Methods: One male student aged 22 years who converted his career from decathlon to keirin race was enrolled in the study. His physical characteristics were 177.0 cm as his height and 73.4 kg as his weight. His best record as 3 years decathlete was 5,362 points and he was mostly good at the pole vault. The participant changed his main training goal from the improvement of decathlon performance into that of the vertical jump, the back muscle strength and bicycle pedaling ability as the qualification exam requirements since June 1st. The term from June to October was defined as the general preparation period and 2 months from June to the end of July were the muscular hypertrophy period. As a control test, the back muscle strength, vertical jump and bicycle pedaling based on the qualification exam were performed in the participant. The maximum revolution per minute by bicyle pedalling was recorded at 0.1 kp and 12 kp load value by utilizing POWERMAX-VII (COMBI). The circumference of the thigh and the body composition were also recorded to see his body characteristics. Strength training was introduced once every 3 days mainly composed of high clean, squat, single-leg leg press and dead lift. The isometric training above the knee during dead lift was also performed. For jump training, the depth jump which was performed before June was altered to the squat depth jump, and the either jump training or bicycle pedaling training was used once every 3 days. The rest day was set in once every 3 days and such light exercise was provided on that day. The participant had a chance to learn about the sport specific training for bicycle pedaling from the former keirin athlete on a regular basis. Results: The vertical jump and back muscle strength were improved by 5 cm (8.2%) and 56 kg (31.0%) at 8 weeks after the onset of the training. Bicycle pedaling at 0.1 kp and 12 kp load value were improved by 22 rpm (9.6%) and 38 rpm (57.6%) respectively. The body characteristics of the thigh circumference and his weight were increased by 5 cm (8.5%) and 6.7 kg (9.1%) respectively. The participant's introspective report revealed that “the training was going well.” Discussion: The reason why the vertical jump was improved was considered as a reflection from the training effect of high clean with the specificity of the joint angle and also that of the squat depth jump. There was a characteristic that the squat depth jump could be performed by almost same joint angles with vertical jump because it made the knee and hip joint 90° flexion. The isometric training of dead lift could be affected for the back muscle strength from both the way of muscular contraction and joint angles at knee and hip. The single leg leg-press influenced on the pedaling ability at 12 kp load value and on the thigh circumference. The future training should include the low-intensity high-speed training to improve the pedaling ability at 0.1 kp load value as the second-stage exam requirement with remaining and improving his current performance. Practical Applications: The training performed in the study suggested that even a decathlete that has been familiar with training could get more improved in the vertical jump, back muscle strength, body characteristics and so on.

The Influence of Lower Limbs on the Bat Velocity in the Baseball Batting

Kohei Murakami,1Masahiro Kageyama,2Hajime Nakashima,1,3and Akira Maeda2

1Graduate School of Physical Education, National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan;2National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan; and3National Institute of Technology, Anan College, Tokushima, Japan

Introduction: In baseball batting, high-bat velocity at ball impact is particularly important for the improvement of the batting performance such as greater distance and high velocity of a batted ball. High-bat velocity could be produced through the coordination from lower limbs, pelvis, shoulder, arms to hands what is called the open kinetic chain (Elliott, 2000). However, most of previous studies regarding motion factors which affected the bat velocity focused on the trunk, upper limbs or a bat, therefore the effect of lower limbs function during baseball batting on the bat velocity is still unclear. The purpose of this study was to clarify differences in the ground-reaction force and the moment affected by lower limbs, in relation to differences in the bat velocity. Methods: The subjects were 18 collegiate baseball players (age: 20.8 ± 2.6 year old, height: 171.5 ± 4.2 cm and weight: 69.7 ± 5.8 kg). The subjects were performed tee-batting (hitting a ball placed on a tee), all tee-batting were performed indoors. A ball was supposed as passing over the center of the home base at the height of greater trochanters of a subject's femurs. After the completion of the warm-up exercises, the subjects were asked to perform 5 times at maximal effort with an interval of enough time between the trials, to hit toward the net set at the center. In this study, a right-handed batter used right leg as a pivot leg and left leg as a stride leg, and vice versa. Three-dimensional coordinates were measured using a motion analysis system (Eagle System, Motion Analysis Corporation) with 12 Eagle cameras with a sampling rate of 500 Hz and a shutter speed of 2000 Hz. The GRF of the pivot and stride legs during baseball batting was measured using 2 multicomponent force plates (9287C, Kistler Corporation), each of which had a sampling rate of 2,000 Hz. Results: On the basis of maximum bat velocity at ball impact, the subjects with bat velocity greater than the mean were assigned to the high-velocity group (HG), while the subjects with bat velocity lower than the mean were assigned to the low-velocity group (LG). Therefore, 18 subjects were assigned to either the HG (n = 9, height: 172.2 ± 5.0 cm, weight: 74.2 ± 4.9 kg, bat velocity: 128.5 ± 4.0 km·h−1) or LG (n = 9, height: 170.8 ± 3.1 cm, weight: 67.1 ± 4.1 kg, bat velocity: 117.4 ± 3.6 km·h−1). The results were as follows: (a) the impulse of moment around the vertical axis at the swing phase (the period from when the stride foot makes contact with the ground until the point the bat was impacted) was significantly higher in HG than in the LG (p ≤ 0.05). In addition, both the impulse of moment around the vertical axis affected by pivot leg at the period from the first half to middle of swing phase and that around the vertical axis affected by stride leg at middle of swing phase were significantly higher in HG than in the LG (p ≤ 0.05). Discussion: The result of this study indicates that high-bat velocity batter can generate greater angular momentum around the vertical axis in order to increase the trunk rotation. Therefore, current result suggests that high-bat velocity batter can generate greater momentum by interlock the moment of both legs and the trunk rotates effectively. Thus, these findings obtained here indicate that for high-bat velocity, the energy of the lower limbs during baseball batting plays an important role in order to transfer to the trunk, arms and a bat. Practical Applications: It is necessary to obtain a large rotation motion of the trunk produced by lower limbs for increasing bat velocity. To do that, it is important that the introduction of the resistance training which is similar to the motion of baseball batting such as a side throw training with a medicine ball. The body weight of HG was heavier than that of LG. With all these matters, it is considered that low-bat velocity batter needs to increase the body mass in order to increase bat velocity. As a conclusion, it is suggested that for increasing bat velocity, an increase of the body weight is also important in addition to the training for the improvement of rotation motion.

A Cross-Sectional Study on Age-Related Development of Ball Velocity and Force/Power in Baseball Pitchers

Masahiro Kageyamaand Akira Maeda

National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan

Introduction: To examine the characteristics of development in baseball pitchers would help coaches to understand their players' current capacity and also be useful in choosing the best method of resistance training. A cross-sectional study in baseball pitchers was performed in order to investigate strength and power considering age differences. The purpose of this study was to clarify the characteristics of changes in ball velocity and the force/power output-generating capacity produced from the upper limbs, lower limbs and trunks of baseball pitchers aged 12–22 years. Methods: The subjects were 106 baseball pitchers belonging to baseball clubs (12–13 years: n = 26, 14–15 years: n = 33, 16–17 years: n = 18, 18–19 years: n = 23 and 20–22 years: n = 6). All subjects were measured for height, weight, ball velocity, hand grip strength, back muscle strength, torque of knee extension, power of knee extension, isometric trunk rotation strength, trunk rotation power, distance of side throw and back throw with a medicine ball. Ball velocity was measured using a radar gun. Results: Ball velocity and the strength/power produced from upper limbs, lower limbs and the trunk in baseball pitchers were observed to increase over time from 12 to 19 year old. These observed changes were relatively greater mainly in muscle strength and power from the trunk and lower limbs compared to that of the upper limbs. In addition, considering the measured values and the rate of change upon aging, the increasing rate of ball velocity in the ages of 14–15 years and 18–19 years was greater than the other age groups, and the increasing rate of the strength and power produced from the trunk and lower limbs was higher than that from the upper limbs, and also showed a higher value than ball velocity. Discussion: The results in this study showed that ball velocity and the strength/power produced from upper limbs, trunk and lower limbs in baseball pitchers increased over time in the ranges from 14–15 to 18–19 year old, and also those changes were obvious in the trunk and lower limbs. High ball velocity pitchers have been observed to exhibit greater stride knee extension (Kageyama et al., 2014; Matsuo et al., 2001), trunk rotation motion and trunk twist movement (Fleisig et al., 1999; Kageyama et al., 2014; Matsuo et al., 2001; Stodden et al., 2001) during the arm acceleration phase (the period from when the stride foot makes contact with the ground until the point the ball is released). Taking these findings into account together with the current results, the fact that the strength and power produced by the trunk and lower limbs increased dramatically with aging could be considered as an important part of the body function in the acceleration phase during the pitching motion because the motion factors in the trunk and lower limbs were essential to pitch at high velocity. Therefore, the conclusion from this study is that the development of strength and power of the trunk and lower limbs in baseball pitchers could influence the differences in development of body parts with aging. The important role of the acceleration phase for pitching at high velocity was also noted. Practical Application: This study indicated that the change in ball velocity at the age of 14–15 years could be affected by an increase in the strength and power associated with secondary sexual characteristics, and the change in ball velocity at the age of 18–19 years could be influenced by both differences in development of body parts with growth and the function of the lower limbs and trunk. From the above, it is considered that the introduction of high-intensity resistance training to enhance ball velocity is appropriate if utilized after 16 year old, and also it is assumed that the improvement in the strength of the lower limbs and the trunk are more important than the upper limbs. In addition, the findings in this study could be considered as important information for baseball players and coaches, not only to evaluate the strength and power produced by the lower limbs, upper limbs and trunk, but also to investigate specialized training methods.

Two-Year Changes in Anthropometric and Motor Ability Values in Youth Female Soccer Players

Norikazu Hirose,1Mariko Shimada,2and Raldy Mariano3

1Waseda University, Tokyo, Japan;2Japan Institute of Sports Sciences, Tokyo, Japan; and3Waseda University, Tokyo, Japan

Introduction: Previous research studies cite body size and motor abilities (such as sprint speed, change of direction (COD) ability and muscular power) as factors that distinguish elite from sub-elite youth players, and these abilities are considered useful as talent identification indexes. Thus, as “talent may be characterized by properties that are genetically transmitted and partly innate,” it is necessary to examine the differences in the ranking of anthropometries and motor abilities during adolescence. This present study examined 2-year changes in anthropometric variables and motor abilities in elite female youth soccer players to identify potential talent identification indexes. Methods: Height, weight, lean body mass (LBM), 40-m sprint speed, muscular power (5-step bounding), and change of direction (COD) ability (10 m × 5 COD), and Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) were measured in 12- and 15-year-old soccer players and repeated after 2 years (at 14 and 17 years of age). The rank correlation between each measurement value was analyzed using the Spearman rank correlation test. Correlations between longitudinal changes in all measurement items were also analyzed using the Pearson correlation coefficient test. Values of p ≤ 0.05 were considered statistically significant. Results: Both groups had small ranking changes in height (12- to 14-year-olds: ρ = 0.77, 15- to 17-year-olds: ρ = 0.94; p < 0.01), LMB (ρ = 0.76, ρ = 0.87; p < 0.01), 40-m sprint speed (ρ = 0.80, ρ = 0.90; p < 0.01) with a statistically significant correlation between the initial values and those obtained 2 years later. However, 10 m × 5 COD ability and Yo-Yo IR1 in both group and muscular power in 12- to 14-year old group had a large ranking change between the first- and second-year values. Discussion: These results imply that ranking change in sprint speed during normal circumstances of soccer practice over time is minimal. Thus, sprint ability appears to be a useful talent identification index for elite youth female soccer players. On the other hand, muscular power had limitations as a talent identification index as it was useful only for the 15- to 17-year old group. The results also suggest that rankings for COD ability and Yo-Yo IR1 change significantly throughout the growth phase. These attributes are regarded as foundational for future training guidance because they indicate that adaptability to training is high, suggesting the need for more targeted COD and speed endurance training throughout the growth phase. Practical Application: Coaches will be able to predict future sprint performance of youth female soccer players based on current sprint speed. This result implies that sprint speed can be used to aid identification of future elite female soccer players. Additionally, the sprint ability is a determinant of soccer performance, thus specific training to improve sprint ability is warranted, especially from 15 to 17 years old. Finally, the ability to change direction, muscular power, and speed endurance are highly trainable during adolescence. Thus, coaches should have a training program dedicated to improving these metrics to improve soccer performance.

