Common in asthmatics, exercise asthma results in sometimes severe attacks induced by physical exercise. Similar attacks also occur in people without an underlying allergic condition. This condition does not contraindicate all sports, but requires appropriate treatment and regular monitoring. 

Definition

Exercise asthma is an acute syndrome associated with transient obstruction of the airways, caused by violent or prolonged efforts leading to hyperventilation. We also talk about exercise asthma, or exercise-induced asthma. 

The bronchial spasm associated with the contraction of the airways, or exertional bronchospasm, is accompanied by swelling of the bronchial mucosa and the formation of a mucous plug. These phenomena cause a narrowing of the bronchial passages (bronchoconstriction) which can constitute an emergency situation.

Extremely common in asthmatics and in people with atopia (predisposed to allergies), exertional bronchospasm can also affect people without any underlying asthmatic or allergic pathology, mainly athletes. This is why specialists sometimes prefer the terms “exercise-induced bronchoconstriction with or without asthma”.

Causes

Physical exertion greatly increases the volume of inhaled air and is accompanied by a tendency to breathe through the mouth and not through the nose. A large volume of unfiltered and unheated air thus enters the airways, causing cooling and dehydration in the bronchi.

These thermal and water phenomena are accompanied by irritation of the bronchial mucous membranes and the release of chemical mediators that cause bronchospasm, according to mechanisms still poorly understood.

In asthmatic subjects, the great sensitivity of the bronchi – we speak of bronchial hyperresponsiveness – favors the onset of exercise asthma.

Diagnostic

Symptoms and physical examination are not sufficiently sensitive and specific criteria to make the diagnosis.

Different pharmacological or physical tests can be performed to confirm the diagnosis.

• The stress test is carried out on a bicycle or a treadmill. We measure the maximum expiratory volume per second (FEVXNUMX) before and after exercise.
• Bronchial provocation tests aim to reproduce symptoms under controlled conditions. The bronchial response to the inhalation of increasing doses of substances known to cause bronchoconstriction (the closing of the bronchi) such as metacholine or mannitol, for example, is evaluated by measuring the pulmonary function between each inhalation.
• The eucapnic voluntary hyperpnea test consists of evaluating the reaction of a hyperventilated patient for 6 minutes with dry air loaded with CO2 (5%).

The people concerned

Exercise asthma affects around 90% of asthmatics.

Studies have also estimated that about 10 to 50% of athletes may have bronchospasm (a spasm of the bronchi) on exertion, depending on the sport practiced.

Endurance sports and winter sports requiring intense and prolonged efforts are the most concerned: cycling and running, cross-country skiing, ice sports on the skating rink, etc.

Risk factors

The risk of seizure is increased outdoors in cold, dry weather. Other risk factors are air pollution and a high concentration in the atmosphere of bronchial irritants or pollens.

Seizures occur more easily in people with asthma whose asthma is poorly controlled and / or with severe inflammation of the bronchi or respiratory tract infection.

Although the practice of swimming is generally recommended for asthmatics, chlorine is an irritant of the bronchi favoring the occurrence of asthma on exertion in certain subjects.

The symptoms are those of asthma:

• shortness of breath or difficulty in breathing
• cough,
• wheezing,
• chest tightness …

These symptoms are inconsistent and insignificant. They can occur after a few minutes of effort, but most often appear within 15 minutes of stopping it.

Most of the time, there is a refractory period in the hours which follow, during which the repetition of the same effort does not result in symptoms or attenuated symptoms.

Severe asthma attacks are a life-threatening emergency.

People being treated for chronic asthma should stick to their disease-modifying treatment.

Medicines from the anti-leukotriene class (Singulair) prescribed as an adjunct to this treatment have shown some efficacy in preventing exercise-induced asthma.

Inhalation of bronchodilators 10 to 15 minutes before exercise is recommended.

The practice of sport is not contraindicated but must be adapted to the respiratory state and the form of the day, and it is advisable to take into account the weather conditions and the quality of the air (pollution peaks, dust or room cleaning products…).

Preventive measures very often make it possible to avoid the crisis or to limit its intensity.

A sufficiently long and progressive warm-up is recommended. At the end of the activity, stopping the effort should not be sudden and the return to calm should be gradual.

Thinking of breathing through the nose rather than through the mouth is also beneficial. We can also sometimes try to wear a scarf in front of the mouth.

Finally, at the slightest sign of an attack, the effort must be interrupted and, if necessary, another breath of the bronchodilator should be taken again. The inhaler should always be readily available.