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

Abstract

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.

Effects of Different Assistive Seats on Ability of Elderly in Sit-To-Stand and Back-To-Sit Movements

“…The total STS time in the N condition (2.2 ± 0.3 s) was similar to that reported by Kuo et al, Millington et al, and Rutherford et al [7,12,23]. Compared with the method used in the present study for defining each movement phase of the STS and BTS movements, Mourey et al [11] determined the start and end points of the motion in accordance with a change of the exceeding a threshold of 10% of the peak forward angular velocity of the trunk.…”

“…Moreover, among the old nonfallers and old fallers, the old fallers had a lower muscle power and required a longer time to leave their seat. Rutherford et al [7] found that the hip and knee joint angles of the elderly were significantly greater than those of young adults while standing up. The elderly also showed greater activity of the lower extremity muscles.…”

“…Older people are more likely to struggle to carry out standing-up or sitting-down tasks than younger people as a result of impaired balance due to reduced muscle strength, stroke, Parkinson's disease, and so on. Furthermore, elder adults who are unable to stand up independently are at greater risk of falls [3,4], and frequently suffer a reduced quality of life [5][6][7][8][9].…”

“…Many different mechanism designs for lifting seats have been proposed, including booster seats, spring-loaded flap seats, and ejector chairs. However, while some studies have reported that seating devices with mechanical assists reduce the mechanical demands of the STS task, others have argued that these designs interfere with balance and cause the patients to adopt abnormal motion mechanisms [7,[17][18][19]. Rutherford et al [7] investigated the mechanics of STS transfer when using a portable lifting-seat device and concluded that most mechanism factors were reduced during the STS process.…”

“…In addition, a time delay was found between power stopping and the moment at which the participants actually stood up when using the power-lifting seat. However, besides the study of Rutherford et al [7], the literature contains little information on the effects of the structural design of assistive lifting-seats on the instability or abnormal motion phenomena of the elderly in performing STS and BTS tasks. Furthermore, even though Rutherford et al compared the mechanical effects of assisted and nonassisted transfer in the performance of STS motion, no such investigation was performed for BTS transfer [7].…”