Changes in Lower Limb Coordination across Running at Different Speeds and Inclinations: Continuous Relative Phase Analysis

The aim of this study was to evaluate the changes in segmental coordination when running at different inclinations and speeds. 18 recreational runners performed running trials at three inclinations (0°, 3° and 6°) and three speeds (preferred speed, fast and slow) were measured with Vicon motion capturing system. The phase angle, continuous relative phase (CRP) and variability of CRP (VCRP) were calculated. Statistical models were performed to compare means for each running condition at each gait point: one-way ANOVA with Bonferroni post-hoc analysis for those data points with homogeneity of variances and Welch ANOVA with Games-Howell post-hoc analysis for those with heterogeneity of variance. Effect size (ω²) was computed to indicate whether the significant effects were trivial. Our results demonstrated that compared with the running speeds, participants who ran on different inclined surfaces showed higher Ankle-Knee CRP but lower Knee-Hip CRP and its variability, which is susceptible to running related injuries. These data suggest that runners should have a higher concern on joint loading and sports recovery when running at inclined surfaces.