Exercise-induced asthma is asthma that is triggered by vigorous or
prolonged physical activity. Most people who have chronic asthma will experience
symptoms when they exercise. However, many people without chronic
asthma develop symptoms only during exertion.
During normal breathing, the air we breathe is first warmed and moistened by
the nasal passages. During exercise, people tend to breathe through the mouth,
which means that they inhale colder and drier air. In exercise-induced asthma,
the muscle bands around the airways are sensitive to these changes in
temperature and humidity of the inhaled air and react by contracting (or spasming), which narrows the airway. This results in symptoms of asthma, which
include:
- Coughing
- Tightness in the chest
- Wheezing
- Unusual fatigue while exercising
- Feeling short of breath while exercising
Other factors that can influence the degree of symptoms with exercise are
the presence of pollens and pollutants in the air and upper
respiratory infections.
The symptoms of exercise-induced asthma generally begin within five to 20
minutes after the start of physical activity, or 5-10 minutes after brief
exercise has stopped. If you are experiencing any of these symptoms with physical exertion,
tell your doctor.
You should not avoid exercise because of exercise-induced asthma. There
are steps you can take to control the symptoms and allow you or your child
to maintain normal physical activity.
Inhaled medications taken prior to exercise can control and prevent
exercise-induced asthma symptoms. The preferred medications are the short-acting beta2
agonist inhalers (i.e. albuterol); taken 15-20 minutes before
exercise, these medications can prevent the airways from spasming and can provide
control of exercise-induced asthma for as long as 4 to 6 hours.
Other medications that may be
useful are the long-acting bronchodilators that provide 12-hour control (salmeterol,
formoterol). When these medications are taken before work or school,
exercise-induced asthma symptoms may be avoided
with any physical activity throughout the day. It is important, however, to
always have a short-acting bronchodilator available in case symptoms still
occur.
If these measures fail to control exercise-induced asthma symptoms, your physician may
determine that you need daily therapy to control the underlying inflammatory
process that results in unstable airways.
In addition to medications, a warm-up phase before exertion and a
cool-down period afterward can help prevent exercise-induced asthma. Exercise should be limited during
high pollen days (if allergic) or when temperatures are extremely low and air
pollution levels are high. The presence of viral upper respiratory infections
can also increase symptoms, so you should restrict exercise if you have such
an infection.