Author(s): GARCIA-AGUIRRE, A.4,5, BALTASAR-FERNANDEZ, I.1,2,3,6, ALCAZAR, J.1,2,3, ARA, I.1,2,3, RODRIGUEZ-MAÑAS, L.2,7, ALEGRE, L.M.1,2,3, GARCIA-GARCIA, F.J., Institution: UNIVERSIDAD DE CASTILLA LA MANCHA, Country: SPAIN, Abstract-ID: 1854

INTRODUCTION:
Lower-limb muscle power declines earlier and more steeply than muscle strength and mass and has been proposed as a crucial determinant of muscle function in older adults. In particular, sit-to-stand (STS) power, and especially relative STS power (normalized by body mass), has been associated with adverse health outcomes. However, observational associations between low relative STS power and adverse outcomes may be confounded by age, comorbidity, baseline function, and psychosocial factors. This study aimed to estimate the associations between low relative STS power and the incidence of frailty, disability, cognitive impairment, hospitalization, and mortality using causal inference statistical approaches to minimize baseline confounding.
METHODS:
A total of 1876 participants (56.4% women; 75.4 ± 6.1 years) from the Toledo Study of Healthy Aging were included. Muscle power was assessed using the 30-second STS test and the Alcazar equation, and low relative STS power was defined as <2.53 W/kg in men and <2.01 W/kg in women (1). Incidence of cognitive impairment (Mini-Mental State Examination), basic (Katz Index; BADL) and instrumental activities of daily living disabilities (Lawton and Brody Scale; IADL), frailty (Clinical Frailty Scale), and medication intake were evaluated over a mean follow-up of 5.96 years. Hospitalizations and all-cause mortality were ascertained over mean follow-up periods of 6.8 ± 3.1, and 9.7 ± 3.5 years, respectively. To reduce confounding by baseline characteristics, propensity scores were estimated using a comprehensive set of covariates to balance groups and isolate the association of relative STS power with adverse outcomes. Primary analyses were conducted using 1:1 nearest-neighbour Propensity Score matching with a calliper of 0.2 and exact matching by sex.
RESULTS:
Individuals with low relative STS power showed higher odds of developing BADL disability (OR [95%CI] = 1.78 [1.16 – 2.75]; p<0.009) and frailty (OR [95%CI] = 2.16 [1.34 – 3.47]; p<0.001), and a tendency toward developing IADL disability (OR [95%CI] = 1.78 [1.00 – 3.17]; p=0.051) and cognitive impairment (OR [95%CI] = 1.54 [0.92 – 2.58]; p=0.099). Low relative STS power was also associated with a higher risk of hospitalization (HR [95%CI] = 1.41 [1.13 – 1.75]; p= 0.002) and all-cause mortality (HR [95%CI] = 1.66 [1.36 – 2.02]; p<0.001).
CONCLUSION:
Low relative STS power was independently associated with the incidence of BADL disability, frailty, hospitalization, and all-cause mortality. These findings support the clinical relevance of assessing relative STS power as a simple and feasible biomarker for identifying individuals at higher risk of adverse health outcomes.
References
1. Garcia-Aguirre M, Baltasar-Fernandez I, Alcazar J, Losa-Reyna J, Alfaro-Acha A, Ara I, et al. Cut-Off Points for Low Relative 30-s Sit-to-Stand Power and Their Associations With Adverse Health Conditions. J Cachexia Sarcopenia Muscle. 2025;16(1):e13676.