Author(s): SIERRA-RAMON, M.1,2,3, GARCIA-AGUIRRE, M.1,2,3, MUNOZ-MUNOZ, M.1,2,3, GUTIERREZ-REGUERO, H.1,2,3, GARCIA-ALBIN, D.1,2,3, BALTASAR-FERNANDEZ, I.1,2,3,4, BUENDIA-ROMERO, A.1,2,3, ARA, I.1,2,3, ALEGRE, L.M.1,2,3, GARCIA-GARCIA, F.J.2,5, ALCAZAR, J.1,2,3, Institution: UCLM, Country: SPAIN, Abstract-ID: 2054

INTRODUCTION:
The Sit-to-Stand (STS) test is widely used in geriatrics to assess physical function and allows the estimation of STS power through validated equations (1). While STS power improves the prediction of adverse outcomes, the relative contribution of directly-measured neuromuscular power versus cardiorespiratory fitness to power values obtained across different STS durations remains unclear. This study aimed to examine the contribution of maximal power (Pmax) and oxygen consumption at the second ventilatory threshold (VO₂@VT2) to STS power across short and long STS protocols.
METHODS:
A total of 114 middle-aged participants from the Toledo Study for Healthy Aging in Middle Age were included (56.1% women; age = 54.3 ± 1.4 years). Absolute STS muscle power was estimated in the 5-repetition (5STS), 30-s (30STS), and 60-s (60STS) STS tests (1). Pmax (W) was derived from the force–velocity profile in the leg press exercise, and VO₂@VT2 (L·min-1) was identified during an incremental cycle-ergometer test. Analysis of variance was used to analyse power differences between STS protocols. Pearson correlations and multivariate linear regressions were performed to determine the independent contribution of Pmax and VO₂@VT2 to STS power. Analyses were adjusted for age and sex.
RESULTS:
STS power differed significantly between the 5STS (women: 348 ± 81 W; men: 571 ± 111 W), 30STS (women: 334 ± 76 W; men: 566 ± 117 W), and 60STS (women: 290 ± 70 W; men: 501 ± 114 W) in both sexes (all p < 0.001); except between 5STS power and 30STS power in men (p = 1.000). Of note, 5STS duration was 6.37 ± 1.73 s in women and 5.62 ± 0.91 s in men. Across STS protocols, STS power showed consistent positive associations with both Pmax (5STS: r = 0.203, p = 0.031; 30STS: r = 0.312, p = 0.001; 60STS: r = 0.319, p = 0.001) and VO₂@VT2 (5STS: r = 0.306, p = 0.001; 30STS: r = 0.364, p < 0.001; 60STS: r = 0.336, p < 0.001). Age- and sex-adjusted regression models explained 61–65% of the variance (adj-R²: 5STS = 0.618; 30STS = 0.659; 60STS = 0.618). Pmax was a consistent significant independent predictor in all tests (5STS: std. β = 0.214, p = 0.045; 30STS: std. β = 0.225, p = 0.026; 60STS: std. β = 0.24, p = 0.025). Notably, VO₂@VT2 did not predict 5STS power (std. β = 0.080, p = 0.330) but was a significant predictor for 30STS power (std. β = 0.164, p = 0.036) and 60STS power (std. β = 0.188, p = 0.024).
CONCLUSION:
Maximal neuromuscular power was a significant determinant of STS power across all STS durations. However, as the test duration increased (30STS and 60STS), cardiorespiratory fitness became a significant contributor. These findings suggest that longer STS protocols capture a mixed physiological profile, relying on both neuromuscular and aerobic capacities.
Funding
CB16/10/00456; CB16/10/00477; 2025-GRIN-38408; TEC 2022-007; SBPLY/19/180501/000312; PI031558; PI07/90637; PI07/90306; RD 06/0013; PI18/00972; SBPLY/23/180225/000155; JDC2023-052593-I; FPU22/04260.
Reference
Alcazar J et al. Experimental Gerontology. 2018;112:38–43.