Anticipatory changes in control of swing foot and lower limb joints when walking onto a moving surface traveling at constant speed

Adapting to a predictable moving surface such as an escalator is a crucial part of daily locomotor tasks in modern cities. However, the associated biomechanics have remained unexplored. In a gait laboratory, fifteen young adults walked from the ground onto a moving or a static surface while their kinematic and kinetic data were obtained for calculating foot and pelvis motions, as well as the angles and moments of the lower limb joints. Between-surface-condition comparisons were performed using a paired t-test (α=. 0.05). The results showed that anticipatory locomotor adjustments occurred at least a stride before successfully walking onto the moving surface, including increasing step length and speed in the trailing step (p<. 0.05), but the opposite in the leading step (p<. 0.05). These modifications reduced the plantarflexor moment of the trailing ankle needed for stabilizing the body, while placing increased demand on the knee extensors of the trailing stance limb. For a smooth landing and to reduce the risk of instability, the subjects adopted a flat foot contact pattern with reduced leading toe-clearance (p[removed]. 0.05), mainly through reduced extension of the trailing hip but increased pelvic anterior tilt and leading swing ankle plantarflexion (p[removed]