Master of Science (MS)
To date, it remains unclear how passive dynamics and active neural control contribute to arm swing during human locomotion. The passive hypothesis attributes arm swing to the passive transfer of energy from the legs to the arms via biomechanical linkages, while the active hypothesis states that arm swing is actively driven by muscles via neural mechanisms. The present study aims to investigate this phenomenon further by disrupting the biomechanical linkages, thereby directly challenging the passive hypothesis. Ten healthy individuals walked on a treadmill with and without an apparatus that constrained pelvis rotation at 3 different speeds (2 mph, 3 mph, and 4 mph). Spatial (upper and lower limb movement amplitudes) and temporal (movement frequencies and phase relationships between segment trajectories) aspects of limb movement were analyzed. The pelvis rotation was reduced by an average of 60.6% while constrained. As the treadmill speed increased, the movement amplitude of the upper and lower limbs increased. While the pelvis was constrained, arm swing amplitude decreased and the muscle activity of the upper limbs and lower limbs was similar to walking in the unconstrained condition. The movement frequency patterns and phase relations between segment trajectories were also conserved irrespective of speed and pelvis constraint conditions. These results provide evidence that passive elements are a significant factor in arm swing amplitude. However, the conserved EMG patterns and movement frequencies are suggestive of an underlying neural drive that contributes to the maintenance of the temporal aspects of gait. These observations are most likely due to passive dynamics in addition to neural mechanisms that maintain the rhythmic locomotor pattern via upper and lower limb central pattern generators (CPGs).
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Canton, Stephen Paul, "Active Versus Passive Control of Arm Swing: Implication of the Restriction of Pelvis Rotation during Human Locomotion" (2015). LSU Master's Theses. 242.