Walking and running: How leg compliance shapes the way we move

Abstract

The function of the human leg during walking and running is complex. One issue is the segmented structure of the leg, which consists of thigh, shank and foot. The situation is further challenged by the parallel arrangement of muscles spanning a single or multiple leg joints. How is the leg function organized to make typical movements such as walking and running possible and easily accessible? In this paper, we review a number of biomechanical models based on the spring-mass model, which may help to better understand how compliant leg function can be used and properly adjusted to selected movement tasks. This includes the emergence and stabilization of walking and running patterns. One general characteristic of movements based on compliant leg function is the functional redundancy in the leg adjustment, i.e. at a given speed, walking or running can be achieved with different leg strategies. This principle of redundant leg adjustments fulfilling the same general goal of movement is a key for understanding the organization of human locomotion.