www.slate.com/.../
In a nutshell
"Anthropometric measurements of large populations show that systematic differences exist among blacks, whites and Asians. The published evidence is massive: blacks have longer limbs than whites, and because blacks have longer legs and smaller circumferences (e.g. calves and arms), their center of mass is higher than that in other individuals of the same height. Asians and whites have longer torsos, therefore their centers of mass are lower.
These structural differences, they argue, generate differences in performance. Using equations about the physics of locomotion, they analyze racing as a process of falling forward. Based on this analysis, they conclude that having a higher center of body mass in a standing position is advantageous in running but disadvantageous in swimming."
