Water polo (WP) is a sport that places high strength and high-intensity and endurance demands on the athlete because it is a high-intensity intermittent sport, with a predominance of sprint swimming and wrestling. The importance of nonswimming activities (e.g., throwing, passing, and wrestling), which account for around 69% of playing time, has been previously highlighted (10,35). Competitive performance in WP depends not only on strength but also on the ability to exert force at the speed required by this discipline. In addition to technical and tactical skills, it has been argued that muscular strength and power are the most important factors that give a clear advantage in elite competitions (10). Appropriate anthropometric characteristics and WP throwing ability are also important to success (13). Despite the increase in professionalization of this sport, there is a paucity of research on the performance characteristics of elite players, and little data are available for WP players over an entire season. Because of the increased demands of technical training and competition, in-season strength and conditioning could be proposed to maintain adequate levels of strength and power over the playing season. Although WP playing in itself can enhance many of these factors, elite competitors must engage in additional WP-specific conditioning, including exercises to develop high-intensity intermittent anaerobic effort, speed, change of direction, strength, and power.
Empirical information on training methods that increase throwing ability is also limited, and most of the research to date has been conducted in other sports such as baseball or handball (14,27). Sport coaches and scientists agree that the main determinants of throwing velocity are technique, the timing of movement in consecutive limb segments, and the strength and rate of force development of the upper and lower body (17). In WP, the authors reported that factors thought to influence the throwing velocity include upper and lower body and trunk strength, throwing technique, and vertical jumping ability (13,26). Each of these factors can be improved by appropriate training, particularly resistance exercises. General resistance training with exercises for the upper body with loads of 60–80% 1 repetition maximum (1RM) seems to influence throwing velocity positively (41). Chelly et al. (5) previously highlighted the contribution of the lower body to throwing ability, underlining that coaches should include strength and high-intensity programs not only for the shoulders and arms but also for the lower body. Biweekly training of this type seems sufficient to induce substantial gains not only in peak power output and dynamic strength but also in throwing velocity (21).
Research on WP has focused mainly on the physiological profiles (23,28,35,40) and swimming capabilities of elite athletes (11,30). Nevertheless, in the last decade, technical and tactical aspects of matches have also been investigated (23,24,36), even considering potential differences between competition levels. Nevertheless, no study has focused on the analysis of a specific strength and high-intensity training program implemented in-season to enhance the performance of elite WP players.
We thus hypothesized that elite WP players who supplemented their normal in-season WP training with an 18-week program of biweekly heavy-resistance and high intensity–oriented exercises for both lower and upper body would enhance their muscular strength and other qualities critical to WP performance (throwing velocity, swim sprinting, and jumping abilities).
Experimental Approach to the Problem
This study was designed to assess the effects of 18 weeks of biweekly (36 sessions) strength and high-intensity training in-season on muscular strength and other qualities critical to WP performance of elite players. To achieve this, the participants were randomly allocated to undergo an additional program of strength and high-intensity training or only receive usual in-water training. All the tests were carried out before (baseline-test) and after the training period (posttest). These included (a) anthropometric measures, (b) vertical countermovement jump (CMJ) performance, (c) maximal strength (1RM; kilograms) (bench press [BP] and full squat [FS]), (d) throwing velocity, and (e) 20-m maximal sprint swim performance. After the initial measurements, a team of experienced players (n = 27) was randomly allocated to either the control (standard in-season regimen) (C; n = 11) or experimental group that received the additional strength and high-intensity training (S; n = 16). During each training session, the participants were instructed in proper execution of all the exercises and all sessions were supervised. The participants undertook the strength and high-intensity exercises between 18.00 and 19.00 hours (in a weight training facility) and the WP training (in a swimming pool) from 21:00 to 23:00 hours. The participants were also instructed to avoid any strenuous physical activity and to maintain their usual dietary habits for the duration of the study.
