Figure 1.

(A) participants walked and crossed an obstacle 20 times, during which the dominant limb was always the leading limb. Foot clearance was calculated as the vertical (V) distance between the markers on the obstacle and on the toe at the moment of obstacle crossing. Because of anthropometric differences between older and younger adults, each parameter was normalized to the participant's leg length to account for between-subject differences. (B) Definition of the pre-crossing and post-crossing phases for the leading and trailing limbs. The moment of obstacle crossing was defined as the moment when the toe marker crossed the obstacle marker in the anterior–posterior (AP) direction. Each phase was shown as the normalized movement time. In the pre-crossing phase, 0% represented toe-off, and 100% represented the moment of obstacle crossing. In the post-crossing phase, 0% represented the moment of obstacle crossing, and 100% represented heel contact.