Coordinated responses of limb movement during human bipedal locomotion to external perturbation

Limb movement responses during human walking to mechanical perturbation were studied. Hip, knee and ankle joint angles of both right and left legs from subjects walking on a treadmill were measured. Walking rhythm was delayed by perturbations at early swing phase, advanced at late swing phase, and not modified at stance phase. The result was summarized in phase delay functions. The authors defined a relative phase to describe interlimb phase relationship, and analyzed how it changes depending on the perturbation phase. The delay functions obtained for both right and left legs can explain the phase dependent changes in the relative phase. Then, the control mechanism of human locomotion was discussed.