Sit-to-stand transfer mechanics in healthy older adults: A comprehensive investigation of a portable lifting-seat device

Purpose: To evaluate lower extremity mechanics and muscle activation associated with the sit-to-stand transfer using a portable lifting-seat device and to compare these data to an unassisted transfer in healthy young and older adults. Methods: Bilateral lower extremity and low back musculature electromyography, three-dimensional leg and trunk motion, and ground reaction forces were recorded from 10 young (mean age = 25) and 10 older (mean age = 69) adults during five trials of (i) no assist and (ii) assisted transfers. Data were time normalized to represent the period of seat-off to standing. Peak sagittal plane joint angles, moments, and muscle activity profiles were calculated. Analysis of variance models was used to test for main effects and interactions (α = 0.05). Results: Trunk, hip, and knee angles were significantly reduced and dorsiflexion increased with assisted transfer (p < 0.05). Peak hip and ankle joint moments were reduced (p < 0.05) and no change found in knee moments (p > 0.05). Peak muscle activity was lower during the assisted transfer (p < 0.05). Seat device effects were similar between age groups. Older adults used higher relative muscle activation. Conclusion: Variables indicative of sit-to-stand functional demand were reduced with lifting-seat device use. Data provide a framework for future recommendations on product prescription, use, and research pertaining to the advancement of adaptive seating.