“Sometimes I can’t catch my breath when I’m riding, especially in the winter. I’ve never been told that I have asthma before – but could that be what this is?”
– J.S., Asheville, NC
Melissa Marotta writes:
First off, sorry to hear about your discomfort! Feeling like you can’t breathe is an incredibly scary experience for a lot of people. There are a number of conditions that could produce symptoms like yours, including the “exercise-induced bronchospasm” (formerly called “exercise-induced asthma”) phenomenon that I will describe in this article – so I encourage you to see your physician to help you figure out what’s going on for you, personally. This way, you can sooner get the appropriate treatment you need.
Many people have heard of exercise- or exertion-induced bronchospasm (EIB) but there is often some confusion about what the term actually describes. It refers to narrowing of the airways in association with exercise, both amongst people who have asthma (90% of patients with asthma experience an exacerbation of symptoms with exertion) and amongst people who do not. Research suggests that greater than 10% of general population may also suffer from EIB. Studies of elite athletes report a prevalence of EIB between 11-50%1. At particular risk are those athletes engaged in activities that require large volumes of air to be moved (i.e., cyclists, runners, swimmers, skiers, rowers, etc.) and those who exercise in cold, dry, or polluted (i.e., indoor rinks) conditions2.
Symptoms of EIB can be quite varied, let alone vague (i.e., non-specific discomfort, breathlessness, fatigue that might be “expected” under conditions of heavy exertion). Thus, EIB often goes undetected. Athletes, in particular, may be less likely to complain about discomfort1. That’s why it’s extremely important that you are aware of this phenomenon, so as to help those you coach (or yourself!) to recognize it and seek appropriate diagnosis and treatment.
What are the symptoms of EIB?
EIB manifests itself commonly with chest discomfort (which many people describe as “tightness”), shortness of breath, coughing and/or wheezing (a high-pitched noise on expiration). These symptoms typically occur within 6-8 minutes after exercise begins, with a peak in severity 5-15 minutes after exercise ends2. Without treatment, symptoms typically subside after 30 minutes1.
Still, some people experience more subtle symptoms: headache, abdominal pain, cramps, dizziness, fatigue2, and decline in physical performance. Often, those suffering from EIB can identify specific environments in which their symptoms occur (i.e., cold weather, indoor ice rinks, swimming pools1, or with exposure to dust, cigarette smoke, etc.2).
What causes EIB?
The current conceptualization of asthma is that it is not a single disease; rather, a collection of similar processes with varied triggers, symptoms, and severity3. In short, EIB is the constriction of the airways after prolonged hyperventilation (breathing too much) of dry, cold, or polluted air. The three components that explain EIB are as follows: 1) drying out of the airways; 2) reactive response to un-warmed air; and 3) airway inflammation2.
Dry air causes airways to narrow. At rest, dry air typically gets humidified by the upper airways (using moisture from the airways’ epithelial lining, which can replace its moisture). During exercise, we move more air – thus, we recruit the lower (smaller) airways to help humidify. This evaporation from the lower airway surface triggers the release of signaling molecules (histamine, prostaglandins, leukotrienes) that promote construction of the airways, and result in cough and mucus production1. The dryer the air and the greater the air volume we inhale, the more smaller airways we recruit (and thus, dehydrate). Repetitive dehydration can permanently damage these airways’ lining, making them leaky and unable to release signaling molecules that typically counteract the constricting signals2.
Moreover, exercise compels us to inhale large volumes of air. When said air is significantly colder than body temperature (and the sheer volume overwhelms our capacity to sufficiently warm it), the blood vessels in our airways have a reactive response that makes them leak out extra fluid (edema)1. This is called “pulmonary edema” – the same process we see when people with heart problems often have fluid and puffiness in their legs. Free fluid in the airways? No wonder someone can’t breathe.
We also know that there is an inflammatory component of EIB that is somewhat different than typical asthma, though the mechanism is still not quite understood2.
How do I know if I suffer from EIB?
As previously mentioned, there are a number of common conditions that may mimic symptoms of EIB – conditions that call for very different treatment than EIB. So it is important to encourage anyone experiencing EIB symptoms to see their doctor to help sort it all out.
