The Relationship of Knee-Extensor Strength and Rate of Torque Development to Sit-to-Stand Performance in Older Adults

Abstract

To investigate the association of knee-extensor strength and power to performance in the 30-second sit-to-stand test (30sSTS) in healthy older adults. In a cross-sectional study of 29 healthy older adults aged 60-82 years (12 male, 17 female), hierarchical regression was used to determine the relationship of knee-extensor concentric and eccentric strength, peak rate of torque development (peak RTD) using isokinetic dynamometry, and momentum variables with the number of sit-to-stand repetitions completed in 30 seconds (30sSTSreps). Concentric (180°/s) and eccentric (90°/s) knee-extensor strength were significant independent predictors of 30sSTSreps after controlling for physical activity level, height and weight (adjusted R (2)=0.425, p=0.004; adjusted R (2)=0.427, p=0.004 respectively), as was concentric (90°/s) knee-extensor peak RTD (adjusted R (2)=0.424, p=0.004). Peak linear vertical momentum (PLVM) (adjusted R (2)=0.615, p<0.001) accounted for 36% of the variance. Generation of PLVM is an important predictor of 30sSTSreps; knee-extensor concentric and eccentric strength and power are associated with improved performance in this common functional task. Focusing on these parameters in exercise interventions may improve functional performance and give insight into specific factors related to success on the test.