Judo is a high-intensity intermittent combat sport (17) in which competitors try to throw their opponents onto their backs using different techniques (leg, ashi-waza; arm, te-waza; hip, koshi-waza; and sacrifice, sutemi-waza) or to score during groundwork combat using immobilizations (ossae-waza), strangles (shime-waza), or elbow joint locks (kansetsu-waza) according to the traditional judo classification. Judo matches are limited to a 5-minute interval that can be extended until 1 athlete scores or until the end of a new 3-minute period, although extra time is required in <2% of the total number of matches in high-level competition. However, the mean length of a judo match is approximately 3 minutes, and a decisive score (ippon) is obtained within 3 minutes in >50% of the matches (25). Typically, judo athletes perform 20–30 seconds of activity with a 5- to 10-second interval (30,37), resulting in a high physiological demand (17,18).
To improve both the technical and physical components, judo athletes are submitted to many sessions of uchi-komi (technique repetition without throwing) using different techniques and time structures (5). Because physiological measurements during judo matches are not easily conducted because of technological limitations and the risk of injury or damage to the equipment as a consequence of the intense contact between judo athletes, few studies have investigated the physiological demand of judo-specific training methods (2,16,27,34,35). Knowledge of the physiological responses during these tasks would help to improve judo training protocols (10), especially providing better control of the training stimulus imposed on the athlete. Additionally, because judo includes many techniques, it is important to know how the athletes respond to them and which training protocols would result in a higher number of repetitions.
High-intensity intermittent exercise has been shown to stress both the aerobic and anaerobic pathways (22,39), which is important to the physical conditioning of judo athletes. During a match, the anaerobic system provides energy for the short, quick, all-out bursts of maximal power needed to perform the techniques, whereas the aerobic system contributes to the athlete's ability to sustain effort for the duration of the combat and to recover during the brief periods of rest or reduced effort (18,21). Uchi-komi in judo is performed during 10- to 30-second periods of effort to simulate the segments of activity typically observed during a match (30). There have been few investigations on high-intensity intermittent exercise physiology comparing different lengths of effort and pause intervals while keeping the effort-to-pause ratio constant (11,31,32). However, this information is relevant for optimization of the training prescription and to provide a better understanding of the mechanisms involved in this type of exercise (15,23,28,33).
Thus, the objective of this study was to compare the physiological response and performance (number of repetitions) in different uchi-komi protocols, varying the time structure (18 × 10 seconds/10 seconds, 8 × 20 seconds/20 seconds, and 6 × 30 seconds/30 seconds) and the technique used (o-uchi-gari, seoi-nage, and harai-goshi, representing the leg, arm, and hip techniques, respectively). The main hypotheses of this study are that the leg technique will result in a lower physiological response compared with the other techniques, as leg techniques normally do not require trunk rotation or pronounced knee flexion compared to the others and that the longer intermittent protocol (6 × 30 seconds/30 seconds) will result in a higher physiological response compared with the medium (9 × 20 seconds/20 seconds) and short (18 × 10 seconds/10 seconds) protocols, despite the 1:1 effort-pause relationship in all protocols.
Experimental Approach to the Problem
This study was conducted during 3 sessions, with a minimal time interval of 48 hours and a maximum of 2 weeks between the first and last test sessions (Figure 1). In the first session, after measurement of the body mass and height of each athlete, the oxygen uptake at rest (V[Combining Dot Above]O2rest) was measured for 5 minutes in a standing position. In the first session and in the following 2 sessions, the athletes performed 9 uchi-komi sessions (3 techniques and 3 time structures), that is, 3 sessions per day. Therefore, it was possible to compare the physiological responses associated with 3 different techniques (1 from each traditional judo classification, i.e., leg, arm and hip techniques) and 3 time structures that varied in the length of the effort and pause periods while maintaining an effort-pause ratio of 1:1. These results will allow coaches to improve their knowledge of the training stimulus based on the use of judo-specific exercises that are frequently used in this sport. The testing order was determined at random using computer-generated random numbers. Forty to 60 minutes of passive rest was given between the uchi-komi sessions. This time interval was determined in a pilot study to be long enough for the blood lactate concentration ([LA]), heart rate (HR), and oxygen uptake (V[Combining Dot Above]O2) to return to the concentrations at rest: [LA]—1–3 mmol·L−1; HR—60–85 b·min−1; V[Combining Dot Above]O2—5–10 ml·kg−1·min−1. Additionally, the athletes included in this pilot study were able to recover their performance for the same number of repetitions as in the first set of uchi-komi.
