Jan 29, 2015Breathing Easier
Exercise-induced bronchospasm is a surprisingly common condition that can seriously hinder an athlete’s ability to perform. But in most cases, it’s easy to neutralize with the right management strategies.
By Dr. Jonathan Parsons
Jonathan Parsons, MD, FCCP, is Associate Professor of Internal Medicine at Ohio State University and Associate Director of the OSU Asthma Center. He can be reached at: [email protected].
If you’ve worked around competitive athletes long enough, you’ve almost certainly seen it. Perhaps in a cross country runner who coughs excessively during or immediately after a long training run. Or a swimmer who wheezes and has trouble breathing deeply after a few consecutive laps in the pool. Maybe it’s a soccer player who shows signs of fatigue and shortness of breath very early in practices and games, even though she’s clearly in excellent physical shape.
Athletes who exhibit symptoms like these may be suffering from a condition called exercise-induced bronchospasm. EIB is surprisingly common, but it often goes unrecognized and undiagnosed, so there are no firm statistics on exactly how many athletes it afflicts. What we do know is that if ignored, it can greatly disrupt an athlete’s performance and overall quality of life.
Like with many underdiagnosed conditions, much of the suffering caused by EIB is avoidable. Once it has been identified in an athlete, there are several effective treatment options, and symptom management is fairly simple in most cases. For that reason, every sports medicine professional should know about this illness and be prepared to help athletes seek the care they need.
DEFINING THE CONDITION
EIB involves acute, transient airway narrowing that occurs with exercise. The most common symptoms are coughing, wheezing, and/or chest tightness during and/or after athletic activity. Asthmatics are at highest risk, with roughly 40 to 50 percent experiencing the condition, but it also occurs in up to 10 percent of people who are not known to have chronic asthma. In these individuals, lung function is normal at most times, and exercise may be the only stimulus that causes respiratory symptoms.
The cause of EIB remains somewhat of a mystery. The prevailing theory is that large volumes of air inhaled during exercise overwhelm the humidification mechanisms of the upper airway and lungs, causing the airway lining to become dehydrated and irritated. This leads to inflammation, which in some people results in episodes of bronchospasm.
In studies of athletes in particular, the prevalence of EIB has ranged from 11 to 50 percent, depending on the testing method and the athletic population studied. These numbers likely reflect the fact that athletes generally work out more frequently and more vigorously than non-athletes, so they’re more apt to experience EIB symptoms.
In some larger screening studies, up to 30 percent of athletes who reported no history of EIB were actually found to be EIB-positive. Many athletes who experience breathing difficulty during exercise simply interpret it as a normal side effect of hard work and thus don’t seek medical help. And many healthcare providers, athletic trainers, parents, and coaches are unfamiliar with EIB, so athletes under their care put up with the symptoms and do not receive treatment.
Another potential problem is the stigma associated with breathing trouble during exercise. Athletes with broncho-spasm are often unfairly labeled as out of shape or giving poor effort, which may spur them to push themselves harder and make the condition even worse. Furthermore, some are afraid to talk openly about their symptoms for fear of losing playing time. This stigma may be one of the most significant barriers to proper intervention in athletes with EIB.
RISK FACTORS & DIAGNOSIS
Bronchospasm can occur in any athlete in any setting. Athletes who compete in high-ventilation endurance sports involving continuous, intense aerobic activity with minimal interruption, such as long-distance running, soccer, and lacrosse, may be at increased risk, but there is conflicting data on which sports have the highest incidence. Some reports have found increased prevalence of EIB in winter sport athletes, likely due to their increased exposure to cold, dry air.
Other environmental factors can play a role as well. For swimmers, the chlorine compounds used to maintain pools may act as a trigger for EIB. And athletes who compete on ice may be exposed to small amounts of carbon monoxide and nitrogen dioxide from the ice resurfacing machinery, which can irritate sensitive respiratory systems.
