O.4.1-8 Association of sit-to-stand capacity and free-living performance using thigh-worn accelerometers among 60-90-year-old adults

Five times sit-to-stand (STS) test is commonly used as a clinical assessment of lower-extremity functional ability, but its association with free-living performance has not been studied. Therefore, we investigated the association between laboratory-based STS capacity and free-living STS performance using accelerometry. The results were stratified according to age and functional ability groups.

This cross-sectional study included 497 (63% women) participants aged 60–90 years from three independent studies. A thigh-worn tri-axial accelerometer was used to estimate angular velocity in maximal laboratory-based STS capacity and in free-living STS transitions over 3-7 days of continuous monitoring. Functional ability was assessed with Short Physical Performance Battery (SPPB).

Laboratory-based STS capacity was moderately associated with the free-living mean and maximal STS performance (r = 0.52 - 0.65, p < .01). Angular velocity was lower in older compared to younger and in low- versus high-functioning groups, both in capacity and free-living STS variables (all p < .05). Overall, angular velocity was higher in capacity compared to free-living STS performance. The STS reserve (test capacity – free-living maximal performance) was larger in younger and in high-functioning compared to older and low-functioning groups (all p < .05).

Laboratory-based STS capacity and free-living performance were found to be associated. However, capacity and performance are not interchangeable, but rather provide complementary information. Older and low-functioning individuals seemed to perform free-living STS movements at a higher percentage of their maximal capacity compared to younger and high-functioning individuals. Therefore, we postulate that low capacity may limit free-living performance.

This study was supported by the Research Foundation Flanders, Belgium, the Academy of Finland, the Finnish Ministry of Education and Culture and an Advanced Grant from the European Research Council.