A Study of Teaching Method for Squat by Student Training Coaches

Honami Tsukada,1,2Miyuki Mori,4Michihisa Aoyama,3Hiroki Takeuchi,3Kenichi Seki,1and Toshiharu Yamamoto4

1Body Conditioning Factory Co., Ltd., Nagano, Japan;2Ueda Orthopedic Clinic Personal Conditioning Center, Nagano, Japan;3AR-Ex Medical Research Center, Tokyo, Japan; and4International BUDO University, Chiba, Japan

Objective: A squat as a fundamental exercise for lower limbs is well known for the effective training and is introduced in various kinds of competitive sports. However, a lot of reports regarding a teaching method of it and points to be careful were seen here and there while those teaching methods are dependent on coaches. When talking about one-repetition maximum (1RM) which is used to assess the squat ability, it could be confused when we compare and investigate measured values in the case that how to perform when the measurement is not standardized. The purpose of this study is to reveal the present condition regarding a teaching method for squat at the actual field by student training coaches. Methods: Subjects were 150 student training coaches under the education about the training at either university or technical colleges which have the physical education or sports courses. The questionnaire survey was carried out with utilizing a questionnaire method. The valid response rate was 88%. The contents of the questionnaire included following questions: how long they have taught about weight training, what kind of squat they teach, the purpose why they introduce squat as a part of training menu, teaching method of each kind of squat, and what kind of squat they use to measure 1RM. Results: The type of squat introduced to this study by student training coaches were as follows; parallel squat 31%, half squat 19%, full squat 13%, and quarter squat 9%. It is observed that the purposed angles of knee and hip joints were not unified in the response of the question to ask how deep parallel squat should be down. In the type of squat used to assess 1RM, parallel squat was utilized in 62% of responses followed by full squat in 20%, half squat in 16%, and both quarter and front squat in 1%. The parallel squat was the most introduced type of all in teaching situation and also was used to measure 1RM but there seemed to be a difference between the teaching method and the purpose why they introduced to the training menu. Discussion: The result in this study showed differences in teaching methods on each type of squat by student training coaches. It is assumed that those differences seemed to be from a specificity of sports and different perspectives of each coach. It is necessary to adjust teaching methods upon obvious reasons including the sports movement, clients' age and alignment. However, in case of the measurement for 1RM, the outcomes could not be accurately compared if there is no standard. From the above, the standardized teaching methods for each type of squat upon the purpose were needed for the sake of being able to accurately compare especially measured values of 1RM. The future study should be included the investigation recruiting certified strength and conditioning coaches with enough experiences and knowledge. Practical Application: There are many variations of squat depending on the purpose but it is important to understand why the method would be used after clarifying the aim of training thoroughly when teaching. In addition to that, it is necessary to understand how different types of squat affect measured outcomes especially when recording 1RM. It is also essential to make sure that requirements and types of squat at the time of measurement are corresponded to compare to others' measured values.

The Impact Affected by Hyperextended Knees on Underwater Dolphin Kicking

Satoshi Iizuka,1Atsushi Imai,2and Koji Kaneoka2

1Graduate School of Sport Sciences, Waseda University, Saitama, Japan; and2Faculty of Sport Sciences, Waseda University, Saitama, Japan

Objective: There are a lot of swimmers with a high joint flexibility in the competitive swimming field and it is generally beneficial for the competitive swimming performance but the hypermobility could be the cause of injuries. One of those is hyperextended knee often seen in knee joints of competitive swimmers. In the underwater dolphin kicking motion, a phase difference of flexion and extension by 3 joints in lower limbs is believed to cause a big influence on the propulsive force. However, there is no previous report to show a positive influence of hyperextended knees on their performance. The purpose of this study is to reveal the impact given by joint flexibility of knee joints for the performance of underwater dolphin kicking. Methods: Seventeen male competitive swimmers who belong to swimming clubs at college sports unions were enrolled in the study. Two attempts of 20 m underwater dolphin kicking without breathing were performed with making the maximum efforts by each subject in the swimming pool with a water depth of 1.3 m. The underwater light emitting markers (Kirameki, Nobby Tech) were applied at 4 spots: the greater trochanter of femur, knee joint fissure, lateral malleolus and tiptoe over their right side of body surfaces. The underwater high-speed cameras (HAS-200, DITECT) were placed under the water at 7.5 and 12.5 m from the start line and recorded from the right side of swimmers. From recorded movies, the angle of a knee joint and an ankle, and a swimming speed during swimming motion were calculated. The angle of the knee joint was defined as the angle produced by 3 spots including a greater trochanter of femur, knee fissure and lateral malleolus of ankle. The maximum flexion angle was also defined as the minimum knee joint angle because the angle described above would be the smallest at the moment of maximum flexion. In addition to that, the static range of motion for a knee joint and an ankle were measured on the ground. The Pearson correlation coefficient was utilized to investigate the relationship between each joint angle and a swimming speed. Results: The tendency of a positive correlation was observed between both the angle of hyperextended knee during swimming motion (r = 0.43, p = 0.09) and the maximum planter flexion angle of ankle (r = 0.43, p = 0.08), and a swimming speed. There is a significant positive correlation between a swimming speed and both the minimum knee joint angle during swimming motion (r = 0.54, p = 0.03) and the static maximum planter flexion angle of ankle on the ground (r = 0.50, p = 0.04). Discussion: The correlation (or the tendency) with a swimming speed was observed in the angle of hyperextended knee during swimming motion, the minimum knee flexion angle, the maximum planter flexion angle of ankle and the maximum planter flexion angle of ankle on the ground. The approved correlation between the angle of hyperextended knee and a swimming speed was the result which affirmed previous hypothesis. As the reason why it is faster if the angle of knee flexion is small when dolphin kicking, it is considered that an increasing knee joint flexion causes reduced speed because the thigh and lower leg parts would have resistance from knee flexion position at the beginning of the downbeat. A swimmer who is able to hyperextend their knees has a capacity of faster dolphin kicking because they could secure a wide stroke for kicking while limiting a knee flexion not to reduce the speed. Not only each of knee or ankle joint but also both 2 joints are important to produce stronger propulsive force. When performing underwater dolphin kicking as a whipping motion, it is necessary to obtain the flexibility of each joint and the muscle strength to control them for keeping transmitting the energy repeatedly from the core to feet. Practical Application: The result in this study concluded that it is effective to instruct swimmers in limiting knee flexion angles when teaching dolphin kicking for the improvement of their performance.

Effects on the Oxidative Stress and the Oral Immune Function by Acute High-Intensity Exercise

Ryota Sone,1Kai Matsuba,1Nobuhiko Eda,2and Koichi Watanabe1

1University of Tsukuba, Ibaraki, Japan; and2Waseda University, Saitama, Japan

Objective: The oxidative stress is raised by the production of active oxygen at the time of overworking because of the accumulation of fatigue due to repetitive high-intensity exercise performed by athletes. It is thought that the oxidative stress could give an influence on the production of pro-inflammatory cytokines which is related to the secretion of salivary secretory immunoglobulin A (SIgA) as a barometer for the oral immune function. From the above, it is thought that there is a possibility which the oxidative stress is indirectly connected with the oral immune function. The secretion of salivary SIgA has been used as a barometer for the relationship of upper respiratory tract infection as known as the greatest number of the incidence in athletes. However, there is no previous report so far regarding the investigation of both the degree of oxidative stress and the salivary SIgA secretion rate at the same time from the acute high-intensity exercise. The purpose of this study is to examine the effects on the oxidative stress and the oral immune function by acute high-intensity exercise, and the relationship between them. Methods: Healthy male graduate students carried out in the study by a randomized crossover design after setting 2 conditions: the control condition defined as a sitting resting and the exercise condition which composed of 50 minutes ergometer exercise at 80% V̇o2peak with using the V̇o2peak measured in advance for the reference. In the exercise condition with an ergometer bike, the 50 minutes exercise performed after a warm-up to increase it by 80% V̇o2peak in first 10 minutes. It was measured d-ROMs test (the barometer of oxidative stress degree) by the using FREE CARRIO DUO (WISMERLL) both before and after the intervention, and the salivary SIgA secretion rate (the oral immune function) by the ELISA using saliva samples both before and 2 hours after the intervention. Results: As a result of 2-way analysis of variance, there was a significant interaction (p = 0.019) between these 2 conditions in the d-ROMs test measured as the standard of oxidative stress degree. In the exercise condition, there was a significant increase (p = 0.003) in pre-exercises (265 ± 10 U.CARR) compared to post-exercises (289 ± 13 U.CARR). On the other hand, no significant change was observed in the intervention of both of 2 conditions regarding the salivary SIgA secretion rate measured as the oral immune function. There was also no significant difference between the exercise and resting conditions. Discussion: The increase of the oxidative stress degree was observed in the intervention of acute high-intensity exercises in this study but it ranged from normal to light meaning the relationship with the disease was not reported. On the other hand, there is no observed change in the salivary SIgA secretion rate used as a barometer for the oral immune function by the exercise intervention. Therefore, it is thought that it is necessary to individually assess both the oxidative stress degree and the salivary SIgA secretion rate on 50 minutes high-intensity exercise. Practical Application: An increase of the oxidative stress from normal to light level was seen after 50 minutes high-intensity exercise but individual differences were noticed regarding the extent of an increase. That is to say, the interpretation with considering individual extent of a change is needed when the oxidative stress degree is used as a management tool for the condition in the field.

