Associations Among Physical Activity, Protein Intake, And Clinical Indicators Of Sarcopenia

Abstract

Sarcopenia is characterized by age-related loss of skeletal muscle mass and function, and is associated with increased risk of falls, fractures, and mortality. Physical inactivity and inadequate protein intake are lifestyle factors that may contribute to the development and progression of sarcopenia. Weight-adjusted skeletal muscle index (wSMI), grip-strength (GRIP) and gait-speed (GAIT) are utilized clinically to diagnose sarcopenia. Phase-angle (PhA), obtained via bioelectrical impedance, is predictive of muscular strength and may also be predictive of sarcopenia. The PURPOSE of the study was to evaluate the relationships among indicators of sarcopenia, habitual physical activity, protein intake, and PhA in older adults. METHODS: In 96 subjects (68W/28 M, 68±6years) gait speed, grip strength (dynamometer), body composition (bioelectrical impedance), and habitual physical activity (7-day accelerometry) were measured. wSMI [skeletal muscle mass (SMM)÷body mass (BM)] was also calculated. In a subset of 34 subjects, habitual dietary intake was determined (3-day diet recall). Partial correlations (controlling for age and sex) were utlized to examine the relationships among variables of interest. Significance was set to ɑ< 0.05. RESULTS: Mean values were SMM: 28±6 kg; wSMI: 0.4±0.1; GRIP: 28±9 kg; GAIT: 1.5±0.4 m/s; PhA: 4.9±0.7°; moderate-intensity PA (MOD PA): 58±31 min/day; sedentary time (SED): 707±82 min/day; relative protein intake (RPI): 0.8±0.2 g protein/kg body mass. MOD PA was significantly (p< 0.05) correlated with wSMI (r= 0.28), PBF (r= -0.25), and RPI (r= 0.42). RPI was additionally correlated with PhA (r= 0.37) and body mass (r= -0.44). There was a trend towards a significant correlation between RPI and wSMI (r= 0.29, p= 0.11). GAIT was significantly correlated with activity counts per minute (r= 0.23), PBF (r= -0.47), wSMI (r= 0.45). GRIP was significantly correlated with SMM (r= 0.40). CONCLUSIONS: These data show that greater PA and RPI are associated with better scores for some of the clinical indicators of sarcopenia. Thus, increased PA and RPI intake may represent effective strategies for decreasing the risk of sarcopenia.