Six weeks of knee extensor isometric training improves soccer related skills in female soccer players

Abstract

Objectives: Resistance training (RT) programs are often utilized to improve strength and power and thus enhance soccer performance. However, there is little research examining isometric knee extensor RTs effects upon soccer related skills. Design: The aim of this study was to examine the effects of knee extensor isometric training in female soccer athletes. Method: Sixteen female, university level, amateur soccer players (age 20.5 ± 1.1 years) were assigned to either a control or experimental group. The experimental group trained 1x/week for 6-weeks performing repeated maximal voluntary isometric con tractions (MVIC) for the knee extensors alongside regular soccer training and the control group participated in soccer training alone. Knee extension MVICs were performed at seven joint angles and peak torque measured. Results: Outcome measures included, countermovement jump (CMJ), kicking distance (KD), straight sprint speed and zigzag sprint speed, with (SSB and ZSB, respectively) and without (SS and ZS, respectively) a ball. Significant increases (p < 0.05) in knee extensor MVIC (28.9%) occurred in the experimental group. Significant differences (p < 0.05) between the experimental group and control group were found for change in CMJ (2.24% vs -0.78% respectively) and KD (8.8% vs -2.5% respectively); however, change in SSB, ZSB, SS, or ZS were non-significant for both within- and between-group comparisons. Conclusions: Results indicate that a 6-week isometric knee extension RT intervention can improve jump height and kicking abili ty of amateur female soccer players.