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Background: Age-related decline in muscle oxidative capacity reduces muscle function and physical performance, leading to disability and frailty. Whether age-related decline in oxidative capacity is modified by exercise and other lifestyle practices is unclear. Therefore, we tested the hypothesis that physical activity is associated with better oxidative capacity, independent of age., Design: Cross-sectional study performed in the Baltimore Longitudinal Study of Aging, conducted by the Intramural Research Program (IRP) of the National Institute on Aging (NIA)., Setting: NIA IRP Clinical Research Unit, Baltimore, MD., Participants: Participants included 384 adults (54.7% women), aged 22 to 92 years, seen between 2013 and 2017., Measurements: Muscle oxidative capacity was measured in vivo using phosphorous magnetic resonance spectroscopy. We determined the postexercise time constant (τ PCr ; in seconds) for phosphocreatine (PCr) recovery, with lower values of τ PCr, (ie, more rapid recovery of PCr levels after exercise) reflecting greater oxidative capacity. Time spent in moderate-to-vigorous physical activity (MVPA) was assessed using wearable accelerometers that participants wore 5.9 ± 0.9 consecutive days in the free-living environment., Results: In linear regression models, higher τ PCr was associated with older age (standardized β = .39; P < .001) after adjusting for sex, race, height, and weight. After including MVPA as an independent variable, the standardized regression coefficient of age decreased by 40%, but remained associated with τ PCr (β age = .22; P < .001) and had a smaller standardized regression coefficient than MVPA (β MVPA = -.33; P < .001). After adjusting for health status, education, and smoking history, the standardized regression coefficient for age decreased 12% (β age = .20; P = .003), while the standardized coefficient for MVPA decreased only 3% (β MVPA = -.32; P < .001)., Conclusion: Study findings suggest that MVPA is strongly associated with muscle oxidative capacity, independent of age, providing mechanistic insights into the health benefits of exercise in older age. J Am Geriatr Soc 67:1695-1699, 2019., (© 2019 The American Geriatrics Society.)

Background: In older persons, lower hand grip strength is associated with poorer cognition. Little is known about how the rate of muscle contraction relates to cognition and upper extremity motor function, and sex differences are understudied., Methods: Linear regression, adjusting for age, race, education, body mass index, appendicular lean mass, and knee pain, assessed sex-specific cross-sectional associations of peak torque, rate of torque development (RTD), and rate of velocity development (RVD) with cognition and upper extremity motor function., Results: In men (n = 447), higher rate-adjusted peak torque and a greater RVD were associated with faster simple finger tapping speed, and a greater RVD was associated with higher nondominant pegboard performance. In women (n = 447), higher peak torque was not associated with any measures, but a greater RTD was associated with faster simple tapping speed and higher language performance, and a greater RVD was associated with higher executive function, attention, memory, and nondominant pegboard performance. In women with low isokinetic peak torque, RVD was associated with attention and memory., Conclusions: RVD capacity may reflect neural health, especially in women with low muscle strength., (Published by Oxford University Press on behalf of The Gerontological Society of America 2018.)

Purpose: Acceleration capacity affects physical function, but whether it differentially affects men versus women or weak versus strong individuals is less known. We investigated whether knee extension rate of velocity development (RVD, a measure of acceleration) is associated with walking performance independent of peak torque and whether the relationships differ in men versus women and in weak versus strong individuals., Methods: Relationships of RVD with walking performance were assessed in 326 women and 365 men aged 26-96 years enrolled in the Baltimore Longitudinal Study of Aging. Tests included knee extension peak torque and RVD assessed during a 180°·s - 1 isokinetic strength test and four walking performance measures (usual-paced and fast-paced 6 m walks and 2.5 min usual-paced and 400 m fast-paced walks). Sex-stratified linear regression models were adjusted for age, race, height, appendicular lean mass, fat mass, peak torque, knee pain, and RVD*peak torque interaction., Results: In men, RVD was not independently associated with any walking performance measure (p > 0.05), and, for the 6 m-usual walk only, there was a significant RVD*peak torque interaction (p < 0.0001). In women, RVD was independently associated with usual-paced walks (p < 0.05) and there were significant RVD ∗ peak torque interactions for all measures. Strength-specific analyses indicated that RVD was most associated with performance among weaker individuals., Conclusion: RVD is associated with walking performance in women, but less in men, and is most related to performance when strength is low. Strategies to accomplish motor tasks may be sex-specific. Future studies are needed to understand the mechanisms underlying such sex differences., (Published by Elsevier Inc.)