Impact of High Intensity Endurance Exercise in Hypoxia on Energy Metabolism

Daichi Sumi,Chihiro Kojima, and Kazushige Goto

Ritsumeikan University, Shiga, Japan

Introduction: Acute physiological responses during endurance exercise in hypoxia have been well demonstrated (Katayama et al. 2009). However, most of previous studies using hypoxia selected low to moderate intensity exercise (e.g., 50–80% of V̇o2max) with relatively short duration of exercise (≤ 60 minutes, Koelwyn et al. 2012), which did not correspond with typical training protocol among trained endurance athletes. The purpose of the present study was to determine energy metabolism during high-intensity endurance exercise in moderate hypoxia among endurance athletes. Methods: Nine trained endurance athletes (169.8 ± 2.2 cm, 57.1 ± 1.1 kg, V̇o2max 62.8 ± 1.6 ml·kg−1·min−1) completed 2 different trials on different days, consisting of exercise in moderate hypoxia (H, FiO2:14.5%) and in normoxia (N, FiO2:20.9%). They performed interval type of endurance exercise (10 × 3 minutes running at 95% of V̇o2max with 60 seconds of active rest at 60% of V̇o2max) followed by 30 minutes continuous running at 85% of V̇o2max in either hypoxia or normoxia. Venous blood samples were collected before the exercise and during 120 minutes of post-exercise period. Expired gases and percutaneous oxygen saturation (SpO2) data were collected during exercise session. Results: During exercise session, the oxygen uptake and SpO2 were significantly lower in the H than in the N trials (p < 0.0001). Respiratory exchange ratio during exercises remained significantly higher in H trial than in N trial (p < 0.0001). The H trial revealed significantly greater exercise-induced elevation of blood lactate compared with N trial (p = 0.02). Serum FFA concentrations increased significantly with exercise after the exercise in both trials, with no significant difference between the 2 trials. Hypoxia-induced reduction of SpO2 (% change in SpO2 between H and N trials) during the exercise was significantly corrected with hypoxia-induced elevation of blood glucose concentration (p = 0.01) Discussion: The augmented lactate response in the H trial was observed with concomitant elevation of RER during the exercise. These results suggest that carbohydrate metabolism during exercise was promoted in hypoxia, which correspond with previous findings (Friedmann et al. 2004; Katayama et al. 2009). Furthermore, we have found a significant correlation between the SpO2 and the area under the curves for blood glucose concentration. There was also a tendency of correlation between hypoxia-induced reduction of SpO2 and blood lactate elevation (p = 0.06). These results suggest that the subjects with greater reduction of SpO2 in hypoxia promote anaerobic (glycolytic) energy supply. In summary, endurance exercise in moderate hypoxia elicited lactate response, and the reduction of SpO2 might be a factor for augmented carbohydrate metabolism. Practical Applications: Strenuous training in moderate hypoxia promotes anaerobic energy metabolism (lactate metabolism) compared with the same training in normoxia. Therefore, the use of hypoxia during endurance training session may be an efficient strategy to improve lactate metabolism for endurance athletes (e.g., middle-long distance runner, cyclists).

Injuries Occurrence in the Non-Professional Rugby Team

Tomonori Sasaki,1,2Yoshimasa Setoguchi,1Naoto Yoshida,2Hiromu Takahashi,2and Akira Okuma1

1Midori Clinic, Mie, Japan; and2HondaHEAT, Mie, Japan

Objective: In rugby, it is not difficult to be suggested that the increased opportunity in the contact play resulting from the sport specificity leads to increase the number of getting injured. The accumulation of fatigue also affects the incidence of injuries at the end of the season. The purpose of this study is to reveal the tendency of injuries by the investigation of injuries on one season in the company rugby team which belongs to the top league. Methods: The study term was from April in 2015 to January in 2016 and the team (53 males) belong to the Japan Rugby Top League was recruited. An injury was classified according to the standard by the WR. The number of injuries was recorded and the incidence of an injury was defined if a player skipped training at least one day due to an injury. The term in this study was consisted of the Practice period which mainly included practice games (from June to August), the Pre Season period mainly including pre-season games (from September to October) and the In Season period which mainly had official games. An injury was classified upon each time of the incidence and the frequency of the injury incidence on each period was measured. The concussion recognized as an important topic in collision sports was also classified and measured by same methods described above. The assessment of the fatigue was performed with utilizing values from the degree of the subjective fatigue scaled 5 levels (5 being the most) which was a requirement for conditioning check introduced twice a week in the team and then the mean values from each season were calculated. Results: In the classification of the injury incidence upon body parts, a face and head showed the highest as 15.5% followed by knee: 12.5%, neck and cervical: 10.5%, and shoulder and clavicle: 11.1%. In that of injuries, the sprain and ligamentous injury were 24.7% followed by the meniscus, cartilage and disc: 14.9%, and the muscle tear, muscle strain, muscle damage and muscle cramp: 13.9%. The concussion was the fifth greatest result of all. The frequency of the injury incidence showed 26.7% in the Practice period, 24% in the Pre Season period and 40.9% in the In Season period, therefore it tended to be higher in the In Season period. From the result which showed the highest rate in sprain and ligamentous injury in the injury classification, the incidence number tended to be higher in the In Season period because it was 19.2% in the Practice period, 34.2% in the Pre Season period and 41.1% in the In Season period. The same result was also seen in the concussion meaning the frequency of incidence seemed to be higher in the In Season period because it was 9.7% in the Practice period, 29% in the Pre Season period and 54.8% in the In Season period. The degree of fatigue was as follows: 2.81 in the Practice period, 2.66 in the Pre Season period and 2.57 in the In Season period meaning it tended to be lower as the season progressed. Discussion: The team in this study was promoted to the top league in 2014 and the level of opponents was stronger than that in the previous season, therefore it is predicted the reason why the number of injuries was increased. It is thought that their condition was in good because the degree of subjective fatigue in players tended to be lower in the In Season period while the number of game would increase. From the above, this study assumed that there was no direct relationship between the fatigue and the number of injuries. The number of injury could be increased due to an increase of the number of game and a rise of the level of opponents at the game because of collision sports. Practical Application: It is easily guessed to raise the number of injuries when the opportunity of contact plays increase due to the sport specificity. This study concluded that there is a small relationship between the frequency of the injury incidence and the degree of subjective fatigue in the team. It is also necessary that this study should be continued to investigate regarding factors which could cause an increase of the frequency of the injury incidence. For the number of incidence in concussion, the study regarding a factor to increase it is needed as well as the frequency of the injury incidence. As a conclusion, the research in the future about a factor with a strong relationship with the incidence of injuries should be continued to assess and it is necessary to reduce the frequency of the injury incidence in the In Season period.

Acceleration Ability in Athletes of Various Sports

Hiroki Toma,Jun Murakami, Yuji Tamura, Taijiro Hide, and Toshihiro Ito

Fukuoka University, Fukuoka, Japan

Objective: In the field sports except the track and field, approximately 10–30 m sprint is usually seen but it is hard to observe whether the appearance of athlete's maximum speed exists or not. It is also difficult to compare their running motions in the same way because the running motion in field events is begun when they are already in moving. For the comparison between events, it should be performed under the same starting method. The purpose of this study is to provide the reference for training by measuring the characteristics of events in acceleration ability at 50 m run from the start under being at rest with recruiting students specialized at sports in the college. Methods: Subjects in the study were 900 male college students majored in sports. The breakdown of specialized events and the classification for the type of events were as follows: the track and field type (sprint distance: n = 39, long distance: n = 27, jumping: n = 27, throwing: n = 14 and mixed: n = 5), the score and measure type (rhythmic gymnastics: n = 16, artistic gymnastics: n = 23, swimming: n = 26 and yachting: n = 5), the goal type (american football: n = 9, soccer: n = 128, basketball: n = 49, handball: n = 40, rugby: n = 56 and lacrosse: n = 8), the net type (tennis: n = 18, soft tennis: n = 15, badminton: n = 7, volleyball: n = 36 and table tennis: n = 13), the baseball type (baseball: n = 126 and softball: n = 9), the martial arts type (kendo: n = 31, judo: n = 38, shoaling: n = 5 and wrestling: n = 19) and independence (subjects who not belong to anything: n = 111). The photoelectric tube system was used for the measurement of 50 m run and to measure their lap times for each 10 m and finishing time, and then the analysis by comparison of the type of events was performed. Results: The result of finishing time showed the fastest time in the track and field type at 6.65 ± 0.46 seconds followed by the baseball type (6.71 ± 0.27 seconds), the goal type (6.78 ± 0.32 seconds), independence (6.85 ± 0.35 seconds), the net type (6.94 ± 0.30 seconds), the score and measure type (7.14 ± 0.28 seconds), and the martial arts type (7.22 ± 0.45 seconds). In the result of the time from 0 to 10 m, the baseball type showed the fastest time (1.84 ± 0.10 seconds) followed by the goal type (1.85 ± 0.11 seconds) and the track and field type (1.86 ± 0.14 seconds). The track and field type showed the fastest time in each interval time after 20 m and it was maintained. The fastest maximum speed was observed in the track and field type followed by the baseball, goal, independence, net, score and measure and martial art types. In each interval achieved the maximum speed, the track and field, score and measure, goal, net and baseball types appeared in the interval from 30 to 40 m but it was obtained before 20–30 m in types of the martial arts and independence. Discussion: There is a high correlation between the maximum speed and finishing time in 100 m run and the same result was seen in 50 m run in this study. The rank of both the maximum speed and finishing time upon the types of events were same and it is assumed that there is a possibility to be a factor for the improvement of finishing time in 50 m run by enhancing the maximum speed. The maximum speed in 100 m run was observed most frequently at 50–60 m, therefore it is generally said that the field sports which normally have 10–30 m for the sprint distance was often relied more on the acceleration than the maximum speed. However, there is a significant superior result in the track and field type which showed the high maximum speed regarding an acceleration relative to the goal type (p ≤ 0.05) when recording the term from 10 to 20 m and from 20 to 30 m in case of the comparison for the goal type defined as the field event as an example. Therefore, it is necessary to understand that concluding unwisely such as the training for improving acceleration is more important than that for the maximum speed could become the way to consider which might be rejected for the improvement of the performance. Practical Application: This study revealed the characteristics of acceleration, maximum speed and finishing time from each event. After considering them, the purpose and method of daily running training could be reconsidered upon these references described above.

