2025, Spring Adirondac Adirondoc
Recently, a reader asked me for some information on exercise-induced asthma (EIA). Although I have covered asthma generally a couple of times, the reader was absolutely correct that EIA is a “special case” that can be very relevant to the hiker.
First, a little refresher on asthma itself. This is a condition in which the tubes that carry air into the depths of the lungs tighten and narrow, making it difficult to move air in and out. This limits the exchange of” old air” for “newer air” with a higher oxygen content. This, in turn, limits activity. When the lungs are examined during an episode of asthma, one finds that the entry of air is diminished and there is often an audible wheeze upon breathing out. We call this narrowing of the air tubes “bronchoconstriction.” Folks with asthma find that a variety of triggers can set off bronchoconstriction. Certain allergens in the air, such as pollens, are a common trigger, as are the viruses that cause respiratory infections. For individuals with EIA, the trigger is a change in the volume, temperature, or humidity of air moving into the lungs.
Although there is considerable variability among patients, typically the signs of EIA develop within a few minutes of beginning exercise. The condition peaks after about fifteen minutes, when shortness of breath, coughing, and weakness develop; sometimes, there is a worrisome tightness in the chest. Often, the symptoms improve after about an hour. If symptoms improve, there may be a period of a few hours when the bronchoconstriction is less bothersome, only to return later. It should be noted that most of the studies on EIA have been done with exercise that occurs in bursts, such as running; the pattern of symptoms in the hiker, especially walking over changing terrain, may be different.
Many people with established asthma find that exercise is one of their triggers. In these cases, the diagnosis is pretty straightforward. A bigger challenge is the individual who has no other signs of asthma, but who develops shortness of breath with exercise. A number of other heart, lung, or airway problems can cause symptoms resembling EIA, so a careful workup is needed. This often involves some sort of”provocation” on a treadmill or similar device.
The treatment for EIA in folks with known asthma begins with optimizing the overall control of their disease. There are a host of drug options for controlling asthma these days, with inhaled steroids typically as the cornerstone. With modern approaches to treatment, good control should be possible in almost everyone. For these folks, EIA symptoms generally respond to a short-acting beta agonist inhalation such as salbutamol (Albuterol®). If they find that the onset of symptoms with exercise is predictable, a preventive dose of inhaler fifteen minutes or so before exercise is often useful.
There is much less data available on the best treatment for EIA in folks who do not have underlying asthma. Most authorities recommend starting with inhaled beta agonists in these individuals as well.
EIA that does not respond to these measures can be a real challenge, but there are several options. I strongly recommend consultation with an experienced asthma specialist in such cases. These individuals may respond toother inhaled drugs such as ipratropium, or may need oral medications such as montelukast. I cannot stress highly enough that intractable EIA is treatable, but it generally requires expertise outside the wheelhouse of most general physicians.
One critical point about EIA in closing. Although the goal for most patients with asthma is to avoid triggers, no one with asthma should avoid exercise! There is much evidence that aerobic exercise is good for patients with asthma, as it is for almost everyone else. The goal of treating EIA is to ensure that exercise can be undertaken comfortably.
Tom Welch, MD, is a physician at Upstate Medical University in Syracuse and an active member of the Wilderness Medical Society. He is a licensed professional guide and a certifying instructor for the Wilderness Education Association, and has guided groups in the Adirondacks, Montana, and Alaska. More information is available at adirondoc.com, his website and blog. Leonard Weiner, MD, SUNY Distinguished Professor of Infectious Diseases at Upstate Medical University, reviewed this column and provided helpful suggestions.
Topics: General First Aid, asthma, emergencies, exercise