RESULTS: 32 subjects (47% female, 66±9 yrs, BMI 30.4±6.3 kg/m2, smoking hx 35±29 pkyrs, 2.3±0.8 on the 0-4 GOLD scale) participated. Most were on multiple inhaled medications with 20% on oral steroids. Baseline averages were: 44±21 for QOL (range 8-84), 21±17 for exNO (range 5-89), and 58±10 for FEV1/FVC % Pred (range 33 to 78%). Peak VO2 averaged 11.4±3.1 ml/kg/min and the IBDLCO averaged 72% of the SBDLCO (r=0.88, SB vs IB methods). Using univariate regression, both the SB and IBDLCO were predictive of VO2peak; but the SBDLCO/Qc ratio (r=0.63, p<0.001) was the best predictor of exercise capacity (VO2peak expressed in ml/kg/min) with maximal expiratory flows over the mid to lower lung volumes being the most significant predictors (r=0.49, p<0.01). Using multiple and stepwise regression, only BMI added additional predictive value to the SBDLCO/Qc for predicting aerobic capacity (r=0.73).