Backcountry health & safety

Exercise-induced asthma

by Susan Bradford, Ph.D., Richard Fantozzi, M.D., and Bill Fantozzi, Wilderness Remote and ER Instructor

Strenuous physical activities such as cross country skiing, climbing and long-distance running can trigger exercise-induced asthma. It is typically seen in individuals participating in sports that require continuous physical exertion. Since it is exacerbated by cold temperatures, it is plausible to encounter asthmatic symptoms in AMS victims. Activities that involve sporadic physical exertion (such as hiking, recreational biking and swimming) are considered less likely to trigger an exercise-induced asthma attack.

People who are sensitive to poor air quality and temperature extremes may be prone to exercise-induced asthma. Factors that may trigger an attack include stress and airborne particulate matter from fires, soil, or vegetation. Underlying physical conditions may also play a large role in a person’s susceptibility to exercise-induced asthmatic attacks, but these factors are beyond the scope of this article.

Understanding the physiology

Once an asthmatic attack begins the body responds by producing copious amounts of mucus in the lungs resulting in coughing and/or wheezing. Airflow to the lungs is restricted as the bronchi swell. Mouth breathing allows cold air directly into the lungs, which may exacerbate the attack.


Symptoms of exercise-induced asthma include shortness of breath, wheezing, coughing, and/or chest pain. The symptoms may quickly resolve after stopping physical activity or continue for up to one hour (12).


A person experiencing an exercise-induced asthmatic attack should immediately stop all physical activity. If symptoms do not resolve themselves, the person should be immediately transported to the closest medical facility.

Individuals that know they are prone to asthma may carry an inhaler to be used as directed by a physician. Prescription bronchodilator inhalers, such as albuterol (ventolin, proventil) typically given immediate results and reduce swelling of the bronchi in up to 90% of exercise-induced asthmatic attacks (12). Even after use of an inhaler it is important to observe the individual’s ease of breathing, since asthma attacks can be life-threatening.

The use of an inhaler prior to physical exertion may be recommended by their physician as a preventative measure.


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San Diego, California