LONG-TERM CHANGE IN EXERCISE CAPACITY, BODY-MASS, AND PULMONARY-FUNCTION IN ADULTS WITH CYSTIC-FIBROSIS

Study objective: Cross-sectional studies in patients with cystic fibro sis (CF) have shown that exercise capacity is correlated with pulmonar y function and body mass. We have examined whether the same relationsh ips are seen longitudinally in adults with CF. Design: Subjects who fi rst performed progressive maximal cycle ergometry between 1986 and 198 9 were retested using an identical protocol a mean of 6.3 years later. Participants and settings: Adults with CF attending a regional center . Measurements and results: The principal exercise measures were peak oxygen uptake (VO2peak), ventilation (VE(peak)), oxygen saturation, an d heart rate. Spirometry, weight, and height were also recorded at eac h time point. At baseline, subjects had a mean age of 19.8 years, body mass index (BMI) of 19.0, FEV( )of 69% predicted, VO2peak of 1.56 L/m in, and VE(peak) of 48.9 L/min. At repeated testing after a mean inter val of 6.3 years, the FEV(1) had fallen significantly to 54% predicted (p<0.001) and the BMI had risen significantly to a mean of 20.9 (p<0. 001). There were no significant differences in VO2peak or VE(peak), al though VE(peak) was a significantly higher proportion (72% vs 61%) of predicted maximal voluntary ventilation. Conclusions: Adults with mild to moderate pulmonary dysfunction were able to increase body mass and maintain VO2peak despite a declining FEV(1). VO2peak was not reduced by the decrease in FEV(1) because VE(peak) was unaffected. Improved nu trition may have contributed to maintaining fitness.