Stay Out of the Heat to Avoid Exercise-Induced Asthma

Thinking of heading outdoors to exercise on a very hot day? If you have asthma, you may want to think again before you step out of your air conditioned place. High temperatures, humidity and pollen counts, coupled with poor air quality, can be a dangerous combination even for people without respiratory problems. But if you have asthma, the risks are magnified.

The Asthma-Exercise Connection

When you exercise, you typically breathe through your mouth instead of your nose, and therefore you directly inhale the various allergy and asthma irritants that are in the air so that they will travel right into your lungs without being filtered out. If your airways are sensitive, this can cause them to react and become inflamed.

The Heat and Humidity Combination

While this can happen at any time of year, the experts say that when the temperature peaks, you have an even greater likelihood of experiencing these asthma symptoms. One of the reasons is that the heat generated on hot summer days can increase the level of unhealthy ozone (smog) in the air. Therefore, the Environmental Protection Agency recommends that when ozone is high (often in the afternoon and evenings), people should stay inside. It is also worth noting that when you do jog or participate in more strenuous activity outside, your breathing rate increases and it causes more of the unhealthy air to go into your lungs. This can worsen your asthma symptoms and can even cause respiratory infections.

Exercise Good Judgment

So if you want to exercise outside in the summer, you may wonder what you can do to protect yourself. You don't have to hide indoors all summer, but you do have to make an effort to protect yourself and be prepared. Here are some recommendations to help you work out as safely as you can:

  • Exercise in the morning hours (before 11 a.m.), when things are still on the cooler side.
  • Select exercises that will take less of a toll on your body in the warm weather, such as walking or biking, rather than high intensity activities like running.
  • Consider swimming, which builds endurance and is a good way to stay in shape.
  • Drink water to stay hydrated - not only while you exercise, but all day long for the best results.
  • Spend a few minutes before and after your workout to warm up and cool down. This will help prepare your body for exercise and help prevent an asthma attack.
  • Pay attention to how you feel and stop if you think you've done enough.

Be Prepared

Even with the best of planning, it's always possible that when you exercise outdoors, your symptoms can flare. Therefore, always carry your bronchodilator so you will be prepared.  In addition, you may want to ask your doctor about pretreating your symptoms before you begin your workout. A recent study published in the Journal of Allergy & Clinical Immunology found that using a fast-acting inhaler preventatively can head off symptoms for several hours.


Allergy and Asthma Network, from an article on asthma and its relationship to exercise available at

From Web MD's Guide, Asthma and Exercise, available at

From a recent report in the Journal of Allergy & Clinical Immunology (June 2007). You can access the articles in this issue at