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[Exercise is Medicine]

Exercise for Asthma Patients: Little Risk, Big Rewards

Vincent Disabella, DO, with Carl Sherman

Series Editor: Nicholas A. DiNubile, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 26 - NO. 6 - JUNE 98


In Brief: The standard exercise recommendation—20 to 30 minutes at 60% to 85% of maximum heart rate four or five times a week—should be part of asthma management. Not only will patients benefit in a general way, but improved fitness is likely to reduce airway reactivity and medication use. The capacity to exercise, however, requires good general control of asthma, including use of inhaled corticosteroids and avoidance of triggers. In addition, patients must be taught to prevent exercise-induced bronchoconstriction by using inhaled medications and strategies like avoiding cold-weather exercise.

Not so many years ago, to prescribe exercise for people with asthma would have been regarded as imprudent, if not irresponsible. Strenuous physical activity can trigger bronchospasm, cause an attack, and put the asthma patient at risk, the reasoning went. Patients were routinely counseled to play it safe and avoid exertion.

But the thinking about asthma and its management has changed dramatically in recent years. It is now universally recognized that chronic asthma, which affects 14 million to 15 million Americans (1), is fundamentally a disease of airway inflammation, and that with appropriate focus on that component, symptoms can be effectively controlled in nearly all cases.

How Exercise Helps

With the management modalities currently available, virtually all asthma sufferers not only can but should exercise. They stand to reap the same benefits as others from regular physical activity through a reduced risk of cardiovascular disease, diabetes, and other health problems. In addition, some studies have found that exercise can improve the course of the disease itself. Reductions in airway responsiveness have been shown in patients who followed aerobic exercise programs (2). Some research (3) also suggests that asthma sufferers who exercise regularly have fewer exacerbations, use less medication, and miss less time from school and work.

When they are physically fit and free from significant airway obstruction, people who have asthma respond to exercise very much like others, and their maximal heart rate, ventilation, blood pressure, and work capacity fall within the normal range (4). Sedentary asthma sufferers, on the other hand, produce more lactate and are more subject to acidosis than unfit individuals without asthma who undertake similar physical exertion (5).

It is unfortunate, then, that asthma sufferers tend to be inactive and deconditioned (6). The reasons for this most likely have more to do with fear, misinformation, and inadequate management than with intrinsic limitations imposed by the disease. That things could be otherwise is suggested by the substantial numbers of active children and adults, recreational athletes, and even elite athletes whose exertions are not deterred by their disease. In the 1984 Olympics, for example, 26 of 597 athletes had a documented history of chronic asthma (7).

There is abundant evidence that when asthma is untreated, tolerance for even mild activity is curtailed, but with effective management even patients who have fairly severe asthma are able to exercise and, in many cases, participate in competitive sports (8). One essential means to this end is a protocol that keeps asthma generally under control, with an emphasis on anti-inflammatories, other medications when needed, and environmental interventions as described below. The other is treatment targeted specifically to patients who experience exercise-induced asthma (EIA).

Exercise as Trigger

Exercise is one of the well-known triggers of bronchoconstriction. Almost all individuals who have chronic asthma will have symptoms when they exercise at a sufficient intensity (9), and many people with no other asthma symptoms experience EIA (see "Exercise-Induced Asthma," below).

Symptoms may be obviously pulmonary—chest tightness, shortness of breath, coughing—but for many patients they take the form of stomachache, chest pain, or nausea (10). EIA symptoms typically appear after 8 to 10 minutes of vigorous exercise and may worsen after activity is terminated. Episodes usually remit completely within 30 to 60 minutes and do not increase airway reactivity or induce long-term deterioration in lung function. Whether EIA induces a late-phase reaction 4 or more hours after the initial episode in some patients is a matter of controversy (11).

One interesting feature of EIA is the occurrence in about half of individuals of a "refractory" period: If exercise is repeated within 1 hour of the first bout, bronchial narrowing recurs but is less severe than the previous episode. Within this period it may be possible to exercise longer and more strenuously without difficulty (12).

Although the exact mechanism of EIA is obscure, most investigators believe that changes in temperature and moisture levels within the airway are responsible. Airway temperature falls as respiration increases during exertion, then rises rapidly when exercise ends—a process that appears to eventuate in bronchial narrowing. Rapid breathing may increase evaporation of water from the surface of the bronchial mucosa, leading to mast-cell degranulation and smooth-muscle contraction (13).

