Step time variability and pelvis acceleration patterns of younger and older adults: effects of footwear and surface conditions.

This study investigated the effects of various shoe features and surfaces on step time variability and pelvis accelerations (RMS) during walking in six younger and 22 older adults. Participants walked at a self-selected speed in five shoe conditions (standard, elevated heel, soft sole, hard sole, and high collar) on two surfaces: level and irregular. Results showed an age-related reduction in step time variability on the irregular surface and increased medio-lateral (ML) acceleration RMS in older people walking on the irregular versus the level surface. When wearing the elevated heel shoes, both young and old participants displayed significant reductions in pelvis ML accelerations, suggesting a compensatory strategy to counteract for lateral instability resulting from heel elevation. Overall, the findings demonstrate that older people are less able than younger ones to meet the stepping adaptability required for negotiating an irregular surface and, as a possible consequence, have more difficulty maintaining frontal plane stability on such a surface.