Abstract
OBJECTIVES: To examine the association between relative sit-to-stand (STS) power and age, establish sex-specific cut-off points, and evaluate their associations with adverse outcomes in Colombian older adults. DESIGN: Cross-sectional, population-based study. SETTING: Health, Well-being, and Aging Study (SABE-Colombia, 2014-2015). PARTICIPANTS: 3051 community-dwelling adults aged ≥60 years (56.6 % women; mean age 68.6 ± 6.4 years). MEASUREMENTS: Relative STS power (W·kg⁻¹) was estimated using a validated equation. Quantile regression examined age-related changes across percentiles (Q10-Q90). Receiver operating characteristic (ROC) curves with the Youden index determined cut-off points. Age-adjusted logistic regression tested associations with frailty, functionality as gait speed and handgrip strength (HGS), and depression. RESULTS: Optimal cut-offs for low relative STS power were 2.11 W·kg⁻¹ for men and 1.63 W·kg⁻¹ for women. Prevalence of low STS power was 34.3 % in men and 34.8 % in women, increasing with age in both sexes. Quantile regression revealed steeper age-related declines at higher percentiles, particularly among men. Low relative STS power was significantly associated with frailty and low functionality. CONCLUSION: Relative STS power is a simple, clinically feasible biomarker to identify functional impairment in older adults. The sex-specific thresholds reported for Colombian populations reflect demographic differences in muscle physiology and decline. Their integration into geriatric practice may enhance early detection, guide preventive interventions, and ultimately improve health outcomes in aging populations.