Dietary and Physical Activity Correlates of Muscle Mass in 60-65-Year-Old Seniors: A Gender-Specific Analysis

Introduction: Sarcopenia and loss of skeletal muscle mass represent major public health concerns in aging populations. Although both diet and physical activity (PA) are recognized as modifiable determinants of muscle mass, their effects may differ by sex. This study aimed to examine dietary and behavioral correlates of muscle mass amongst community-dwelling adults aged 60-65 in Central Poland. Methods: The study included 134 women and 138 men. Body composition was assessed using bioelectrical impedance (Maltron Bioscan 920, Essex, UK). Dietary intake was evaluated using a 24 h recall analyzed with Dieta 5.0 software. PA was measured using the Seven-Day Physical Activity Recall Questionnaire and the Stanford Physical Activity Indices. Statistical analysis included bivariate correlations and general linear modeling performed separately for women and men. Results: In women, skeletal muscle mass (as a percent of body mass) showed significant positive associations with protein intake per kilogram of body weight, magnesium, phosphorus, and moderate health-related PA. Concomitantly, there was a negative correlation with lipids such as long-chain polyunsaturated fatty acids (PUFA). In multivariate models, protein intake remained the only predictor. In men, only protein intake per kilogram of body weight demonstrated a significant association with muscle mass; no other dietary or PA factors were retained in the model. Conclusions: The findings indicate that dietary and behavioral factors influencing muscle mass vary by sex. While muscle mass in women is linked to multiple nutritional and lifestyle factors, men appear primarily responsive to total protein intake. These sex-specific differences may underscore the importance of tailored strategies in sarcopenia prevention.