Abstract
(1) Background: The purpose of this study was to evaluate the day-to-day variability and year-to-year reproducibility of an accelerometer-based algorithm for sit-to-stand (STS) transitions in a free-living environment among community-dwelling older adults. (2) Methods: Free-living thigh-worn accelerometry was recorded for three to seven days in 86 (women n = 55) community-dwelling older adults, on two occasions separated by one year, to evaluate the long-term consistency of free-living behavior. (3) Results: Year-to-year intraclass correlation coefficients (ICC) for the number of STS transitions were 0.79 (95% confidence interval, 0.70–0.86, p < 0.001), for mean angular velocity—0.81 (95% ci, 0.72–0.87, p < 0.001), and maximal angular velocity—0.73 (95% ci, 0.61–0.82, p < 0.001), respectively. Day-to-day ICCs were 0.63–0.72 for number of STS transitions (95% ci, 0.49–0.81, p < 0.001) and for mean angular velocity—0.75–0.80 (95% ci, 0.64–0.87, p < 0.001). Minimum detectable change (MDC) was 20.1 transitions/day for volume, 9.7°/s for mean intensity, and 31.7°/s for maximal intensity. (4) Conclusions: The volume and intensity of STS transitions monitored by a thigh-worn accelerometer and a sit-to-stand transitions algorithm are reproducible from day to day and year to year. The accelerometer can be used to reliably study STS transitions in free-living environments, which could add value to identifying individuals at increased risk for functional disability.
Highlights
Sit-to-stand (STS) transitions are necessary in daily living [1] and a good STS ability is an important factor in maintaining functional independence [2]
Wilcoxon test signed-rank test and correspondence the two time evaluated two-way correlation coefficients (ICC, absolute points was with evaluated withrandom two-wayintraclass random intraclass correlation coefficients (ICC, agreeabsoment, single measures)
AgreementAgreement between testbetween and retest was analyzed by Bland–Altman lute agreement, single measures)
Summary
Sit-to-stand (STS) transitions are necessary in daily living [1] and a good STS ability is an important factor in maintaining functional independence [2]. Performance technique used and measured in the laboratory may differ from free-living [3,4] and, it has been noted that maximal physical performance does not necessarily equate with functioning in daily activities [5]. Identifying sit-to-stand transitions (STS) in a free-living environment may provide added value to an otherwise laboratory-bound comprehensive performance assessment. The widely used 5x STS test [8,9,10], 10x STS test [11] and sit-to-walk [12] movement kinematics of the different phases have been interpreted successfully with body-fixed gyroscope and/or accelerometer sensors
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