Asthma and Sports

Exercise-induced asthma (EIA) and exercise-induced bronchospasm (EIB) are the terms that are usually used to describe the transient narrowing of the airways that follows vigorous exercise. However, there are some minor yet important differences in these two conditions.

The term, EIA, is used to describe symptoms and signs of asthma provoked by exercisewhile EIB describes a reduction in lung function after an exercise test or a natural exercise and is usually seen in elite athletes who do not generally have asthma. EIB occurs in approximately 10% of individuals who are not known to have asthma. These patients who have EIB but not asthma do not exhibit the typical features of chronic asthma (i.e., frequent daytime symptoms, nocturnal symptoms, impaired lung function). Exercise can be the only stimulus that triggers respiratory symptoms in these patients.

Most individuals who experience EIB will have normal baseline lung function, and spirometry alone is not adequate to diagnose EIB. In patients evaluated for EIB who have a normal physical examination and normal spirometry, bronchoprovocation testing is recommended.

The airway inflammation pattern is also different in these two conditions; inflammation in asthma is usually associated with eosinophilia whereas isolated EIB in elite athletes seems to be more associated with neutrophilic or mixed-type airway inflammation and, hence, the efficacy of inhaled corticosteroids in this cohort is very unclear. Hence, the first-line treatment to minimize or prevent symptoms of EIB is the prophylactic use of short-acting bronchodilators shortly before exercise. Inhaled corticosteroids are a first-line therapy in terms of controller medications for athletes who have asthma and experience EIB.

Because of such close similarities between these terms, both are used interchangeably in much of the literature published across the world. Hence, it must be borne in mind that either term signifies the transient narrowing of the airways following exercise and that atopy causing chronic asthma and bronchial hyper-responsiveness to thermal, mechanical or osmotic stimuli (seen more commonly in elite athletes) are not mutually exclusive.

The exact mechanism of exercise-induced asthma is not fully understood. However, currently, there are two main accepted hypotheses to explain the relationship between physical activity and exercise-induced asthma (Figure 1).

In one of the hypotheses, it has been suggested that airway cooling due to respiratory heat loss followed by hyperaemia and pulmonary vasodilatation could be the reason for asthma symptoms after exercising. Airway cooling may stimulate receptors in the airways, causing bronchoconstriction through vagal stimulation. Furthermore, inhalation of cold air can induce vasoconstriction of the bronchial circulation, resulting in secondary reactive hyeraemia, further leading to oedema and airway narrowing. There is also considerable evidence to indicate that EIA is effected through the release of mediators from mast cells and other inflammatory cells of the airways.

The other hypothesis suggests that water loss from the airways may be the reason for EIA. The reason for this water loss is the increasing ventilator rate, especially during inhalation of cold air. This respiratory water loss increases the periciliary fluid lining the surface of respiratory mucosal membranes, leading to the influx of chloride and calcium ions into the bronchial epithelium, which further results in mediator release and, consequently, the pathophysiology of exercise-induced asthma.

Because inflammation has been understood as the pathophysiologic basis for chronic asthma, evidence for inflammation has been studied in EIA and similar mediators have been found. Some studies have shown that exhaled nitric oxide (NO) changes after exercise in patients with EIA, and that this change is directly correlated with the drop in the forced expiratory volume in 1 second (FEV₁) after exercise. Studies have shown other inflammatory markers to be present in patients with EIA at rest and also after exercise. There are also studies showing a 50% incidence of a late asthmatic response in exercise-induced asthma, supporting the evidence for inflammation in EIA.

This suggests that EIA is more than just a set of independent events after exercise; rather, frequent exercise may lead to chronic inflammatory changes in the airways. This is an important concept when treatment is considered; daily anti-inflammatory controller medications for the inflammation may be required in addition to pre-exercise medications.

The usual presenting symptoms of EIA include cough, wheezing, shortness of breath or chest tightness during or after usually 6-8 minutes of strenuous exercise. The other symptoms that may occur in some patients because of EIA and should be considered during diagnosis are the subtle symptoms of 'feeling out of shape', headaches, abdominal pains, muscle cramps, fatigue or dizziness (Table 1).

Different types of sports may result in different clinical presentations (Table 2).

