The Effects of Stable versus Unstable Surface Resistance Training on Performance of Female Soccer Players

Abstract

PURPOSE: The purpose of the present study was to compare the effects of resistance training performed on either a stable or unstable surface on performance tests in female soccer players. METHODS: Nineteen NCAA Division II female soccer players were assigned to either an unstable training group (UST. 19.0 ± 0.47 years; 1.69 ± 0.64 m; 67.8 ± 7.7 kg) or a stable training group (ST. 19.6 ± 0.49 years; 1.64 ± 0.32 m; 62.7 ± 6.3 kg). Player positions were distributed evenly between the groups. Both groups followed a five week periodized resistance training program comprising three sessions per week with workout schemes designed to develop maximum muscular strength. Both the UST and ST groups performed the same exercises during each workout, with the UST performing two of the exercises in each session on an unstable surface. Pre- and post-training measures of straight-line sprint speed, planned and reactive agility, aerobic capacity and depth jump height (DJ) and countermovement vertical jump height (CMJ) were taken. RESULTS: There were no significant main effects for time or group by time interactions reported for straight-line sprint speed, planned agility, aerobic capacity or DJ (p > 0.05). A significant main effect for time was reported for reactive agility (mean difference: -0.24 s; p < 0.001) with both the UST and ST groups demonstrating improvements during the post-training testing session. The ST group demonstrated a significant increase in CMJ during the post-training session in contrast to the decline demonstrated by the UST group (ST group mean difference: 0.04 m; UST group mean difference: -0.01 m; p = 0.027). CONCLUSION: Performing resistance training exercises on an unstable surface confers no advantage over traditional resistance training exercises for improving the speed and aerobic capacity of female soccer players. Furthermore, the use of an unstable surface may inhibit the effects of resistance training on measures of explosive strength, an important variable in soccer performance.