Changes in stepping response to lateral perturbations immediately following a single bout of physical activity

Abstract

Fatiguing exercise can adversely alter postural stability and therefore may contribute to falling. However, older adults rarely perform exercise to fatigue. This study aimed to determine whether undertaking a single bout of moderate-intensity physical activity, similar to that experienced during daily activity or rehabilitation, altered the ability to recover balance with an outward step response to a lateral perturbation. Thirty-four healthy older adults (mean: 76±5 years) and 31 healthy young adults (29±6 years) underwent a 14-minute, self-paced, moderate-intensity physical activity protocol. Before and immediately after the protocol, their responses to lateral waist-pull perturbations were recorded. For participants who used a single outward step response before and after the perturbation, the changes to the timing of the step phases and the hip abductor muscle activity onsets were compared. Young adults responded with an outward step in 55% of trials before and 70% after activity, whereas this frequency was 35% before and 36% after among older adults. When performed, the timing of steps and muscle activity onsets were not adversely altered following the physical activity in either group, apart from a slightly later stance limb gluteus medius onset after activity, found in both groups. Before and after activity, older adults responded with a single outward step to arrest a fall less frequently than young adults. This may place older adults at risk of overbalancing. However, when responding with this strategy, both young and older adults demonstrated few changes immediately following moderate-intensity physical activity compared with before. They appear to be not adversely affected by moderate physical activity.