Plyometric Training Improves Not Only Measures of Linear Speed, Power, and Change-of-Direction Speed But Also Repeated Sprint Ability in Young Female Handball Players

ABSTRACT: Chaabene, H, Negra, Y, Moran, J, Prieske, O, Sammoud, S, Ramirez-Campillo, R, and Granacher, U. Plyometric training improves not only measures of linear speed, power, and change-of-direction speed but also repeated sprint ability in young female handball players. J Strength Cond Res 35(8): 2230-2235, 2021-This study examined the effects of an 8-week plyometric training (PT) program on components of physical fitness in young female handball players. Twenty-one female adolescent handball players were assigned to an experimental group (EG, n = 12; age = 15.9 ± 0.2 years) or an active control group (CG, n = 9, age = 15.9 ± 0.3 years). While EG performed plyometric exercises in replacement of some handball-specific drills, CG maintained the regular training schedule. Baseline and follow-up tests were performed for the assessment of linear speed (i.e., 5-, 10-, and 20-m time), change-of-direction (CoD) speed (i.e., T-test time), muscle power (i.e., countermovement jump CMJ height and reactive strength index RSI), and repeated sprint ability (RSA) (RSA total time RSAtotal, RSA best time RSAbest, and RSA fatigue index RSAFI). Data were analyzed using magnitude-based inferences. Within-group analyses for the EG revealed moderate-to-large improvements for the 5-m (effect size ES = 0.81 0.1-1.5), 10-m sprint time (ES = 0.84 0.1-1.5), RSI (ES = 0.75 0.1-1.4), RSAFI (ES = 0.65 0.0-1.3), and T-test time (ES = 1.46 0.7-2.2). Trivial-to-small ES was observed for RSAbest (ES = 0.18 -0.5 to 0.9), RSAtotal (ES = 0.45 -0.2 to 1.1), 20-m sprint time (ES = 0.56 -0.1 to 1.2), and CMJ height (ES = 0.57 -0.1 to 1.3). For the CG, within-group analyses showed a moderate performance decline for T-test time (ES = -0.71 -1.5 to 0.1), small decreases for 5-m sprint time (ES = -0.46 -1.2 to 0.3), and a trivial decline for 10-m (ES = -0.10 -0.9 to 0.7) and 20-m sprint times (ES = -0.16 -0.9 to 0.6), RSAtotal (ES = 0.0 -0.8 to 0.8), and RSAbest (ES = -0.20 -0.9 to 0.6). The control group achieved trivial-to-small improvements for CMJ height (ES = 0.10 -0.68 to 0.87) and RSI (ES = 0.30 -0.5 to 1.1). In conclusion, a short-term in-season PT program, in replacement of handball-specific drills, is effective in improving measures of physical fitness (i.e., linear/CoD speed, jumping, and RSA) in young female handball players.