METHODS: Cross-sectional study in healthy non-smokers, non-obese adults with normal spirometry. Symptom limited incremental exercise testing on a cycle ergometer with measurements of oxygen uptake (VO), work rate, ventilatory variables and ABG at rest and peak exercise. Analysis of group 2 differences was tested using unpaired test and ANOVA and 95% confidence limits were calculated. t RESULTS: We included 171 healthy adults, 53% men. At peak exercise: VO 95.5±14.7% predicted, work rate 101.9±16.0% predicted