 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.
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 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.
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