Menopause: The Journal of The North American Menopause Society Vol. 22, No. 3, pp. 297/303 DOI: 10.1097/gme.0000000000000313 * 2014 by The North American Menopause Society
Sex-specific relationships of physical activity, body composition, and muscle quality with lower-extremity physical function in older men and women Chad R. Straight, MS,1 Anne O. Brady, PhD, MS,2 and Ellen Evans, PhD, MS1 Abstract Objective: This study aims to determine the sex-specific relationships of physical activity, body composition, and muscle quality with lower-extremity physical function in older men and women. Methods: Seventy-nine community-dwelling men (n = 39; mean [SD] age, 76.1 [6.2] y; mean [SD] body mass index, 27.3 [3.8] kg/m2) and women (n = 40; mean [SD] age, 75.8 [5.5] y; mean [SD] body mass index, 27.0 [3.8] kg/m2) were assessed for physical activity via questionnaire, body composition via dual-energy x-ray absorptiometry scanning, leg extension power using the Nottingham power rig, and muscle quality (W/kg; the ratio of leg extension power [W] to lower-body mineral-free lean mass [kg]). A composite measure of physical function was obtained by summing Z scores from the 6-minute walk, 8-ft up-and-go test, and 30-second chair-stand test. Results: As expected, men had significantly greater levels of physical activity, lower adiposity, greater lean mass, higher leg extension power, and greater muscle quality compared with women (all P G 0.05). In linear regression analyses, muscle quality and physical activity were the strongest predictors of lower-extremity physical function in men and independently explained 42% and 29% of the variance, respectively. In women, muscle quality (16%) and percent body fat (12%) were independent predictors after adjustment for covariates. Conclusions: Muscle quality is the strongest predictor of lower-extremity physical function in men and women, but sex impacts the importance of physical activity and adiposity. These findings suggest that older men and women may benefit from different intervention strategies for preventing physical disability and also highlight the importance of weight management for older women to preserve physical function. Key Words: Body composition Y Physical activity Y Muscle quality Y Physical function Y Older adults Y Muscle power.
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he prevalence of physical limitations (defined by the Centers for Disease Control and Prevention as difficulty with activities such as walking 1/4 mile, ascending 10 stairs, and lifting or carrying 10 lb) increases with age, from 17% among adults aged 50 to 59 years to 43% among adults 80 years or older.1 Importantly, the likelihood of limitations in functional activities is greater in women than in men aged 65 to 74 years (31% vs 24%), 75 to 84 years (46% vs 37%), and 85 years or older (66% vs 50%), which highlights an increasing sex disparity in risk for disability with advancing age.2 Relative to men, older women have lower physical activity levels,3,4 greater adiposity,5,6 less lean mass,5,6 and lower muscle quality,7
Sex-specific relationships of physical activity, body composition, and muscle quality with lower-extremity physical function in older men and women Chad R. Straight, MS,1 Anne O. Brady, PhD, MS,2 and Ellen Evans, PhD, MS1 Abstract Objective: This study aims to determine the sex-specific relationships of physical activity, body composition, and muscle quality with lower-extremity physical function in older men and women. Methods: Seventy-nine community-dwelling men (n = 39; mean [SD] age, 76.1 [6.2] y; mean [SD] body mass index, 27.3 [3.8] kg/m2) and women (n = 40; mean [SD] age, 75.8 [5.5] y; mean [SD] body mass index, 27.0 [3.8] kg/m2) were assessed for physical activity via questionnaire, body composition via dual-energy x-ray absorptiometry scanning, leg extension power using the Nottingham power rig, and muscle quality (W/kg; the ratio of leg extension power [W] to lower-body mineral-free lean mass [kg]). A composite measure of physical function was obtained by summing Z scores from the 6-minute walk, 8-ft up-and-go test, and 30-second chair-stand test. Results: As expected, men had significantly greater levels of physical activity, lower adiposity, greater lean mass, higher leg extension power, and greater muscle quality compared with women (all P G 0.05). In linear regression analyses, muscle quality and physical activity were the strongest predictors of lower-extremity physical function in men and independently explained 42% and 29% of the variance, respectively. In women, muscle quality (16%) and percent body fat (12%) were independent predictors after adjustment for covariates. Conclusions: Muscle quality is the strongest predictor of lower-extremity physical function in men and women, but sex impacts the importance of physical activity and adiposity. These findings suggest that older men and women may benefit from different intervention strategies for preventing physical disability and also highlight the importance of weight management for older women to preserve physical function. Key Words: Body composition Y Physical activity Y Muscle quality Y Physical function Y Older adults Y Muscle power.
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he prevalence of physical limitations (defined by the Centers for Disease Control and Prevention as difficulty with activities such as walking 1/4 mile, ascending 10 stairs, and lifting or carrying 10 lb) increases with age, from 17% among adults aged 50 to 59 years to 43% among adults 80 years or older.1 Importantly, the likelihood of limitations in functional activities is greater in women than in men aged 65 to 74 years (31% vs 24%), 75 to 84 years (46% vs 37%), and 85 years or older (66% vs 50%), which highlights an increasing sex disparity in risk for disability with advancing age.2 Relative to men, older women have lower physical activity levels,3,4 greater adiposity,5,6 less lean mass,5,6 and lower muscle quality,7