The Effect of the Low-Intensity Eccentric Exercise on the Muscle Strength and Flexibility

Satoru Nishida,Kiyoshi Maehara, and Shumpei Miyakawa

Tsukuba University, Ibaraki, Japan

Objective: Previous reports have suggested that performing the transient low-intensity eccentric exercise (Ecc-Ex) in advance caused the reduction of muscle damage after the high-intensity Ecc-Ex. However, the detailed mechanism about it is still unclear. The purpose of this study is to investigate the effect of the transient low-intensity Ecc-Ex on the muscle strength and flexibility. Methods: Fourteen healthy male collegiate students participated in this study. They were excluded if they have had hamstring strain injury. Subjects performed the Romanian deadlift (RDL) without loading as the low-intensity hamstring Ecc-Ex. Before and after the RDL, muscle strength and flexibility were measured on both legs. Before starting this experiment, subject performed a warm-up by stationary bike for 5 minutes (50 w, 60–70 rpm). RDL was performed 3 sets of 8 repetitions as started at standing position with holding a plastic bar and then put it down as low as possible for 5 seconds and bring it back to the start position for 2 seconds. For the assessment of muscle strength, 3 maximum voluntary eccentric knee flexion were performed continuously at the 3 angular velocity (30, 60, 180 deg·s−1) for the range of 80° from a knee-extended position (10°) to a knee-flexed position (90°) by the isokinetic dynamometer in prone position. Peak torque and angle of peak torque were calculated from averaging the date from 3 attempts. For the assessment of flexibility, passive torque (PT), range of motion (ROM) and pennation angle (PA) were measured. PT was measured by the isokinetic dynamometer. While each subject was in sitting position and hip was flexed 120°, the knee was extended passively at 5 deg·s−1 from 90 degree knee flexion to a point of onset of pain, and during which the torque was recorded. PT was defined as the torque of this point. ROM was measured by SLR test. The angle of hip flexion at onset of pain was recorded. A longitudinal ultrasound image was obtained for PA. PA was defined as the angle between the fascicle and deep aponeurosis. It was calculated by Image J. ROM, PA was measured 3 times, and the mean of 3 measures was used for analysis. Results: After the RDL, peak torque decreased significantly at all angular velocity, but APT showed no significant change. On the other hand, ROM increased and PT, PA decreased significantly after the RDL. Discussion: It could be considered that this result was affected by the exercise protocol and the intensity in this study. The purpose of the RDL is to load on hamstrings more eccentrically by flexing the hip. However, it is assumed that the isometric contraction of hamstrings followed by the extension of tendon occurred at the little hip flexed position because the intensity of RDL was low in this study. If the tendon was extended, muscle activity was inhibited by the Ib inhibition through the golgi tendon organ. Therefore, the result in this study such as the improvement of flexibility and reduction of muscle strength could be influenced by the Ib inhibition. On the other hand, the reduction of pennation angle suggested that the muscle length was extended by RDL. To achieve more hip flexion during RDL, an increase of required torque and muscle extension were required. Finally, muscles could be elongated as a result of eccentric muscle activity to correspond these requirements. According to these results, it is suggested that the low-intensity RDL could cause similar outcomes with static stretching such as an increased flexibility and reduced muscle strength. Practical Application: This study revealed that the low-intensity Ecc-Ex is effective to improve muscle flexibility. It is generally thought the high flexibility and muscle strength are important to prevent muscle strain. It is believed that the flexibility and muscle strength are improved effectively by performing higher intensity RDL.

Longitudinal Change of Physical Characteristics in College American Football Players—A Case of a Public School in Kansai Collegiate American Football League Division I

Shinto Kinoshita,1Takeshi Sakaguchi,1and Daichi Yamashita2

1Kobe University RAVENS, Hyogo, Japan; and2Japan Institute of Sports Sciences, Tokyo, Japan

Purpose: American football requires various physical factors such as muscular strength, speed, and others. Although American football is the most popular sport in the United States, Japan is also one of the power houses, because Japanese national team has never been ranked below fourth in the World Championship games. The long-term goal of strength and conditioning coaches is to develop Japanese athletes who are comparable to athletes play for the United States national team in physical characteristics. Therefore, the purpose of this study was to clarify Japanese college athlete's trainability in terms of longitudinal change of physical characteristics. Methods: Subjects were 108 college American football players in Kansai Collegiate American Football League Division I. Measurements were conducted late in July and early in August at the end of preparatory phase and preseason training in 2014, 2015, and 2016. The dependent variables were body mass (kg), bench press (kg), squat (kg), power clean (kg), 40-yard sprint (sec), pro-agility quickness (sec), and standing long jump (cm). Inclusion criterion was the measurement taken continuous 2 years. Annual differences were calculated and quantified in 2 groups; linemen and skill player. Results: The changes between years (between freshman and sophomore year, between sophomore and junior year, and between junior and senior year) were reported. Body mass (kg) changed by +7.8, −1.2, and −0.4 in linemen group and by +5.9, −1.0, and +1.0 in skill player group. XRM squat (kg) changed by +39.1, +10.0, and +13.3 in linemen group and by +30.8, +9.5, +10.9 in skill player group. In 40-yard sprint, the time (sec) changed by −0.06, −0.07, and −0.35 (mean of 2 players) in linemen group and by −0.19, −0.15, and −0.19 in skill player group. Discussion: According to the longitudinal study in NCAA Division I football players (Jacobson et al., JSCR, 2013), the changes of strength in squat were +26.0, +16.5, and +9.0, and the changes in 40-yard sprint were −0.05, −0.00, and −0.03 in each year. Although the increase in muscular strength was similar in both Japanese and American college football players, we found Japanese college athletes are still able to improve sprint time. Practical Application: In this study, we found differences in longitudinal change in physical characteristics between Japanese and American college athletes. It was clear that physical characteristics at freshman year remarkably differed between 2 countries; yet, by collecting date of longitudinal changes in physical characteristics among Japanese athletes, new training methods and athlete development policies will be proposed to close the gap in the future.

The Effect of Footworks of Baseball Catchers in Throwing to Second Base

Chiharu Suzuki,1Masahiro Kageyama,2Masahumi Fujii,1and Akira Maeda2

1Graduate School of Education, National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan; and2National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan

Purpose: For baseball catchers, 3 footwork steps to throw out a runner trying to steal the second base are generally identified. “Lead step” is that the driving foot initially takes a little forward step, and the plant foot, then, shifted forward. “No step” is that the plant foot moves forward without the driving foot taking a little forward step. “Back step” is that the driving foot initially steps backward, and the plant foot, then, shift forward. It has not been investigated which step is the most effective among these 3 footwork steps. Methods: Nineteen healthy males with experience of playing catcher were recruited. Three different steps were tested with 5 throws with maximum effort to a target placed 10 meters away; hence, each subject threw a total of 15 balls. Ground reaction force and 3-dimension references during throwing motion were measured with the use of 2 force platform and optical motion capturing system (Mac3D). The throwing velocity was measured by a radar gun, and the fastest throw in each step was used for analysis. Based on a previous study (Sawamura et al., 1997), the throwing motion was divided into 7 phases; (a) catching ball (catch), (b) gripping ball (grip), (c) driving foot's contact to the ground (PLC), (d) planting foot's contact to the ground (SLC), (e) the throwing elbow reaches the most posterior position (top), (f) ball releasing (release), and (g) the ball reaches the second base (2B). The time between (a) and (f) was defined as motion time, the time between (f) and (g) was defined as throwing time, and the time in all phases are total throwing time. Results: Back step method demonstrated the fastest motion time and total throwing time. Lead step method showed the fastest throwing velocity. Back step method exhibited a significantly positive correlation between motion time and displacement distance of center of mass. Discussion: We found the back step method showed the shortest motion time but the lowest throwing velocity. This might attribute to that back step method required shortest displacement distance of center of mass, and lead step method produced the high velocity of center of mass displacement and resulted in the high throwing velocity. However, the results proved that shortening the motion time lead to shortening the total throwing time instead of increasing throwing velocity. Therefore, utilizing back step method will assist baseball catchers improve the caught stealing percentage in which catcher throw out a runner stealing the second base. Practical Applications: It is believed catchers using back step method could shorten the motion time and total throwing time, which could help to improve caught stealing percentage. We asked 2 catchers to conduct footwork drills specialized for baseball catchers for 2 weeks; one was an average catcher (average catcher), and the other was the catcher scored the slowest total throwing time (novice catcher). The purpose of the drills was to help the average and the slowest catchers to improve the total throwing time as fast as the quickest throwing catcher (expert/pro). The 2-week drills mirrored the back step method, and individualized footwork drills were assigned to and completed by the average and the slowest catchers. As the results, both the average and novice catchers shorten the motion time. The drill was especially effective for the novice catcher. These results indicate it is effective to assign drills depending on individual's level of play, instead of completing training tasks without specific goals. When expected the first base runner to steal the second, a catcher is more prepared to throw. This is an exception in which catchers prefers to throw faster throwing velocity over the shorter motion time by using the lead step method. It is speculated that utilizing different footwork steps according to individual's playing level, motion time, throwing velocity, and game situation could improve the caught stealing percentage.

Physical Characteristics and Performance of Collegiate and Under-19 Japanese Top-Level American Football Players

Daichi Yamashita,1Yoshihiko Ito,1Masaki Asakura,2Hiromi Wajima,1and Shinzo Yamada3,4

1Japan Institute of Sports Sciences, Tokyo, Japan;2Deers Football Club, Tokyo, Japan;3University of Tsukuba, Ibaraki, Japan; and4Japan American Football Association, Tokyo, Japan

Introduction: American football is a collision sport that requires high levels of physical abilities such as strength, power, speed, and quickness. Japan is one of the leading nations in American football. To enhance performance in international competitiveness, it is important to design elite development pathway in American football in Japan. The purpose of this study was to investigate physical abilities between collegiate and under-19 American football players in Japan. Methods: The performance tests were held in March 2016 for the Japan American Football Association football academy program. They were 4-day programs held at 2 sites (eastern and western parts of Japan) that aimed to select a trial 55-player roster for the second World University Championship in June and a trial 45-player roster for the International Federation of American Football U-19 World Championship in July. We measured height, weight, vertical jump, broad jump, 40-yard dash, pro-agility shuttle, 3-cone drill, and ball throw test. The physical and performance data were compared between top-level collegiate and U-19 American football players in Japan, who were selected for the second tryout (n = 63 and 82, respectively). Players were categorized into one of 3 groups based on playing position: skill players, big skill players, and linemen. A comparison between the 2 aged groups across the 3 positional groups was performed by unpaired t-tests or Mann-Whitney test for data with normal and non-normal distribution, respectively. Results: Top-level collegiate skill players had significantly superior in the pro-agility shuttle and 3 cone drill than top-level U-19 players. Top-level collegiate big skill players had significantly superior in body weight, medicine ball throw than top U-19 players. Top collegiate linemen had significantly superior in height, vertical jump, medicine ball throw, the pro-agility shuttle, and 3 cone drill than top U-19 players. Discussion: Our results showed that the physical abilities of U-19 players were different from those of collegiate players in each group based on playing position. In comparison between age groups, it may suggest that U-19 big skill players may need to enhance power aspect while U-19 skill players may need to improve quickness aspect. Meanwhile, the comparison of NFL combine invited players, who are considered to be the highest level collegiate players in the world, with top-level collegiate players in Japan may infer that there is another elite athlete development pathway to have great success in international competitions. For example, top-level collegiate skill players in U.S. were much superior both in size (91.7 kg in weight) and speed (4.49 seconds in 40-yard dash) to those in Japan (78.0 kg and 4.94 seconds, respectively) (Sierer et al., JSCR, 2008). Practical Applications: It is important for strength and conditioning coaches to design strength training programs for talented youth football players, with careful consideration of their goals in the future, whether to play in the national or international level.