Besides gathering a complete account of the patient’s symptoms, identifiable triggers, and family history, physicians perform a thorough physical exam – including measuring pulmonary function with an instrument called a spirometer, both at rest and in response to “provocation” challenges (to simulate conditions that trigger bronchospasm).1,2
What else might cause symptoms similar to EIB? Vocal cord dysfunction, for example, may result in the same inspiratory wheezing that we hear in asthma (though it does not usually cause chest pain). Gastroesophageal reflux disease (GERD) can also mimic asthma’s chest discomfort – in addition to triggering asthma independently, since acid triggers nervous system receptors in the esophagus to launch a reflex bronchospasm. During exercise, blood flow to the gut is decreased and gastric emptying is slowed, thus increasing reflux symptoms. If suspected exercise-induced bronchospasm symptoms are accompanied by sore throat or cough, GERD should be thoughtfully considered4. Other important conditions to consider include acute pulmonary (i.e., pneumothorax or pulmonary shunt) or cardiac (pericarditis, coronary vasospasm) conditions, panic attacks, and musculoskeletal problems2. Overtraining, improper training, and overuse (particular of the upper extremity) can cause inflammation and chest discomfort, too4.
If I’m diagnosed with EIB, how do I treat it?
EIB is currently treated the same way as typical asthma: athletes are encouraged to 1) use an inhaled short-acting B2 agonist (i.e., albuterol) 15 minutes before exercise; 2) include an adequate warmup; 3) avoid environmental triggers (i.e., cold, specific pollutants/emissions).
B2 agonists like albuterol act directly on the airways, dilating them. By using this kind of medication before exercise, many people find that they can stave off EIB because the airways have been “pre-dilated,” if you will. If B2 agonists fail to completely resolve symptoms, physicians may also recommend inhaled steroids, or certain medications that prevent release of or block the “pro-constriction” signals I described earlier (i.e., leukotriene modifiers or blockers; mast cell stabilizers to prevent histamine release)1. For the record, there is extensive literature that B2 agonists are not performance-enhancing drugs (i.e., they’re not banned because they don’t do anything extra besides helping people who can’t breathe, well, breathe)5.
I also emphasize the importance of the warmup. Since EIB episodes typically occur within 6-8 minutes of beginning exercise, people have their episodes early. Researchers hypothesize that during an episode, there is a release of catecholamines (“fight or flight” signals, like epinephrine and norepinephrine) that actually dilate the airways and cause a so-called refractory period, wherein another EIB episode cannot take place1.
As for trigger avoidance, athletes should also try to breathe through their noses to better warm incoming air and to even wear a mask in cold environments1.
We know that exercise-induced bronchospasm is common and that it is responsible for significant symptoms amongst the general population, including elite athletes. We know that symptoms of EIB can range from nearly undetectable to severe. We know that health consequences of untreated asthma of any kind can be significant, so it is important to be on the lookout for it.
So should every athlete be screened for EIB? There are no studies available at this point that show that the benefits of screening asymptomatic athletes for EIB would outweigh the costs2. But if you or someone you coach is having chest or breathing discomfort while they exercise, resist the temptation to minimize it. Get it checked out.
Remember: Your breath is your fuel – for exercise, for life. Don’t compromise it.
The author is a third-year medical student at the University of Vermont College of Medicine. She is also a STAR 3 Spinning instructor, Certified Personal Trainer (American Council on Exercise), and author of the popular indoor cycling coaching blog, Spintastic (http://spintastic.blogspot.com/).
1. Parsons JP, Mastronarde JG. Exercise-induced bronchoconstriction in athletes. Chest. 2005. 128:3966-3974
2. Billen A, Dupont L. Exercise induced bronchoconstriction and sports Postgrad MedJ. 2008. 84:512-517
3. Wenzel SE. Asthma: defining of the persistent adult phenotypes. Lancet. 2006; 368:804–13
4. Singh AM, McGregor RS. Differential Diagnosis of Chest Symptoms in the Athlete. Clinical Reviews in Allergy & Immunology. 2005. 29:87-97
5. Carlsen KH, Anderson SD, Bjermer L, Bonini S, Brusasco V, Canonica K, Cummiskey J, Delgado L, Del Giacco
SR, Drobnic F, Haahtela T, Larsson K, Palange P, Popov T, van Cauwenberge P. Treatment of exercise-induced asthma, respiratory and allergic disorders in sports and the relationship to doping: Part II of the report from the Joint Task Force of European Respiratory Society (ERS) and European Academy of Allergy and Clinical Immunology (EAACI) in cooperation with GALEN. Allergy. 2008. 63:492-505.