The role of nutritional status, airway obstruction, hypoxia and abnormalities in serum lipid composition in limiting exercise tolerance in children with cystic fibrosis.

This study investigated the roles of hypoxia, pulmonary mechanics, nutritional status and 
serum fatty acid composition in limiting exercise tolerance in cystic fibrosis. 
Twenty children with CF of carrying severity performed two progressive exercise 
tests on a cycle ergometer, once while breathing air, once while 
breathing O2. The children with the lower maximal mid-expiratory flow rates 
tended to have very little respiratory reserve at the final work 
load. We conclude that nutritional status and airway obstruction are closely 
correlated with exercise tolerance in CF and that, unlike the adult 
with chronic obstructive pulmonary disease, exercise limiting dyspnoea occurs in the 
presence of normal end-tidal CO2. 