Exercise-induced asthma is common in speedskating, both ice and inline, with up to 50% of athletes tested showing evidence of the disease. Diagnosis is usually based on symptoms, and symptoms can vary. A skater could experience typical symptoms of shortness of breath, cough, wheezing, or chest tightness, or more unusual symptoms of headache, stomach or side-ache, chest pain, or simply a feeling of being out of shape(which doesn't count if you actually are out of shape). Symptoms may occur during or after exercise.

Some general information about asthma would probably be useful before talking more specifically about the causes of exercise-induced asthma. Garden variety asthma has two main components: constriction of the bronchial (or breathing) tubes and swelling of the breathing tubes. Asthma symptoms are initially caused by constriction, with more severe asthma progressing to symptoms caused by swelling. In either case, the body perceives something abnormal in the breathing tubes, and uses its best possible defense, the cough. Unfortunately, the body will never be able to cough away swelling or tightness of the breathing tubes.

In exercise-induced asthma, we have generally the same problem, although the constriction of the breathing tubes is the main cause. There are two main theories as to why this happens with exercise. The first is that when an athlete begins to exercise, the rapid breathing leads to drying of the upper airways. This local dehydration leads to a reaction which causes release of chemicals which lead to inflammation and constriction. The second theory involves exercise causing heat loss from the airways. The body attempts to re-warm the airways by dilating the local blood vessels, which leads to bronchial constriction.

With these theories in mind, it is easy to see why exercising in dry, cold air is likely to provoke exercise induced asthma.

Diagnosis

Generally, diagnosis is based on symptoms. If an athlete is complaining of shortness of breath, cough or wheezing shortly after beginning exercise, it is reasonable to start medical therapy. If a baseline condition of asthma is suspected, it is more important to have pulmonary function testing. The most important component of pulmonary function testing in evaluating exercise-induced asthma is the amount of air which can be expelled in the first second of a maximal exhalation (FEV1). This should be checked at rest, and if abnormal, suggests baseline asthma. In exercise-induced asthma, the FEV1 at rest should be normal, but after exercise may drop by 15% or more. It is important that the testing should be done at the site of exercise (outdoors, ice rink, etc.) as up to 80% of testing will be negative in the office, yet positive when tested on location.

Treatment

Treatment is relatively straightforward. The warmup period is of critical importance, as a ten minute warmup at 80% intensity can provide up to 40 minutes decreased airway reactivity. The usual first line of medical therapy is an inhaler containing albuterol. This helps prevent airway constriction and should be used 15 minutes before exercise. If symptoms are still not controlled, an inhaler of cromolyn may be used to prevent the release of the chemicals which lead to airway swelling. A new inhaler containing salmeterol can provide coverage for up to 12 hours, useful in a multi-event competition. This medicine will start to decrease its effectiveness after 9 hours. Albuterol is still recommended for rescue after symptoms have started, as salmeterol has no immediate effect. Newer oral tablets for asthma have been shown to be helpful for exercise-induced asthma and need only be taken once daily (Montelukast). Side effects include headache and cold-like symptoms. Inhaled steroids are extremely useful if baseline asthma is diagnosed and symptoms are not controlled with albuterol. Steroids in tablet form are not approved by the USOC or IOC.

Photo © Lauri Dowling