Although symptoms are usually what triggers the athlete to seek medical attention, it has been shown that self-reported symptoms do not necessarily correlate well with the presence of EIA and can give both false-positive and false-negative results. However, to solve this dilemma, a good patient history, including family history of asthma or a personal history of recurrent allergic rhinitis or sinusitis, which increase the likelihood of EIA, should be taken into account. The following are the factors that should also be considered during the diagnosis of EIA (Table 3):

After a thorough history is taken, a physical exam should be performed, including ear, nose and throat examination for signs of nasal allergies, sinusitis or otitis; a cardiac exam to look for murmurs or arrhythmias; and a chest exam to evaluate for wheezing, rales or rhonchi. All this is to rule out the alternate diagnosis and confirm the presence of EIA.

There are several important differential diagnoses to EIA and EIB in an athlete, such as laryngeal inspiratory stridor (also known as exercise-induced vocal cord dysfunction) and hyperventilation during exercise. These conditions should be borne in mind, as many such patients have been given unnecessary drugs for the treatment of asthma, including both inhaled steroids and beta₂-agonists, which will have no effect upon the exercise-induced laryngeal stridor (most often occurs in young well-trained athletic girls from approximately 15 years of age).

Table 4 gives a brief account of the alternate diagnosis of exercise-induced asthma in sports.

When an athlete participates in international sports, a combination of the medical history and laboratory tests should be documented as a basis for the diagnosis of asthma and the possibility of using asthma medication. The laboratory tests may either be the demonstration of EIB, reversibility to inhaled beta₂-agonists or the demonstration of bronchial hyperresponsiveness to direct or indirect stimuli.

Table 5 describes the procedure for the diagnosis and the application to obtain approval for using inhaled steroids and/or inhaled beta₂-agonists in sports. As a change of existing rules may be issued, the responsible physician should keep informed through the websites of WADA and IOC (international Olympic Committee) for the Olympic Games. As medical regulations for the assessment of bronchial hyperresponsiveness through pharmacological provocation may vary somewhat between different countries and country-specific regulations should be observed (such as regulations established by the National Anti- Doping Agency for India), a combination of positive responses to step 1 and either steps 2, 3 or 4 is required.

Management of asthma in athletes is similar to management in non-athletes, with attention to patient education, reduction of relevant environmental exposures, treatment of associated comorbid conditions, individualized pharmacotherapy, prevention of exacerbations and regular follow-up. The management of the athlete with asthma should follow current national or international guidelines (like Global Initiative for Asthma [GINA]). The following is a management flow chart recommended by the IOC.

The prevention and management of EIB is a key issue in athletes. The following are the steps recommended by the Australian Association for Exercise and Sports Science:

The non-pharmacological management of asthma in athletes is important. This includes identifying and reducing exposure to asthma triggers whenever possible and especially during training. Prophylaxis of EIA includes premedication and warm-up. A beta-agonist should be used if asthma symptoms develop and exercise should be restarted. Traditionally premedication with inhaled beta-agonists 15 minutes before exercise improves EIA symptoms and exerts a protective effect.

Drug treatment of asthma in elite athletes should follow standard guidelines, with treatment individualized to achieve asthma control and the effects of the treatment monitored. Any medications prescribed must comply with the WADA regulations. All beta₂- adrenoceptor agonists (beta₂-agonists) and, in particular, oral preparations are prohibited. Inhaled corticosteroids and some inhaled beta₂-agonists can be used in accordance with the relevant section of the International Standard for TUE. Systemic corticosteroids are prohibited and require a standard TUE.

Table 6 gives an overview of the asthma drugs for which the athlete must apply for use through a TUE from January 1, 2012, according to the WADA regulations.

People with asthma may need to take special care when doing adventure sports. Some of them are mentioned below:

The following table compiles a list of high-risk and low-risk activities for asthmatics with exercise as a trigger.

EIA is a condition that may be found in athletes at any level, from recreational to elite athletes. However, if properly treated, most individuals can exercise to their fullest capacity and potentially reach elite athlete status. The diagnosis may be very obvious, but some subjects may present with unusual symptoms. It is important for the physician, certified athletic trainer and coach to be aware of the possible symptoms that may suggest this condition. It is also important to offer the correct treatment for the asthmatic athlete in accordance with his/her disease severity and the rules of the sport. The aim is to help athletes with asthma fulfil their potential in physical activity and sports in spite of their illness.