The athletes were required to refrain from exercise for 24 hours before each trial, to maintain their habitual sleep time and to not ingest any food 3 hours before the test sessions. They were also instructed to replicate their food and water intake for all trials, and the athletes were not undertaking any weight loss effort during the period of this study. All the athletes were familiarized with the procedures adopted and had performed the tests previously at least once in other studies. All the tests performed by the same athlete were conducted at the same time of the day. Because the tests were conducted in a laboratory, the temperature was fixed at 24° C, and the relative humidity was between 40 and 60%.
Ten male judo athletes (25 ± 6 years old, 73 ± 9 kg body mass, 173 ± 5 cm height, and 15 ± 6 years of judo experience with a brown or black belt) voluntarily participated in this study after reading and signing an informed consent explaining all the risks and benefits of this investigation. All the athletes were nonsmokers, and none of them received any pharmacological treatments or had any type of neuromuscular disorder or cardiovascular, respiratory, or circulatory dysfunction. All the athletes were evaluated during their competitive period. To take part in this study, the athletes were required to have the following characteristics: (a) participate in official judo competitions during that year; (b) participate in training at least 3 times per week; (c) be a brown (first kyu) or black belt (first dan); (d) be ≥18 years and <35 years; and (e) compete in the under 100-kg categories. All the procedures received local ethics committee approval (protocol 2007/2003).
The techniques used were o-uchi-gari (leg technique, ashi-waza), seoi-nage (arm technique, te-waza), and harai-goshi (hip technique, koshi-waza). The choice of these techniques was based on the following criteria: (a) each technique is among the 3 most used in high-level judo competition considering the classification analyzed (leg, arm, and hip techniques); (b) 1 technique (o-uchi-gari) involves pushing the partner to throw him, whereas the other 2 involve a pulling action; 1 technique is executed with only 1 foot on the ground and the opposite leg performing a sweeping action (harai-goshi); and the other technique (seoi-nage) involves ground contact with both feet and a more pronounced knee flexion during the entrance movement.
Each technique was stopped just before the throwing phase as commonly executed in uchi-komi judo sessions. During this process, the athlete who received the technique (uke) allowed the performer (tori) to execute the technique with no resistance to his movements. All the partners were from the same weight category. The above criteria were used to simulate the common practice performed during judo training sessions in this type of exercise (uchi-komi).
The time structure adopted in this study was based on the following criteria: (a) the total activity duration was identical to the mean time typically observed in competition, that is, 3 minutes (17,18,30); (b) the effort-pause ratio was maintained at 1:1 (18 × 10 seconds/10 seconds, 9 × 20 seconds/20 seconds, and 6 × 30 seconds/30 seconds). Although the effort-pause ratio during judo matches is 2:1, during competition, judo athletes do not perform high-intensity actions throughout the contest, as one part of the activity period is spent performing the low-intensity actions of grip preparation (30). Additionally, this type of procedure has been used frequently during judo training sessions (5,20). The number of repetitions was registered, and to compare the time structure, the total number of repetitions performed was used. The number of technique repetitions during each minute of effort was also determined.
Physiological Measurements During Uchi-komi Protocols
Each athlete was submitted to 3-minute-effort uchi-komi protocols, performing as many repetitions as possible (all-out) with the partner in a static position. This procedure is typical in training sessions and has been used in other studies (3,5,29). Test-retest studies from our group have indicated that uchi-komi exercise similar to that used in this study is repeatable (ratio limits of agreement: 0.95–1.1) when a total of 76–78 repetitions are performed (3). All the uchi-komi sessions were performed in a 2-m × 2-m tatami area.