The clinical manifestations of EIB are extremely variable, ranging from mild impairment of performance to severe respiratory distress and even respiratory failure in rare cases. Besides coughing, wheezing, chest tightness, and shortness of breath, more subtle evidence of EIB can include fatigue, symptoms occurring repeatedly in specific environments (such as pools, ice rinks, or freshly mowed fields), and performances that fall consistently below expectations given an athlete’s conditioning level.
Generally speaking, exercise at a workload of at least 80 percent of maximal oxygen consumption for at least five to eight minutes is required to produce EIB in most athletes. When someone begins working out, their airway naturally dilates slightly to increase oxygen intake, and EIB symptoms may begin soon after. Sometimes, they do not appear at all until after exercise concludes. Symptoms often peak five to 10 minutes after exercise and can remain significant for 30 minutes or longer if no therapy is provided. But for unknown reasons, some athletes spontaneously recover baseline airflow relatively quickly, even in the absence of intervention.
One significant challenge to identifying and diagnosing EIB is the non-specific nature of its symptoms–an upper respiratory tract infection, vocal cord dysfunction, cardiac arrhythmia, cardiomyopathy, gastroesophageal reflux disease, and several other conditions can all produce similar effects. Thus while a complete medical history and physical exam should be performed any time an athlete has respiratory complaints associated with exercise, if healthcare providers rely on symptoms alone for a diagnosis, research shows they will be incorrect over half of the time. Objective diagnostic testing is an essential step in suspected cases of EIB.
The comprehensive history and exam can help rule out other disorders, and specific testing such as an EKG or echocardiography may be required in some cases. As part of a medical history, the athlete should be asked if specific symptoms arise in particular environments or during certain activities. Timing of symptom onset relative to exercise and/or recovery is also helpful information.
Objective testing for EIB typically begins with spirometry (an assessment of lung function performed using specialized equipment) before and after inhaled bronchodilator therapy. This helps identify athletes who have asthma at baseline respiratory levels, but since most people who experience EIB are not asthmatic, spirometry alone is not enough to diagnose the condition. Without introducing environmental stress and an adequate volume of exercise, which is not part of a standard spirometry evaluation, potential EIB symptoms won’t be triggered.
Once spirometry has ruled out the possibility of asthma, a form of testing called bronchoprovocation is usually recommended. This is somewhat like a stress test for the lungs and respiratory system, and not all bronchoprovocation techniques are equally valuable or accurate in assessing EIB.
The International Olympic Committee recommends one such test called the eucapnic voluntary hyperventilation (EVH) challenge to document EIB in athletes. EVH testing involves close monitoring during a six-minute period of rapid, intense breathing that simulates the breathing rate during rigorous exercise. Lung function is assessed before and after the challenge to determine if there is any decline relative to the individual’s baseline. This method is portable and relatively inexpensive, can be standardized between laboratories, and has been found highly effective in diagnosing EIB.
Another form of bronchoprovocation involves field-exercise challenge tests, in which the athlete performs activities typical of their sport and lung function is evaluated afterward. Most often, these tests involve the use of a peak expiratory flow meter before and after the exercise challenge. This type of testing has proven less effective than EVH in general, and it doesn’t lend itself to standardization in protocol from one setting to the next. Pharmacological challenge tests, such as the methacholine challenge test, have also been found less sensitive to EIB in athletes. If EVH testing is unavailable, treadmill- or ergometer-based testing of lung function in a laboratory is probably the next best choice.
A positive bronchoprovocation test indicates the need for treatment of EIB. If all of the above tests are negative, a physician should reconsider alternative diagnoses.
The most common therapeutic recommendation to minimize or prevent symptoms of EIB is the preventive use of short-acting bronchodilators–in particular, selective beta-2 receptor agonists such as albuterol–shortly before exercise. A typical recommended dose is two puffs of an agonist roughly 15 minutes before exercise, providing peak bronchodilation in 15 to 60 minutes and protection from EIB for at least three hours in most people.
