Exercise-Induced Bronchoconstriction

What is Exercise-Induced Bronchoconstriction?

Exercise-induced bronchoconstriction (EIB) is a condition that causes the airways to narrow during physical activity. EIB is common, affecting between 40% and 90% of people with asthma, and up to 20% of people without asthma. Regular exercise is well-known to be beneficial for everyone, and is a key part of maintaining good health. However, EIB can cause breathlessness, cough, chest tightness, and wheezing during exercise, which may lead some people to avoid physical activity.

Avoiding exercise due to EIB can lead to social isolation, especially in teenagers, and it can also result in obesity and poor health. Interestingly, regular exercise has been shown to improve the severity of EIB, enhance lung function, and reduce airway inflammation in people suffering from asthma and EIB.

Detecting EIB early, confirming its diagnosis with a change in lung function during exercise, and effective treatment can greatly improve a patient’s quality of life. When managed correctly, patients can engage in physical activities without any restrictions, including competitive sports at an elite level.

Non-medical treatments tackle the root cause of EIB, such as a sudden increase in ventilation and stress on the respiratory system. These treatments include warm-up exercises and protecting the airways from cold, dry air, pollutants, and allergens. On the other hand, medical treatments address the symptoms by preventing the airways from narrowing. These treatments include drugs like short-acting beta-agonists (SABA), inhaled corticosteroids (ICS), leukotriene receptor antagonists (LTRA), and mast cell stabilizing agents (MCSA). These medications are effective and typically do not cause significant side effects.

What Causes Exercise-Induced Bronchoconstriction?

Exercise-induced bronchoconstriction, or EIB, is a term that describes the narrowing of the airway that can occur during physical activity. This term is preferred over “exercise-induced asthma,” as recommended by the American Thoracic Society and the American Academy/College of Allergy, Asthma, and Immunology. EIB can also be categorized as either EIB with asthma (EIBa), or EIB without asthma (EIBwa).

The cause of EIB is usually a sudden large increase in the amount of air entering the airways during exercise. This air needs to be warmed and moistened, and in some people, this process can lead to changes in the inflammation levels, nerve function, and blood flow in their airways. This ultimately leads to a tightening of the muscles in the bronchial tubes (the tubes that carry air in and out of the lungs).

Symptoms of EIB include shortness of breath (dyspnea), coughing, a feeling of tightness in the chest, increased mucus production, and wheezing.

Risk Factors and Frequency for Exercise-Induced Bronchoconstriction

Exercise-induced bronchoconstriction, or EIB, is a condition that affects 40% to 90% of people with asthma and up to 20% of people without asthma. It is particularly prevalent among elite athletes, affecting 30% to 70% of them, especially those participating in winter sports and female athletes. People with asthma often seek medical attention for breathing problems, and EIB can suggest that their asthma is not well controlled.

Current projections indicate that by 2024, about 400 million people will have asthma, and a large percentage of them will also have EIB. Every year, around 250,000 people die from complications related to asthma. Though it has no cure and can significantly affect everyday life activities like sleep, work, school, and exercise, treating asthma and EIB can effectively reduce the death rate in patients with asthma. Therefore, correctly identifying and treating EIB is crucial.

The likelihood of experiencing EIB can depend on the sport a person plays. Sports carry differing levels of risk:

• High-risk sports include long-distance running, cycling, cross country or downhill skiing, ice hockey, ice skating, high altitude sports, swimming, water polo, and triathlons. These sports involve long periods of exercise, often in challenging environments like cold, dry air or chlorinated pools.
• Medium risk sports include soccer, rugby, football, basketball, volleyball, baseball, cricket, and field hockey, where athletes usually perform less than 5 to 8 minutes of continuous exercise.
• Low-risk sports include non-long distance track events like sprints, tennis, fencing, gymnastics, boxing, golf, weightlifting, bodybuilding, and martial arts.

Currently, there isn’t enough quality evidence to support screening for EIB. More research is needed to create a reliable tool for measuring symptoms.