Examination of Hip Abductor Strength in Relation to Straight-Line and Change of Direction Sprints

Takashi Yasojima1and Fuminori Takayama2

1School of Health and Social Services, Saitama Prefectural University, Saitama, Japan; and2Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan

Purpose: The players of field and team sports are required the rapid changing direction in addition to the straight sprinting in the games. Nonetheless, the sprint with change of direction (COD) is likely to induce lower extremity injuries. Hence, various injury preventive methods have been studied, and the improvement of hip abductor function found to be one of effective methods for the prevention of lower extremity injuries. On the other hand, it is unclear how the hip abductor function are associated with performances of straight-line and COD sprints. The purpose of this study was to examine the relationships between hip abductor strength and both sprints speed. Methods: Twenty-six healthy male undergraduate students (age: 20.7 ± 1.3 years, height: 168.7 ± 4.8 cm, body mass: 62.8 ± 5.7 kg) with experience in playing soccer (12.2 years) were participated in this study. After a series of warm-up period, each subject performed the tests for hip abductor strength, time of straight-line and COD sprints. Hip abductor strength was measured by a hand-held dynamometer and pull-sensor (MT-100, Sakai Medical Co., Ltd.). For the measurements, a subject was in a side-lying position and performed maximum isometric contraction of hip abduction for 3 seconds. Two trials were completed with 120 seconds of rest period between trials. The highest value was used, and normalized to body weight of each subject for analysis. The straight-line and COD sprinting times were measured by photocells timing gates (Racetime2, Microgate). For the COD test, the subject was instructed to turn 180° (180 COD) or 90° (90 COD) at the mid-point of the 10 m testing platform, and the time was measured at the finish lines. The straight-line sprint test consisted of the 20 m testing platform, and the time was measured at 10 and 20 m, respectively. The subjects performed twice to each test, and the best time were used for analysis. For statistical analysis, Pearson's correlation coefficient was obtained to examine the relationships among hip abductor strength, time of the straight-line (10 and 20 m) and COD (180 COD and 90COD) sprints. Results: The hip abductor strength were significantly correlated with 180COD test time (r = −0.57 ∼ −0.71, p ≤ 0.05), and 10 m and 20 m times of sprint test (r = 0.40–0.67, p ≤ 0.05). Time in 90COD test was significantly correlated with 10 m and 20 m times of sprint test (r = 0.63–0.74, p ≤ 0.05). Discussion: The correlations between sprint times and COD test times demonstrated that the straight sprint speed was affected to the ability of rapid changing direction. Hip abductor strength was related to the time in 180 COD test but not correlated with the time in 90 COD. The biomechanical study in basic COD movement reported that the hip abduction torque contributed to adjust direction of force in side steps at different distances. Therefore, the hip abductor might play important role to modulate the direction of force in larger angle of changing direction such as 180 COD. Practical Application: To improve the ability of changing direction, it is suggested that the modulation function by hip abductor should strengthen in conjunction with the enhancement of propulsion function in the movement.

A Study for Developing Recovery Methods in Baseball Team—Amateur Baseball Team

Masashi Kasahara,1Toshiharu Yamamot,1Chihiro Ohta,2and Yosuke Akutsu3

1International Budo University, Chiba, Japan;2Keio University of Rugby team, Kanagawa, Japan; and3Japan Soccer College, Niigata, Japan

Purpose: It is believed the necessity of recovery from fatigue is important to maintain or improve athlete's condition. When choosing a recovery technique, it is required to consider sports characteristics, timings of recovery, and recovery techniques, and select proper recovery method. We operationally defined tactical recovery as utilizing various recovery methods based on situations. Because insufficient information on tactical recovery has been provided to date, we select an appropriate technique through trial-and-error. Therefore, the aim of this survey was to collect preliminary information regarding recovery methods used in amateur baseball teams in Japan. The information would be used to develop a tactical recovery in baseball. Methods: A set of questionnaire was sent to 35 conditioning personnel who were responsible for implementing recovery sessions at amateur baseball teams. Items asked included how is in charge of recovery sessions, whether any recovery session is conducted, the goal of recovery, method and time of recovery, any considerations, and so forth. The survey was collected, and we analyzed the results. Results: Thirty-four teams completed the survey (97.1%). Percentage of teams implemented recovery sessions was 92%. In terms of recovery sessions, 43% of teams “implemented at every practice,” 37% teams “implemented irregularly (as needed),” and 9% of teams implemented a few times per week.” The 31% of teams rated preventing flexibility loss as the top priority of recovery session during a practice, and the 54% of teams reported preventing energy depletion (replenishing energy?) as the top priority of recovery session following a practice. In a day before a match, the targets of recovery session were energy depletion (89%), psychological stress (71%), abnormal fluid accumulation in the extremities (11%), delayed onset muscle soreness (DOMS) (66%), fatiguing chemicals (lactic acid?) (86%), and flexibility loss (91%); on the other hand, if no game is played in the following day, the targets of recovery session were energy depletion (77%), psychological stress (31%), abnormal fluid accumulation in the extremities (9%), DOMS (74%), and flexibility loss (89%). Considerations for recovery sessions were categorized into age, sleeping, environment, and technique. Age was divided into pre-retire, intermediate, and rooky levels. In sleeping, quality of sleep needed to be secured. In environment, climates should be taken into account. In techniques, individual characteristics and amount of practice time should be considered. Discussion: The results indicated almost all the teams implemented recovery session in some manner as a team, but less than half of the teams provided a recovery session every time. This might be because the practice was often divided into pitchers and other position players, and practice times vary among playing positions. Next, approaching to energy depletion was the top priority in recovery sessions except during a practice. Because baseball practices are lengthy, and baseball games also last for hours in Japan, taking an approach to the energy expenditure is important. Psychological stress individually varies depends on whether a team has a game on the next day or not, and psychological stress is not considered in the recovery session if the team does not have a game on the next day. Practical Application: The most important aim of recovery session in baseball was energy replenishment. Psychological burden is clearly higher when a game is scheduled on the very next day compared to when no game is scheduled. Therefore, it is speculated that an appropriate psychological recovery method should be chosen according to the next game schedule.

The Analysis of Muscular Activities During Shoulder Girdle Muscles Exercises―Focusing on Muscular Activities of the Rhomboid

Gen Adachi,1Tomoki Oshikawa,1Satoshi Iizuka,1Atsushi Imai,2and Koji Kaneoka2

1Graduate School of Sport Sciences, Waseda University, Saitama, Japan; and2Faculty of Sport Sciences, Waseda University, Saitama, Japan

Purpose: Shoulder girdle muscles exercises have been considered to reduce the risk of subacromial impingement of the rotator cuff. The purpose of this study was to clarify muscular activities of the rhomboid during shoulder girdle muscles exercises as a specialized warming-up exercise that are implementable on a sports field. Methods: Six healthy males (Mean ± SD: age = 22.0 ± 3.0 y, height = 168.2 ± 6.2 cm, body mass = 62.5 ± 9.9 kg) participated in this study. Muscular activities were measured by a wireless electromyography (S&ME Co.). The electrodes were put into a 23-gauge needle and inserted at the mid-point between the medial base of the scapular spine and the inferior scapular angle guided by using ultrasonography (LOGIQ e,GE Co.). The needle penetrated through the trapezius and reached into the rhomboid. Participants performed 4 exercises; (a) scapular open-close exercise that included scapular adduction in a quadruped position; (b) trunk rotation exercise without pelvic rotation in quadruped position; (c) lat-fly T exercise that include the scapular adduction and the trunk extension with the elbow maximally extended and the shoulder joint 90° abducted and externally rotated in prone.; and (d) jump push-up exercise in which a participant maximally push himself up in the air from the position of normal push-up position. Each exercise tested 5 times and the muscular activities were recorded. In the middle 3 trials were used for analysis. The recorded muscular electrical activity was standardized by the root mean square value of the maximum voluntary contraction (%MVC). For the statistical analysis, one-way analysis of variance with a post-hoc test (Bonferroni correction) was conducted. The level of significance of p ≤ 0.05 was accepted for this study. Results: The muscular activities of the rhomboid during each exercise were as follow. Scapular open-close was 26.1 ± 22.2% MVC. Trunk rotation was 27.0 ± 19.7% MVC. lat-fly T was 29.0 ± 18.4% MVC. Jump push-up was 38.0 ± 34.3% MVC. No significant difference was observed in rhomboid activities among exercises. Discussion: In this study, we found the electrical activity of the rhomboid that is not measured by a surface electromyography. Because the muscular activities were recorded between 26.1 and 38.0% in each exercise, the body-weight exercises as a specialized warming-up exercise that activated the rhomboid muscle appeared to be valid. Practical Application: The results of this study could be applied to shoulder girdle muscular exercises as a specialized warming-up exercise. The rhomboidal activity was insufficient for strength training during the body-weight exercises; therefore, additional load such as dumbbell should be used for a training.

A Study of Injury Occurrence in Throwers of Track and Fields

Koto Harayama1and Sayumi Iwamoto2

1Graduate School, Toyo University, Saitama, Japan; and2Toyo University, Saitama, Japan

Purpose: Preventive measures for acute and overuse injuries are often implemented in athletic settings, and as the first step, acute and overuse injury studies have generally been conducted. Competition of track and field has 3 events such as running, jumping, and throwing, and each event requires different skills. Only a few acute and overuse injury studies focusing on each of the 4 major throwing discipline have been completed to date. Therefore, the aim of this study was to clarify the fact on acute and overuse injuries in the 4 major disciplines (shot put, discus throw, javelin thrown, and hammer throw) among throwers who competed at college level. Methods: Colleges which sent many athletes to the 84th intercollegiate track and field meeting agreed to participate in this study. A total of 145 college athletes from 6 schools were recruited at the 84th Emperor's cup of Japan college track and field meet. A set of questionnaire was developed based on International Olympic Committee (IOC) injury surveillance system. Items included acute injuries, overuse injury rate, injured body parts, mechanism of injury, and so forth. The results were analyzed by disciplines and sexes. Results: The total response rate was 79.8%, valid response rate was 90.6%, acute and overuse injury rate was 67.7%, injury rate in males was 45.9%, and injury rate in females was 54.1%. Injury rates among the 4 disciplines were as follows; shot put = 68.2% (males = 53.3%, females = 46.7%), discus throw = 57.6% (males = 36.8%, females = 63.2%), javelin throw = 77.6% (males = 42.2%, females = 57.8%), and hammer throw = 56.3% (males 61.1%, females = 38.9%). The most frequently injured body part was the lumbar spine and lower back in shot put (males = 37.5%, females = 38.5%), discus throw (males = 45.5%, females = 36.4%), and hammer throw (males = 24.1%, females = 30.8%). In javelin throw, the most commonly injured body part was the elbow (males = 35.9%, females = 32.6%). The mechanisms of injury by the disciplines were as follows; weight training in men's shot put (75.0%), discus throw (54.5%), hammer throw (58.6%), and women's discus throw (36.4%). Injuries during specific throwing in each discipline were 74.4% in men's javelin throw, 53.8% in women's shot put, 67.4% in javelin throw, and 61.5% in hammer throw. Discussion: The lumbar spine/lower back was commonly injured site in both men's and women's shot put, discus throw, and hammer throw. Weight training (WHAT EXERCISE?) was the common mechanism of injury in men's shot put, men's discus throw, men's hammer throw, and women's discus throw. From these results, it is suggested overload weight training involving specific movement in throwing event should stress on the lumbar spine/lower back area. Injuries on the lumbar spine/lower back occur during a throwing movement specific for women's shot put requires lumbar rotation. It implies the axis of the rotation stresses the lumbar spine/lower back by the force to rotate back to neutral position and the ground reaction force. Practical Application: In this study, it is proposed to clarify the weight training program and implement individual prevention measures such as educating proper overload and posture in addition to proposing necessary protective device for the lumbar spine. Examining the weight training program would assist in protecting throwers from acute and overuse injuries.

