Countermovement Jump Asymmetry Using Center Of Mass Velocity With Ncaa D1 Athletes: Statistical Parametric Mapping

In athletics, optimizing performance is important for success. It is relevant to quantify metrics that correlate to performance using an assessment like a countermovement jump (CMJ). An imbalance in vertical ground reaction force (GRFv) has been cited as a metric that is negatively correlated with performance. However, factors such as sequencing and direction of application necessitate a more appropriate metric to assess asymmetries.Center of mass velocity (CoMv) has been shown to be the most accurate predictive metric of performance in CMJs. However, as with all non-discrete metrics, it is hard to determine an appropriate, a priori analysis methodology given the complexity of time-series data. Statistical Parametric Mapping (SPM) addresses these issues. PURPOSE: to evaluate inter-limb asymmetries in CoMv using SPM during the braking and propulsive phase of a CMJ, and to compare the relative asymmetrical magnitude to bilateral jump height. METHODS: 15 male football athletes participated in study. Two force plates sampling at 1000hz captured kinetic data and calculated CoMv. Subjects performed 3, unilateral CMJs per leg, starting on their left leg and alternating between right and left legs. Unilateral tests were followed by 3 bilateral CMJs. Data was limited to the breaking and propulsive phase of CMJ. Data was compiled in custom excel spreadsheets and exported MATLAB where they were time-normalized representing 0-100% and averaged across the 3 trials per subject. These values served as the input for SPM analysis. Significance was set at α < 0.05. The maximal 1D test statistic were exported to SPSS per subject and compared to average bilateral jump heights via linear regression. RESULTS: Only one subject demonstrated an inter-limb asymmetry that was significant at approx. 95% of periodization. When subjects were rank ordered by magnitude of difference and compared to average bilateral jump height using linear regression, there was a significant correlation (R = 0.622, p = 0.007, SEE = 0.0607). CONCLUSION: The lack of significant difference in performance of unilateral jumps is reasonable when considering the athletic level of the sample. The significant regression demonstrates the validity of CoMv as a metric to evaluate inter-limb asymmetry, and the value of -0.622 is a relatively strong predictor of performance.