Pace length effects in human walking: "groucho" gaits revisited

In the present study, the authors explored the effect of manipulating the distance between footfalls (pace length) in level walking in 3 men. The translational kinetic energy to gravitational potential energy (E(k)-E(p)) exchange was found to be maintained until pace length reached approximately 110% of single limb length. Beyond that pace length, the compliance of the support limb increased, apparently to allow the muscular absorption of excess kinetic energy. E(p) oscillations decreased with increasing limb compliance, and the participants could control that relationship with pace length alone. The authors compared the present results with previous descriptions of the relationship between limb compliance and pace length in running. An analog of the running relationship holds for walking as well. The trigger for those gait modifications has not yet been identified, however. The present results have implications for the exploration of the integrated control of mechanical consequences in human locomotion and for understanding the walk-run transition in bipeds other than humans, such as ground-dwelling birds.