A Study of the Cognition of the Team Tactics in Collegiate Female Football Players

Nozomu Hasegawa,1Akihito Koakutsu,2Naoyuki Takeda,3Norikazu Yao,4and Masato Otake5

1Aichi Toho University, Aichi, Japan;2National Defense Academy, Kanagawa, Japan;3Nagoya Managment Junior College, Aichi, Japan;4Tokai University, Kanagawa, Japan; and5Nihon University, Tokyo, Japan

Purpose: The importance of tacticss in team sports has recently been reported as a major factor for competitions. Many of previous surveys on tactics had, however, been responded by coaches and lacked athletes' cognitions of their team tactics (Koakutsu, 2016a). Japan Football Association (2015) stated, “The number of football team emphasizing team work instead of individual skills has recently increased, and the collective team strength would predict the team's record at the end of the season.” The importance of team work along with proper tactics has also been recognized in women's football. Therefore, the aim of this study was to examine future elite female football players on the cognition of their team tactics. Methods: A total of 169 college female football players who were selected to their regional teams responded the survey. The mean age was 19.82 ± 0.95 years, and mean playing experience was 11.44 ± 2.83 years. The survey was conducted during the “Region—Region Collegiate Women's football Match in 2015.” Coaches of each team distributed a set of questionnaire to their player. A total of 44 questionnaires with 4-level Likert scale was previously used (Koakutsu, 2016a) to ask initial feeling on suggested team tactics. All players agreed that the data collected would be quantified and would not be able to identify the individuals. Results: Exploratory factor analysis (EFA) was conducted. Taken fixed value and interpretable factors into account, 4 factors are selected. Next, the variable in which common factors lower than 0.20 or the variable in which factor loadings lower than 0.40 in any factors was deleted, and another exploratory factor analysis was run. The results showed each variable was related to each factor and showed a simple structure with significant factor loading (>0.40). The number of items loaded was 5 for the first factor (Crombach's α = 0.77), 4 for the second item (Crombach's α = 0.63), 3 for the third item (Crombach's α = 0.72), and 2 for the second item (Crombach's α = 0.63). A confirmatory factor analysis (CFA) was run to validate the 4 factors (14 items) derived from the results of our EFA, and the model derived from CFA demonstrated a sufficient fit index with the goodness of fit index (GFI) = 0.908, adjusted GFI = 0.864, comparative fit index (CFI) = 0.909, and root-mean-square error of approximation (RMSEA) = 0.065. Discussion: The factors are named as the followings. The first factor was “dependency” in which players were dependent on team strategies or coaches to execute the team tactics. The second factor was “solution monitoring” in which players attempted to learn from mistakes or to find a solution. The third factor was “skills” in which player relied on their individual skills to execute their team tactics. The fourth factor was “confusion” in which players demonstrated difficulties in understanding given team tactics. The results of this study showed that female players depend on coaches and tactics, and this results were not so different from the one previous study which female players were more dependent compared to male players (Matsui and Yamashita, 2014). Practical Application: To understand cognitive structures of college female football players could improve coaching efficiency and assist players to more effectively master their team tactics.

Propulsive Acceleration and Velocity of 1 vs. 1 in Soccer With Relation to Wins and Losses

Tomohiro Kai,Yohei Takai, Tomohito Wada, Hiroaki Kanehisa, and Tetsuo Fukunaga

National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan

Introduction: It is considered that quantification for performance of 1 vs. 1 in soccer is a determinant factor relating to the competitive level of a team. However, it is unclear how velocity and acceleration of attackers and defenders differ between wins and losses in 1 vs. 1 of real soccer scene. Therefore, this study aimed to quantify the velocity and propulsive acceleration of 1 vs. 1 in soccer with relation to wins and losses. Methods: Collegiate soccer players (N = 23) performed 1 vs. 1 on indoor artificial grass. Pitch size was 16.5 m by 40.3 m. Attackers intended to go through the line set away from 20 m behind defender with and without a ball. Defenders attempted to stop attacker's movement propulsion, and rob the ball. When the attacker passed the defender, this was defined as “Win.” When the defender took the ball of the attacker, or kicked out a ball of the attacker, these situations were defined as “Loss.” Players' x- and y-coordinate were determined at 20 Hz by using 2-dimensional position coordinate measuring system (ZXY sports tracking system, CHYRONHEGO, New York). Velocity was calculated by differentiating the x- and y-coordinate, and propulsive acceleration was calculated by differentiating the velocity. The angle defender-attacker vector and an imaginary horizontal line parallel to the goal line with the origin in the defender's position were determined to identify the minimum distance between the defender and the attacker (minθ) (Passos et al., 2009). Velocity and propulsive acceleration were averaged over 3 seconds before the minimum distance minθ. Results: In 1 vs. 1 without a ball, velocity was higher in wins than in losses for both attackers (4.30 ± 1.39 m·s−1 for Win, 3.50 ± 1.29 m·s−1 for Loss) and defenders (2.85 ± 1.44 m·s−1 for Win, 2.42 ± 1.02 m·s−1 for Loss), and in velocity of the attackers was higher than in the defenders. Propulsive acceleration was higher in wins than in losses for both attackers (1.07 ± 0.69 m·s−2 for Win, 0.51 ± 0.69 m·s−2 for Loss) and defenders (1.09 ± 0.77 m·s−2 for Win, 0.72 ± 0.44 m·s−2 for Loss), without significant position-related differences. In 1 vs. 1 with a ball, the position- and win/loss-related differences in velocity (attackers: 3.92 ± 1.37 m·s−1 for Win, and 2.97 ± 1.10 m·s−1 for Loss, defenders: 2.98 ± 1.35 m·s−1 for Win, and 2.65 ± 0.98 m·s−1 for Loss) and propulsive acceleration (attackers: 0.56 ± 0.71 m·s−2 for Win, and −0.07 ± 0.73 m·s−1 for Loss, defenders: 0.60 ± 0.78 m·s−1 for Win, and 0.36 ± 0.80 m·s−1 for Loss) were the same as those observed in 1 vs. 1 without a ball. Discussion: The current results indicate that, when attacker beats defender with and without a ball, both players produce higher propulsive acceleration and velocity in Win compared to Loss, regardless of with and without a ball. For soccer players and their coaches, therefore, to enhance propulsive acceleration and velocity which can be achieved in a very short time will be essential to improve the performance of 1 vs. 1 in real soccer scenes. Practical Applications: For soccer players, the profiles of velocity and acceleration in 1 vs. 1 of soccer are critical information for improving their competitive levels. These present findings make contribution to design strength training and technical training programs aiming to enhance the performance of 1 vs. 1 in real soccer scene for soccer players.

Longitudinal Changes of Physical Strengths in Japan Top-League Rugby Players

Jumpei Okuno,1Ryusuke Serizawa,1Masaki Yoshikai,1and Daichi Yamashita2

1NTT Communications Shining Arcs Rugby Club, Chiba, Japan; and2Japan Institute of Sports Sciences, Tokyo, Japan

Introduction: The changes of top-level athletes' physical abilities that has been discussed on are mainly of student athletes (Jacobson et al., JSCR, 2013, etc.). On the other hand, even though professional and works teams' athletes have spent great amount of time to improve physical performance, few studies quantify the trainability of athletes of professional and works teams. Thus, the degree of physical development has been poorly understood. Therefore, the purpose of this study was to evaluate the annual development of physical characteristics in rugby players belonging to a works rugby team in Japan. Methods: Forty-six rugby players from a Japan Top-League team participated in this study. In 2014 and 2015 during spring season, 60-kg and 70-kg bench press mean power, 20-kg squat jump power, bench press 1RM, back squat 1RM, chin-up 1RM, 10-m sprint time, and the anaerobic test were tested. For both forwards (average age of 27.9), and backs (average age of 26.1), 2014 and 2015 test results were compared using unpaired t-test. Results: For forwards, bench press, Chin-up, back squat, 10-m sprint, and anaerobic test showed significant improvements. For backs, 70-kg bench press mean power, 20-kg squat jump mean power, bench press, chin-up, 10-m sprint, and anaerobic test improved significantly. Discussion: Both forwards and backs showed improvement in more than a half of the testing elements. With the longitudinal study done with collegiate American football players, it reported that no improvement in sprint speed after their sophomore year (Stodden and Galitski, JSCR, 2010, Jacobson et al., JSCR, 2013). Interestingly enough, however, this study with top-level athletes in Japan at the average age of over 26 years showed that there was improvement in sprint ability. Practical Applications: According to the results of this study, it becomes clear that there is trainability in Japan Top-League rugby players. Since long term athletic development has been the focus of attention today, and prescribing physical training programs for under-age athletes draw increasing attention, tracking the performance changes on a longitudinal basis of post-graduate athletes like this study would lead to long-term player development.

Appropriate Velocity in VBT to Improve Explosive Power for College Soccer Players

Jun Tanaka

International Pacific University, Okayama, Japan

Introduction: In soccer, it is important to improve explosive power to sprint and change of direction. In season, they have a game at every weekend, so it is necessary to carry out training while maintaining condition. Velocity Based Training (VBT) that monitoring velocity during exercise can avoid an unnecessary effort and prevent excessive fatigue and overtraining. Therefore VBT is suitable as in-season conditioning for soccer players. The purpose of this study was to clarify the relationship between explosive power and body composition, strength, power by the power characteristics of college soccer players, and to determine the appropriate velocity in squat VBT. Methods: Twenty-four Division1 college soccer players (n = 3 GK, n = 21FP) were participated in this study. Height, Body weight (BW), abdominal girth, skinfold were measured, and calculated to %body fat, fat mass, lean body mass (LBM). All subjects performed standing long jump (SLJ), and back squat was performed with maximal voluntary speed at several different weight, and mean velocity (V), mean power (P) were recorded in every rep by FITROdyne. The equation of regression was made from velocity-load relations and power-load relations. 1RM (load at elevation velocity 0.3 m·s−1), 1RM/BW, maximum power (P.max), P.max/BW, load at P.max (L@P.max) and Velocity at P.max (V@P.max) were calculated by the equation of regression. In addition, load (L@V) and power (P@V) at each velocity (0.40–1.10 m·s−1) in every 0.05 m·s−1 were calculated. Correlation between SLJ as index of explosive power and (1) body composition (%body fat, fat mass, LBM), (2) strength (1RM, 1RM/BW), (3) power (P.max, P.max/BW, L@P.max, V@P.max), (4) speed (L@V and P@V at each velocity 0.4–1.1 m·s−1) were investigated. Each mean value between SLJ higher group (HG) and SLJ lower group (LG) were compared. Results: LBM (r = 0.571), P.max (r = 0.623), L@P.max (r = 0.518), L@V 0.45∼0.9 m·s−1 (r = 0.474–0.523) and P@V 0.65∼1.05 m·s−1 (r = 0.424–0.531) were correlated with SLJ. (p ≤ 0.05) In particularly, 0.75 m·s−1 (r = 0.523) as L@V and 0.80 m·s−1 (r = 0.531) as P@V showed the highest correlation. P.max (p < 0.01) and LBM, 1 RM, L@P.max, L@V 0.4∼0.9 m·s−1, P@V 0.65∼0.95 m·s−1 (p ≤ 0.05) were significantly different between HG and LG. Discussion: The results of the present study suggest that increasing LBM, 1RM and P.max is important to improve explosive power. Also the results suggest that VBT at 0.65–0.9 m·s−1 is in effect because of relations between SLJ and load and power of the velocity zone. Especially V@P.max appear in the about 0.65–0.75 m·s−1 for every player, so this velocity zone is effective in VBT. Practical Applications: It is important for soccer player to manage training load and quantity to prevent excessive fatigue in season. Therefore VBT is one of the effective methods. VBT at the velocity zone the result suggested expect to improve explosive power, so it is effective for conditioning in season when strength and power are apt to decrease. It is not sure about the suitable velocity to increase 1RM and LBM by VBT yet. Therefore it is recommended to do high weighted training by %1RM simultaneously to increase 1RM and LBM.

