Author(s): K Niranjan, PK Senthilkumar and P Uma

Abstract:

Obesity significantly impairs cardiorespiratory fitness, as evidenced by reduced VO₂ max levels. While concurrent training (combined aerobic and resistance exercise) has emerged as an effective intervention, the relative contributions of Fat-Free Mass (FFM) preservation versus fat loss to VO₂ max improvements remain unclear, particularly in young obese populations. This study investigated these relationships in a controlled trial.

Methods: Forty sedentary obese men (age 22.3±2.1 years; BMI 33.2±1.9 kg/m²) were randomized to either a 12-week supervised concurrent training program (n=20) or a control group (n=20). The intervention consisted of three weekly sessions incorporating moderate-intensity aerobic exercise (60-70% heart rate reserve) and resistance training (60-70% 1RM). Primary outcomes included VO₂ max measured via graded treadmill cardiopulmonary exercise testing and body composition assessed through bioelectrical impedance analysis (InBody 370).

Results: The intervention group demonstrated significantly greater improvements in VO₂ max compared to controls (Δ4.20 vs Δ0.70 mL/kg/min, p<0.001), with a large effect size (η²=0.64). VO₂ max changes showed strong positive correlation with FFM gain (r=0.62, p<0.001) and inverse correlation with fat loss (r=-0.71, p<0.001). Multiple regression analysis revealed both FFM (β=0.49, p<0.001) and fat loss (β=-0.53, p<0.001) as significant independent predictors, collectively explaining 75% of VO₂ max variance (R²=0.75).

Conclusion: In young obese men, 12 weeks of concurrent training significantly enhances VO₂ max through dual mechanisms of lean mass preservation and fat reduction, with adiposity loss demonstrating marginally greater influence. These findings support the implementation of integrated exercise programs targeting both body composition components to optimize cardiorespiratory fitness in this population. The results provide evidence-based guidance for exercise prescription in obesity management.

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