The condition, known as exercise-induced bronchospasm (EIB), is a temporary narrowing of the airways that occurs during or after physical activity. It can include such symptoms as wheezing, coughing, shortness of breath, chest tightness, fatigue or decreased athletic performance.
Most of the estimated 18 million Americans who have chronic asthma are at risk for EIB if their asthma is not well-controlled, says Dr. Gilbert D'Alonzo, director of the Airways Disease Center at Temple University Health Sciences Center in Philadelphia.
But, he adds, millions of other people may suffer EIB even though they have no signs of asthma when they aren't exercising.
"So when you add these two groups together, you're probably talking about 30 million people in the United States who are at risk for exercise-induced asthma or bronchospasm," D'Alonzo says.
It can be a challenge diagnosing EIB in people who don't have chronic asthma because they seem normal when they visit their doctor, D'Alonzo says.
One way to check is to have your doctor give you a small device called a peak-flow meter, which measures how fast you can exhale air in one breath. It's used before and after exercise to check for reduced air flow.
People with allergies seem more predisposed to EIB and they need to watch for telltale symptoms, says Dr. William S. Silvers, of the Allergy, Asthma and Immunology Clinic of Colorado.
"If they don't have the endurance they think they should have, if they're having coughing and chest tightness, they may well have exercise-induced asthma" and should consult their doctor, Silvers says.
Exercise-induced asthma can be fatal; since 1995, there have been 75 deaths in the United States, according to a Temple University Hospital registry that tracks the condition.
Most of those deaths involved people with severe, chronic asthma that was undertreated, D'Alonzo says.
He and Silvers stress that asthma shouldn't prevent anyone from playing sports.
"Athletes shouldn't let their asthma control them; they should control their asthma and do whatever sport they want to do," as long as their condition is diagnosed and treated, D'Alonzo says.
Ways to avoid or minimize exercise-induced asthma include taking medication before exercise, doing a thorough warm-up and cool-down, and wearing a scarf over your mouth and nose if you're exercising in cold air. You might also choose an activity less likely to trigger EIB, such as swimming.
And try to avoid EIB triggers, which include cold air, heavy air pollution, and high pollen counts.
Public education about the condition is essential, both doctors say.
"We've had countless situations where the athlete has almost wanted to give up the sport and then, once we figure out what's actually going on, we get them to feel so much better that they're very happy with their athletic prowess," D'Alonzo says.
To prove the point that asthma shouldn't be a barrier to activity, 15 years ago Silvers started an annual ski day for children with asthma.
"The focus is to know that despite having asthma, you should be able to do everything that anybody else can do as long as you understand your symptoms and understand your treatment," he says.
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