VE/VCO2 slope in lean and overweight women and its relationship to lean leg mass

Abstract

Ventilation/carbon dioxide production (VE/VCO2slope) is used clinically to determine cardiorespiratory fitness and morbidity in heart failure (HF). Previously, we demonstrated that lower lean leg mass is associated with high VE/VCO2slope during exercise in HF. In healthy individuals, we evaluated 1) whether VE/VCO2slope differed between lean and overweight women and 2) the relationship between lean leg mass and VE/VCO2slope in overweight sedentary (OWS), overweight trained (OWTR) and lean, trained (LTR) women. Methods: Gas exchange and ventilation were collected during a treadmill peak oxygen uptake test (VO2peak) in 40 women [26 OWS (29 ± 7 yrs., mean ± SD), 7 OWTR (33 ± 5 yrs) and 7 LTR (26 ± 6 yrs)]. Body composition was measured by dual X-ray absorptiometry. Results: VO2peak was highest in LTR (46.6 ± 8 ml/kg/min) compared with OWTR (38.1 ± 4.9 ml/kg/min) and OWS women (25.3 ± 4.8 ml/kg/min, p 0.05). Higher lean leg mass was associated with lower VE/VCO2slope in overweight women (OWS + OWTR: r = −0.55, p < 0.001), contrasting with higher VE/VCO2slope in LTR women (r = 0.86, p < 0.001). Conclusions: These findings suggest VE/VCO2slope may not differentiate between low and high cardiorespiratory fitness in healthy individuals and muscle mass may play a role in determining the VE/VCO2slope, independent of disease. Keywords: Ventilatory efficiency, Body composition, Peak VO2, VE/VCO2slope, Obesity