Meeting Abstract
26.5 Saturday, Jan. 4 14:30 Plantarflexion component of stride length in bipedal walking WHITCOME, K/K*; DYER, R/E; University of Cincinnati; University of Cincinnati katherine.whitcome@uc.edu
Because energy for locomotion in the form of muscle force production is necessary to support the body and swing the limbs, increase in stride frequency per distance and speed will increase the cost of locomotion. Routine walking should therefore favor low stride frequency and long strides. The effects of swing-limb rotations on stride length in human bipedal walking are well understood. During swing phase limb segments reach peak sagittal plane rotations placing the swing foot well ahead of the center of mass. Although stance limb segments also rotate during contralateral swing, their effect on stride length is less well known. Our aim was to investigate the kinematic link between terminal stance plantarflexion and travel distance. We focused on the period of lag foot heel rise milliseconds before the lead foot heel strike. We expected greater angular rotations of the stance limb v lead limb, generating a greater percentage of stride length as the swing limb prepares for ground contact. We captured 3D kinematics of 23 healthy adults at treadmill speeds of 1.25 m/s and 1.50 m/s. We calculated sagittal plane angles of both limbs including the thigh, knee and foot and the spatiotemporal components of stride length and proportion of stride duration. We found that heel rise of the stance limb occurs during only 7-8% of stride duration, yet is associated with 20% of total stride length. Although swing limb kinematics produce modest rotations that contribute little to stride length late in swing phase (1° thigh extension, 2° knee extension, 1° plantarflexion), stance limb rotations are significantly greater (7° thigh extension, 2° knee extension, 11-13° plantarflexion). In particular, because the stride lengthens as the lead hip, knee and foot are statically positioned for touchdown, it appears that support limb rotations in late terminal stance contribute markedly to overall stride length.
