An unstable rocker-bottom shoe alters lower extremity biomechanics during level walking

Abstract

Biomechanical data for gait in unstable rocker bottom shoes reported in the literature is not comprehensive across available shoe types. Purpose: The objective of this study was to comprehensively evaluate centre of pressure (COP), ground reaction force (GRF), joint kinematics and kinetics, and electromyography (EMG) of selected muscles while walking in an unstable shoe compared to a control shoe. Methods: Fifteen subjects performed five walking trials at 1.3 m/s and 1.8 m/s in control and unstable shoes. Kinematic, GRF and EMG data were simultaneously collected. Results: The unstable shoe caused an increased mediolateral COP displacement. Greater loading rate of initial peak vertical GRF, reduced ankle plantarflexion range of motion (ROM) and greater total sagittal-plane ankle ROM were also observed for the unstable shoe compared to the control shoe. Peak dorsiflexion and plantarflexion moments, peak knee flexion moment as well as EMG activation of tibialis anterior and rectus femoris were reduced in the unstable shoe. Finally, the peak inversion moment and hip abduction moment were increased in the unstable shoe. Conclusion: These results suggest that the unstable shoe presents challenges to the body to maintain mediolateral stability and therefore helps improve involved ankle and hip muscles. Furthermore the demands for the lower extremity muscles related to the sagittal-plane motions were reduced in the unstable shoe.