Body anthropometry affects spatiotemporal preferences in walking and running.

Despite a general similarity of walking and running gaits in healthy humans, spatiotemporal parameters vary considerably between individuals. While this variation is well recognized, the underlying causes are poorly understood. In this study, we examined whether differences in body mass, relative segment lengths (e.g. relative leg length and relative foot length) and relative segment masses (e.g. relative foot-shoe mass) contribute to the spatiotemporal variability, beyond what is accounted for by the Froude number. We collected anthropometric and spatiotemporal data from 103 trained runners (65 males, 38 females) walking (1.25 and 2 m s-1) and running (2-4.17 m s-1) on a force-measuring treadmill. Linear mixed-effects models assessed the contribution of anthropometric factors to inter-individual differences in gait. Froude number alone accounted for most of the variation in spatiotemporal variables (R2=0.71-0.92 in walking; R2=0.01-0.94 in running). Including anthropometric predictors improved model performance, particularly for variables with lower Froude dependence, increasing R2 to 0.77-0.93 (walking) and 0.16-0.94 (running). Specifically, heavier individuals and those with larger relative foot lengths exhibited longer stance times and higher duty factors (P≤0.033), without differences in stride frequency (P≥0.164). In walking, these longer stance times were primarily driven by prolonged double support time (P<0.001). Additionally, greater relative foot-shoe mass reduced stride frequency via longer leg swing times in both gaits (P≤0.007). We suggest that this spatiotemporal variability reflects individual strategies to minimize the metabolic cost of locomotion by adjusting the trade-off between stance-phase and swing-phase metabolic demands.