Abstract: Objective: The aim of this study was to investigate the effect of unilateral muscle strength training on specific physical performance indicators in adolescent male soccer players. Methods: Twenty adolescent male soccer players were recruited and divided into the experimental group (N=10) for a 6-week unilateral muscle strength training of barbell rear-foot elevated squat and the control group (N=10) for a 6-week bilateral muscle strength training of deep squat. Tests were conducted to evaluate agility, speed, left foot standing balance and right foot standing balance. Statistical methods were used to compare all parameters of the pre-test and post-test of the unilateral and bilateral training groups using paired samples t-test, and α= 0.05 was used as the level of significance test. Results:6 week unilaterial and bilaterial training both significantly improved agility, balance and speed in male adolences football players. Significantly better improvements were found for unilaterial training compared to bilaterial training with significantly greater changes in variables: agiligty (t=-2.979;P<0.01), balance (left foot standing, t=-2.944,P<0.01; right foot standing, t=-3.063,P< 0.01), and 30 m sprint (t=2.938;P<0.01).Conclusion: The inclusion of unilateral training in a muscle strength training program can be effective in producing positive benefits and improvements in the performance of other specific abilities (agility, speed, and balance, etc.) in adolescent male soccer players.

Key words: unilateral strength training, soccer players, specific physical ability, sports training