Knee extension rate of force development and peak torque: associations with lower extremity function

Authors

• S Studenski
• L Ferrucci

Abstract

The ability to generate muscle force quickly decreases with aging and is important for daily activities. Most studies measure muscle performance as peak torque (PT), which does not account for speed component. The rate of force development (RFD), a metric widely used in sports, captures the dynamic component of muscle performance and may be useful in aging research. We assessed whether RFD is associated with lower extremity performance (LEP) independent of PT. Data on demographics, body composition (DXA), LEP, PT and RFD were obtained from 1092 adults (age 26 to 96 years) enrolled in the Baltimore Longitudinal Study of Aging. RFD was obtained during a 3-sec isometric knee extension at 120-deg and PT from a test of 30 deg/sec concentric knee extension. LEP was assessed as a 6m gait speed at usual and fast pace (6m-usual and fast), a 400m walk at fast pace (400m), and distance covered in a 2.5min walk at normal pace (2.5min) and global LEP by the Health ABC physical performance battery. Analyses used sex-stratified generalized linear regression models adjusted for age, race, BMI, appendicular lean mass, fat mass, and PT as covariates. In men, independent of PT, RFD was a significant (p< 0.05) predictor of all LEP measures except the 400m and the 2.5min walks. In women, independent of PT, RFD was only a significant correlate of the 6m-fast walk (p=0.02). In conclusion, in men, RFD contributes independently to physical function but RFD contributes less commonly in women. Understanding this sex difference requires further research.

Scientific Focus Area: Epidemiology

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