Dehydration Makes Exercise-Induced Asthma Worse, Study by UB Researchers Finds

SEATTLE -- If athletes from elite to novice needed yet another reason to drink plenty of fluids during exercise, a new study by University at Buffalo exercise scientists provides it.

Their research shows that dehydration may induce bronchospasm even before exercise and make exercise-induced asthma worse. Results of the study were presented here today (June 4) at the annual meeting of the American College of Sports Medicine.

“The message continues to be, ‘Drink fluids whenever you get the chance,’” said Frank Cerny, Ph.D., associate professor and chair of the UB Department of Physical Therapy, Exercise and Nutrition Sciences. “If you have asthma, dehydration may make it worse, particularly during exercise.”

Cerny said exercise-induced asthma probably is caused by heat and water loss from the airways. “By dehydrating yourself, the airways also become dehydrated,” he noted. “We first observed this problem in high-school and college athletes -- that as they became dehydrated, they seemed to have more trouble with their asthma.”

Asthma is a major health problem in the U.S., with experts placing the incidence among children as high as 40 percent. Cerny said 80 - 90 percent of asthma sufferers experience exercise-induced bronchospasm, and that about 10 percent of elite athletes have the condition.

In their current study, UB researchers put eight persons between the ages of 19 and 29 with exercise-induced asthma, and eight persons of similar age without the condition, through six minutes of high-intensity exercise on a cycle ergometer and/or treadmill. Each person’s forced vital capacity -- the volume of air blown out in one second (FEV1 ) -- was measured before and after exercise, both when fully hydrated and after 24 hours without fluids.

Results showed that among the non-asthmatics, hydration status had no effect on the FEV1 before, during or after exercise. However, the FEV1 of the asthmatics was significantly lower, both before and after exercise, when they were dehydrated, compared to their respiratory performance when completely hydrated.

Researchers found that the rate of respiratory decline remained the same in the asthmatics during exercise, regardless of their state of hydration, but they started out with less capacity when they were dehydrated, Cerny said.

“Asthmatics are more sensitive than non-asthmatics to dehydration, but we need to investigate this condition further to determine how it affects pulmonary function,” he said.

Paula Maxwell, a doctoral student in the UB Department of Physical Therapy, Exercise and Nutrition Sciences, was the lead researcher on this study, working with Cerny. Additional researchers were Patricia Ohtake, Ph.D., UB assistant professor of physical therapy, exercise and nutrition sciences, and John Leddy, M.D., associate director of UB’s Sports Medicine Institute.