Invariant aspects of human locomotion in different gravitational environments

Previous literature showed that walking gait follows the same mechanical pa radigm, i.e. the straight/inverted pendulum, regardless the body size, the number of legs, and the amount of gravity acceleration. The Froude number, a dimensionless parameter originally designed to normalize the same (pendul um-like) motion in differently sized subjects, proved to be useful also in the comparison, within the same subject, of walking in heterogravity. In th is paper the theory of dynamic similarity is tested by comparing the predic tive power of the Froude number in terms of walking speed to previously pub lished data on walking in hypogravity simulators. It is concluded that the Froude number is a good first predictor of the optimal walking speed and of the transition speed between walking and running in different gravitationa l conditions. According to the Froude number a dynamically similar walking speed on another planet can be calculated as where V-PLANET = V(EARTH)rootg(PLANET)/g(EARTH) V-EARTH is the reference speed on Earth. (C) 2001 Elsevier Science Ltd. All rights reserved.