Age-related adaptations in acceleration and deceleration control during gait

This study aimed to clarify the age-related adaptations in propulsive and braking mechanisms during gait acceleration and deceleration. Spatiotemporal gait parameters; the anteroposterior (AP), mediolateral (ML), and vertical (V) components of the ground reaction force (GRF); and the center of mass external moment (COM M_ext) were analyzed and compared between younger and older adults. Thirty younger and thirty older healthy participants were enrolled. The participants performed walking trials under normal, maximum, acceleration, and deceleration conditions; kinematic and kinetic data were collected using a three-dimensional motion capture system and force plates. The spatiotemporal gait parameters, GRF AP, GRF V, and COM M_ext were analyzed. Differences between younger and older adults were examined across gait conditions. During acceleration, older participants exhibited significantly smaller anterior GRF AP in the second half of the stance phase and slower gait speed compared with younger participants. During deceleration, older participants exhibited significantly smaller posterior GRF AP in the first half of the stance phase and higher cadence compared with younger adults. Older participants also exhibited greater GRF V in the first half of the stance phase during acceleration and deceleration, and lower values in the second half of the stance phase during acceleration compared with younger adults. Older participants exhibited reduced anterior GRF AP during the second half of the stance phase under acceleration, limiting their ability to increase gait speed from the initial step. During deceleration, insufficient braking force within a single step necessitated an increased number of steps to reduce speed.