Fig. 1

Gait cycle of crossing obstacles. (a & b: left and right limb, respectively, as leading limb during obstacle crossing; Eight instance: I, trailing limb heel strike event; II, leading limb toe-off event; III, leading limb toe-above obstacle event; IV, leading limb heel strike event; V, trailing limb toe-off event; VI, trailing limb toe-above obstacle event; VII, trailing limb heel strike event; VIII;, leading limb toe-off event)