The Effect of Step Characteristics to Sprint Running Performance

Norihiro Shima

Tokai Gakuen University, Miyoshi, Japan

Introduction: Short sprint running with uphill slope and downhill slope was performed as training to improve sprint performance. However, it is not clear how these training change sprint characteristic. The purpose of this study was to investigate the 20-m sprint time, step length, step rate, and ground contact time during downhill and uphill sprint running. Our rationale was that these data would aid in the understanding of downhill and uphill for sprint training. Methods: Fourteen healthy men (20 ± 2 year old), who participated in a sports activity ran 20-m sprints on uphill and downhill slope of 2 and 6° and flat (0°) in random order. Sprint time was measured twice at 5 slopes (6, 2, 0, −2, and −6°) by using phototube sensor, with a sufficient rest between sprints, and the highest value was selected for analysis. Step length, step rate, and ground contact time were recorded during 20-m sprints by means of the Optojump system (Micro gate, Bolzano, Italy). Results: Twenty meter sprint time and ground contact time at downhill were shorter than at flat and uphill slope. Step length at downhill slope was longer than at flat and uphill slope. However, step rate was not different between slopes. Twenty meter sprint time at flat was correlated with the step rate at downhill slope of 6°. Subject with shorter 20-m time was higher step rate at downhill slope sprint. Discussion: The results of the present study suggest that shorter 20-m sprint time at downhill slope is due to shorter ground contact time and longer step length without the changes in step rate. The changes in step length at downhill sprint may be affected by the gravity. However, sprint running at downhill may be better training for shortened ground contact time. Even though there is no difference between slopes in the step rate, 20-m sprint time at flat is associated with the step rate at downhill slope of 6°. These results suggest that subjects with short sprint time have the characteristics of the higher step rate during downhill slope sprint. Practical Applications: In the results of the present study, over-speed sprint training at downhill slope would change ground contact time. However, this shortened ground contact time increase injury risk because of higher ground reaction force at downhill and of higher slops during running (Gottschall and Kram 2005). The present study also shows that the sprinter who has the higher step rate at downhill sprint running is the better sprint time at short distance such as 20-m. Keeping and/or no braking down step rate at downhill sprint is important for sprint time at short distance.

Characteristics of Physical Strength in Japan Top-League Rugby -Comparison of Game Members and Non-Game Members

Ryusuke Serizawa,1Masaki Yoshikai,1Jumpei Okuno,1and Daichi Yamashita2

1NTT Communications Shining Arcs Rugby Club, Chiba, Japan; and2Japan Institute of Sports Sciences, Tokyo, Japan

Introduction: By taking advantage of the success of Japan rugby national team at Rugby World Cup 2015, its rugby development to compete internationally has been in rising curve. The purpose of the study was to quantify the physical strength of Japan Top-League rugby players, and to clarify the differences between game members and non-game members. Methods: Data of 49 players from a Japan Top-League rugby team were participated in this study. The testing subjects of 10-m sprint time (s), 60 kg power bench press (mean power, W·s−1), 20-kg squat jump (mean power, W·s−1), bench press 1RM (kg), back squat 1RM (kg), chin-up 1RM (kg) were analyzed. The definition of game members (n = 25) were those who have played more than 5 matches out of 10 Top-League matches (3 matches are from LIXIL Cup), and the non-game members (n = 21) were who have played less than 4 matches. A comparison between the 2 groups was performed by unpaired t-tests. Results: In forwards, chin-up (body weight + plates) results for game members showed higher values than non-game members (members: 150.1 kg, non-members: 130.9 kg, p < 0.01). In backs, back squat results for game members showed greater values than non-game members (members: 201.9 kg, non-members: 175.8 kg, p ≤ 0.05). No other variables showed notable differences. Discussion: Top-League is the top-ranked rugby union league in Japan, and its players are required to obtain very high physical strength profiles. Within the league, this study found out that there are the differences in physical strength between game members and non-game members. As with the study of physical strength of American football draft prospects (Sierer et al., JSCR, 2008), the testing subjects that showed no greater differences are still important results to understand the minimum requirements in physical strength. Practical Applications: This study disclosed the standard in physical strength of Japan Top-League rugby players. It becomes guideline to understand the physical strength that Top-League players have to have. Furthermore, it may influence program-designing of physical training program for non-game members to compete.

The Movement Characteristics of Rugby Top-League Players Using Global Positioning System

Masaki Yoshikai,1Jumpei Okuno,1Ryusuke Serizawa,1and Daichi Yamashita2

1NTT Communications Shining Arcs Rugby Club, Chiba, Japan; and2Japan Institute of Sports Sciences, Tokyo, Japan

Introduction: Recently, the use of GPS technology in rugby matches has expanded largely, the position-specific characteristics of matches have been analyzed and utilized for practices especially in rugby advanced countries such as in Europe. The purpose of this study is to quantify the characteristics of GPS game movement in Japan Top-League rugby union. Methods: All the players who have played all of the 10-game league matches of 2015–2016 season have worn GPS units (GPSports HPU 15 Hz). Using preceding studies as references, data of 66 forwards and 60 backs who have played more than 60 minutes for each of the 10 matches are reviewed for this study. Total distance, high intensity (>18 km·h−1) distance, distance travelled per minute, and maximum velocity were recorded. A comparison between the 2 position groups was performed by unpaired t-tests. Results: Total distance of 5,274 m for forwards and 6,172 m for backs, distance travelled per minute of 66 m for forwards and 72 m for backs, high intensity running distance of 336 m for forwards and 613 m for backs, and maximum velocity of 26.3 km·h−1 for forwards and 28.6 km·h−1 for backs. For all the variables, backs scored are superior than forwards. Discussion: According to the preceding study (McLellan et al., JSCR, 2011) that quantified the characteristics of internationally-recognized high intensity sports, National Rugby League (NRL), the results were that the total distance of 4,982 m for forwards, 5,573 m for backs, and high intensity running of 232 m for forwards, 440 m. The results show that the GPS characteristics of Top-League players are higher intensity than that of NRL. It suggests that the differences by country and by league may possibly influence the GPS characteristics. Practical Applications: No study until this one to quantify the GPS characteristics of Japan Top-League rugby union; therefore, this study is essential for the future of study for rugby union in in Japan to standardize and establish the GPS characteristics. Furthermore, by comparing the difference by country and by league, it may become useful information planning for international rugby matches.

Kinematic Characteristics of Upper Body Movements During Uchi-Mata Throw in the Elite and College Judo Athletes

Takanori Ishii,1Yoshihiko Nakamura,2Yosuke Ikegami,2Hideyuki Nagao,3Naoki Itami,4and Shigenobu Nakai5

1Ryotokuji University, Tokyo, Japan;2The University of Tokyo, Tokyo, Japan;3Japan Institute of Sports Sciences, Tokyo, Japan;4Tokai University, Kanagawa, Japan; and5Japan Broadcasting Corporation, Tokyo, Japan

Purpose: Kinematics of judo throw may be different between elite and non-elite judo athletes. Our previous study demonstrated that upper body rotation movement appears to occur at a later timing during the turning phase of seoi-nage in elite judo athletes than college judo athletes. On the other hand, no difference was found in the whole motion time between the elite and college athletes (Ishii et al., 2015). Because a judo athlete attempts to control an opponent's movement by gripping up his/her judo-gi (jacket), the later timing of upper body rotation may lead a delay of the opponent's reaction for defense. Therefore, we hypothesized the kinematic characteristics that differentiate the elite and college judo-throw skill may not be linear and rotational velocity, but sequences of the upper and lower body rotation movements during the turning phase of judo throw. The aim of the present study was to elucidate kinematic characteristics of the upper body movement during uchi-mata (inner-thigh throw) throw in elite judo athletes. Methods: An Olympic-level elite judo athlete who was skilled in uchi-mata technique and a college judo athlete who had a 12-year judo experience participated in this study. Three-dimensional motion data were captured using a Motion Analysis System during the planned uchi-mata sparring with or without a faint movement and during free judo sparring. The analyzed period was set between the time when the athletes gripped up opponent's gi and when the opponent completed a break-fall. Three time points (E1–E3) during the throwing motion were arbitrarily defined for further analysis. E1 was at the time when the thrower lifted the pivot foot off the mat, E2 was at the time when the pivot foot of the thrower contacted on the mat, and E3 was the time when the opponent's leg contacted to the judo mat after the throw. Three variables were calculated: (a) turning time (E1 to E2), (b) the horizontal trunk rotation angle of the thrower relative to the opponent, and (c) the trunk inclination angle of the opponent relative to the thrower. Results: The turning time of planned uchi-mata without a feinting movement was 0.36 and 0.32 seconds in the elite and the college judo athlete, respectively. In addition, the turning time in the planned uchi-mata with one feint movement was 0.36 and 0.34 seconds in the elite judo athlete and the college judo athlete, respectively. The turning time of uchi-mata in the free sparring was 0.32 seconds in the elite athlete and 0.40 seconds in the college athlete. The trunk rotation angles at E1 in planned uchi-mata sparring a with and without a feint movement in the elite athlete were 27 and 21° smaller than those in the college athlete, respectively. The elite athlete also demonstrated 8° smaller trunk rotation angle in free judo sparring than the college athlete. Finally, the elite athlete started leaning his trunk anteriorly at the earlier timing during uchi-mata in all the 3 condition. Discussion: It has been believed by coaches that elite judo athletes execute uchi-mata faster than non-elite judo athletes do; however, the Olympic-level judo athlete showed little difference in the uchi-mata throwing time compared to the college athlete. The finding is also similar to our previous finding in seoi-nage investigation. Interestingly, the elite athlete showed shorter turning time in the free spurring than the planned uchi-mata throws, but the college athlete showed the opposite. Finally, our result demonstrated the elite athletes started leaning and turning their upper body at the later timing than the college athletes during the turning phase of uchi-mata, suggesting that elite athletes are utilizing the skill that delays an opponent's defensive reaction to throw an opponent in any situation. Practical Application: Many judo coaches have implemented “speed throw drill” and ask an athlete to repeat the sparring drill movement as fast as possible in a given time. Those coaches are likely to focus on the improvement of rotational velocity during the turning phase in the drill; however, the current result suggests that coaches need to pay more an attention to the kinematic sequence of upper and lower body rotation in the turning motion rather than the velocity. In addition, coaches may need to develop movement drills to gain such kinematic rotation sequence and training program to improve rotational strength and flexibility in horizontal plane.