The procedures were approved by the Institutional Ethics Review Committee (Pablo de Olavide University, Seville, Spain) in accordance with the current national and international laws and regulations governing the use of human subjects (Declaration of Helsinki II). Before participating in the study, the subjects were fully informed about the protocol, and a written informed consent was obtained from each subject before testing as well as written informed consent from the parents/guardians of the 2 subjects under 18 years old. The subjects were free to withdraw from the study without penalty at any time. A questionnaire regarding medical history, age, height, body mass, training characteristics, injury history, team WP experience, and performance level was completed before participation. An initial examination by the team physician focused on orthopedic and other conditions that might preclude resistance and high-intensity training, and all the participants were found to be in good health. The subjects, 27 national-level male WP players (age 20.43 ± 5.09 years), height (180.33 ± 5.90 cm), body mass (81.43 ± 8.48 kg), body fat (12.43 ± 3.21%), mean WP experience 8.5 ± 4.1 years, were randomly divided into the S and C groups; these 2 groups were well matched in terms of their initial characteristics.
The participants were habituated with the test procedures before the measurements were taken. In addition, several warm-up sets were recorded before the actual maximal and explosive tests. All the tests were conducted within a single day for each athlete and the time of testing for baseline and post testing was held consistent for individual athletes. Before the tests, the participants carried out a standardized warm-up consisting of 10 minutes submaximal running at 9 km·h−1 followed by light stretching and a specific warm-up of vertical jump and FS with low loads (2 sets of 10 repetitions at 20% of body mass) as familiarization trials with the assessment exercises. Additionally, care was taken to allow sufficient rest between all the tests to limit the effects of fatigue on subsequent tests.
Height was measured using a wall-mounted stadiometer (Seca222, New York, NY, USA). Body mass was measured using a medical scale, and fat mass, fat-free mass, and percentage of body fat were estimated using bioimpedance (Tanita, BC-418 MA, Tokyo, Japan).
The CMJ test was performed using an infrared curtain system (Ergo-Jump, MuscleLabV718, Langesund, Porsgrunn, Norway) to measure flight and contact times. The jump height was determined from the flight time using standard calculation. Five trials were completed with 1 minute of rest between trials. The 2 extreme values of the 5 trials were eliminated (best and worst), and the mean of the 3 central values was used for the subsequent statistical analysis.
Maximal Dynamic Strength One-Repetition Maximum
For the lower body, maximal dynamic strength (1RM) was determined as the highest weight that could be lifted through the full range of motion of an FS with correct technique. The participants performed the FS from a fully extended position starting with shoulders in contact with the bar. On command, the participants performed a controlled eccentric squat to a knee angle of 60°, followed without pause by a concentric leg extension (as fast as possible) returning to full extension. The trunk was kept as straight as possible and a Certified Strength and Conditioning Specialist conducted this test and checked for correct technique. A safety belt was used by all the participants. The tests were performed in a squatting apparatus (Smith machine, Model Adan-Sport, Granada, Spain). Velocity of displacement was determined using a squatting apparatus in which the barbell was attached at both ends, with linear bearings on 2 vertical bars allowing only vertical movements. Besides, bar displacement, peak, and mean velocity (meters per second) were recorded using a distance encoder attached to 1 end of the bar. The distance encoder recorded the position and the direction of the bar to an accuracy of 0.0003 m. A computer program (T-Force System, Ergotech, Murcia, Spain) was used to calculate the velocity of displacement for each repetition of the FS performed throughout the whole range of motion. Warm-up consisted of a set of 10 repetitions at loads of 40–60% of the perceived maximum. Thereafter, 5–6 separate single attempts were performed until the subject was unable to extend the legs to the required position. The last acceptable lift with highest possible load was determined as 1RM. The rest period between trials was always 2 minutes. For the upper body 1RM test, the BP was selected and implemented according to the methods described above but for the BP movement (22). The 1RM BP was chosen because it involves some arm muscles that are specific to overhand throwing. The test was also performed in a Smith machine as for the FS. The athletes lowered the bar from a fully extended arm position until the bar was at chest height but not touching and then immediately extended the arms as fast as possible to return to the starting position. Warm-up consisted of a set of 10 repetitions at loads of 40–60% of the perceived maximum. Thereafter, 4–6 separate single attempts were performed until the subject was unable to extend the arms to the required position. The last acceptable lift with the highest possible load was determined as 1RM. The rest period between trials was always 2 minutes.
