Body Composition Analysis by Dual Energy X-ray Absorptiometry and Exercise Performance in Underweight Patients With COPD

Study objectives The aim of this study was to examine the effect of body composition on maximal exercise performance in patients with COPD. Methods The study was carried out on 27 patients with COPD and was confirmed by pulmonary function testing. Body composition was measured by dual energy x-ray absorptiometry (DXA). Exercise performance was conducted on a cycle ergometer and was measured as maximal work rate (WRmax) and maximal oxygen uptake ( V ˙ o 2 max). Bone mineral content (BMC), lean mass (LEAN), and fat mass (FAT) were assessed by DXA and were expressed as a percentage of ideal body weight, BMC, LEAN, and FAT. Results LEAN% correlated significantly with V ˙ o 2 max (r = 0.66, p=0.0002) and WRmax (r = 0.70, p < 0.0001). No significant correlation was found between FAT% and exercise performance. By stepwise regression analysis, variables significantly contributing to WRmax and V ˙ o 2 max were LEAN% and the maximal voluntary ventilation. Total variance explained in these models was 81% for WRmax and 82% for V ˙ o 2 max. Conclusion Lean mass was an important determinant of maximal exercise performance in patients with COPD.