Oxygen uptake (K4 b2, Cosmed, Italy) and HR (Polar Team Systems, Polar, Finland) were measured continuously and at 6 minutes after all the uchi-komi protocols. The gas analyzer was fixed to the athletes' thorax during the execution of harai-goshi and seoi-nage and to their backs during the o-ouchi-gari execution. The mean oxygen uptake and HR during the effort and pause phases were calculated. At 1, 3, and 5 minutes after the end of each test, blood was collected from the ear lobules to measure the lactate concentration. This measurement was obtained using the Yellow Spring 1500 Sport lactimeter (Yellow Springs, USA). The highest value measured was considered the peak lactate concentration ([La−]peak). The difference between the [La−]peak and pretechnique lactate concentration ([La−]rest) was expressed as a delta value ([La−]delta). The fast component of excess postexercise oxygen consumption was determined using a modified double exponential decay equation (19). A value of 1 mmol·L−1 [La-] delta was considered to be equivalent to 3 ml O2 kg−1 body mass (14). To estimate the total energy expenditure and oxygen consumption during each uchi-komi protocol, the oxygen consumption during the effort and pause phases, the fast component of excess postexercise oxygen consumption and the energy derived from the anaerobic lactic energy system were summed and converted to kilojoules, assuming that 1 L of oxygen consumed was equivalent to 20.9 kJ (26). The total energy expenditure was also expressed relative to the total number of repetitions.
The data were analyzed statistically using the Statistical Package for Social Sciences 13.0 (SPSS Inc., Chicago, IL, USA). The descriptive analysis consisted of the mean and SD. For all measured variables, the sphericity estimated was verified according to the Mauchly's W test, and the Greenhouse-Geisser correction was used when necessary. The comparison of the physiological responses ([La−], the mean V[Combining Dot Above]O2 during effort and pause, the amplitude and time constant of the fast phase of excess postoxygen consumption in each protocol) was conducted through a 2-way analysis of variance (technique and time structure). To evaluate the number of technique repetitions, the HR during each minute of effort and pause, the V[Combining Dot Above]O2 during each minute of effort, and the concentrations of blood lactate at rest and at 1, 3, and 5 minutes after each protocol, a 3-way analysis of variance (technique, time structure and period) was used. When a significant difference or interaction was observed in the analysis of variance, a Bonferroni test was conducted to identify the differences between the conditions. The effect size (eta-squared; η2) of each test was calculated for all analyses. Statistical significance was set at p ≤ 0.05.
Table 1 presents the number of repetitions performed in the different conditions for each minute of effort.
There was a significant main effect observed for the techniques (F = 19; p < 0.001; η2 = 0.32), with higher values observed during the execution of o-uchi-gari compared to both harai-goshi and seoi-nage (p < 0.001 for both comparisons). There was also a significant main effect for time and the number of repetition (F = 64; p < 0.001; η2 = 0.44), with higher values in the first minute compared with the second and third minutes (p < 0.001 for both comparisons) and higher values in the second minute compared with the third minute (p = 0.003). There was no main effect (p > 0.05) for time structure on the number of technique repetitions.
Heart rate differed across time for both the activity (F = 183; p < 0.001; η2 = 0.710) and pause periods (F = 95; p < 0.001; η2 = 0.552), with lower values observed in the first minute (effort: 159 ± 9 b·min−1; pause: 159 ± 13 b·min−1) compared with the second (effort: 172 ± 6 b·min−1; pause: 172 ± 7 b·min−1) and third minute (effort: 176 ± 7 b·min−1; pause: 175 ± 7 b·min−1) and lower values observed in the second minute compared with the third minute (p < 0.001 for all comparisons). There was no main effect (p > 0.05) for time structure or technique on the HR.
Oxygen consumption differed over time during activity (F = 767; p < 0.001; η2 = 0.904), with lower values during the first minute (32.51 ± 3.21 ml·kg·min−1) compared with the second (41.47 ± 4.20 ml·kg·min−1) and third minutes (42.96 ± 4.29 ml·kg·min−1), and lower values in the second compared with the third minute (p < 0.001 for all comparisons).
Table 2 presents the blood lactate concentration, the oxygen consumption during the activity and pause phases, and the amplitude and time constant of the fast phase of excess postoxygen consumption during each protocol.
