Intersegmental coordination scales with gait speed similarly in men and women.

We applied principal component analysis (PCA) to thigh, shank, and foot elevation angles to examine the impact of speed on intra-limb coordination during gait. The specific aims were to (1) determine speed-related changes in segment loadings on three principal components (PCs) and (2) examine differences between men and women. The subjects (26 women, 21 men) walked overground at five self-selected paces (very slow, slow, normal, fast, very fast). PCA yielded percent variation (PV) explained by each PC and thigh, shank, and foot loadings on PC1-PC3. These parameters were regressed against the speed normalized to body height (BH/s) to derive individual and aggregate slopes and P values, separately for men and women. PV1 increased with speed, whereas PV2 and PV3 decreased (all P < 0.001). The loadings of thigh and foot segments on PC1 increased with speed (0.14 and 0.04 per BH/s, P < 0.001, respectively), and the loading of shank decreased (-0.10, P < 0.001). Compared to PC1, the changes in segment loadings on PC3 were the opposite (thigh -0.18, shank 0.09, foot -0.04 per BH/s, P < 0.001). The changes in segment loadings on PC2 were inconsistent and generally small. The only significance (P = 0.006), albeit a minor difference between men and women, was in the slope of thigh loading on PC2 (-0.005 ± 0.019 and 0.015 ± 0.026 per BH/s, respectively). We conclude that intersegmental coordination during gait scales with speed, with the greatest impact on the thigh segment, but no differently between men and women.