Abstract

The purpose of this study was to determine the effects of a 12-week contrast training (CT) program (isometric + plyometric), with no external loads, on the vertical jump, kicking speed, sprinting, and agility skills of young soccer players. Thirty young soccer players (age, 15.9 +/- 1.43 years; weight, 65.4 +/- 10.84 kg; height, 171.0 +/- 0.06 cm) were randomized in a control group (n = 13) and an experimental group (n = 17). The CT program was included in the experimental group's training sessions, who undertook it twice a week as a part of their usual weekly training regime. This program included 3 exercises: 1 isometric and 2 plyometric, without external loads. These exercises progressed in volume throughout the training program. Performance in countermovement jump (CMJ), Balsom agility test (BAT), 5-, 10-, 20-, and 30-m sprint, and soccer kick were assessed before and after the training program. A 2-factor (group and time) analysis of variance revealed significant improvements (p 0.001) in CMJ, BAT, and kicking speed in the experimental group players. Control group remained unchanged in these variables. Both groups significantly reduced sprint times over 5, 10, 20, and 30 m (p = 0.05). A significant correlation (r = 0.492, p 0.001) was revealed between Delta BAT and Delta average kicking speed. Results suggest that a specific CT program without external loads is effective for improving soccer-specific skills such as vertical jump, sprint, agility, and kicking speed in young soccer players.