There was no main effect of technique on blood lactate (pre, peak, and delta), oxygen uptake during activity, or the amplitude and time constant of the fast phase of the excess postoxygen consumption. However, there was main effect of time structure on oxygen uptake during the effort phase (F = 4; p = 0.025; η2 = 0.087), with higher values during the 10-second protocols compared to the 30-second protocols (p = 0.022).
For blood lactate, there was a main effect for the time of measurement (F = 6; p = 0.001; η2 = 0.075), with lower values recorded at rest compared with all other time points (p < 0.001) and lower values recorded 1 minute after a protocol compared with 3 minutes after a protocol (p = 0.008).
Table 3 presents both the absolute (kilojoules) and relative (kilojoules per repetition) energy expenditure during each protocol performed using each of the 3 techniques.
There was no main effect for time structure or technique on the absolute energy expenditure (p > 0.05). However, there was a main effect for technique on the total energy expenditure per repetition (F = 6; p = 0.001; η2 = 0.128), with o-uchi-gari resulting in lower values compared with seoi-nage (p = 0.003).
Our results demonstrated that there was no effect of technique on the blood lactate concentrations, the oxygen consumption during the pause phases, the amplitude and time constant of the fast phase of the excess postoxygen consumption, or the total absolute energy expenditure, despite the higher number of repetitions during the execution of o-uchi-gari compared with both harai-goshi and seoi-nage. The shorter time structure (10 seconds/10 seconds) resulted in higher oxygen uptake during the activity phases compared with the longer time structure (30 seconds/30 seconds). As expected, there was a significant effect of time on the number of repetitions, with higher values in the first minute compared with the second and third minutes and higher values in the second minute compared with the third minute. The opposite was observed for HR and oxygen consumption, which increased over time during both the effort and the pause periods.
The decrease in the number of repetitions over time is consistent with other reports studying all-out activities (6,22,23,31). This decrease can be explained by the increase in the relative aerobic contribution because of a decrease in glycolysis and an inability to restore all of the phosphocreatine degraded during the effort periods (22,38,40). No difference was found concerning the number of repetitions among the time structures investigated in this study, suggesting that when a 1:1 effort-pause ratio and all-out effort are used, judo athletes are able to perform the same number of repetitions during uchi-komi.
The increase in oxygen uptake across time during the different uchi-komi protocols is similar to that presented in other studies using high-intensity intermittent exercise (4,6,31). This result seems to be a consequence of the short period of the intervals used, which were not long enough to result in a decrease in the oxygen uptake to the resting values.
The similar oxygen consumption observed for each of the techniques performed seems to be a result of a compensatory effect concerning the number of repetitions, that is, as o-uchi-gari can be considered simpler and faster than the other 2 techniques, it could be performed a higher number of times during each protocol, resulting in a similar physiological demand as the other techniques.
The higher oxygen uptake during the activity phases in the protocols with a shorter time structure (18 × 10 seconds/10 seconds) than compared with those with a longer time structure (6 × 30 seconds/30 seconds) can be attributed to the higher number of sets performed during the shortest protocol used in our study, which resulted in a higher number of accelerations and decelerations to begin and end the movements for each set. This result is similar to that reported by Christmass et al. (11), who a found higher oxygen uptake during a short protocol (6 seconds:9 seconds) compared with a long protocol (24 seconds:36 seconds) when analyzing subjects running at 109 ± 5% of the velocity associated to V[Combining Dot Above]O2max. Additionally, the V[Combining Dot Above]O2 values measured during these protocols were higher than those observed during a 5-minute interval of nage-komi (technique entrance followed by a throw) using 1 throw every 15 seconds until the completion of the interval, seoi-nage (33.71 ± 5.68 ml·kg·min−1) harai-goshi (32.28 ± 5.10 ml·kg·min−1), and o-uchi-gari (29.97 ± 6.10 ml·kg·min−1) (16), and a 1-minute interval of uchi-komi plus a 2-minute interval of randori (match simulation; 32.03 ± 13.23 ml·kg·min−1) (13), and randori performed either continuously (39 ml·kg·min−1) or intermittently (28–31 ml·kg·min−1) (27). However, the V[Combining Dot Above]O2 values measured in our study were slightly lower than those reported in the last 2 phases (45.95 ± 1.17 and 45.87 ± 0.69 ml·kg·min−1) of the Special Judo Fitness Test (21), which is the most frequently used specific test to evaluate judo athletes. However, these values were similar to those measured in the third minute of a match simulation (40.73 ± 4.05 ml·kg·min−1) (2), suggesting that these uchi-komi protocols, which are commonly used during judo training sessions, are an efficient method for impose stress on the oxidative metabolism pathways, similarly to reports on specific and complex judo activity during match simulation. Recently, high-intensity intermittent exercise has been used to improve both the aerobic and anaerobic fitness of combat sports athletes, such as karate athletes (33), wrestlers (15), and judo athletes (28), although in these studies, the training stimulus was not specific to the combat sports analyzed. Thus, the use of uchi-komi as a training stimulus may be a better training stimulus because it is specific to the sport.
