PHYSICAL ACTIVITY, PROTEIN INTAKE, AND APPENDICULAR SKELETAL MUSCLE MASS IN OLDER MEN

Abstract

707 Aging is associated with physical inactivity, low energy intake, and loss of skeletal muscle mass. It is currently unclear whether regular physical activity and adequate dietary protein intake can attenuate the loss of skeletal muscle mass. We hypothesized that the maintenance of physical activity and dietary protein intake would attenuate the age-related decline in total appendicular skeletal muscle mass. Total appendicular skeletal muscle mass was determined by dual energy x-ray absorptiometry in 44 healthy, older Caucasian men (age = 49 - 85 y). Physical activity level was determined from a uniaxial accelerometer over a 9-day period. Dietary protein intake was estimated from a 3-day food record. Aging was inversely associated with total appendicular skeletal muscle mass in older men (r = −0.43; slope = −0.119 kg/y; P < 0.01). An age effect on appendicular skeletal muscle mass persisted after controlling for standing height and physical activity (r = −0.34; slope = −0.120 kg/y; P = 0.03). Furthermore, an age effect on appendicular skeletal muscle mass persisted after controlling for standing height and dietary protein intake (r = −0.38; slope = −0.103 kg/y; P = 0.01). These cross-sectional data suggest that maintaining regular physical activity and adequate protein intake may not offset the age-related loss of appendicular skeletal muscle mass in older men. Supported by NIH (F32AG-05791 and Univ. of Vermont GCRC, RR-00109)