Exercise-induced bronchospasm (EIB) is the obstruction of the airflow due to the shrinkage of airways in the lungs during physical exertion. This causes difficulties in breathing. It is different from exercise-induced asthma (EIA) which is an exacerbation of asthma due to exercise. However, EIB can occur even in patients without a history of asthma.
The symptoms of exercise-induced bronchospasm usually begin after 5-20 minutes of continuous exercise and may include:
- Difficulty in breathing
- Shortness of breath
- Chest pain
- Chest tightness
- Fatigue with exercise
- Wheezing (whistling or squeaky sound while breathing)
- Poor athletic performance than original
Patients with EIB cannot perform exercises for more than half an hour at a time.
Exercise-induced bronchospasm usually occurs with the inhalation of the air, which is cooler and drier when compared to the air in the lungs. This causes an increase in the rate of breathing (hyperventilation) leading to a loss of water and heat from the lungs. This results in the dehydration and increase in the osmolarity of the cells in the airways. Consequently, inflammatory mediators are released causing an increased response leading to EIB.
Exercise-induced bronchospasm can occur in anyone irrespective of their age. The factors that make a person more prone to develop EIB are:
- High pollen count in the air
- Chlorine in the swimming pools
- Certain lung diseases or infections of the respiratory tract
- Breathing through the mouth
- Running, swimming, soccer or other activities that need deep breathing
- Insecticides, fertilizers, and pesticides
- Spring and autumn seasons
- Certain allergies
The diagnosis of EIB is based on the symptoms, physical examination and breathing tests performed on the patient. A breathing test involves measuring the volume of air blown out of the lungs by using a spirometer or a peak flow meter. Later, a bronchodilator medicine is given for widening the airways, and the test is repeated. The results of the two tests are compared to check for an improvement in the airflow. This helps to rule out chronic asthma.
Sometimes an exercise challenge test may be performed. The patient is asked to use a stationary exercise equipment or run on a treadmill to increase the breathing rate. The doctor checks if exercises trigger EIB.
Lung function tests may be ordered to rule out conditions, which might produce similar symptoms such as allergies, vocal cord dysfunction, certain lung or heart diseases.
Treatment aims at relieving the symptoms while improving the performance. The medications are prescribed as per the severity of the condition. The treatment options include:
- Short-acting bronchodilator drugs are the mainstay of treatment and should be taken 15 minutes before exercising. They act by opening the airways, and the effect lasts for 4 to 6 hours. It is not recommended to use these drugs on a daily basis as it can lead to the development of tolerance.
- Long-acting bronchodilator drugs relax the airways and act for about 12 hours and may be taken 30 minutes before exercising.
- Inhalation corticosteroids suppress the inflammation of the airways may be taken for nearly 2 – 4 weeks to get the maximum benefit.
- Mast cell stabilizers act for 4 hours and should be taken 15 minutes before exercising.
- Anti-leukotriene drugs act by inhibiting the inflammatory activity and are helpful in some people. The effect of these medicines lasts for about 24 hours, and they should be taken once daily.
It is possible to prevent exercise-induced bronchospasm to a large extent by taking the below measures:
- Performing warm-up and cool-down exercises for about 15 minutes before and after exercising
- Avoiding extremely cold temperatures while exercising or covering the nose and mouth with a mask
- Breathing through the nose to allow warm and humid air to enter the lungs
- Discontinuing exercises temporarily if affected by cold, flu or other respiratory infections
- Quitting smoking
- Avoiding exercises when the pollen levels are high