When the total energy expenditure was expressed relative to the total number of repetitions, there was an effect of technique resulting in lower values with o-uchi-gari compared to seoi-nage, suggesting that o-uchi-gari can be considered less energetically costly. Therefore, the athletes were able to perform a higher number of repetitions during o-uchi-gari execution compared with other techniques. This result may be a consequence of the movement pattern, especially because of the requirement for trunk rotation and knee flexion during seoi-nage, which increase the length of time required to perform a single repetition (16). Thus, when the number of repetitions is fixed, the use of seoi-nage can result in higher energy expenditure compared with o-uchi-gari. However, when the all-out approach is used, the same total energy expenditure is achieved using these 2 techniques, whereas a higher energy demand per repetition would be achieved during the seoi-nage protocol compared with o-uchi-gari.
The HR was similar for all of the techniques, although the techniques differed with respect to the total energy expenditure per repetition. This result is similar to that reported in another study (16) that analyzed nage-komi (technique application and throwing). Thus, the use of HR to report the effort intensity during the intermittent performance of uchi-komi cannot be recommended, as suggested by others (7,24). Our results are consistent with those of Achten and Jeukendrup (1), who reported that the HR responds too slowly during high-intensity intermittent exercise, which limit its use to estimate the intensity of effort. Another explanation for the lack of a significant relationship between the HR and energy expenditure during uchi-komi in judo is the important contribution of the arm muscles, which would disrupt the common association found during V[Combining Dot Above]O2 and HR during lower body cyclic exercises. The absence of a difference in HR among the time structures employed is similar to that found in the fifth minute of the 6:9 seconds (161 ± 8 b·min−1), 12:18 seconds (167 ± 6 b·min−1), and 24:36 seconds (166 ± 7 b·min−1) protocols performed at 120% of the V[Combining Dot Above]O2max velocity (31), and for the 6:9 seconds (169 ± 11 b·min−1) and 24:36 seconds (170 ± 9 b·min−1) protocols performed at the same intensity, as reported by Price and Moss (32). Thus, when intermittent exercise is performed at the same absolute intensity (31,32) or at maximal effort (all-out), as in this study, using the same effort-pause ratio in all protocols, it seems that the HR is similar among protocols, even when the duration of effort and pause are different.
Few studies have measured HR during uchi-komi (5,24). When a similar volume of uchi-komi was performed (all-out repetitions during 5 × 30 seconds/30 seconds), higher values of HR were found (191 ± 5 b·min−1) (24). However, in that study, there is no information concerning the type of technique performed, although another protocol including 30 repetitions of 20–30 seconds is presented in the same article, which indicates that the athletes were most likely submitted to a basic technique repetition exercise (hikidashi) where only the judogi's sleeve and lapel are pulled, but no technique is defined. This approach would allow a higher number of repetitions per second and would explain the higher HR reported in that study compared with the present one. Another study (5) compared the HR in different uchi-komi protocols, including 6 sets of 40 seconds with 40-, 120-, and 200-second intervals between them. The longest protocol resulted in lower HR values in the second, fourth, and sixth sets compared with the 2 protocols. No difference was found between the 2 shortest protocols, which achieved similar values to those reported in this study.
