What Is Exercise-Induced Asthma?
Exercise-induced bronchoconstriction (EIB), as referred to by the American thoracic society (ATS), is a transient phase of narrowing of the airways (bronchoconstriction) following exertion. It may or may not cause the clinical signs and symptoms associated with asthma and is largely reversible.
How Common Is Exercise-Induced Asthma?
Exercise-induced asthma (EIA) is a common entity, occurring in almost 40 % to 90 % of the patients suffering from asthma. It can also occur in 20 % of the people who do not have a previous history of asthma. Therefore, around 30 % to 70 % of winter sports athletes suffer from the condition and seek help.
What Causes Exercise-Induced Asthma?
EIA is caused due to the sudden increase in the amount of air to be humidified and heated after entering the airways. This increase in demand causes neuronal, vascular, and inflammatory changes that clinically present as signs and symptoms of EIA.
What Is the Mechanism Involved in the Development of EIA?
The following mechanism is associated with EIA;
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There is an alteration in the lungs' normal functioning due to the thermal changes, water loss, and irritant exposure occurring while exercising.
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The demand for humidification of the air by the lungs increases, hence cooling and dehydration of the airway cells take place.
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Dehydration in the cells results in the release of reactive oxygen species and inflammatory mediators that cause constriction of the bronchi muscles and mast cell degranulation.
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Reduction in nasal breathing leads to mouth breathing which exposes the patient to more irritants and pollutants. The exposure initiates oxidative stress and inflammatory reactions.
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Prolonged exercise suppresses the immune system and increases susceptibility to viral respiratory infections.
What Risk Factors Are Associated With EIA?
Factors contributing to the development of EIA include:
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History of familial asthma.
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History of allergic rhinitis.
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Exposure to smoking.
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Dry environment.
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Exposure to respiratory irritants.
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Living in high areas of pollution.
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Participants in high-risk sports, such as the prolonged playing of swimming in chlorinated pools, cycling, running downhill, ice hockey, ice skating, etc.
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Females.
What Are the Clinical Signs and Symptoms Linked to EIA?
EIA patients many a time, remain undiagnosed due to the asymptomatic nature of the condition. Patients with symptoms start having the symptoms within eight minutes of vigorous exercise. The symptoms include:
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Difficulty in breathing (dyspnea).
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Wheezing.
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Tightness of the chest.
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Coughing.
How Long Do the Symptoms Associated With EIA Lasts?
The clinical manifestations of EIA usually start within eight to ten minutes of vigorous exercise. After initiation, the symptoms resolve spontaneously by thirty to ninety minutes with a refractory period of one to three hours. There is no initiation of the symptoms in the refractory period, even while performing exercises.
How Is EIA Diagnosed?
The clinical diagnosis of EIA is not very accurate. Direct and indirect testing methods along with spirometry provide more reliable results.
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Direct stimulation of the bronchial muscle with Methacholine is known to induce constriction of the bronchial muscles.
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Alternative or indirect testing methods that are specific to EIA are:
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Exercise challenges testing of patients with EIA in a dry, controlled environment. However, patients should not have entered the refractory period before the test. A fall in FEV (forced expiratory volume) below 10 % is diagnostic of EIA.
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Allergy testing for common allergens.
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Pulmonary function testing.
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Fractional excretion of nitric oxide (FENO) is better suited to distinguish EIA from other causes of asthma, especially in children.
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Airway provocation tests use mannitol to dehydrate the respiratory epithelium, which induces EIA.
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When to Go for a Consultation With a Specialist?
A consultation with a specialist is imperative if the coughing and wheezing do not stop for a long period and are increasingly making it difficult to breathe.
What Measures Are Adopted to Manage Patients Suffering From Exercise-Induced Asthma?
Either pharmacologic interventions or non-pharmacologic interventions primarily do management of exercise-induced asthma.