Ballistic strength production during a WP over arm throw was evaluated in a swimming pool. For the throw, the subjects were instructed to use their preferred technique to throw a WP ball as fast as possible through a standard goal. Throw tests were undertaken after a 15-minute standardized warm-up and using a standard WP ball (mass 450 g, circumference 0.71 m). To simulate a typical WP-ball action, the players were allowed to put resin on their hands, and they were instructed to throw with maximal velocity toward the upper right corner of the goal. The coaches supervised this test closely to ensure that the required techniques were followed. Each subject continued until 3 correct throws had been recorded, up to a maximum of 3 sets of 3 consecutive throws. One to 2 minutes of rest was allowed between the sets of throws and 10–15 seconds between 2 throws of the same set. The throwing velocity was measured using Stalker-Sport-Radar (Stalker K-Band Sport Radar 1-888, Plano, TX, USA). The radar device was positioned on a tripod behind the thrower. The 2 extreme values of the trials were eliminated (best and worst), and the mean of the central values was used for the subsequent statistical analysis.
Twenty-Meter Maximal Sprint Swim
Maximal sprint swim times were recorded for a 20-m distance, in an indoor swimming pool of 25 m. The participants were positioned 1 m off the wall (upright position facing the far end of the pool), before they were signaled to start the sprint with a random sonorous sound. Infrared beams were stationed at the sprint start and end points (0 and 20 m) with time measured to the nearest 0.01 seconds using an electronic timing system (Muscle Lab.V7.18, Ergotest Technology, Langesund, Norway). Before the test, the participants carried out a standardized warm-up consisting of 5 minutes of submaximal swimming followed by some half speed sprints (2 sets of 15 m) as familiarization trials. Three trials were completed, with 5 minutes of rest between trials, and the shortest time was used for the subsequent statistical analysis.
Strength and high-intensity training took place 2 d·wk−1 (Monday and Wednesday) for the S group during 18 weeks of the intervention (36 sessions) immediately before normal WP training. The training was individualized for each participant based on their maximal strength with a printed schedule of volume, density, and intensity of the training (number of sets and repetitions, rest intervals, daily load). Each session lasted 30–45 minutes, 10 minutes of standard warm-up (5 minutes of submaximal running at 9 km·h−1, stretching exercises for 5 minutes and 2 submaximal exercises of jump [20 vertical jump, 10 long jumps], 15–30 minutes of specific strength training and 5 minutes of cooldown including stretching exercises). The training program employed by each group is outlined in Table 1. All the training sessions for all groups were fully supervised, and training diaries were maintained for each participant. All the participants were instructed to maintain their normal daily activities throughout the 18-week study, including participation in recreational sporting activities. However, no additional strength or other forms of training were permitted.
Descriptive statistics (mean ± SD) for the outcome measures were calculated. The intraclass correlation coefficient (ICC) was used to determine the reliability of the measurements. The training-related effects and the differences between groups were assessed using a mixed-design factorial analysis of variance with the contrast F of Snedecor. Effect sizes (ESs) were also calculated using Cohen's d. Statistical significance was accepted at an alpha level of p ≤ 0.05.
At baseline, no significant differences between groups were observed in any of the anthropometric, strength or sprint variables tested. After 18 weeks of training, no significant changes were observed in any of the physical characteristics analyzed.
Height in Countermovement Jump
Statistically significant increases (p ≤ 0.05) occurred in the CMJ (2.38 cm; 6.9%; ES = 0.48) in the S group. No differences were observed after training in the magnitude of the changes among the groups. The ICC was 0.95 for CMJ measurements indicating high reliability.
Maximal Dynamic Strength One-Repetition Maximum Full Squat and Bench Press
Maximal dynamic strength 1RM FS and BP (kilograms) increased (p ≤ 0.05) in the S group (11.06 kg; 14.21%; ES = 0.67) and (9.06 kg; 10.53%; ES = 0.66), respectively. Differences (p ≤ 0.05) were observed after training in the magnitude of the increase between the S and C groups. The ICC for the strength tests was 0.88.
Throwing velocity (kilometers per hour) increased (p ≤ 0.05) in the S group (1.76 km·h−1; 2.76%; ES = 0.25). No differences were observed after training in the magnitude of the changes among the groups. The ICC was 0.85.
Twenty-Meter Swim Sprint Time
Maximal sprint swim time (seconds) decreased (p ≤ 0.05) in the experimental group (−0.26 seconds; 2.25%; ES = 0.29). Differences (p ≤ 0.05) were observed after training in the magnitude of the increase between the S and C groups. The ICC was 0.91.
