Fat mass is negatively associated with the physiological ability of tissue to consume oxygen

Abstract Aims: To describe the relationship between variables related to body composition and peak oxygen uptake ( V ˙ O 2peak) and to verify whether fat mass can affect these relationships. Methods: Eighty participants underwent cardiopulmonary exercise testing to measure V ˙ O 2peak and a body composition assessment to measure fat mass, fat free mass (FFM), and total body mass (BM). Results: There were significant relationships between V ˙ O 2peak relative to FFM (fat free mass) (mL/kgFFM/min) and absolute fat mass (kg) (r=-0.50, p<0.001) and relative fat mass (%) (r=-0.56, p<0.001). Absolute V ˙ O 2peak (L/min) had a high positive relationship with FFM (r=0.83, p<0.0001); the relationship between V ˙ O 2peak (L/min) and FFM remained high and positive even when accounting for absolute fat mass (kg) (r=0.83, p<0.001). V ˙ O 2peak relative to total body mass (mL/kgBM/min) showed a high negative relationship with relative fat mass (%) (r=-0.89, p<0.001) and a positive relationship with fat free mass (kg) (r=0.57, p<0.001), which did not change when accounting for fat mass (kg) (r=0.56, p<0.001). Conclusion: These data indicate that the physiological ability of tissue to consume oxygen ( V ˙ O 2peak in mL/kgFFM/min) is negatively associated with fat mass. Moreover, the individual’s cardiorespiratory capacity to transport oxygen for working muscles ( V ˙ O 2peak in L/min) is strongly related to absolute FFM, and this association is not affected by fat mass. Finally, a better body mass composition (high FFM and low fat mass) is important for aerobic physical fitness ( V ˙ O 2peak in mL/kgBM/min) and improved physiological ability of tissue to consume oxygen ( V ˙ O 2peak in mL/kgFFM/min).