As every athlete involved in an aerobically taxing sport knows, effective breathing can be key. Muscles will not keep working (and you won’t keep going) if you can’t breath. Oxygen delivery to working muscles depends on several factors, but the ability to rapidly move a large volume of air in and out of the lungs is critical. When oxygen demand exceeds supply, an effort can continue for only a short period before you must slow down or stop. No gas, no go. That’s the law!
Exercise induced bronchospasm (EIB) causes tightening of involuntary muscles surrounding medium to small airways. This narrowing of thousands of tiny airways limits the rate at which air can be moved into and out the lung. The “button” that turns on brochospasm in susceptible athletes is a receptor in the lining of the airways that respond to rapid changes in the temperature and humidity of the airway, conditions that frequently occur with such sports as running and biking out of doors. Rapidly breathing cold, dry air is a particularly strong trigger. Fortunately, the airways not only have an “on” button that when pushed tells the airway muscles to tighten, but also an “off” button that will relax the tightened airways, relieving the obstruction and allowing air to flow freely. This muscle- relaxing button is called a beta-receptor. Not only are these beta-receptors found throughout the airways, but also in the heart and nervous system where, as you might imagine, they have different effects.
The most important medication used in the treatment of asthma is albuterol, a beta agonist. In other words albuterol “pushes” beta-receptor buttons causing rapid relaxation of the airway muscles and bronchodilation. Because of the beta-receptors in the heart and nervous system, albuterol can also cause an increase in heart rate and a sensation of nervousness.
Not surprisingly, the most frequently used treatments for EIB is albuterol. Two inhalations of albuterol fifteen minutes prior to an exercise cession will provide prevent bronchospasm for up to four hours. Albuterol can also be used when needed to provide rapid relief of asthma symptoms such as wheezing, chest tightness, and shortness of breath within five minutes. Albuterol is so effective in preventing exercise-induced bronchospasm that response to treatment with albuterol is often used as a test to confirm EIB. If a patient is suspected of having EIB but does not improve with albuterol before exercise, an alternative diagnosis should be considered.
Albuterol is very effective in preventing symptoms of EIB but it does have limitations. In athletes who train daily, albuterol can become less effective over time so that, not only does it become less effective in preventing EIB but can also become less effective during an asthma attack. This is unlikely to be a problem if albuterol is not used daily.
Because of the concerns associated with daily use of albuterol, it is suggested that an athlete with EIB who exercises daily use an inhaled corticosteroid in addition to the albuterol. Although steroids are not bronchodilators, they are very effective controllers of inflammation and are felt to maintain the effectiveness of albuterol after several weeks of daily use; inhaled steroids may also effectively control EIB without the need for albuterol.
Another medication that has been used for EIB is monteleukast or Singulair. Monteleukast is preferred by many because it is a tablet (chewable for children) rather than an inhaler, can be used daily, and does not have the concerns associated with an inhaled steroid. It does not benefit all who use it and many find it significantly less effective than albuterol or an inhaled steroid.
Albuterol is called a short-acting-beta agonist (SABA) because of it relatively short (four-six hours) duration of action. Long-acting-beta agonists are also available which provide protection from EIB for up to 10 hours. This would seem to be ideal for many athletes although because of the concern about loss of effectiveness with daily use and the possibility that this kind of medication could mask a worsening asthma attack, it has been recommended that LABAs not be used without the concomitant use of an inhaled corticosteroid. Fortunately, there are several products available that combine an inhaled corticosteroid with a LABD including Advair, Serevent, and Dulera. The LABD in Serevent and Dulera can work as quickly as albuterol and can therefore be used as a very effective daily treatment for EIB.
Several non-pharmacologic treatment options may be effective in some with EIB. These include warming up slowly before a hard workout to create a “refractory” state in the airways, preventing bronchospasm and wearing a mask to limit exposure to cold, dry air.
For patients with allergies who also have EIB, adding an antihistamine may be helpful.