Postural Control in Response to Unilateral and Bilateral External Standing Perturbations in Young and Older Adults
Abstract
Balance is an important determinant of physical function and falls risk. This study sought to determine the effect of unilateral and bilateral perturbations, with and without cognitive load, on leg muscle activity in healthy young and older adults, as well as identify the influence of ankle power on postural and functional performance. Using a split-belt treadmill system, participants experienced unilateral and bilateral accelerations of the treadmill, without and with the Stroop test. Surface electromyography (EMG) from eight lower limb muscles was recorded from the right leg. EMG onset latency following perturbation onset, and root mean square of the muscle bursts were calculated for each perturbation. Unlike young adults, older adults did not demonstrate a distal to proximal muscle activation, suggesting that older adults adopt a unique response to postural perturbations – a response prioritized over cognitive load. Further, a higher level of ankle muscle power favoured better balance in older adults.