The Relationship Between Hip Extensor Strength, Jump Height and External Hip Flexion Moments During Jumping

Abstract

External hip flexion moments have been reported as the biomechanical variable most predictive of maximal jump height (MJH) during a drop vertical jump, however, this relationship has not yet been established during more basketball-specific tasks, such as a one-step countermovement jump (CMJ). Additionally, the extent to which the strength of the hip extensors influence external hip flexion moments and MJH during a one-step CMJ are unknown. Identifying the relationship between MJH, external hip flexion moments, and hip extensor strength during a one-step CMJ may be valuable to optimize MJH performance. PURPOSE: To identify the relationship between MJH, external hip flexion moments, and hip extensor strength during a one-step CMJ. METHODS: Twenty-three Division-1 collegiate basketball players (11M, 12F) participated in the study. Established 3D motion analysis techniques were utilized to collect three trials each of a one-step CMJ while leading with the preferred and non-preferred jumping leg. Hip extensor strength was measured as the average of the middle 3 of 5 isokinetic, concentric hip extensor strength trials performed at 60º/sec and normalized to body mass. Pearson product-moment correlations were performed to identify relationships between MJH, external hip flexion moment and hip extensor strength (p<0.05). RESULTS: There was a significant positive correlation between MJH and external hip flexion moment of both legs measured during the one-step CMJ when leading with the preferred (Lead: r=0.90, p=<0.001; Trail: r=0.66, p=0.001) and non-preferred (Lead: r=0.85, p=<0.001; Trail: r=0.53, p=0.01) jumping leg. Concentric hip extensor strength was not significantly correlated to either MJH or external hip flexion moment. CONCLUSIONS: External hip flexion moments explain up to 81% of the variance of MJH values during a one-step CMJ, yet concentric hip extensor strength measured at 60º/sec was not related to MJH or hip flexion moments. Further examination of hip extensor function (e.g. activation, strength at higher speeds) may warrant further investigation.