Ítem
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Optimal Reactive Strength Index
Título de la revista
Autores
Ramirez-Campillo, Rodrigo
Alvarez, Cristian
García-Pinillos, Felipe
Sanchez-Sanchez, Javier
Yanci, Javier
Castillo, Daniel
Loturco, Irineu
Chaabene, Helmi
Moran, Jason
Izquierdo, Mikel
Fecha
2018-04
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Editor
The Journal of Strength and Conditioning Research
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Resumen
Abstract
This study aimed to compare the effects of drop-jump training using a fixed drop-box height (i.e., 30-cm [FIXED]) vs. an optimal (OPT) drop-box height (i.e., 10-cm to 40-cm: generating an OPT reactive strength index [RSI]) in youth soccer players' physical fitness. Athletes were randomly allocated to a control group (n = 24; age = 13.7 years), a fixed drop-box height group (FIXED, n = 25; age = 13.9 years), or an OPT drop-box height group (OPT, n = 24; age = 13.1 years). Before and after 7 weeks of training, tests for the assessment of jumping (countermovement jump [CMJ], 5 multiple bounds), speed (20-m sprint time), change of direction ability (CODA [Illinois test]), strength {RSI and 5 maximal squat repetition test (5 repetition maximum [RM])}, endurance (2.4-km time trial), and kicking ability (maximal kicking distance) were undertaken. Analyses revealed main effects of time for all dependent variables (p < 0.001, d = 0.24-0.72), except for 20-m sprint time. Analyses also revealed group 3 time interactions for CMJ (p, 0.001, d = 0.51), depth jump (DJ) (p < 0.001, d = 0.30), 20-m sprint time (p < 0.001, d = 0.25), CODA (p < 0.001, d = 0.22), and 5RM (p < 0.01, d = 0.16). Post hoc analyses revealed increases for the FIXED group (CMJ: 7.4%, d = 0.36; DJ: 19.2%, d = 0.49; CODA: 23.1%, d = 20.21; 5RM: 10.5%, d = 0.32) and the OPT group (CMJ: 16.7%, d = 0.76; DJ: 36.1%, d = 0.79; CODA: 24.4%, d = 20.34; 5RM: 18.1%, d = 0.47). Post hoc analyses also revealed increases for the OPT group in 20-m sprint time (23.7%, d = 0.27). Therefore, to maximize the effects of plyometric training, an OPT approach is recommended. However, using adequate fixed drop-box heights may provide a rational and practical alternative.
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Keywords
Adolescent , Athletic Performance , Humans , Male , Muscle Strength , Physical Fitness , Plyometric Exercise , Running , Soccer
