This study investigated the effect of obstacles of different heights on the locomotion of 15 healthy subjects. The following parameters were studied: (1) the distance of the toe and heel markers from the obstacle during toe-off and heel contact, respectively, (2) the minimum clearance distance of the toe and heel markers, and (3) the angular displacements and velocities of the hip, knee, and ankle. Results show significant differences in joint angular kinematics and clearance distances as obstacle height increased. The kinematic and distance differences exhibited both strong linear and non-linear trends. Toe-off distance and heel contact distance did not change significantly with changes in obstacle height.
Austin, Gary P., Garrett, Gladys E., Bohannon, Richard W. "Kinematic Analysis of Obstacle Clearance During Locomotion." Gait & Posture 10.2 (1999): 109-120.