Exercise-induced asthma

Exercise-induced asthma is when the airways narrow or squeeze during hard physical activity. It causes shortness of breath, wheezing, coughing, and other symptoms during or after exercise.

The medical term for this condition is exercise-induced bronchoconstriction (brong-koh-kun-STRIK-shun). Many people with asthma have exercise-induced bronchoconstriction. But people without asthma also can have it.

Most people with exercise-induced bronchoconstriction can continue to exercise and remain active if they treat symptoms. Treatment includes asthma medicines and taking steps to prevent symptoms before physical activity starts.

Symptoms of exercise-induced bronchoconstriction usually begin during or soon after exercise. These symptoms can last for an hour or longer if untreated. Symptoms include:

• Coughing.
• Wheezing.
• Shortness of breath.
• Chest tightness or pain.
• Fatigue during exercise.
• Poorer than expected athletic performance.
• Avoiding activity, which happens mostly in young children.

See your health care provider if you have symptoms of exercise-induced bronchoconstriction. A few conditions can cause similar symptoms, so it's important to get a diagnosis as soon as you can.

Get emergency medical treatment if you have:

• Shortness of breath or wheezing that is quickly getting worse, making it hard to breathe.
• No improvement even after using a prescription inhaler for asthma attacks.

It's not exactly clear what causes exercise-induced bronchoconstriction. For a long time, the cause was thought to be cold air. However, recent studies found dry air to be a more likely culprit. Cold air contains less moisture than warm air. Breathing in cold, dry air dehydrates the air passages. This causes them to constrict, reducing air flow. Other factors, such as chlorine or other fumes, can irritate the lining of the airways and contribute to breathing difficulties as well.

Exercise-induced bronchoconstriction is more likely to occur in:

• People with asthma. About 90% of people with asthma have exercise-induced bronchoconstriction. However, the condition also can occur in people without asthma.
• Elite athletes. Although anyone can have exercise-induced bronchoconstriction, it's more common in high-level athletes.

Factors that can increase the risk of the condition or act as triggers include:

• Dry air.
• Cold air.
• Air pollution.
• Chlorine in swimming pools.
• In a gym setting, fumes from perfume, paint, new equipment or carpet.
• Activities with long periods of deep breathing, such as long-distance running, swimming or soccer.

If not treated, exercise-induced bronchoconstriction can result in:

• Serious or life-threatening breathing difficulties, particularly among people with poorly managed asthma.
• Lower quality of life because of inability to exercise.