Relative sit-to-stand power: cut-off points and their association with negatives outcomes in older adults

Background: 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-off points for low relative STS power (STS rel ), ii) to provide normative data for well-functioning older adults and iv) to assess the impact of low STS rel on negative outcomes. Methods: : 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. Results: : Among men, STS rel 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-off values for low STS rel were 2.5 W∙kg -1 in men and 1.9 W∙kg -1 in women. Low STS rel 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 STS rel 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. Conclusions: : STS rel declined with increasing age in both men and women. Due to the adverse outcomes related to STS rel , the reported cut-off points can be used as a clinical tool to identify this condition among older adults.