The primary aim of this study was to determine whether elite male WP players could enhance muscle strength and other qualities critical to WP performance (throwing velocity, swim sprinting, and jumping abilities) by an in-season program of strength and high-intensity training for the upper and the lower body. The important finding of our research was that our results substantiate our hypothesis that resistance and high-intensity training in-season enhances the strength output of both upper and lower body, whether assessed by jumping (6.90%) or swim sprinting (2.25%), 1 RM BP (10.53%) and FS (14.21%) test, or throwing velocity (2.76%). Other studies have examined the influence of strength training and jump height on overhead throwing velocity of elite WP players (4,26), but this is the first study to examine the gains of jumping and swim sprinting performance, using resistance and high-intensity exercises such as the BP, military press and pull-ups for the upper body and FS and plyometric exercises for the lower body.
Vertical jumping ability is an essential component in WP, and it is frequent in both defensive (e.g., blocking and stealing) and offensive (e.g., passing and shooting) WP maneuvers. The classical dry-land vertical jump test differs somewhat from WP-specific vertical jumping (in-water vertical jump) (29); nevertheless, this study showed gains in vertical jump height (6.9% for CMJ) on land. These results can be compared with the results of other studies (11) that showed an improvement of 15% in vertical jump height. Furthermore, in comparison with the results published by other researchers who performed this test in athletes of other sports, it appears that WP players have a relatively high capacity to increase explosive strength that is comparable with that of junior soccer players (6) (7.5%), or swimmers (15). Christou et al. (7) also found respective gains of 14.4% in the CMJ of soccer players over 8 weeks of strength training. Gorostiaga et al. (18) studied the influence of resistance training on the jump performance of handball players, and they reported meaningful increases in a group that had previously engaged only in team practice (6%), but no changes of the CMJ in either resistance training or control groups. Also, we observed no meaningful (2.5%) improvements in the CMJ height relative to controls, underlining importance that the introduction of resistance and high-intensity training did not interfere with jump development. Foot speed is the most important factor contributing to performance in the eggbeater kick used in a WP hold. Thus, WP players need to develop the ability to maintain high speeds of foot movement throughout the eggbeater kick cycle to improve the vertical jumping ability (32). Clearly WP requires different skills to land based jumping but still requires high leg extensor power.
The WP requires high force and power and neuromuscular and aerobic endurance because it is a high-intensity intermittent sport, with a predominance of sprint swimming and wrestling. Several studies have provided information on the physiological and fitness characteristics of these athletes (2,29,40), but no data on strength have been published. Several studies have shown the effectiveness of high intensity–oriented and heavy-resistance training in improving strength and motor performance (12,31). The results of this investigation concur with those studies showing that a combined program can meaningfully increase strength performance. Interestingly, this study also illustrates that the magnitude of increases in maximal strength performance was almost the same for the upper (10.53%) and the lower (14.21%) body. These findings have replicated that of Gorostiaga et al. (19) who reported that specific resistance training improves the strength of both the upper extremity muscles (23%) and the leg extensors (12.2%) in handball players. In this study, gains for the upper bodies (10.53% for 1RM BP) were even smaller than those previously observed (19), possibly because of differences in the initial status of the players or the training exercises that were undertaken. The greater increase of 1RM lower body strength in this study could be explained by the importance of eggbeater kick as a cyclical action of the lower body and the combination of in-water and resistance training may have elevated the adaptations. Marques and González-Badillo (25) also noted a 28% increase of 1RM BP, after 12 weeks of resistance training (2–3 sessions per week) in high level handball players, which is much higher than the 10.53% gain of 1RM BP that we observed despite their training loads being very similar to ours; 70–85% of concentric 1RM BP, whereas ours were in the range 60–80%.