Signs and Symptoms of Exercise-Induced Bronchoconstriction

Exercise-induced bronchoconstriction, a type of breathing problem that can happen during or after exercise, has various symptoms. People may experience mild to serious chest tightness, wheezing, coughing, and shortness of breath within 15 minutes after a short period of intense exercise. It’s worth noting that severe symptoms leading to respiratory failure and death are very rare. Cold, dry air or environments with a high concentration of lung irritants can increase the frequency of these symptoms. Usually, these symptoms ease on their own within 30 to 90 minutes and a period of 1 to 3 hours of protection against bronchoconstriction follow, where continuous exercise won’t lead to breathing problems. However, some people may not show any symptoms, causing the condition to be underdiagnosed.

People who have personal or family history of asthma, personal history of allergies or hay fever, exposure to cigarette smoke, those who take part in high-risk sports, live or train in areas with high pollution levels, and females are at higher risk for developing this condition. There are also small studies suggesting that sugar-sweetened beverages may increase the risk by promoting inflammation and obesity.

Testing for Exercise-Induced Bronchoconstriction

Sometimes, a doctor might have difficulty diagnosing a patient based on symptoms alone, especially if the patient doesn’t show any signs. When it comes to diagnosing exercise-induced bronchoconstriction (EIB), multiple types of tests can be used, including the measurement of any changes in your lung function from your normal state.

One method for testing lung function involves directly stimulating the muscles in the airways of your lungs with a substance called methacholine. However, this only correctly identifies EIB in about 59-91% of cases.

Another method (referred to as “indirect testing”) is specifically for diagnosing EIB. This involves exercising in a controlled environment with cold, dry air because those conditions trigger symptoms in people with EIB. Other alternatives to exercising involve breathing tests either with dried air or with specific substances that can cause EIB-like symptoms. These alternatives haven’t been widely studied, and their success in identifying the condition might vary.

For an exercise challenge test, the guidelines include recommendations on how much you should breathe, how fast your heart should beat, how long you should exercise at your full capacity, and which medications to avoid before the test. Measurements of your lung function, particularly the amount of air you can force out in one second (known as FEV1), will be taken at different periods during the exercise. A fall in FEV1 of more than 10% would suggest that you have EIB. The severity of EIB can range from mild (10-25% reduction), moderate (25-50% reduction), to severe (50% or more reduction). Some labs use a higher cut-off value of 15% for diagnosing EIB as it is more specific.

The doctor might also use pulmonary function tests, where you have to blow air into a specific device to measure how well your lungs are working. There’s also a suggestion to potentially use a test that measures the level of nitric oxide you exhale (known as FENO testing) to diagnose and gauge the severity of EIB. The FENO test is beneficial because even younger children can perform it. High levels of nitric oxide suggest inflammation in your airways.

Treatment Options for Exercise-Induced Bronchoconstriction

Short-acting beta 2 agonists (SABA), which are medications that quickly relax the muscles in the airways, are often used shortly before exercise to minimize the risk of an asthma attack. They work rapidly and can provide relief for 2 to 4 hours. However, people may start to become less responsive to these drugs if they’re used frequently. Despite this, they’re generally the first choice for treatment and don’t usually cause many side effects. The way they work involves both relaxing the muscles in the airways and inhibiting the release of substances from specific cells, called mast cells, that can cause inflammation and worsen asthma.

Inhaled corticosteroids (ICS) are additional medications that can be used if a person’s asthma symptoms aren’t well managed with SABAs alone, or if someone is taking SABAs daily. These drugs take longer to work – around 2 to 4 weeks to reach their full effect – but are useful in those with underlying asthma. They are also taken regularly, rather than just before exercise, and work by reducing inflammation in the lungs. A significant number of asthma patients may not find relief with SABAs and benefit from adding ICS to their treatment plan.

A third type of medication known as leukotriene receptor antagonists (LTRA) can also be helpful for inflammation reduction and are taken daily. They also take around 2-4 weeks to achieve their full effect, and could be an option for those who don’t respond well to other treatments. Like ICS, the effectiveness of leukotriene receptor antagonists varies from patient to patient.

