Purpose: To examine the effects of drop height on drop-jump (DJ) performance and on associations between DJ and horizontal-jump/sprint performances in adolescent athletes. Methods: Male (n = 119, 2.5 [0.6] y post-peak-height velocity) and female (n = 120, 2.5 [0.5] y post-peak-height velocity) adolescent handball players (national level) performed DJs in randomized order using 3 drop heights (20, 35, and 50 cm). DJ performance (jump height, reactive strength index [RSI]) was analyzed using the Optojump Next system. In addition, correlations were computed between DJ height and RSI with standing-long-jump and 20-m linear-sprint performances. Results: Statistical analyses revealed medium-size main effects of drop height for DJ height and RSI (P < .001, 0.63 ≤ d ≤ 0.71). Post hoc tests indicated larger DJ heights from 20 to 35 and 35 to 50 cm (P ≤ .031, 0.33 ≤ d ≤ 0.71) and better RSI from 20- to 35-cm drop height (P < .001, d = 0.77). No significant difference was found for RSI between 35- and 50-cm drop height. Irrespective of drop height, associations of DJ height and RSI were small with 5-m-split time (−.27 ≤ r ≤ .05), medium with 10-m-split time (−.44 ≤ r ≤ .14), and medium to large with 20-m sprint time and standing-long-jump distance (−.57 ≤ r ≤ .22). Conclusions: The present findings indicate that, irrespective of sex, 35-cm drop heights are best suited to induce rapid and powerful DJ performance (ie, RSI) during reactive strength training in elite adolescent handball players. Moreover, training-related gains in DJ performance may at least partly translate to gains in horizontal jump and longer sprint distances (ie, ≥20-m) and/or vice versa in male and female elite adolescent athletes, irrespective of drop height.
Olaf Prieske, Helmi Chaabene, Christian Puta, David G. Behm, Dirk Büsch and Urs Granacher
Helmi Chaabene, Yassine Negra, Jason Moran, Olaf Prieske, Senda Sammoud, Rodrigo Ramirez-Campillo and Urs Granacher
This study examined the effects of an 8-week Nordic-hamstring exercise (NHE) training on components of physical performance in young female handball players.
Participants were allocated to an experimental (EG; n=10; age: 15.9 ± 0.2 years) and a control group (CG; n=9; age: 15.9 ± 0.3 years). The EG performed NHE (2-3 sessions/week) in replacement of some handball-specific drills whereas the CG followed regular handball training. Pre- and post-training, tests were carried-out for the assessment of sprint speed (5 m, 10 m, 20 m), jump performance (countermovement jump [CMJ] height), change-of-direction (CoD [T-test]), and repeated-sprint-ability (RSA total-time [RSAtotal], RSA best-time [RSAbest], RSA fatigue-index [RSAFI]). Data were analyzed using magnitude-based inferences.
Within-group analyses for the EG showed moderate performance improvements for 5 m, 10 m, 20 m (effect-size [ES] = 0.68-0.82), T-test (ES=0.74), and CMJ (ES=0.85). Trivial-to-small improvements were observed for RSA (ES=-0.06-0.35). For the CG, within-group outcomes showed performance decrements with moderate (T-test [ES=0.71]), small (5 m [ES=0.46], and RSAbest [ES=0.20]), and trivial magnitude (10 m [ES=0.10], 20 m [ES=0.16] and RSAtotal [ES=0.00]). Further, trivial-to-small performance improvements were found for CMJ (ES=0.10) and RSAFI (ES=0.5). Between-group analyses revealed small-to-large effects in favor of EG for 5 m (ES=1.07), 10 m (ES=0.66), 20 m (ES=0.53), T-test (ES=1.38), and RSA (ES=0.68 to 0.78). A trivial between-group difference was demonstrated for CMJ (ES=-0.01).
The NHE training intervention, in replacement of some handball-specific drills, was more effective than regular handball training in improving physical performance (i.e., linear sprint-time, jumping, CoD, and RSA) in young female handball players.
Yassine Negra, Helmi Chaabene, Senda Sammoud, Olaf Prieske, Jason Moran, Rodrigo Ramirez-Campillo, Ali Nejmaoui and Urs Granacher
Purpose: To examine the effects of loaded (LPJT) versus unloaded plyometric jump training (UPJT) programs on measures of muscle power, speed, change of direction (CoD), and kicking-distance performance in prepubertal male soccer players. Methods: Participants (N = 29) were randomly assigned to a LPJT group (n = 13; age = 13.0 [0.7] y) using weighted vests or UPJT group (n = 16; age = 13.0 [0.5] y) using body mass only. Before and after the intervention, tests for the assessment of proxies of muscle power (ie, countermovement jump, standing long jump); speed (ie, 5-, 10-, and 20-m sprint); CoD (ie, Illinois CoD test, modified 505 agility test); and kicking-distance were conducted. Data were analyzed using magnitude-based inferences. Results: Within-group analyses for the LPJT group showed large and very large improvements for 10-m sprint time (effect size [ES] = 2.00) and modified 505 CoD (ES = 2.83) tests, respectively. For the same group, moderate improvements were observed for the Illinois CoD test (ES = 0.61), 5- and 20-m sprint time test (ES = 1.00 for both the tests), countermovement jump test (ES = 1.00), and the maximal kicking-distance test (ES = 0.90). Small enhancements in the standing long jump test (ES = 0.50) were apparent. Regarding the UPJT group, small improvements were observed for all tests (ES = 0.33–0.57), except 5- and 10-m sprint time (ES = 1.00 and 0.63, respectively). Between-group analyses favored the LPJT group for the modified 505 CoD (ES = 0.61), standing long jump (ES = 0.50), and maximal kicking-distance tests (ES = 0.57), but not for the 5-m sprint time test (ES = 1.00). Only trivial between-group differences were shown for the remaining tests (ES = 0.00–0.09). Conclusion: Overall, LPJT appears to be more effective than UPJT in improving measures of muscle power, speed, CoD, and kicking-distance performance in prepubertal male soccer players.