Many people with asthma find that their symptoms get worse when they exercise, especially in cold weather. With effective treatment and management, however, people can usually exercise without symptoms arising.

Exercise does not cause asthma, but it can trigger symptoms in people who already have the condition.

According to the Allergy and Asthma Foundation of America (AAFA), the correct term for exercise-induced asthma is exercise-induced bronchoconstriction (EIB).

In this article, we look at why exercise causes asthma symptoms and ways that people can manage and prevent them.

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EIB occurs when asthma symptoms arise during or after exercise, which explains the common name: exercise-induced asthma.

Exercise and other strenuous activities naturally result in shortness of breath. Heavy breathing and dehydration can narrow the airways to the lungs in people with or without asthma. The medical term for this narrowing is bronchoconstriction.

However, bronchoconstriction has a stronger effect in people with asthma than in others. People with asthma typically have airway inflammation and excess mucus production. These factors narrow the airways, making breathing especially difficult.

When exercise causes bronchoconstriction, it can lead to wheezing, coughing, and chest pain, which may be mild to severe.

Up to 90 percent of people who have asthma experience EIB during exercise. According to the AAFA, EIB might be one of the most common causes of asthma symptoms in teenagers and young adults.

The majority of individuals with asthma have a mild form that responds well to treatment. However, in 5–10 percent of people with asthma, the condition is severe, which means that symptoms do not respond well to treatment.

Most people who encounter EIB are able to manage their symptoms and continue exercising and performing other routine activities. Preventive measures and medications can help manage asthma symptoms during or after exercise.

Coughing is the most common symptom of EIB. It is often the only symptom.

EIB can also cause other asthma-related issues, such as:

  • wheezing
  • tightening of the chest
  • shortness of breath
  • decreased endurance in exercise and activity
  • a sore throat

Typically, EIB symptoms do not begin at the start of exercise or other strenuous activity. They tend to start at some point during the activity, then worsen 10–15 minutes after a person finishes.

Anyone can experience wheezing, coughing, and shortness of breath during or after exercise. In people with asthma, these issues tend to be more severe.

According to the American College of Allergy, Asthma & Immunology, “EIB is caused by the loss of heat, water or both from the airways during exercise when quickly breathing in air that is drier than what is already in the body.”

Strenuous activity, such as playing sports, tends to require a person to breathe in quickly, often through the mouth. This can result in dehydration and breathing difficulty.

When a person breathes heavily, they usually do so through their mouth. This allows cold, dry air to reach deep into the airways without first being warmed by passing through the nose. This can trigger asthma symptoms.

Certain factors can make asthma symptoms more likely to arise during exercise. Some include:

  • cold, dry air
  • pollution or smoke in the air
  • a high pollen count
  • breathing heavily through the mouth
  • chlorine fumes
  • having an upper respiratory infection
  • air pollutants in gyms, such as from cleaners, perfumes, fresh paint, or new equipment
  • chemicals used to clean equipment or ice rinks, for example

The dryness of the air is more likely to trigger EIB than the temperature. Quickly breathing in dry air dehydrates the airways, causing them to narrow, and this restricts airflow in the body.

However, people who run outdoors in the winter do have a high risk of developing EIB.

Certain sports are more likely to trigger asthma symptoms than others. These include activities that require very deep breathing, such as running.

When exercise triggers asthma symptoms, people may avoid it and lose the health benefits that exercise can bring and miss out on otherwise enjoyable activities.

In people with severe asthma or asthma that is not managed effectively, EIB can result in serious and even life-threatening complications, including difficulty breathing.

Speak to a doctor to identify the best ways to manage asthma symptoms, including any related to exercise.

The first step toward managing EIB is to consult a physician and develop a treatment plan.

Many controller medications can help prevent asthma symptoms, even during exercise. In addition, a person with asthma can treat any EIB symptoms with short-acting medications.

Anyone who experiences regular EIB should speak with their healthcare provider, especially if any symptoms do not subside quickly or respond well to a rescue inhaler.

People can often prevent or reduce the severity of asthma symptoms that occur during or after exercise. Follow a doctor’s instructions about using medication, including which to use and when to use them.

A person with asthma should always keep a rescue inhaler with them, even during exercise, in case a severe asthma attack occurs.

The following prevention tips may also help reduce symptoms:

  • Warm up before exercise to loosen the airways and move mucus around.
  • Cool down fully after exercise to slow the breathing gradually.
  • Wear a scarf over the nose and mouth when exercising outdoors during the colder months or when pollen counts are high.
  • Avoid exercising with a viral infection.
  • Choose forms of exercise that are less likely to trigger symptoms. Exercises that involve heavy breathing are more likely to restrict the airways.

Exercise cannot cause asthma, but it can trigger symptoms, including an asthma attack, in people who already have the condition.

People who do not have asthma can develop similar symptoms if they experience EIB.

Most people with asthma have a mild form that responds well to medications. Following a doctor’s instructions about medicines can help manage, and possibly prevent, asthma symptoms during exercise.