Another category of medication, mast cell stabilizing agents (MCSA), can be employed before exercise, although they’re not as commonly used in the United States. These drugs aim to inhibit the activity of mast cells, thereby preventing them from releasing substances that worsen asthma.

When there’s a need for more treatment options, short-acting muscarinic antagonists (SAMA) can be applied. These are drugs that block a specific type of receptor in the muscles of the airways, helping them to relax. They are less effective than SABAs and are generally used in combination with them.

Antihistamines might be of benefit if the patient has underlying allergies, and long-acting beta 2 agonists (LABA) are not typically recommended due to their potential side effects.

Non-drug treatments are also an important part of managing exercise-induced asthma. One strategy is for a person to perform a bout of vigorous activity for around 10 to 15-minutes, followed by two hours of reduced activity. This can help alleviate asthma symptoms for the next few hours. Other measures might include wearing a mask to warm and humidify the air that’s inhaled during exercise, or wearing a mechanical barrier mask and avoiding exercise in environments with a high concentration of allergens or pollutants. Diet changes may also be helpful, supplemented with regular exercise to build endurance and tolerance, and weight management if the person is overweight.

Training in controlled breathing techniques can lessen symptoms, reduce the need for medication, lower associated anxiety and depression, and improve the quality of life. This can be facilitated through yoga or supervised breathing training. Respiratory muscle training, which involves specific exercises to strengthen the breathing muscles, has shown potential in some studies, although more research is required.

Other treatments to help control asthma include interventions such as non-invasive positive pressure ventilation and respiratory muscle training, which have both been shown to reduce symptoms and improve lung function. However, it’s important to note that these treatments should be customized to each individual’s needs and should be considered as part of a comprehensive management plan for exercise-induced asthma.

What else can Exercise-Induced Bronchoconstriction be?

If you feel tightness in the chest, are wheezing, coughing, or find it hard to breathe when you exercise, there could be a problem with your airways. Diagnosing a condition called exercise-induced bronchoconstriction (EIB) by these symptoms alone can be tough. Doctors need to perform tests to see how your lung function changes when you are exercising.

Problems with your nasal airway like exercise-induced rhinosinusitis, allergies, upper airway cough syndrome, upper respiratory infection, or structural abnormalities can also cause these symptoms. These conditions can happen alongside EIB because your nasal airway helps to filter, humidify, and control airway resistance. You can manage these upper airway conditions by avoiding triggers and irritants, taking medications like MCSA and LTRA’s (used for EIB), using an intranasal corticosteroid, a decongestant, or undergoing immunotherapy.

• Problems with the pharynx and larynx (parts of your throat) like EILO (previously called exercise-induced vocal cord dysfunction) can mimic the symptoms of EIB. However, athletes with EILO need different treatment. Doctors would use tests, including an exercise test visualizing the larynx, to make sure the diagnosis is correct.
• Lower airway diseases, like asthma, respiratory tract infection, or gastroesophageal reflux disease (GERD), could be other reasons for these symptoms.
• Cardiac causes of breathing difficulty during exercise, especially in children, should be considered.
• GERD, a gastrointestinal disorder, should also be evaluated.
• Less common causes include exercise-induced pulmonary edema (seen mainly in water sports or at high-altitude winter sports), saltwater aspiration syndrome, and smoking. In teenager athletes, the evaluation for the cause of their cough should also include asthma, EIB, respiratory tract infection, upper airway cough syndrome, and environmental exposures. It’s important to note that no studies have found a link between exercise-induced cough and cardiac abnormalities.

What to expect with Exercise-Induced Bronchoconstriction

With the right treatment, athletes can match their peers in performance. They can even participate and win a medal in the Olympics and other international competitions.

Possible Complications When Diagnosed with Exercise-Induced Bronchoconstriction

Complications can arise if asthma isn’t managed well. These could include a decrease in physical activity and a shift towards a sedentary lifestyle.

Possible Complications:

• Poorly managed asthma
• Reduction in physical activity
• Sedentary lifestyle