Maximum walking speed and lower limb length in hominids

✍ Scribed by Webb, David

• Book ID: 102645592
• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 873 KB
• Volume: 101
• Category: Article
• ISSN: 0002-9483
• DOI: 10.1002/(sici)1096-8644(199612)101:4<515::aid-ajpa6>3.0.co;2-u

✦ Synopsis

In 1984, Helene (Am. J. Physics 52:656) and Alexander (Am. Scientist 72:348-354) presented equations which purported to explain how lower limb length limited maximum walking speed in humans. The equations were based on a simplified model of human walking in which the center of mass (CoM) "vaults" over the supporting leg. Increasing walking speed by increasing stride frequency or stride length would increase the upward acceleration of the CoM in the first half of stance phase, to the point that it would be greater than the downward pull of gravity, and the individual would become airborne. This constitutes running by most definitions.

While these models ignored various mechanical factors, such as knee flexion during midstance, that reduce the vertical movement of the CoM, the general idea is plausible inasmuch as the CoM of the body does oscillate vertically with each step. One hypothesis tested here is whether it is indeed the interaction between the pull of gravity and the individual's own upward acceleration that determines at what speed (or cadence) he changes from walking to running.