Compensatory stepping: The biomechanics of a preferred response among older adults

The purpose of this study was to evaluate age-related differences in the me chanics of the compensatory stepping response to balance threats. A moving platform was used to disturb the balance of 16 younger (21 to 35 years) and 19 older (68 to 88 years) adults. Backward platform translations consisted of 15-cm displacements with peak accelerations ranging from 9.4 to 15.2 m/ s(2). Older adults were more likely to use a step to recover balance and st epped at lower perturbation magnitudes than younger adults. Group differenc es were not found in time to step initiation or segmental momentum. The lac k of group differences in momentum revealed that lover perturbation acceler ations created an equivalent or greater magnitude of body motion in older a dults compared to higher accelerations experienced by,younger adults. Older adults also showed a reduced ability to attenuate the input acceleration a nd experienced significantly greater linear acceleration of the head.