Long-acting bronchodilators work in a similar manner but may last for up to 12 hours. However, these agents often lose their effectiveness over time, so close follow-up is recommended when using these medications. In addition, there has been recent controversy about the use of long-acting beta-2 receptor agonists as the sole form of treatment in asthmatics, creating another cause for concern among physicians.
For asthmatic athletes who experience EIB, inhaled corticosteroids are a common form of therapy. These are effective in reducing airway inflammation and are usually prescribed to athletes only when short-acting beta-2 receptor agonists prove ineffective.
Other drugs called leukotriene modifiers and mast cell stabilizers have also been found in a limited number of studies to be effective in treating EIB. But because they are much more expensive and generally less effective than beta-2 receptor agonists and corticosteroids, they are prescribed much less often.
Not all treatment and management strategies rely on pharmacology. Many athletes find that an adequate warm-up period reduces symptoms of EIB during their training and competitive activity. In fact, in some athletes with asthma, research has found that a “refractory period” phenomenon occurs, in which aerobic warmup renders them free of EIB symptoms for up to two hours. That effect has not been proven consistently across different populations or observed in studies of non-asthmatics, but it’s still good advice for athletes who struggle with EIB to pay special attention to their warmup period, gradually increasing respiratory demand through progressively more challenging activities.
Another non-pharmacological strategy to reduce the frequency and severity of EIB symptoms is simply breathing through the nose rather than the mouth as much as possible, as this allows air to be warmed, filtered, and humidified before it reaches the trachea and lungs. Some athletes have found it helps to wear a facemask during activity for the same reasons, especially when outdoor conditions are very cold and dry. And of course, avoidance of known triggers (such as ice resurfacing machine exhaust, freshly cut grass, or highly chlorinated pools) can be helpful as well.
Acute management of EIB requires athletic trainers and coaches to be prepared to intervene immediately when symptoms arise in an athlete. Athletic trainers should have a pulmonary function measuring device, such as a peak flow meter, available at all athletic practices and competitions. A rescue inhaler with a spacer should be on hand as well, and a nebulizer can serve as a valuable backup in an emergency, particularly for teams with athletes who have been prescribed medication to treat EIB.
All coaches and athletic trainers should be aware of the signs of respiratory distress. If an athlete appears to be experiencing symptoms, he or she should be removed from activity immediately for evaluation, preferably by a physician. A standard rule of thumb is that any time an athlete’s peak expiratory flow is lower than 80 percent of their baseline personal best, they should not participate in athletic activity.
Criteria for safe return to play after an acute episode of EIB are based on expert medical opinion only. Most physicians agree that no athlete should return to play until lung function returns to baseline levels. However, there is no recognized consensus protocol, and individual care from a physician is the safest approach.
Many athletes who struggle with EIB find the condition highly frustrating, as it’s a hindrance to optimal performance that they can’t “push their way through” with hard work and greater effort. But by seeking proper treatment and using common-sense management strategies, respiratory trouble doesn’t have to hold anyone back from success in their chosen sport.
Sidebar: ASTHMA EDUCATION
While exercise-induced bronchospasm can affect athletes whether or not they are asthmatic, those who have been diagnosed with asthma are at greatest risk for serious breathing complications during workouts. A study completed in 2004 identified 61 deaths over a seven-year period related to asthma in close association with a sporting event or physical activity. Of those deaths, 81 percent occurred in people under age 21, and 57 percent occurred among those considered to be competitive or elite athletes. Strikingly, almost 10 percent of the victims had no known history of asthma.
When an asthmatic will be participating in sports, a management plan should be created by the individual’s physician, and he or she may provide instructions for athletic trainers, coaches, and others who might be present to provide immediate care in the event of an attack. These resources can help you learn more about managing asthma in athletes:
• The NATA Position Statement on Management of Asthma in Athletes can be downloaded at: www.nata.org/statements/position/asthma.pdf.
• Winning With Asthma is an athletics-centered asthma education program created by the Minnesota Department of Health and the Utah Department of Health, with funding from the Centers for Disease Control and Prevention (CDC): www.winningwithasthma.org.