Nieman, David C. Dr.PH, FACSM
Exercise triggers my asthma attacks. I want to keep exercising, but I feel so bad afterward that I give up. Is there anything I can do?
There is little reason for you to give up exercise because of your asthma. It appears you do not have an appropriate asthma management plan. Although asthma cannot be cured, it can be controlled by establishing a lifelong management plan with a physician specializing in asthma. Individuals who follow this plan and keep their asthma under control can usually participate vigorously in the full range of sports and physical activities. Before reviewing key elements of a plan to manage exercise-induced asthma, let me review current concepts about asthma.
What Is Asthma?
Asthma (which is Greek for “to pant”) is an inflammation of the lungs that causes airways to narrow, making it difficult to breathe. Inflammation makes the airways sensitive to allergens, chemical irritants, tobacco smoke, cold air, or exercise. When exposed to these stimuli, an asthma attack can occur, causing the muscles around the windpipes to tighten, which makes the opening smaller. The lining of the windpipe becomes swelled and inflamed and produces mucus. This leads to coughing, wheezing, chest tightness, and difficulty in breathing, particularly at night or in the early morning.
Asthma is a major public health problem, affecting an estimated 17 million people in the U.S., including 5 million people under age 18 (1–3). During the 1980s, for unknown reasons, asthma rates rose strongly across all age, sex, and racial groups. This may be linked to factors including housing with reduced ventilation, exposure to indoor allergens (such as domestic dust mites in bedding, carpets, and stuffed furnishings and animals with fur, especially cats), tobacco smoke, viral infections, air pollution, and chemical irritants.
Asthma episodes can be prevented, but it is unknown if development of the underlying inflammatory disease can be averted. Inflammation makes the airways hypersensitive to a wide variety of irritants. Causes of the initial tendency toward inflammation in the airways are not yet known for certain, but one of the strongest risk factors is an inherited tendency to have allergic reactions (1–3).
The best way to stop asthma attacks is prevention. Identifying and controlling triggers is essential for the successful control of asthma. The common triggers include
* House dust mites: These are often a major component of house dust and feed on human skin sheddings. They are found in mattresses, blankets, rugs, soft toys, and stuffed furniture.
* Animal allergens from animals with fur: These include small rodents, cats, and dogs, and they can trigger asthma. Animals should be removed from the home.
* Tobacco smoke: This is a trigger whether the patient smokes or breathes in the smoke from others.
* Cockroach allergen: This is a common trigger in some locations. Infested homes should be cleaned thoroughly and regularly.
* Mold and other fungal spores and pollens: These are particles from plants. Windows and doors should be closed, and those with asthma are recommended to stay indoors when pollen and mold counts are highest.
* Smoke from wood-burning stoves and other indoor air pollutants: These produce irritating particles. Vent all furnaces and stoves to the outdoors, and keep rooms well ventilated.
* Colds or viral respiratory infections: These can trigger asthma, especially in children.
* Physical activity: This is a common trigger for most people with asthma.
Exercise-induced asthma (EIA) is triggered as the lining cells of the airway are cooled and dried during exercise. As air is taken into the lungs, it is warmed and humidified, resulting in a cooling and drying of the airway lining. Certain chemicals are then released by the lining cells, which causes the airways to tighten. This cooling and drying is worsened by several factors, including exercising in cool and dry air, a switch from nasal to mouth breathing, and fast and deep breathing from intense exercise. If pollutants and pollen are in the air, the risk of EIA is increased (4).
EIA symptoms are most severe within 5 to 10 minutes after exercise. The EIA attack generally lasts 5 to 15 minutes, and symptoms gradually diminish within 45 to 60 minutes. If the individual exercises again within 30 to 90 minutes of the first bout, the airway tightening is markedly less, and fewer EIA symptoms are experienced.
Management of Exercise-Induced Asthma
Education about asthma and self-management of asthma are key components of an asthma management plan and improve quality of life while reducing days lost for work or school and unscheduled doctors visits (1–4). Proper management of EIA includes
1. monitoring air flow with a peak-flow meter
2. avoiding allergic triggers
3. using medication before exercise
4. modifying exercise habits and practices
Drugs that relax the muscle spasm in the wall of the airways and help to open them (e.g., bronchodilators) are often the first line of treatment in preventing EIA. Doctors recommend using the medication (typically beta2-agonist) from 5 minutes to 1 hour before exercise. Beta2-agonist medications will control EIA in more than 80% of people with asthma and are helpful for several hours. However, because effectiveness does decrease with time, it is preferable to take the medication just before exercise. If breathing problems develop during exercise, a second dose may be needed.
Cromolyn sodium is often prescribed to treat athletes who have EIA. This drug, which also is an inhalant, prevents the lining of the airways from swelling in response to cold air or allergic triggers. Cromolyn sodium can be used up to 15 minutes before engaging in physical activity. Corticosteroids should be used as preventive medicine, usually on an ongoing basis, to help control the underlying inflammation.
In addition to proper medications, control of triggers, and use of peak-flow meters, several modifications to the exercise program have proven valuable (1–4):
* Adequate warm-up and cool-down periods: These help prevent or lessen episodes of EIA.
* Type of exercise: Outdoor running is closely linked with EIA, followed by treadmill running, cycling, and walking. Swimming rarely leads to EIA because warm and humid air near the surface of the water prevents cooling and drying of the airways.
* Length of exercise: Long, intense, continuous exercise (e.g., running and cycling) causes more EIA than repeated short bursts of exercise (generally less than 5 minutes each). Stop-and-go sports like tennis, volleyball, or football may lead to less EIA for some people with asthma.
* Intensity of exercise: High intensity exercise (more than 80–90% of the maximum heart rate) causes more EIA than does exercise at more moderate levels (e.g., walking).
* Nasal breathing: Nasal breathing warms and humidifies the air better than breathing through the mouth.
* Wear a mask or scarf in cold weather: This can increase the temperature and humidity of the inhaled air, reducing cooling and drying of the airway lining.
* Monitor the environment for potential allergens and irritants: Examples include a recently mowed field, refinished gym floor, smoke in the air, or high pollen counts during a spring morning.
Benefits of Exercise Training
Despite the fact that exercise may trigger asthma, the benefits that come from regular physical training are so important that most asthma experts urge that it be included as an important part of the management strategy of people with asthma. Regular exercise builds overall physical fitness, improves psychologic mood state, decreases the risk for other chronic diseases, and improves heart and lung function. Also, several researchers have shown that as the individual with asthma becomes physically fit, EIA attacks are less frequent.