Exercise induced asthma (EIA) is defined as airway obstruction following physical exertion.  It is significant because the development of symptoms following exercise may lead to the avoidance of physical activities, poor physical conditioning, and the development of poor self-esteem. 

1. Incidence
  a. Almost all asthmatics 
  b. 40% of children with allergic rhinitis 
  c. Approximately 10% of the general population without a history of asthma 
  d. 11% of the 1984 US Olympic team had EIA and about 40% were unaware that they had the condition.. 

2. Pathophysiology
  a. Decrease of osmolarity in airway tissues leads to the release of leukotrienes and histamine from mast cells which promote bronchospasm. The drier the environmental air, the greater the loss of water. Heat loss and exposure to cold may also lead to release of these mediators. 
  b. At the beginning of exercise, there is bronchodilitation followed by bronchospasm. 

3. Clinical Manifestations
  a. Wheezing, coughing, shortness of breath and chest tightness 
  b. Bronchospasm usually arises 10-15 minutes after beginning exercise and peaks about 10 minutes after the exercise is completed. Symptoms may last for 60 minutes. Some patients may not manifest symptoms until the exercise is completed. 
   c. Often undiagnosed

4. Diagnosis
  a. History of asthma 
  b. Development of symptoms 
  c. Response to treatment 
  d. Definitive diagnosis in pulmonary function lab through exercise challenge. 

5. Pharmocologic Treatment
  a. Short term beta agonist such as albuterol via Metered Dose Inhaler (MDI). Because of short period of airway reactivity, prophylaxis is successful. Use 15-30 minutes prior to the activity.  Approximately 90% effectiveness. 
  b. Long acting beta agonist via MDI or Diskhaler such as salmeterol. Up to 9 hours of coverage and convenient for children that are in school and not allowed to carry inhalers. Allows for spontaneous activity by the child. 
  c. Cromolyn by MDI 15- 30 minutes prior to activity. Approximately 70 % effectiveness. 
  d. Single dose inhaled steroids are not protective although long-term use will decrease the incidence of EIA. 

6. Non- Pharmologic Treatment
  a. Warm-up period prior to the exercise. This works because there is thought to be a refractory period of about 45 minutes after exercise and may last 2-3 hours. Warming up may allow for the refractory period to be during the desired activity. An example would be short sprints. 
  b. Wearing a mask or bandana, especially in cold weather, to warm and humidify the air breathed in and decrease the loss of heat and moisture. 
  c. Get into good shape 
  d. Encourage nasal breathing to enhance air warming and humidification 
  e. Avoid exercise during high pollution times and high pollen counts. 
  f. Gradual cooling off to prevent rapid rewarming of the airways which may lead to broncospasm. 
  g. Choice of activities may help. Swimming, boating, kayaking are associated with less EIA. Long-distance running is associated with more problems than sprinting. 

References

1. Milgrom H and Taussig LM. Keeping Children with Exercise-Induced Asthma Active. Pediatrics. 1999; 104(3):e38.
   
2. Cuff S, Loud,K. Exercise Induced Bronchospasm.  Contemporary Pediatrics September 2008