What is Exercise-Induced Asthma?
The term exercise-induced asthma is used to describe episodic tightening of the airways, resulting in shortness of breath following exercise. The phrase is misleading since exercise is not a cause of asthma but rather a trigger of bronchoconstriction in those with underlying asthma.
The condition is estimated to occur in seven to 20 percent of individuals without previous history of asthma, and occurs as much as 80 percent in individuals with a previous history of asthma. The proposed mechanism is that airway drying, caused by breathing fast, is a trigger for tightening of the airways. The predictor is a condition known as airway hyper-responsiveness, which is different from the airway inflammation that characterizes asthma.
Understanding the cause and symptoms
Exercise-induced asthma is not a condition to be taken lightly. A recent study published in the Journey of Allergy and Immunology over a seven-year period identified 61 deaths among a group comprised typically of males between the ages of 10 to 20. The event is precipitated by competitive and recreational sports. What’s interesting is that the typical pattern of exercise-induced asthma symptoms is not experienced during the peak of exertion of exercise, but rather later, during the recovery period (post exertion). One proposed mechanism is that during exercise levels of adrenaline-like substances, called catecholamines, increase to cause dilatation of the airways. By the end of the exercise experience, the result is swelling of the inner lining of the airways. The net result is an increased effort of breathing during recovery, when there is an oxygen deficit to resolve, and the heart rate is still high.
How to help prevent exercise-induced attacks
I am not suggesting that asthmatics should refrain from exercise. There are steps that can be taken to mitigate the exercise-induced episodes.
Find out if you’re at risk by getting tested. First one must try to identify individuals who are at risk, before an episode actually occurs. That can be done with what is known as an “exercise challenge,” to see if the exercise results in worsening of spirometric testing.
Find a preventative medication that works for you. Once these patients are identified, there are medications that can be taken prior to exercising that can prevent an episode. These medications are called bronchodilators. There is a short-acting option, which takes effect within minutes, and a long acting (LABA’s) that takes effect in about two hours. The choice depends on what type of exercise is performed.
Is the exercise short in duration and high intensity, or longer duration with an endurance element, like a long-distance runner?
Account for your asthma control. The other factor to consider is the pre-existing respiratory condition of the asthmatic. Asthmatics are classified as intermittent or persistent dependent, based on the frequency of symptoms. One individual may change stages at different times. While in the persistent stage, a patient would benefit from the longer acting drug.
Inhaled corticosteroids are also recommended as one option in the arsenal of preventive measures, but with the caveat that the World Anti-doping Agency has listed inhaled steroids on its prohibited list. So a competitive athlete may have to steer clear of this group of drugs. Personally, I don’t understand that decision, since these inhaled corticosteroids are anti-inflammatory in nature, and not performance-enhancing steroids.
The American College of Sports Medicine recommends the following measures to help limit exercise-induced asthma:
(1) Warm up for 45 minutes before exercise. If possible use alternating work and rest interval training.
(2) Make an effort to breathe in through the nose, since this will warm and moisten the air before it reaches the bronchial tubes. This may not be realistic since the nose is not meant for high frequency air movement and it will probably result in nasal congestion. This highlights the difference between the trained, fit individual who can coordinate high frequency breathing with performance. It is, however, even more important to try to breathe this way during the recovery period, once exercise is over, since that is when one is more vulnerable for exercise-induced asthma.
(3) Be aware of the air quality reports, and try to exercise indoors during the times of poor air quality.
The bottom line
There is no one size fits all approach for this condition. It is more important for asthmatics to recognize their disease, and follow the cardinal rules of gradually increasing exercise efforts, and committing to regular exercise. Just those two habits will help to reduce the risk of exercise-induced asthma. Good cardiovascular fitness will also enable an individual to exercise at a higher intensity while avoiding an asthma attack.