Association between relative free-living sit-to-stand transition thigh angular velocities and difficulties in mobility and daily functioning

BACKGROUND: Sit-to-stand (STS) transitions are common daily activities, and we postulate that completing them with high effort relative to one's capacity may indicate functional difficulties in older age. AIMS: We examined the association between relative free-living STS thigh angular velocity and difficulties in activities of daily living (ADL) and instrumental activities of daily living (IADL), as well as walking and negotiating stairs. METHODS: This cross-sectional study included 230 individuals (53% women) aged 79-89 years. STS capacity was assessed with an instrumented five-times STS test. Free-living STS transitions were monitored in 2-hour intervals over four days using an accelerometer. Associations were examined using Wilcoxon rank-sum test and logistic regression analyses. RESULTS: In total, 47% had ADL/IADL difficulties, 26% reported walking difficulties, and 17% had difficulties negotiating stairs. Participants with any difficulties performed STS transitions at a higher proportion of their STS capacity compared to those without difficulties (p < 0.05). Higher relative free-living STS thigh angular velocity was associated with walking and stair negotiation difficulties in both crude (OR 1.23-1.53; p < 0.05) and adjusted models (OR 1.20-1.40; p < 0.05), while the association with ADL/IADL difficulties weakened after adjustment. CONCLUSIONS: Our findings suggest that performing STS transitions at high intensity may reflect emerging mobility difficulties.