These observations have useful clinical implications: Because EIA is usually less of a problem when patients exercise in warm, moist air than in cold, dry air, patients may be counseled to exercise indoors in cold weather, or to adopt strategies like covering the mouth and nose with a scarf to reduce airway temperature fluctuations when exercising outdoors. It may be helpful to induce a refractory period by timing strenuous exercise to begin after a warm-up and an interval of rest.

But even with intelligent precautions, most asthma patients need pharmacotherapy to prevent EIA. Pretreatment with inhaled beta-adrenergic agonists, generally considered the drugs of choice for this purpose, will reduce or eliminate symptoms in about 90% of patients (14), but other agents may need to be added or substituted in resistant cases. Studies have shown that the use of long-acting beta-2-agonists such as salmeterol xinafoate have protective effects against EIA, especially when used with concomitant inhaled glucocorticoid therapy. The use of salmeterol only once daily to prevent tolerance has been shown to be effective in minimizing the symptoms of EIA (15). The use of long-acting beta-2-agonists has also been shown to improve the symptoms of nocturnal asthma (16).

While improved fitness does not abolish EIA, it has a positive impact on it. Whatever the mechanism, increased ventilation appears to be the EIA trigger; fit individuals use oxygen more efficiently and need to move less air at a given level of exercise intensity.

Untreated EIA is a potent barrier to exercise, but with proper management it need not be a limiting factor. A study (17) of 31 children who had asthma found no correlation between cardiovascular fitness and EIA: Even many in whom EIA (when assessed without preexercise medication) was severe were capable of achieving normal fitness. The same study attested to the efficacy of good general asthma management: The 12 children who regularly received inhaled corticosteroids had significantly less severe symptoms than the other children, which "confirms the importance of inhaled steroids in the prevention of exercise-induced asthma," the authors concluded.

Managing Chronic Asthma

Inhaled medications. Both for the general control of asthma and to enhance the capacity for exercise, daily anti-inflammatory therapy has emerged as the keystone. As recommended in the revised guidelines for asthma diagnosis and management issued last year by the National Heart, Lung, and Blood Institute (NHLBI) (1), I almost always prescribe an inhaled corticosteroid as first-line therapy for my patients of any age who have persistent asthma.

One of the new additions to the asthma armamentarium, the leukotriene modifiers zafirlukast and zileuton, may replace inhaled corticosteroids in selected cases (see Highlight, "Antileukotrienes Control Asthma in Many Patients," page 28). These drugs show great promise for treating patients who have known allergic triggers of their asthma exacerbations. Epidemiologic studies suggest that inhalation of environmental allergens is the most important cause of asthma. Leukotrienes also play a very important role in aspirin-induced asthma (18).

Cromolyn sodium or nedocromil sodium is an alternative for patients who have persistent problems with corticosteroids (ie, oral candidiasis), or these drugs may be added to the regimen. The addition of these drugs should be entertained in patients who suffer from allergies or for whom inhaled glucocorticoid or beta-2-agonist therapy is failing.

Beta-agonists are no longer considered first-line drugs for chronic treatment, although a long-acting agent of this class (salmeterol) may be added for moderate to severe asthma that does not respond adequately to other drugs. A study by Pauwels et al (19) shows that the use of long-acting beta-2-agonists increased lung function, decreased symptoms, and decreased the need for beta-2-agonist rescue therapy in patients on inhaled glucocorticoid therapy. Short-acting beta-agonists (albuterol and terbutaline sulfate) are still recommended as "rescue treatment" for rapid relief of acute symptoms.

Patient education is essential in asthma management, particularly when inhaled corticosteroids are used. Patients should be carefully instructed in inhaler technique, including the use of a spacer to optimize deposition and to prevent oral candidiasis. To this end, patients should also be taught to rinse their mouths with water or an antimicrobial mouthwash after each application of inhaled steroids.

Oral medications. I reserve oral corticosteroids for severe asthma exacerbations and withdraw them as soon as acceptable control has been reestablished. In the absence of other conditions contributing to airway obstruction (such as emphysema or lupus erythematosus), asthma patients should not need long-term systemic corticosteroids.