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Pharmacologic Management of Exercise-Induced Asthma:
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Short-acting beta-agonists (SABA) five to twenty minutes before exercise are the first line of choice to treat exercise-induced asthma. They relax the smooth muscles of the airway. However, patients may develop tolerance to SABA.
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Patients who have developed tolerance to SABA are treated with corticosteroids (inhalational). It is more effective in patients with underlying asthma and takes two to four weeks to show its action.
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Montelukast (leukotriene receptor antagonists) provide long-lasting dilation of the bronchial smooth vessels. The maximum effect is seen after two to four weeks.
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Mast cell stabilizing agents are also prescribed just before exercise.
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Antihistamines are used in case of any allergies.
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Long-acting beta-agonists used on a regular basis are also seen to benefit the people.
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Non-Medical Management of Exercise-Induced Asthma:
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Administration of non-invasive positive pressure ventilation (NIPPV) in children with asthma helps stretch the airway mechanism by inhibiting inflammation and promoting bronchodilation. It is combined with physical and respiratory therapy.
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Physical, respiratory therapy includes a one-hour session of respiratory exercises both supine and sitting, inspiratory muscle training, and bilevel positive airway pressure.
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How Are the Symptoms Associated With EIA Reduced?
The perception of symptoms associated with EIA are managed with:
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Yoga.
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Reduction in use of medicines.
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Breathing training.
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Respiratory muscle training.
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Decrease in anxiety and depression.
How to Prevent EIA?
EIA can be controlled in the following ways:
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Wearing a mask as a physical barrier and avoiding exercise in a place with high pollution and allergens.
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Pools should be disinfected with alternate treatment apart from chlorine.
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Opt for exercises that are less likely to induce exercise-induced asthma after five to eight minutes of the exercise.
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Low and medium-risk sports activities like rugby, football, basketball, tennis, fencing, gymnastics, etc., should be considered.
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Patients should try to increase their exercise tolerance and reduce body weight in case of obesity.
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Caffeine helps in reducing exercise-induced hypoxia (decreased oxygen in tissues) and protects against the narrowing of the airways.
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Dietary modifications such as including vitamin C and E and low salt content in the diet help patients against oxidative damage caused to the airways.
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Use of asthmatic medications.
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Breathing through a scarf.
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Do a 10-minute warm-up before starting with exercises.
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Breathing through the nose to warm and humidify the air.
How Should EIA Patients Exercise?
Patients can follow a few simple measures while exercising to avoid EIA:
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Usually, patients with a history of exercise-induced asthma should opt for low to medium-risk sports activities that are less strenuous.
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The actual exercise should always be followed by a few warm-ups and cooling down sessions, which gives the body time to adjust to the exercise.
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Avoid exercising and sports activities in a dry, cold, or polluted environment.
What Conditions Are Similar to Exercise-Induced Asthma?
Narrowing of the airway and subsequent coughing, wheezing, and difficulty in breathing associated with EIA are difficult to diagnose clinically. The following conditions should be ruled out before forming a conclusive diagnosis:
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Diseases of the nasal airway such as allergic rhinitis, upper airway cough syndrome, and anatomic abnormalities.
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Pharynx and larynx disorders like the exercise-induced vocal cord dysfunctions.
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Lower airway pathologies include asthma, respiratory tract infections, and gastroesophageal reflux diseases.
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Cardiac dyspnea, specifically in children.
What Are the Complications of Exercise-Induced Asthma?
Complications of exercise-induced asthma usually include its sequelae, such as lack of exercise, poorly controlled asthma, and reduction in physical activity.
What Is the Prognosis of EIA?
With proper management, people suffering from exercise-induced asthma can also perform the same exercises as their counterparts. Even athletes can continue with their sports and eventually enroll in competitions.
Conclusion
Exercise-induced bronchitis is a common condition encountered by both asthmatic and non-asthmatic patients. It is often misdiagnosed due to the absence of characteristic clinical features. Proper diagnosis and appropriate treatment and preventive strategies improve exercising tolerance in these patients.
