The prompt diagnosis and treatment of exercise-induced bronchoconstriction (EIB) can ensure healthful outcomes for patients.
By Cassandra Perez
Exercise-induced bronchoconstriction (EIB), also referred to as exercise-induced asthma, describes the acute, transient airway narrowing that occurs during, and most often after, exercise.1 EIB can affect anyone involved in physical activity, but in athletes it is a health problem that is likely more prevalent than is currently clinically recognized.1 The consequences of misdiagnosis or the failure to diagnose entirely can result in the impairment of athlete performance and can be detrimental to one’s health.1
This article will examine the impact of EIB in adult athletes, asthma patients, and the general population, along with effective pharmacologic and nonpharmacologic treatment options that can help manage this condition.
Symptoms and Diagnosis
A number of people who participate in intense aerobic activity and are physically active experience EIB, but the condition is especially common in elite athletes.2 EIB occurs in up to 90% of asthmatic patients and is estimated to occur in >10% of the general population.1
“Exercise is one of the most common triggers of symptoms in patients with asthma. That is why it is so common for EIB to occur in patients with underlying asthma vs the general population without asthma,” explained Jonathan Parsons, MD, MSc, FCCP, director of the Asthma Center at Ohio State University. “Many studies have shown variable prevalence rates for EIB in athletes (with or without asthma), but in general these rates are higher than the general population.”
EIB occurs in a substantial proportion of patients with asthma, but it may also occur in individuals without known asthma.4 Bronchoconstriction that is triggered by exercise in persons with underlying asthma is considered exercise-induced asthma.3
The common symptoms of EIB include wheezing, coughing, dyspnea, and chest tightness, as well as mild impairment of performance to severe bronchospasm and respiratory failure.1 The more subtle evidence of this condition include fatigue, avoidance of activity, or poor performance for conditioning level.1 According to Parsons, however, the diagnosis of EIB is established by changes in lung function after exercise, not on the basis of symptoms, and symptoms such as shortness of breath are neither sensitive nor specific for identifying individuals with EIB.
The diagnosis of EIB with or without concomitant asthma is made on the basis of the presence of a typical symptomatology and documentation of variable airflow limitation.2 Spirometry or diurnal peak flow measurements support the diagnosis of asthma.2 Additionally, further support can be obtained by documenting a significant increase in lung function using forced expiratory volume (FEV) following administration of a bronchodilator or a corresponding decline in lung function following a bronchoprovocation challenge with methacholine.2
Darren Drumsta, MA, product manager for MGC Diagnostics, said methods to distinguish an EIB diagnosis can vary to include physical stimuli or some sort of hyperpnea challenge. “The measurement of FEV1 is the most common and repeatable variable to consider in regards to pulmonary function measurements pre- and post-challenge effort. The criterion used to diagnose EIB is a ?10% fall in FEV1,” Drumsta explained. “In other words, changes in lung function are measured versus presence of symptoms being experienced.”
Drumsta said almost all products from MGC Diagnostics, including the CPFS/D USB spirometer and Platinum Elite body plethysmograph, can measure FEV1 and are capable of aiding in the diagnosis EIB. “Each product lends itself to being utilized in a different way to measure FEV1 through the various diagnostic testing pathways. These devices also give the user some flexibility in terms of other measures such as ECG, or even controlling a cycle ergometer or treadmill that may be used for the challenge effort protocol,” said Drumsta.
Importance of Treatment and Diagnosis
The health consequences of unrecognized or inadequately treated EIB can be significant, and thus accurate diagnosis and prompt treatment are essential. EIB that is not treated can result in a lack of beneficial exercise and poor performance in activities a person may otherwise enjoy, and serious or life-threatening breathing difficulties, especially among those with asthma.5 EIB can also lead to long-term respiratory illness and even death. According to Bill Pruitt, MBA, RRT, CPFT, AE-C, FAARC, senior instructor and director of clinical education in the department of cardiorespiratory care at the University of South Alabama, EIB can limit exercise, put a strain on the cardiopulmonary systems, and can lead to a serious and prolonged asthma attack.1 Also, reviews have identified asthma as a risk factor for sudden death and have reported many deaths that have been attributed directly to EIB.1
Impact on Athletes
Exercise will likely induce bronchoconstriction in a sizeable proportion of the population, but the problem is significantly worse in athletes, with an estimated 70% coping with EIB.2 For example, in a study of college athletes on 8 different sports teams, 56 of 196 athletes (28.6%) self-reported a history of asthma or EIB and 52% reported a history of EIB/asthma or current EIB symptoms.6
Athletes who compete in high-ventilation or endurance sports are more likely to experience symptoms of EIB than those who participate in low-ventilation sports, although this condition can occur in any setting.1 EIB is particularly prevalent in endurance events such as swimming or long-distance running in which ventilation is increased for long periods of time during competition and training.1 In addition, there is also an increased prevalence of EIB in winter sport athletes, and athletes who participate in environments where there may be environmental pollutants are at an increased risk of developing this condition.1
“Among the environmental exposures that have been proposed to contribute to EIB are cold air, dry air, ambient ozone, and airborne particulate matter. Evidence supports increased airway hyper responsiveness and decreased lung function from chronic exposure to air pollutants during exercise,” said Parsons.