A Study of Recovery Methods in Collegiate and Amateur Soccer Teams

Yosuke Akutsu,1Toshiharu Yamamoto,2Masashi Kasahara,2and Chihiro Ota3

1Japan Soccer College, Niigata, Japan;2International Budo University, Chiba, Japan; and3Keio University Rugbyfootball Club, Kanagawa, Japan

Purpose: It is believed the necessity of recovery from fatigue is important to maintain or improve athlete's condition. When choosing a recovery technique, it is required to consider sports characteristics, timings of recovery, and recovery techniques, and select proper recovery method. We operationally defined tactical recovery as utilizing various recovery methods based on situations. Because insufficient information on tactical recovery has been provided to date, we select an appropriate technique through trial-and-error. Therefore, the goal of this survey was to collect preliminary information regarding recovery methods used in soccer teams in Japan. The information would be helpful to develop a strategical recovery in soccer. Methods: Fifty certified trainers attended a trainer's workshop offered by Japan Football Association agreed on the intention of this study. A set of questionnaire was sent to the trainers who worked at soccer teams. The items asked in the survey included person responsible for recovery sessions, whether any recovery session was implemented, goals of recovery session, recovery methods, length of each recovery session, any considerations, and so on. The survey was analyzed, and the results were compared. Results: Thirty trainers completed the survey (60.0%). Percentage of teams implemented recovery sessions was 97%. As for recovery sessions, 50% of teams implemented at every practice, 20% teams implemented irregularly (as needed), and 27% of teams implemented a few times every week. Energy replenishment and during matches (87%) were rated as the most prioritized items to improve to implement recovery sessions. Producing fatigue substance and after matches (83%) were listed as the most prevalent responses. Considerations for recovery sessions were categorized into age, sleeping, environment, and methods. Age was divided by school grades or playing experience. In sleeping, at least 8 hours of sleep was required. In environment, climates should be taken into account by utilizing wet-bulb globe temperature. In methods, the intensity of exercise and length of cooling by ice should be adjusted based on the amount of practice. Discussion: The results indicated most of the teams implemented recovery sessions as a team in some manners because most of drills in a practice were completed by the whole team; therefore, it was believed that the extent of fatigue were similar for every athlete. Next, approaching to energy depletion was the top priority in recovery sessions. In a soccer match, players generally repeat a high-intensity interval exercise between 150 and 200 times. As a result, the use of creatine phosphate (CP) and glycolysis were accelerated; therefore, replenishing energy is essential. Approaching to fatigue substance production was also the most prevalent interest immediately after a soccer match among trainers. It has been believed during one soccer match, a total running distance was approximately 10–13 kilometers, and high-intensity interval exercise with sprinting and jogging was repeated. Hence, the approach to fatigue substance production was actively implemented. Practical Application: The results showed that methods of recovery and timing differed between pre-exercise and post-exercise in soccer. Soccer player need to select an appropriate recovery method (technique and timing) based on the timing of matches/practices.

A Study of Recovery Methods in Elite Rugby Teams

Chihiro Ota,1Toshiharu Yamamoto,2Masashi Kasahara,2and Shigeyuki Tahara1

1Keio University Rugbyfootball Club, Kanagawa, Japan; and2International Budo University, Chiba, Japan

Purpose: It is believed the necessity of recovery from fatigue is important to maintain or improve athlete's condition, but insufficient information on how recovery sessions were completed based on conditions and situations was available. Therefore, the purpose of this survey was collect preliminary information regarding recovery methods used in highest-level rugby teams in Japan. Methods: A set of questionnaire was sent to conditioning coaches who were responsible for implementing recovery sessions at 16 rugby teams (Japan Rugby Top-league) in Japan. The items asked included who was in charge of recovery sessions, whether any recovery session was conducted, the goal of recovery, method and time of recovery, any considerations, and so forth. The survey was collected, and we analyzed the results. Results: Thirteen conditioning coaches completed the survey (81.0%). All teams implemented recovery session in some manners. The top-rated purpose of recovery sessions was “injury prevention” (77.0 ± 9.5%) in any situations. Other purposes of the recovery sessions were “preparation for the following days,” “mental refreshment,” etc. Comparison in different situations showed recovery sessions were done for “prevention of performance reduction” during a match. Two most common concrete aims of recovery sessions were “removing fatigue substance” (82.1 ± 6.3%), and “energy depletion,” (73.1 ± 11.7%). Characteristics in each situation demonstrated “increased psychological stress,” especially following a match, that reached more than 70%. This disclosed recovery sessions were implemented for different purposes in different situations and targets. The 2 commonly reported methods were “replenishing nutrition” (82.1 ± 6.3%), and “icing” (65.4 ± 22.7%). Characteristics in each situation showed a tendency that low-intensity exercise was less frequently completed except a day after a rugby match. Considerations listed in recovery sessions were that older players required a longer recovery session, quality sleep more than 8 hours were required, usage of electric device should be limited, etc. Discussion: It is believed that recovery sessions were implemented daily in any situations except during a rugby match because risks of injuries increase if fatigue were chronically accumulated. Also, it is thought that preventing performance reduction is important because maintaining performance through a match could decide the result of a match. Recovery sessions are believed to be utilized to recover from physical and psychological fatigue because “increased psychological stress” due to too much nervousness (tension?) is anticipated following a match. In addition, “consuming nutrients” is the most prioritized to minimize the decrease of body mass by consuming nutrient after a practice because decreasing body mass might influence physical condition and rugby performance in contacting with other players. The reason of icing has also been reported by previous studies in which inflammations such as contusions in the entire body were seen immediately after practices and matches; therefore, it is considered that daily icing routinely done. Practical Application: Rugby teams in the Top-league tended to alter the recovery program and the priority based on situations and purposes. We found a tendency to consider an influence, especially contacts with other players. The findings are beneficial information to develop recovery protocols.

The Factors Contributing to Alteration in Change of Direction Ability Among Junior High School Soccer Players

Hayato Nakamura1and Norikazu Hirose2

1Waseda University, Saitama, Japan; and2Faculty of Sport Sciences, Waseda University, Saitama, Japan

Purpose: Change of direction ability is an essential in soccer performance, and one of the factors is to change directions. Although it is clear that ability to change directions develops during the peak height velocity age (PHVA), it is unclear which factor is responsible for its development. Therefore, the purpose of this study was to clarify factors contributing to alteration in change of direction ability among junior high school soccer players by comparing alterations in direction-changing motion in each PHVA developmental stage. Methods: A total 20 male junior high school soccer players were recruited and divided into 2 groups based on PHVA; one group (n = 10) was in PHVA (Mid group), and the other group (n = 10) was in post PHVA (Post group). PHVA was calculated by previous heights. Participants performed 5 m sprint with the right foot plant-and-cut movement, and sprinted back to the starting line. The sprint-cut-sprint time was measured as the criterion variable, and 3-dimension motion was analyzed. In addition, anthropometric measurements, muscle mass, knee flexion torque, knee extension torque, and vertical jump height were measured as the predictor variables. The second measurement was conducted 6 months after the first one to calculated variability in each measurement. Multiple regression analysis was conducted, and Pearson product-moment correlation coefficient was also calculated to explain associated variables. The criterion variable was total time in change of direction, and other measurements were the predictor variables. The level of significance was set at 0.05. Results: In Mid group, torso flexion displacement between the right foot contact on the ground and the movement ceased to turn the direction was extracted as a predictor variable (R2 = 0.505, p ≤ 0.05). Relative to the torso flexion displacement, the right hip flexion displacement between the right foot contact on the ground and the movement ceased to turn the direction (r = 0.703, p ≤ 0.05) and the change in horizontal center-of-mass velocity (r = −0.753, P ≤ 0.05) showed significant correlations. In Post group, the change in horizontal center-of-mass velocity between the left foot contact on the ground and the movement ceased to turn the direction (R2 = 0.479, p ≤ 0.05) and the angle of left hip flexion at the left foot contact on the ground (R2 = 0.595, p ≤ 0.05) were extracted. Relative to the change in center-of-mass velocity, the displacement of left hip flexion between left foot contact on the ground and the movement ceased to turn the direction (r = −0.637, p ≤ 0.05) demonstrated significant correlation. Discussion: In Post group, the increased change in center-of-mass velocity and the change in the angle of left hip flexion were extracted, and 2 predictor variables are associated. In short, the greater and the quicker flexion in the hip joint one step prior to change direction assisted to quicker deceleration, and this is suggested to be a factor to develop the change of direction ability in the Post group. In contrast, the increased torso flexion displacement was extracted as a factor to develop the change of direction ability in Mid group, and there was a correlation between the displacement in the right hip flexion and the change in center-of-mass velocity. Therefore, increased movement in deceleration with the pivotal foot influenced the development of change of direction ability in Mid group, and this suggested increasing compensating movement during torso flexion help to decelerate quickly. It was speculated that the decreased range of motion in the lower extremities along with increased height during PHVA influenced the increased compensation. Practical Application: It is important to take an approach based on the stage of development for the adolescent. This indicates that teaching movements to decelerate by the hip joint along with maintaining range of motion is essential for the youth in the growth spurt. On the other hand, it was suggested that teaching movements along with strengthening muscles around the hip joint is required for the youth in post growth spurt stages.

Physical Characteristics of Tall Players in Basketball by Focusing on the Field Test of Endurance

Takeshi Koyama1and Akira Rikukawa2

1Sports Medical Science Research Institute, Tokai University, Kanagawa, Japan; and2School of Physical Education, Tokai University, Kanagawa, Japan

Introduction: Previous studies have shown that Japanese tall basketball players have problems in endurance. Maximal Oxygen uptake (V̇o2max) differs from types exercises to evaluate endurance performance; however, there is no research that examines correlation between V̇o2max in different types exercises and height. The purpose of this research was to clarify characteristics of the endurance in tall basketball players by evaluating V̇o2max in 2 kinds of exercises, cycling and running. Methods: Twenty-eight male college basketball players (height: 186.3 ± 10.0 cm, weight: 83.6 ± 9.4 kg, age: 20.7 ± 1.3 years), were divided into 3 groups (guard, forward, and center) based on their height. Each participant were measured their V̇o2max with cycling and running. Bicycle exercise is using a bicycle ergometer (Wattbike, Japan Sykes Co., Ltd.), to measure the “3-minute aerobic test.” On the other hand, running exercise was determined to “20 m shuttle run (round trip endurance running).” The order of exercise was randomly assigned in all participants, and there was 48 hours interval between each type of exercise. Results: There was no correlation between the V̇o2max in cycling and running (The V̇o2max in cycling: 57.8 ± 4.1 ml·kg−1·min−1, and the V̇o2max in running: 56.7 ± 3.3 ml·kg−1·min−1). With respect to positions, there were no significant differences in V̇o2max between the guard and forward, whereas the V̇o2max with cycling was significantly higher than running in the participants in the center group. Discussion: It is considered that the load of lower limbs at the change of direction in tall players was larger than other position players, because of body weight difference. On the other hand, cycling is less susceptible to the influence of body weight. These results indicate that the V̇o2max by running is underestimated in comparison with the cycling. Practical Applications: Present studies suggest that a kind of exercise for measuring V̇o2max, it is necessary to consider the physical characteristics (such as height and body weight).

© 2016 National Strength and Conditioning Association