Effects of combined resistance and aerobic training on body composition and functional capacity in middle-aged adults: a 12-week intervention study

Background: The deterioration of body composition and functional capacity are hallmarks of the ageing process, yet interventional strategies to mitigate these changes in middle-aged adults remain incompletely characterised. This study investigates the effects of a 12-week combined resistance and aerobic training programme on body composition, muscle strength, and aerobic capacity in adults aged 35-64 years. Methods: Sixty-four sedentary adults (32 males, 32 females; mean age 51.3±6.2 years) completed a supervised 12-week exercise intervention consisting of three weekly sessions combining resistance and aerobic training. Body composition was assessed via bioimpedance analysis (BIA) using an Akern device. Muscle strength was measured using a Jamar Plus+ hand dynamometer, and aerobic capacity was determined through a submaximal cycle ergometer test. Measurements were taken at baseline, week 6, and week 12. Results: Significant improvements were observed in all primary outcome measures. Phase angle increased by 0.6±0.2° (p<0.001), fat mass decreased by 3.6±1.1 kg (p<0.001), and fat-free mass increased by 1.8±0.7 kg (p<0.001). Handgrip strength improved by 4.2±1.3 kg (p<0.001) in males and 3.1±1.1 kg (p<0.001) in females. Estimated V̇O2max increased by 4.6±1.5 ml/kg/min (p<0.001). Notably, improvements in phase angle correlated positively with increases in handgrip strength (r=0.68, p<0.001) and estimated V̇O2max (r=0.57, p<0.001). Conclusions: A 12-week combined resistance and aerobic training programme significantly improves body composition, muscle strength, and aerobic capacity in middle-aged adults. The correlation between BIA-derived phase angle and functional parameters suggests its potential utility as a biomarker for monitoring exercise-induced adaptations.