“EIB is thought to be triggered by the cooling and drying effects of increased minute ventilation that occurs as we exercise. Thus, exercising in a very cold, dry environment might increase the likelihood of occurrence,” Pruitt added. “Dusty or polluted air could also pose a possible threat for someone with EIB as the particles may trigger bronchospasm – particularly if the person was sensitive to these agents.”
The diagnosis and treatment of EIB is essential in athletes, especially high-level athletes, in order to allow them to function and compete.1 The long-term consequences of untreated EIB can be detrimental, and during long periods of intense training, long-term inflammation of the airways can lead to immunosuppression, remodeling, and susceptibility of infections, as well as the development of asthma.2
Pharmacologic and Nonpharmacologic Treatment Options for EIB
The therapeutic options for the treatment of EIB include a number of nonpharmacologic and pharmacologic therapy options. The main goal of treatment for EIB is to allow patients to exercise safely, but secondary goals include keeping athletes of all levels active and helping competitive athletes maximize performance.3 Medication is the mainstay of treatment for individuals with EIB, but those coping with this condition can use nonpharmacologic therapy options as well.3
For patients with EIB but no asthma, nonpharmacologic treatment options include the use of a mask when exercising in cold conditions (such as wearing a mask during skiing) and the use of a low intensity pre-exercise warm-up, which can limit EIB in more than half of cases.2 Additionally, individuals affected with EIB should try to avoid activities in conditions characterized by an abundance of pollutants, allergens, and similar triggers.2 Also, if the environment at the time of exercise is more “threatening,” such as very polluted or cold air, Pruitt said it may be sensible to avoid exercise until the conditions have improved.
Nutrition may also be a factor in EIB, and although further study is needed, a review of the literature suggests that restricting dietary sodium intake for 1 to 2 weeks may reduce bronchoconstriction after exercise in patients with asthma and EIB.3
For most people with EIB, treatment with common asthma medications and preventive measures enable them to exercise and remain active.1 Pharmacologic treatments for EIB include inhaled corticosteroids, cromolyn compounds, leukotriene modifiers, and short-acting beta agonists, and multiple pharmacologic approaches can be employed in the same patient if necessary.1
For individuals with mild EIB, short-acting beta-agonists (SABAs) can be used either as rescue for bronchoconstriction or 5 to 10 minutes prior to exercise to prevent EIB; however, if a short-acting bronchodilator is needed more than twice weekly, the recommendation is to commence a low but regular dose of an inhaled corticosteroid.2 Although this is generally the most effective pre-exercise medication to use, the daily use of SABA is not recommended as the user may develop a tolerance to its effect.5 Parsons notes that pre-exercise SABAs alone are typically effective in 80% of cases, and are often effectual for 2 to 4 hours in protecting against or attenuating EIB. This common therapeutic option can minimize or prevent EIB symptoms, and B2 agonists are considered to be the most effective therapy for the prevention of symptoms of EIB in asthmatic patients.1
The current recommendation for prevention of EIB is to pre-medicate with a SABA, and Pruitt believes using an inhaled SABA is the best approach to prevent the attack. Ipratroupim, or Atrovent HFA, is another pre-exercise medication for EIB that may be effective for some, and this inhaled medication is designed to relax the airways.5
Long-Term Control Medications
Another pharmacologic therapy available is Leukotriene modifiers, which are long-term control medications that include montelukast (Singulair), zafirlukast (Accolate), and zileuton (Zyflo, Zyflo CR). These have been shown to be effective in controlling EIB in patients and have become an attractive therapy for EIB as a result of their oral formulation, efficacy, and once-a-day dosing.1 These oral medications may block inflammatory activity for some people, and these drugs may be used daily or as a preventive treatment before exercise if taken at least 2 hours in advance.5 Potential side effects of these oral medications include behavior and mood changes as well as suicidal thoughts.5
