Abstract
This study assessed the effects of combined muscular strength and resisted sprint training using both sled and weight vest compared with regular soccer training on physical fitness of lower limbs in U-19 elite soccer players. Thirty-four male soccer players (age: 18.8 +/- 0.8 years, height: 1.81 +/- 0.05 m, body mass: 76.4 +/- 4.9 kg, and body fat mass: 11.3 +/- 4.2%) were randomly assigned into a resisted sprint training group (RSTG, n = 20), using both weight vest and sled, and a control group (CONTG, n = 14). Sprinting ability (5 m and 20 m), squat jump (SJ) and counter-movement jump (CMJ) tests, 1 repetition maximum of half-back squat (1RM half-back squat), and soccer ball-shooting speed were assessed before and after a 6-week training program. Within-group interactions showed significant combined muscular strength and resisted sprint training effects were observed for all the tests' measurements (effect sizes = 0.97 and 3.69 for 20-m sprint and SJ, respectively). However, significant increases of performances were observed for 5-m and 20-m sprinting time (eta(2)(p) = 0.25, p < 0.01 and eta(2)(p)= 0.22, p < 0.01, respectively), SJ and CMJ (eta(2)(p) = 0.78, p < 0.0001 and eta(2)(p)( )= 0.34, p < 0.001, respectively), 1 repetition maximum (1-RM) half-back squat (eta(2)(p) = 0.45, p < 0.0001), and soccer ball-shooting speed (eta(2)(p) = 0.41, p < 0.0001) in RSTG with large effect size, whereas the CONTG showed significant performances increase only for CMJ (p < 0.05), 1RM half-back squat (p < 0.01), and soccer ball-shooting speed (p < 0.05). We conclude that combined strength and both horizontal (weighted sled) and vertical (weighted vest) resisted sprint training are more effective than regular soccer training for enhancing sprinting and jumping abilities as well as ball-shooting speed in soccer.