Exercise-induced bronchospasm, EIB, is also known as exercise-induced asthma. This condition is characterized by episodes of chest tightness, breathlessness and wheezing prompted by exercise. The cause is generally related to inhalation of cold, dry air. Treatments are similar to treatments for asthma and include use of inhaled bronchodilators for episodes or breathlessness and steroids to prevent symptom recurrence.
Airway Humidity Theory
According to this theory, air rapidly moving through passages in the lungs can cause drying. This is especially true when air is dry. The drying of the airways causes a series of events that cause constriction of the airways. A study in the "Journal of Applied Physiology" in 2011 found an association between breathlessness in athletes with EIB and low humidity. Another study published in "Respiratory Medicine" in 2006 found that people had decreased breathlessness when exercising in more humid environments.
Air Cooling Theory
Cooling external air also is associated with EIB. Cool air entering passages in the lungs may directly trigger immune cells within the lung; this activates a number of reactions that attempts to warm the passageways. One of the consequences of this reaction can be bronchoconstriction. While the effect of humidity and air may act in different ways, they both can contribute toward EIB. Why certain people are susceptible to this condition is not completely clear. A study published in the "Journal of the Federation of American Societies for Experimental Biology" in 2005 found an association with EIB and certain genetic variants.
Aggravating Factors
Other factors may worsen EIB, such as pre-existing asthma. People with undertreated or undiagnosed asthma are more likely to have worsening symptoms with chest tightness, wheeze and breathlessness while exercising. Factors in the environment, such as chlorinated pools, insecticides and fertilizers also can aggravate symptoms.
Treatment
EIB is treated in a manner similar to asthma. Physicians start treatment with an inhaler to be taken during episodes of breathlessness. This can offer rapid relief of symptoms. In more severe cases, an inhaled steroid can be used to reduce the frequency and severity of each attack. A number of other drugs are available for those who do not respond to these treatments, including montelukast, theophylline, and long-acting beta agonists. Doctors prescribe these drugs in a stepwise fashion until patients feel symptomatically better.
References
- "Journal of the Federation of American Societies for Experimental Biology"; Transcription in Response to Physical Stress--Clues to the Molecular Mechanisms of Exercise-Induced Asthma; T. Hilberg et al.; September 2005
- MayoClinic.com; Exercise Induced Asthma; March 27, 2010
- "Journal of Applied Physiology"; The Effect of Inspired Air Conditions on Exercise-Induced Bronchoconstriction and Urinary CC16 Levels in Athletes.; C. Bolger et al.; July 2011
- "Respiratory Medicine"; Humidity Influences Exercise Capacity in Subjects with Exercise Induced Bronchoconstriction; T Stensrud et al.; September 2006
