The purposes of this study were: (i) to evaluate the association of sit-to-stand (STS) power and body
composition parameters [body mass index (BMI) and legs skeletal muscle index (SMI)] with age; (ii)
to provide cut-of points for low relative STS power (STSrel), (iii) to provide normative data for well functioning older adults and (iv) to assess the association of low STSrel with negative outcomes.
Cross-sectional design (1369 older adults). STS power parameters assessed by validated equations,
BMI and Legs SMI assessed by dual-energy X-ray absorptiometry were recorded. Sex- and age adjusted segmented and logistic regression analyses and receiver operator characteristic curves were
used. Among men, STSrel showed a negative association with age up to the age of 85 years (− 1.2 to
− 1.4%year−1; p < 0.05). In women, a negative association with age was observed throughout the old
adult life (− 1.2 to − 2.0%year−1; p < 0.001). Cut-of values for low STSrel were 2.5W kg−1 in men and
1.9W kg−1 in women. Low STSrel was associated with frailty (OR [95% CI] = 5.6 [3.1, 10.1]) and low
habitual gait speed (HGS) (OR [95% CI] = 2.7 [1.8, 3.9]) in men while low STSrel was associated with
frailty (OR [95% CI] = 6.9 [4.5, 10.5]) low HGS (OR [95% CI] = 2.9 [2.0, 4.1]), disability in activities of
daily living (OR [95% CI] = 2.1 [1.4, 3.2]), and low quality of life (OR [95%CI] = 1.7 [1.2, 2.4]) in women.
STSrel declined with increasing age in both men and women. Due to the adverse outcomes related
to STSrel, the reported cut-of points can be used as a clinical tool to identify low STSrel among older
adults
