Asthma and Exercise


Why exercise triggers asthma attacks?
No one knows the exact mechanism by which exercise triggers asthma attacks. Apparently involved nerve endings that control muscles and glands of the airways, as well as changes in the distribution of blood flow through the lungs.

One of the most accepted hypothesis assumes the following: when we exercise, breathing becomes faster and deeper and this, in turn:
In asthma untreated (or inadequately treated), the lining of the airways is inflamed. Moisture loss and possibly cooling of the mucosa of the airway, the triggers and cause inflammatory cells release chemical mediators inflamed mucosa, with different properties, which among other things, cause contraction of the muscle cells the airways, causing bronchoconstriction and resulting in the typical symptoms of asthma attack.

– Evaporation increases the mucosal surface of the airways, resulting in an increase in the concentration of solutes in cellular environments. This is known as osmotic load increase.
– The airways are rapidly cooled due to the heat losses produced by evaporation.

Evidence to support the hypothesis of the mechanism by which exercise triggers asthma attacks
– Attack of exercise-induced asthma can be simulated (and caused) voluntarily, increasing respiratory rate.
– Breathing warm, moist air reduces or prevents exercise-induced asthma. It seems that in these conditions there is less dehydration and cooling of the lining of the airways. Consequently, there is less release of chemical mediators and less bronchoconstriction and less asthma symptoms.
– Conversely, if inhaled dry, cold air, exercise increases asthma. Drying and cooling the airway mucosa produce a higher release of chemical mediators that cause bronchoconstriction and the typical symptoms of asthma.

Who gets asthma with exercise?
– Almost all asthma patients who exercise, especially if they are in treatment or this is insufficient.
– A minority of patients with severe asthma have asthma triggered by exercise despite the best treatment.
– Children are particularly affected by this problem, as they are much more active than adults and do more exercise.
– When conducting studies, 3% of school-age children have asthma triggered by exercise. These numbers vary somewhat by geographical location.
– When studies are done on athletes, up to 12-15% manifest have or have had asthma with exercise.
– About 20% of the athletes competing in the Olympic Games in 1996 reported having asthma presented with exercise.
– A certain degree of bronchoconstriction has been described in patients with allergic rhinitis, hypersensitivity to grass pollens (hay fever) without exhibiting bronchial asthma. This may indicate that the patient has asthma triggered by exercise undiagnosed occurs because in the airways of these patients often have inflammation and therefore an exaggerated response to the effects of drying and cooling of the tracks air.

Severity of symptoms
The severity of symptoms depends on:
In summary, exercise-induced asthma may appear:
– Individual response (some individuals are much more sensitive than others). This response can, in turn, vary according to the circumstances (worse during a cold or allergic crises).
– The cold dry air: the drier and colder the air, the greater the changes in the lining of the airways and increased the stimulus for the release of inflammatory chemical gauges, which produce bronchoconstriction and increased that lead to more serious symptoms.
– The continued exercise (eg, running) produces more intense attacks intermittent exercise (eg, tennis).
– The intensity of exercise is also important, the more intense, what are the symptoms: intense exercise demands a faster and deeper breathing, resulting in dehydration and cooling of the lining of the airways.

Exercise I can do if I have exercise-induced asthma?
Definitely yes. There are many athletes who have exercise-induced asthma and there are many steps you can take to fix this problem:
Antiasthmatic drugs: Several asthma drugs, usually inhaler, such as albuterol (Ventolin), terbutaline (Terbasmin), salmeterol (Serevent), formoterol (Oxis), sodium cromoglycate, nedocromil (Tilad, etc.). That used before exercise induced asthma avoid exertion.
These drugs, such as salbutamol, terbutaline and cromolyn, are authorized by the committees and sports officials, although this varies from one country to another. Professional athletes should consult with your doctor if you take medicines for asthma, as some preparations contain unauthorized substances, such as ephedrine.

Appropriate exercise type: patients with poorly controlled asthma should try a type of exercise you can tolerate. The swimming and bowling are particularly suitable. They should avoid exercising when your asthma is unstable.

