An investigation of phase difference between forward swings of the thigh and leg during the swing phase of running

Abstract

During running, the lower extremity swings forward in swing phase. The greatest flex in the hip joint occurs just before heel contact, and the thigh swings to the most forward position. Then, the hip joint extends, and the thigh moves slightly backward before the knee joint extends, and the leg swings to its most forward position. In this study, the mechanism of phase difference between forward swings of the thigh and leg in swing phase was investigated in terms of interaction torques of hip and knee joints.

The typical pattern of change in the rotation angles of the hip and knee joints in running was modeled from data obtained during long-distance running. Comparative patterns involving phase difference during which forward swings of the thigh and leg were altered successively also were generated. Lower extremity movements in typical and comparative patterns were computer simulated, and net, muscle, interaction, and gravity torques were calculated.

Results indicated that as phase difference became larger than that found in the typical pattern, larger hip and knee muscle torques were required to compensate for interaction torque in the early swing phase. As phase difference decreased, larger muscle torques were required to overcome the interaction torques in the late swing phase. Consequently, hip and knee net torques could be produced through minimal change of muscle torques in the typical pattern.

Thus, it is likely that phase difference between forward swings of the thigh and leg occurs to minimize change in muscle torque during regulation of the interaction torque.