Reproducibility of maximal exercise ergometer testing in patients with cystic fibrosis

Objectives: Exercise testing in patients with cystic fibrosis (CF) has beco me an important tool in assessing disease severity and predicting overall o utcome. The reproducibility of maximal exercise testing was examined in adu lt subjects with stable CF. Methods: Nine subjects with CF underwent a total of three maximal exercise tests carried out under identical circumstances over a 28-day period, Oxyge n uptake ((V) over dot O-2), minute ventilation ((V) over dot E), respirato ry frequency (f), heart rate (HR), and arterial oxygen saturation (SaO(2)) were measured at rest, at end exercise, and at 40% and 70% of maximum workl oad. Results: There were no significant differences in these measurements among the three tests. Reproducibility of exercise performance was assessed using the coefficient of variation. The mean within-subject coefficient of varia tion for test variables at end exercise are as follows: (V) over dot O-2, 6 .9%; (V) over dot E, 6.2%; f, 5.8%; HR, 3.0%; and SaO(2), 1.1%. The mean wi thin-subject coefficient of variation for test variables at 40% and 70% of maximal work rates are as follows: (V) over dot O-2, 5.2% and 4.6%; SaO(2), 0.3% and 0.9%; HR, 4.0% and 3%; (V) over dot E, 5.7% and 6.5%; and f, 5.8% and 7.2%, respectively. Conclusions: Variables measured during clinical cycle ergometer exercise te sting in adult patients with stable CF are reproducible. No learning effect was found on repeated testing.