Abstract
BACKGROUND: The cardiopulmonary exercise test (CPET) evaluates cardiopulmonary function. In light of the obesity epidemic, it is important to understand how body composition affects interpretation of CPET results. The aim of the present study was to assess the relationship between CPET measures, other than peak oxygen uptake, and body composition. METHOD: A total of 330 participants, aged 50 years, performed both a CPET and dual-energy X-ray absorptiometry (DXA). From the CPET, peak exercise respiratory exchange ratio (RER), ventilatory efficiency (V̇ (E)/V̇ (CO(2)) slope) and work efficiency (ΔV̇ (O(2)) /ΔWR) were recorded. Pearson's correlation was used to assess the association between CPET measures and selected body composition measures, including body mass index (BMI), waist circumference, fat mass, lean mass, body fat percentage and percentage trunk fat to fat mass. All analyses were done stratified by sex. A p-value <0.05 defined statistical significance. RESULTS: RER was negatively correlated with body composition measures; the strongest correlation was observed with waist circumference in females (r= -0.36). V̇ (E)/V̇ (CO(2)) slope had no significant correlations with any body composition measures. ΔV̇ (O(2)) /ΔWR was positively correlated with the body composition measures; the strongest correlation was observed with BMI (r=0.24). The additive role of percentage body fat and percentage trunk fat were studied in a linear regression model using waist circumference and BMI to predict the aforementioned CPET measures and no additive role was found. CONCLUSION: RER and ΔV̇ (O(2)) /ΔWR may be influenced by body composition while V̇ (E)/V̇ (CO(2)) slope is not affected. Adiposity measures from DXA add no additional explanatory value to the CPET measures.