Allergy control. Allergy is a factor in most cases of asthma, so all patients should be tested to identify triggers. The following actions should be taken, as needed, to minimize exacerbating conditions:

  • When sensitivity has been documented, take steps to reduce exposure to dust mites: Have carpets cleaned professionally and often, encase mattresses and pillows in plastic, and wash sheets and blankets weekly in very hot water;
  • Keep indoor humidity below 50% to reduce exposure to mold as well as dust mites;
  • Use poison bait, traps, and careful housekeeping to minimize cockroaches, often a problematic antigen;
  • Ideally, because animal dander is a frequent trigger, remove pets from the house, or at least keep them out of the room where the patient sleeps; and
  • Avoid, to the extent possible, exposure to nonspecific irritants such as tobacco smoke, wood smoke, air pollution, and cleaning agents.

When the allergic component of asthma is prominent, I often prescribe a second-generation nonsedating antihistamine or inhaled ipratropium bromide for use on a regular basis. Immunotherapy (allergy shots) may be indicated for patients whose allergies are due to known triggers and cannot be controlled by avoidance, antihistamines, and inhaled steroids.

Testing. The importance of testing in asthma control is emphasized in the NHLBI guidelines (1); office spirometry is recommended when the disease is first diagnosed, when peak expiratory flow has stabilized, and every 1 to 2 years thereafter. Patients who have moderate to severe asthma should be taught to monitor their own peak flow daily and take preventive measures when a decline heralds an imminent attack.

The Exercise Prescription

Preexercise assessment. In addition to testing for asthma control, testing is also important before beginning an exercise program. A patient's asthma should be well controlled as indicated by both peak flow monitoring and a 1-second forced expiratory volume (FEV1) at or above 80% of expected levels. For middle-aged and older patients who have been inactive, stress testing to assess cardiovascular fitness is also indicated.

Exercise goals. The exercise goal for people who have asthma, as for most people, should be 20 to 30 minutes of activity that raises heart rate to 60% to 85% of maximum, four or five times a week. To the extent possible, I try not to discourage patients from any exercise they find congenial. Still, they should know that they are less likely to encounter difficulties if they make sensible modifications of their exercise practices, such as running indoors when the weather is cold or air pollution is high. (See the Patient Adviser, "Your Guide to Exercising With Asthma")

Cautions. Patients should be counseled to skip their exercise sessions on days when they are wheezing, when allergies are particularly troubling, or when peak flow testing suggests a decline in lung function. The importance of using a hand-held peak flow meter to assess airway hypersensitivity and determine the potential for a difficult day should be made clear to patients who have moderate to severe asthma.

I also emphasize the importance of inducing a refractory period. This can be accomplished by various methods, including 20 to 30 minutes of low-intensity exercise, seven 30-second periods of sprinting separated by short intervals, or a 15-minute warm-up at 60% of VO2 max. These maneuvers should be performed a half-hour before more strenuous exercise (20). After warming up, patients should pretreat themselves with two puffs of a short-acting beta-agonist inhaler to protect against an attack for 2 to 6 hours.

After exercise, a cool-down period of several minutes of stretching or less strenuous activity will allow a gradual rewarming of the airways and make postexercise symptoms less likely.

Patients should be taught to deal with EIA symptoms if they appear despite preventive measures. While some well-trained athletes can "break through" their symptoms (continue to exercise until symptoms remit), this carries unacceptable risks for most patients. They should stop and take two more puffs of the beta-agonist inhaler and seek medical attention if this does not relieve symptoms.

The few patients who continue to be troubled by EIA despite preventive measures might be advised to try activities that have less asthmogenic potential, such as swimming, which exposes the exerciser to warm, moist air that tempers the effect on the airways. Sports that involve short bursts of strenuous activity, such as tennis or half-court basketball, provide less aerobic benefit than more continuous activities like running or biking, but may be more fitting for patients with persistent EIA.

Encourage and Educate

Even when asthma is well-controlled, some patients may need active encouragement and education to overcome their fears. It should be emphasized that far from being contraindicated by their disease, exercise is a valuable adjunct to its management.