Inhaled corticosteroids are recommended as first-line therapy in terms of controller medications for athletes who have asthma and experience EIB.1 These include medications such as include fluticasone (Flovent Diskus, Flovent HFA), budesonide (Pulmicort Flexhaler), mometasone (Asmanex Twisthaler) and beclomethasone (Qvar).5 Also, as airway inflammation is often present in nonasthmatic athletes who have EIB, inhaled corticosteroids can be an effective medicine for treatment.1 Inhaled corticosteroids help suppress inflammation in the airways and the user may need to take the drug 2 to 4 weeks before the maximum benefit is received.5
Combination inhalers, which contain a corticosteroid and a long-acting beta agonist (LABA), are drugs intended to relax the airways.5 Combination inhalers include fluticasone and salmeterol (Advair Diskus), budesonide and formoterol (Symbicort), and mometasone and formoterol (Dulera). Though this drug is intended for long-term control of EIB, a doctor may recommend for use prior to exercise.5
Mast cell stabilizers are an additional treatment option, and these have been shown to be more effective than anticholinergics but less effective than short-acting B2 agonists for managing EIB.3 Mast cell stabilizers, which come in metered dose inhalers and in a solution for nebulizers, work to prevent allergy cells called mast cells from breaking open and releasing chemicals that help cause inflammation.7 Mast cell stabilizers should be used 15 to 20 minutes before exercise.3
Overall, SABAs are recommended first-line agents for pharmacologic treatment, although leukotriene receptor antagonists or inhaled corticosteroids with or without LABAs may be needed in refractory cases.3 Immunotherapy, antihistamines, and omega-3 fatty acids are agents that can also be useful in controlling EIB.2
Most of the aforementioned drugs used to treat EIB can be used by athletes with documented asthma except systemic steroids, systemic B?-agonists, and other adrenergic drugs, according to Parsons. He explained, “There are no restrictions for asthma medications in international competition as long as they are used in normal therapeutic dosages according per the World Anti-Doping Code. The NCAA also permits asthma medications as long as they are prescribed by a licensed health care provider.”
Education and Awareness for A Fit Future
With the evident dangers of undiagnosed and inadequately treated EIB, awareness and education may be the most significant tools in ensuring a healthful future for those at-risk of the condition and athletes in particular. Individuals involved in organized sports or physical activity should be aware of the risk of EIB, and coaches, trainers, and team physicians who care for competitive athletes should be trained in the recognition and treatment of EIB.1 “Social media and advertising the message about EIB may be useful to get the word out. Targeted advertising for college-aged athletes is a given, but it would also be useful to target their coaches and other support personnel in the sports world,” said Pruitt.
According to Parsons, who also believes education is essential, “Continued education of athletic trainers, coaches, parents, and athletes themselves regarding EIB is critical. The message that we convey to coaches, athletic trainers, parents, etc, is that if you suspect there may be an issue, don’t hesitate to get the athlete tested.” RT
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Parsons, Jonathan P., and John G. Mastronarde. “Exercise-Induced Bronchoconstriction in Athletes.” Chest 128.6 (2005): 3966-974. Web.
Gross, Nicholas. “Diagnosing and Managing Exercise-Induced Bronchoconstriction.” Medscape. Medscape, 27 Apr. 2015. Web. 15 Aug. 2016.
Krafczyk, Michael, and Asplund, Chad. “Exercise-Induced Bronchoconstriction: Diagnosis and Management.” Am Fam Physician.2011 Aug 15; 84(4):427-434.
Parsons JP, Hallstrand TS, Mastronarde JG, et al. An official American Thoracic Society clinical practice guideline: exercise-induced bronchoconstriction. Am J Respir Crit Care Med. 2013;187(9):1016-27.
“Exercise-induced Asthma.” Mayo Clinic. Mayo Clinic, 25 Oct. 2014. Web. 15 Aug. 2016.
Burnett, D. M., J. P. Vardiman, J. A. Deckert, J. L. Ward, and M. R. Sharpe. “Perception of Exercise-Induced Bronchoconstriction in College Athletes.” Respiratory Care 61.7 (2016): 897-901. Web.
“Mast Cell Stabilizers.” Mast Cell Stabilizers. Palo Alto Medical Foundation, n.d. Web. 15 Aug. 2016.