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. Implications for Rehabilitation Hip and trunk mechanical demands, and muscle activation were reduced with portable lifting seat device use. Greater ankle dorsiflexion was found with portable lifting seat device use, suggesting this range of motion should be considered when prescribing this device. Healthy older and younger adults used similar knee and trunk joint mechanics yet older adults completed the sit-to-stand trials with greater lower extremity and low back muscle activation.