The ultimate requirement in the game of WP is to throw successfully at the goal. High velocity in the overhead WP throw is an essential component of throwing for the purpose of scoring goals. Factors thought to influence the throwing velocity include upper and lower body and trunk strength, throwing technique, and vertical jumping ability. General resistance training with exercises for the upper body with loads of 60–80% 1RM seems to influence throwing velocity positively (41). An explanation for this is given by Schmidtbleicher et al. (33), who attribute their findings to the size principle of motor recruitment. This implies that only heavy load training ensures the recruitment of fast twitch motor units. Their contention is that low loads do not overload the neuromuscular system sufficiently to induce an adaptation. The results of our investigation concur with those studies showing that a combined strength and high-intensity program can meaningfully increase overhead throwing velocity performance (2.76%). In the study of Bloomfield et al. (4), no increase was found in throwing velocity after resistance training with increasing weight (Pyramid training), possibly because the players were uniformly highly skilled or because the training regimen did not provide sufficient stimulus to all muscle groups relevant to throwing velocity. A possible explanation for the differences in results between these 2 studies is the experience and performance level of the training group. The high relationship between force and throwing velocity (r = −0.63) lends support to the theory that throwing velocity is also influenced by lower body force enhancing the capacity to propel the body out of the water. However, force alone is unlikely to be sufficient in less skilled players whose eggbeater kick is not as proficient. A knowledge of the game also suggests ability to elevate the body in the water would increase strategic options for players during competition by allowing players to shoot or throw the ball past opponents or to intercept or block the ball.
Swim sprinting, acceleration, and rapid changes in direction are inherent to both practice and competition in WP. Additionally, most sprint swims are short (e.g., 10 m–15 m). Strength and speed are 2 major factors determining a swimmer's sprint performance at training and competition (16,38). In fact, some studies have reported that muscular strength correlated meaningfully with swim velocity (1,37). Furthermore, several research studies have reported that upper body muscular strength output correlates highly with swim velocity over short swimming distances (r ∼ 0.87) (20,39). Several authors (8,34) have reported that swimming performance is meaningfully associated with arm strength on dry-land exercises. Other studies suggest swimming velocity is more correlated to the specific force produced in the aquatic environment, being much more specific tests (38). The results of this investigation concur with those studies showing that a combined strength and high-intensity program can meaningfully increase swim sprint performance (2.25%), and muscular strength correlated moderately but meaningfully with swim velocity (r = −0.55). To our best knowledge, no study has examined the associations between swimming performance and dynamic strength of the upper and lower extremities in competitive WP players. The BP and FS exercises were chosen because they activate overall the same muscle groups as used when swimming (9). Thus, using multijoint exercise tests should be advantageous when exploring associations with a dynamic movement such as swimming. Birrer (3) pointed out the importance of BP and triceps extension strength in the pushing phase for all swim strokes. In this study, BP was also moderately related (r = −0.41) to specific swimming performance (20-m sprint tests). Watanabe and Takai (42) analyzed the factors that contribute to swimming performance. Their results suggest that muscle strength was an important explanatory factor of swimming performance over 50 m in both genders. Another factor that could possibly contribute to the different outcomes between previous investigations with respect to the associations between swimming performance is the training and athlete's background. Because we used elite WP athletes with extensive training and competition history, it is likely that further gains are more difficult to achieve.
We have clearly demonstrated that elite male WP players can enhance muscle strength by undertaking an 18-week in-season program of strength and high intensity–oriented training involving exercises for both the upper and the lower-body (BP, FS, pull-ups, and loaded and unloaded jump exercises). Moreover, there is no apparent interference between the development of force and maximal sprint swim performance and WP ball throwing velocity. Rather, these sport specific performance qualities were enhanced considerably by the strength and high-intensity training, over and above that achieved through in-water training. It has proven quite easy and practical to add the proposed regimen to the traditional in-season technical and tactical training regimen. The performance improvements shown in this study are of great interest for WP coaches, because the performance of this sport relies greatly on the specific in-water vertical jump, maximal sprint swim, and throwing abilities that were enhanced by the strength and high intensity–oriented training regimen. Previous authors have found a similar benefit of strength and high-intensity training in other sports, but this is the first study to our knowledge involving elite WP players. It is recommended that WP coaches implement in-season strength and high-intensity training to enhance the performance of their players.
The authors are grateful to the participants of this study for having performed maximal efforts until volitional fatigue. The authors have no professional relationships with companies or manufacturers that might benefit from the results of this study. There is no financial support for this project. No funds were received for this study from National Institutes of Health, Welcome Trust, University, or others. The results of this study do not constitute endorsement of any product by the authors or the National Strength and Conditioning Association.
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