Exercise-induced asthma (EIA) is wheezing and shortness of breath that occur during exercise. It can occur in people who never wheeze at any other time, those who wheeze only when they have an infection or allergy, and those who have asthma at other times. People with EIA can start to wheeze or become short of breath several minutes after they start to exercise and symptoms can become more severe five to 10 minutes after stopping. The shortness of breath and coughing usually improve 30 minutes after stopping exercise, but milder symptoms can continue for four to twelve hours.
What is Asthma?
Asthma means intermittent obstruction in the bronchial tubes that bring air to and from your lungs. Symptoms include coughing, wheezing, shortness of breath and a feeling of chest tightness, pain, or pressure. Your chest may start to feel tight when you:
• inhale allergens such as pollens, dust or mold
• inhale irritants such as hair spray, mothballs, insecticides, fresh paint, cooking fumes, perfume, cleaning agents, smoke, or any noxious odor or air pollutant
• eat foods to which you are allergic
• take aspirin
• have an infection in your respiratory tract
• cry, yell, feel stress or anger, or laugh very hard
• breathe dry or cold air — the primary trigger of EIA
What Causes Exercise-Induced Asthma?
Despite its name, exercise-induced asthma is not caused by exercise. It is usually brought on by hard breathing of dry or cold air, so it is very common in winter sports, affecting up to 50 percent of elite cross-country skiers and many world-class ice skaters and hockey players. It affects an estimated 17 percent of Olympic-level long-distance runners who may or may not be exposed to cold weather. Data from the last five Olympic games show that eight percent of Olympic athletes in all sports suffer from EIA and have permission to use special inhalers before competitions (British Journal of Sports Medicine, 2012; 46 (6): 413). It is the most common chronic health condition among Olympic athletes.
EIA can start at any time in life and affects the majority of people who have asthma, but many people with EIA suffer only when they exercise or when they have a respiratory infection.
How Does Extreme Exercise Trigger Exercise-Induced Asthma?
Elite endurance athletes often train more than 20 hours a week, breathing more than 40 times as much air per minute during that training as when they are resting. This irritates and damages the cells lining the bronchial tubes. Your body heals from injury by producing the same chemicals that it does to fight germs. This is called inflammation that causes swelling of the bronchial tubes that carry air in and out from the lungs. So EIA appears to be caused by the irritation of breathing huge amounts of dry, cold air. Cross-country skiers, and runners and cyclists who train in the winter are at increased risk for this condition.
Exercise-Induced Asthma is a Fluid-Control Disease
Dry or cold air pulls moisture out of the cells lining the bronchial tubes. As these cells lose water, they release chemicals that turn on your immunity in the same way as when you have an infection. These chemicals cause the muscles around the bronchial tubes to contract, constricting them to block the flow of air in and out of the lungs.
EIA may be a genetic disease. People who have EIA perspire, spit and cry the least amount of fluid, and have sweat that contains low amounts of salt. (Chest, September, 2008). Your body produces a chemical called aquaporin to help move water and salt in and out of your cells. The prevailing theory now is that if you have low levels of aquaporin, you produce far less sweat, saliva and tears and are at increased risk for EIA. Mice engineered to not respond to aquaporin do not sweat, do not salivate very much and usually develop EIA.
Treatment of Exercise-Induced Asthma
If you wheeze when you exercise, check with your doctor. Other conditions, including heart problems can cause shortness of breath so you need a diagnosis. If your doctor agrees that you have EIA, you can avoid or lessen attacks by following these tips:
• Breathe through your nose, which brings much warmer and wetter air into your lungs.
• Wear a face mask, which will recirculate the moisture you exhale.
• Drink plenty of water.
• Warm up gradually before exercising more intensely.
• Do some intense exercise 30 minutes before a competition. Bringing on an attack of EIA often helps to prevent a subsequent attack in the next few hours.
• If all else fails, exercise indoors during the winter. Keep a humidifier near you and breathe air from the humidifier intermittently while you exercise.
What Sports are Best for People with EIA?
Swimming attracts the most asthmatics because the moist atmosphere created by the pool helps them to breathe comfortably and avoid asthma attacks. Long-distance racing, soccer and basketball are more likely to cause EIA. Cold-weather sports such as hockey, ice skating or cross country skiing are the sports most likely to cause EIA. Elite athletes with EIA usually get better when they reduce their large training volumes or when they retire from active competition.
Medications for EIA
Three types of medications are usually prescribed:
• Short-acting beta-2-agonist bronchodilator inhaler. You inhale 10 to 15 minutes before you exercise and it will help to protect you for up to four hours. You can also use this to treat symptoms when they occur.
• Long-acting bronchodilator inhaler (salmeterol). Inhale 30 to 60 minutes before exercise and do not repeat for 12 hours. It helps prevent attacks but does not treat symptoms once they occur.
• Cromolyn (nedocromil) inhaler. Inhale 15 to 20 minutes before you exercise. It can also help to prevent the late-phase wheezing that occurs four or more hours after you finish exercising.
If you have frequent symptoms with exercise and these medications do not help, your doctor may prescribe inhaled steroids, but they are loaded with serious side effects including osteoporosis, so you should not take them unless your symptoms are so severe that you are willing to risk the side effects.
Why Do So Many Athletes Take Asthma Medications?
At the Olympic Games in Sydney, Australia in 2000, 607 out of 10,300 competitors (approximately six percent) filed notifications that they needed to take beta-2 agonist asthma inhalers to prevent exercise-induced asthma. Many of the athletes probably did not have asthma. Beta-2 agonists such as albuterol, salbutamol, salmeterol and terbutaline open the closed lungs of asthmatics and help them to breathe. They also increase the amount of fat in the bloodstream to increase energy sources of exercising muscles, help to preserve the muscles’ store of sugar, and help muscles to contract with more force.
Researchers from Orléans, France decided to test the effects of salbutamol inhalation on an athlete’s endurance (British Journal of Sports Medicine, July 2007). They showed that inhaling salbutamol prior to competition made the athletes faster in endurance events and gave them greater muscle strength.
Asthma medications are potent stimulants that can cause irregular heartbeats. It is illegal for Olympic competitors to take albuterol pills. However, asthmatics need their medications, so the Olympic medical committee allows asthmatics to take these same medications by inhaler, provided that a doctor informs the Olympic committee beforehand that the athlete is an asthmatic and is taking this medication. Needless to say, there are unprecedented numbers of asthmatics registered with the Olympic committee and other authorities in sports that monitor drug use.
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Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe's full bio.