Biomechanical Profiles in Cross-Country Runners: PCA Identifies Patterns, Not Injury

Biomechanical Profiles in Cross-Country Runners: PCA Identifies Patterns, Not Injury

Alvin Sherman Library

Running biomechanics reflect coordinated strategies rather than isolated variable effects and are thought to influence injury risk. This study investigates whether distinct running gait patterns identified through principal component analysis (PCA) of biomechanical variables were associated with injury occurrence in collegiate cross-country athletes. Twenty-two university cross-country runners (N=22; n = 5 males, n = 17 females; age range = 18-25 years) completed a 3D biomechanical gait assessment from which we derived step frequency (SF), hip and ankle propulsive power, knee abductor moments (KAM), vertical stiffness (kvert), contralateral pelvis drop (CPD), hip adduction (HADD), time of braking force (tbrake), and ground contact time (GCT). PCA was used to identify distinct biomechanical running profiles. Then we used independent-samples Mann-Whitney U tests to determine the differences in the components between runners who sustained a lower extremity injury (n=9) and those who did not (n=13), p < .05. Three distinct biomechanical running patterns were identified through PCA, explaining 80.3% of the variance. The patterns reflected differences in contact-propulsion (PC1), frontal-plane loading (PC2), and stride regulation (PC3). There were no significant differences between injured and uninjured runners for any component score (PC1: U = 49.0, p = .526; PC2: U = 55.0, p = .815; PC3: U = 74.0, p = .301). While PCA was useful in capturing distinct biomechanical patterns in university distance runners, the factor scores were not beneficial for discriminating injury status, which highlights the need for alternative approaches when linking movement patterns to injury risk.