Lower Limb Muscle Strength Matters: Effect of Relative Isometric Strength on Countermovement and Rebound Jump Performance in Elite Youth Female Soccer Players
Jack Fahey, Paul Comfort, Nicholas J. Ripley
Abstract
Background: Expression of maximal and rapid force in the hip, knee, and plantar flexors is important for athletic performance in female soccer. This study was designed to determine the effect of relative isometric strength in the isometric mid-thigh pull (IMTP) on countermovement jump (CMJ) and rebound jump (CMJ-R) performance in female youth soccer players. Methods: Ninety-six female soccer players (age: 14.1 ± 2.3 years, height: 160.5 ± 9.7 cm, mass: 55.0 ± 10.3 kg) completed three trials of the IMTP, CMJ, and CMJ-R using force plates. Players were categorized as stronger (top quartile, n = 19) and weaker players (bottom quartile, n = 23) based on IMTP relative net peak force. One-way Bayesian independent t-tests were performed between stronger and weaker players. Results: Very large difference in lower limb strength between groups (g = 5.05). Moderate to very strong evidence to support that stronger players had greater countermovement depth and time to take-off with similar jump heights than weaker players. Strong evidence was observed for CMJ-R height, with stronger players falling from a greater height and executing similar ground contact times compared to weaker players. Conclusions: Relative strength has implications for CMJ-R, highlighting the importance of developing relative strength in hip, knee, and plantar extensors.