The increase in the HR during the different period of activity of the uchi-komi protocols was quite similar to the increase reported during a 3-minute match simulation (2). Additionally, the values were quite similar to those measured after a complete duration (5-minute) match simulation (male = 180 ± 11 b·min−1; female = 176 ± 6 b·min−1) (35), suggesting that these uchi-komi protocols can result in similar cardiovascular stress to that imposed during the match.
Blood lactate concentrations did not differ between techniques, which can be explained by the all-out nature of the protocols used in this investigation. The similarity in the blood lactate concentrations among the different time structures is different from the findings of previous studies using supramaximal protocols (11,31,32). These authors found that higher blood lactate concentrations were associated with the longest protocols (24 seconds:36 seconds) when compared with the intermediate (12 seconds:18 seconds) and shortest protocols (6 seconds:9 seconds). However, these studies did not use the all-out approach, which may explain the difference between these studies and ours. Additionally, despite the use of the all-out approach, the blood lactate values after the uchi-komi protocols were slightly lower than those reported after randori (8.9 ± 0.5 to 9.1 ± 1.1 mmol·L−1) (8,9) and all-out nage-komi during the Special Judo Fitness Test (10.8 ± 1.8 mmol·L−1) (19), they were lower than those measured after match simulations (10.1 ± 2.0 to 12.7± 5.0 mmol·L−1) (12,17,21,35), and they were much lower than those reported after competition matches (10.3 ± 2.6 mmol·L−1) (36), especially in international tournaments (10.3 ± 4.7 to 17.2 ± 1.9 mmol·L−1) (37). This result may suggest that although the uchi-komi was performed at the highest intensity possible, the absence of a demand for upper body muscular endurance typically observed during grip disputes (kumi-kata) in judo matches may result in a lower glycolytic demand during this training activity compared with a match simulation or a competition match.
The main findings of this study were as follows: (a) there was no difference concerning the absolute energy expenditure among the techniques or time structures, which can be attributed to the all-out characteristic of the exercise; (b) more repetitions were executed during the o-uchi-gari protocol, because this technique does not involve torso rotation or knee flexion. This technique resulted in lower total energy demand per repetition compared with seoi-nage; (c) the athletes were not able to keep the pace during the 3 minutes of uchi-komi, which may be a consequence of the lower absolute anaerobic systems energy transfer as the time exceed 1 minute; (d) this training protocols resulted in similar oxygen uptake and HR responses compared with match simulations, but it resulted in lower blood lactate concentrations than observed in match simulations.
One of the main principles of training is specificity, but it is common to observe combat sport athletes performing nonspecific, high-intensity, intermittent exercises. This is partly because there are few studies reporting the physiological responses to combat-sport-specific training protocols. Thus, knowledge of the physiological responses during uchi-komi performed intermittently and in an all-out approach can help coaches to improve the training protocols for judo athletes. Our results demonstrated that the physiological responses (V[Combining Dot Above]O2, lactate, and HR) did not differ among the techniques when different amplitudes of a 1:1 effort-pause ratio were used (18 × 10 seconds/10 seconds, 9 × 20 seconds/20 seconds, and 6 × 30 seconds/30 seconds), and the techniques were performed in an all-out condition. The shortest protocol used (18 × 10 seconds/10 seconds) resulted in higher oxygen uptake values during the activity phases, suggesting that it can be used when aerobic power development is the main goal. These uchi-komi protocols resulted in similar oxygen uptake and HR responses than those observed during both match simulations and match competitions, but the blood lactate concentration was lower in our study compared with these specific activities, most likely because of the grip disputes (kumi-kata) that occur during matches. Thus, the inclusion of grip dispute would help to increase the stress on the glycolytic pathway. Another important finding of our study was that the HR did not differ among the techniques or time protocols, whereas the energy expenditure and the number of techniques performed differed among the conditions, suggesting that this variable should not be used to monitor training intensity during the intermittent training protocols.
The authors wish to thank the athletes for their cooperation during the study. This study was supported by FAPESP (2007/51228-0).
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