The role of female pelvic width on walking economy and speed: Benefits with few tradeoffs (335.2)

Abstract

Among human sexually dimorphic features, a few are particularly important for locomotion, namely: overall body size, the proportions and lengths of the lower limbs, and the shape of the pelvic girdle. Across populations, males are absolutely larger in terms of mass, stature and limb length, whereas females have wider pelves relative to size. Variation between the sexes in these traits has consequences for the energetic cost of transport (CoT) and the speed of travel and as such should result in differences including sex‐specific energetic costs and strategies of mobility. Here, data are presented on the energetic differences between males and females (N=39) walking with and without loads. Without loads, females have significantly slower optimal walking speeds (10.9%, p=0.019) but have lower costs at their optimum (23.4%, p=0.002), and a broader base to their optimal walking curve (thus more available walking speeds) (22.1%, p=0.276). Furthermore, people with relatively wider bi‐trochanteric breadths (for their mass; generally females) have even lower costs at their optimal speeds (p=0.036). During loaded walking, a relatively wider pelvis increases both stride length (p<0.001) and speed flexibility (p<0.001), providing a morphological offset for load‐related costs. These data suggest that females’ wide pelves provide energetic and speed‐related benefits during both loaded and unloaded walking.