The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Size or sex—which is more important for determining optimal velocity?


1Anthropology, University of Washington, 2Orthopaedics and Sports Medicine, University of Washington

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Recent reports have demonstrated that morphology influences the minimum cost of transport (minCoT) and its associated optimal velocity. Men have higher minCoT and optimal velocity, but because men are on average larger, it is unclear if the effect is due to a sex-based difference in physiology or morphology or simply size differences.

In order to explore this question, the energetic expenditure (volumetric consumption of oxygen, VO2) of 15 women and 8 men was measured as they walked on a treadmill at 5 self-selected velocities wearing comfortable walking shoes. Standard anthropometrics were measured and optimal velocity and minCoT for each individual was determined from the first derivative of the best-fit curve between velocity, velocity squared and CoT. Participants were grouped dichotomously based on sex and for size as either being in the top or bottom half of the combined distribution for body mass, stature, lower limb length and calf length.

Men were larger than women in body mass (p = 0.002) and stature (p = 0.005), but not lower limb (p = 0.50) or calf length (p = 0.13). The overlap in range was, however, intentionally substantial (e.g. women’s stature range = 1.5-1.74 m; men = 1.57-1.84 m). Men had higher optimal velocity (p = 0.001, 1.38 m/s ) than did women (1.25 m/s). This difference in optimal velocity was similarly pronounced, however, when larger people (p’s < 0. 022) were compared to smaller ones. Additional analysis indicates that sex and size may independently affect optimal velocity.

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