More Sweat Equals Lower Risk of Exercise-Induced Asthma

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By Kathleen Doheny
HealthDay Reporter

MONDAY, Sept. 8 (HealthDay News) -- The more an athlete sweats, the lower the risk of exercise-induced asthma, a new study suggests.

"The same mechanism that makes you sweat controls airway secretion," explained study author Dr. Warren Lockette, head of clinical investigation at the Naval Medical Center, in San Diego.

His report was published in the September issue of Chest.

This latest study follows other research, just published in The Journal of Allergy and Clinical Immunology, that found obese people with asthma likely to have worse control and quality of life than non-obese patients with asthma.

Lockette's team looked at the fluid secretion rates of 56 athletes suspected of having exercise-induced asthma, which can accompany a diagnosis of asthma or exist by itself, only when exercising. Symptoms include shortness of breath, wheezing and coughing.

Lockette analyzed the secretion rates of the athletes' sweat, saliva and tears. They measured air movement through the lungs, called forced expiratory volume (FEV), before and after giving the athletes methacholine, a drug which can cause airways to constrict in asthma patients.

They measured response to pilocarpine, a substance used to induce sweating and saliva production.

Those most sensitive to methacholine, shown by the greatest fall in FEV, were least sensitive to the pilocarpine. In other words, the more hyperactive the airway, the less the sweat production.

The average sweating rates of those who didn't respond to the methacholine were higher -- and they didn't have asthma.

"The same thing that controls how well you sweat controls how well you control airway secretion," Lockette said. "If you are sweating through your skin, you have sweaty airways, meaning you are putting out a lot of fluid, which keeps airways from getting dry. The dryness triggers the asthma."

They also correlated a lower risk of exercise-induced asthma with how much the athletes teared up and salivated. "You may stink, drool or cry, but at least you won't gasp," he joked.

The practical applications are yet to be determined, he said, but perhaps increasing secretions in some way may reduce asthma episodes.

The possibility that exercise-induced asthma is related to sweat secretions doesn't surprise Dr. Clifford Bassett, an assistant clinical professor of medicine at the Long Island College Hospital, SUNY-HSCB, Brooklyn, and clinical instructor of medicine, New York University School of Medicine, who serves as vice chairman of the public education committee for the American Academy of Allergy, Asthma & Immunology.

He added that exercise-induced asthma doesn't rule out activity. "The positive spin is, you can still engage in exercise, even on a high level," he said.

Educate yourself, he advised. Know that exercising in cold air is usually worse than warm air, for instance. The condition is typically treated with bronchodilators, with exact instructions best coming for your allergist or other physician.

More information

To learn more about exercise-induced asthma, visit the American Academy of Allergy, Asthma & Immunology.

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