Appropriate treatment: it is very important to have a proper and optimal treatment of asthma. They should avoid being sub-treaty, ie, with low doses of medication or inappropriate medication. Keep in mind that in some sub-treated patients, asthma attacks during exercise can be particularly dangerous in certain circumstances, such as when there are high levels of air pollution, or very cold days.
Short-term protection
This protection lasts about 3 or 4 hours when the medication is taken before exercise. Usually, this type of inhaler medication should be used only in cases of mild intermittent asthma where inflammatory medication is not used (preventive) and is only used medication to relieve symptoms (bronchodilators), which also are used within once a day. Among the drugs that can help to protect the short term, we have:

Inhalers: used to alleviate symptoms, which contain short-acting bronchodilators (usually blue) such as salbutamol or terbutaline, and which prevent bronchoconstriction when released chemical mediators. Its onset of action is rapid (1-5 minutes) and short duration (4-6 hours at most).

Long-acting bronchodilators: instead of short-acting bronchodilators can be used long-acting bronchodilators (usually green), such as salmeterol or formoterol, which used every 12 hours provide coverage 24 hours a day. These bronchodilators only be used in isolation (ie without preventive medication), in special circumstances, such as the case of a child with mild asthma in a sports activity day long and with limited access to short-acting bronchodilators.

Cromolyn sodium and nedocromil are used less often, but can be useful in amateur or professional athletes.

Long-term protection
Medications “preventive” are very useful in asthma, reducing airway inflammation, which is the main mechanism by which asthma occurs. When used regularly, producing an overall improvement of asthma, which also includes attacks caused by exercise.

To be effective, these medicines must be used regularly and for long periods of time. Are not effective in a single dose taken before exercise and, usually, may need a week or more before they get benefits. The main drugs in this group are:

Inhaled Corticosteroids: such as beclomethasone (Becloforte), fluticasone (Flixotide) or budesonide (Pulmicort). Inhaled corticosteroids are currently the main bronchial asthma treatment efficacy and safety.

Receptor antagonists of leukotriene as zafirlukast (Accolate) and montelukast (Singulair). They come in tablets and its effectiveness is difficult to predict, although have been found useful in the control of exercise-induced asthma.
How can you use the medication to prevent exercise-induced asthma?
There are two ways:
– Short-term protection
– Long-term protection.

Other things you can do to reduce or prevent exercise-induced asthma
– Avoid exercising outdoors on cold or ice making and cold air is drier and cools and dries the lining of the airways, acting as a stimulus for the release of bronchoconstrictor activity of chemical mediators.
– Try to breathe through the nose, and the nostrils warm and humidify the air, which in this way is less stressful for the airways.
-Before starting the exercise, to warm, with short stints of exercise, as this can reduce asthma that follows a period of intense and prolonged exercise. The explanation of this phenomenon is unclear, but there are two factors that may play a role: 1) Short intervals of exercise can improve lung function. 2) Although the heating itself does not cause asthma attacks, may reduce the ability of cells of the airways to release chemical mediators that cause asthma symptoms.
– If exercise is poorly tolerated running, swimming should be tested, since the environment moist air cause less drying pools in the lining of the airways. You can also try an intermittent-type sports (eg, tennis, bowling …) or work out in gyms or indoor (gym, aerobics, paddle, etc..).
– It is preferable to run short distances and speed workout sprint exercises and background, because speed exercises require only a few breaths, so that there is less cooling and drying of the airways.
– Avoid exercising the days you have a lot of pollen if you are allergic to pollens of grasses or other plants, or days you have a lot of pollution. With exercise is to inhale a lot of pollen / air pollution. These substances exacerbate asthma, especially in those patients most likely and unstable.
– The better physical shape you need to breathe with less intensity, reducing stimuli that may trigger asthma attacks.
– The most important thing is to keep asthma under control disease. When asthma is well controlled, asthma attacks caused by exercise are greatly reduced (or even eliminated).

Specific problems of exercise in patients with asthma
– The exercise-induced anaphylaxis. This is an extremely rare disease in which the combination of exercise and food allergy has been eaten immediately before exercise, produce hypotension, collapse and respiratory distress (similar to severe allergic reactions to peanuts suffered by some patients).
– Exercise associated with laughter and excitement can trigger asthma attacks in some children with asthma (birthday parties, visiting friends or relatives …). If this is predictable, treatment should be anticipated using inhaled bronchodilators.
– Occasionally, patients with severe asthma suffer exercise-induced asthma despite optimal anti-asthma treatment. In these cases, it is recommended to do a type of exercise is best and less provocative of asthma.

Dr. Nicola Wilson , a specialist in Pediatrics