NEW YORK, Jun 04 (Reuters Health) -- With the return of hot weather, a word of warning to people with asthma: Dehydration can cause bronchospasm, a constriction or "tightening" of lung airways. And dehydration can make asthma brought on by exercise worse, report researchers.
Lead investigator Paula Maxwell of the University of Buffalo, New York, and colleagues compared airway reactivity after 6 minutes of high-intensity exercise in eight young adults with exercise-induced asthma and eight without the condition. Subjects first exercised when fully hydrated and again after 24 hours of voluntary water deprivation.
Hydration status had no effect on lung function in normal subjects, but the study showed that in individuals with exercise-induced asthma, dehydration resulted in a significant decrease in FEV1, a measure of lung function based on the amount of air blown out in one second.
This decline in lung function was evident both before and after exercise in these individuals, the research team reported Friday at the American College of Sports Medicine meeting in Seattle, Washington.
The investigators also noted that the rate of decline in lung function was the same in asthmatics whether they were hydrated or dehydrated, but when dehydrated, asthmatics start out with worse lung function than usual, and therefore experience more breathing problems than when they have enough water on board.
"Asthmatics are more sensitive than non-asthmatics to dehydration, but we need to investigate this condition further to determine how it affects (lung) function," said study co-author Dr. Frank Cerny, associate professor and chair of the University of Buffalo department of physical therapy, exercise, and nutrition sciences.
"The message continues to be, 'Drink fluids whenever you get the chance,'" he added. "If you have asthma, dehydration may make it worse, particularly during exercise."