References

  1. Highlights of the Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma, National Institutes of Health publication No. 97-4051A. Bethesda, MD, National Institutes of Health, National Heart, Lung, and Blood Institute, May 1997
  2. Cochrane LM, Clark CJ: Benefits and problems of a physical training programme for asthmatic patients. Thorax 1990;45(5):345-351
  3. Szentagothai K, Gyene I, Szocska M, et al: Physical exercise program for children with bronchial asthma. Pediatr Pulmonol 1987;3(3):166-172
  4. Bundgaard A: Exercise and the asthmatic. Sports Med 1985;2(4):254-266
  5. McFadden ER Jr: Exercise performance in the asthmatic. Am Rev Respir Dis 1984;129(2 pt 2):S84-S87
  6. Gong H Jr: Breathing easy: exercise despite asthma. Phys Sportsmed 1992;20(3):159-167
  7. Voy RO: The US Olympic Committee experience with exercised-induced bronchospasm, 1984. Med Sci Sports Exerc 1986;18(3):328-330
  8. Cypcar D, Lemanske RF Jr: Asthma and exercise. Clin Chest Med 1994;15(2):351-368
  9. McFadden ER Jr: Exercise-induced asthma: assessment of current etiologic concepts. Chest 1987;91(6 suppl):151S-157S
  10. Spector SL: Update on exercise-induced asthma. Ann Allergy 1993;71(6):571-577
  11. McFadden ER Jr, Gilbert IA: Exercise-induced asthma. N Engl J Med 1994;330(19):1362-1367
  12. Anderson SD: Exercise-induced asthma, in Middleton E, Reed CE, Ellis EF, et al (eds): Allergy: Principles and Practice, ed 4. St Louis, Mosby, 1993, pp 1343-1367
  13. Anderson SD: Is there a unifying hypothesis for exercise-induced asthma? J Allergy Clin Immunol 1984;73(5 pt 2):660-665
  14. Lemanske RF Jr, Henke KG: Exercise-induced asthma, in Gisolfi C, Lamb DR (eds): Youth, Exercise and Sport: Perspectives in Exercise Science and Sports Medicine. Indianapolis, Benchmark Press, 1989, vol 2, pp 465-511
  15. Simons FE, Gerstner TV, Cheang MS: Tolerance to the bronchoprotective effect of salmeterol in adolescents with exercise-induced asthma using concurrent inhaled glucocorticoid treatment. Pediatrics 1997;99(5):655-659
  16. D'Urzo AD: Long-acting beta-2-agonists: role in primary care asthma treatment. Can Fam Physician 1997;43(Oct):1773-1777
  17. Thio BJ, Nagelkerke AF, Ketel AG, et al: Exercise-induced asthma and cardiovascular fitness in asthmatic children. Thorax 1996;51(2):207-209
  18. O'Byrne PM, Israel E, Drazen JM: Antileukotrienes in the treatment of asthma. Ann Intern Med 1997;127(6):472-480
  19. Pauwels RA, Löfdahl CG, Postma DS, et al: Effect of inhaled formoterol and budesonide on exacerbations of asthma: Formoterol and Corticosteroids Establishing Therapy (FACET) International Study Group. N Engl J Med 1997;337(20):1405-1411
  20. Wilkerson LA: Exercise-induced asthma. J Am Osteopath Assoc 1998;98(4):211-215


Exercise-Induced Asthma

Chronic asthma is not a prerequisite for having exercise-induced asthma (EIA). While patients who have chronic asthma are virtually certain to develop bronchoconstriction if they exercise strenuously enough, 40% of people who suffer from hay fever but have no other asthma symptoms are afflicted with EIA. Overall, an estimated 12% to 15% of the population has symptoms of EIA, and its prevalence among athletes has been reported to be as high as 11% (1).

EIA in an individual who does not suffer from chronic asthma is likely to remain undiagnosed, particularly when symptoms are vague and atypical—chest discomfort, nausea, or stomachache—rather than the classic presentation of cough, shortness of breath, or wheezing (2). Some athletes may simply attribute their difficulties to being out of shape. Relatively mild symptoms may come to the physician's attention only through routine questioning, such as in the course of a preparticipation physical.

A workup for suspected EIA should include office spirometry, done while the patient is at rest, to rule out chronic asthma. If the history makes a diagnosis of EIA equivocal, I use formal exercise testing to confirm the diagnosis. In the rare cases where the diagnosis is still not certain, I use the "gold standard" of a methacholine challenge to test for bronchoconstriction. I also retest the patient 6 to 8 weeks after the initial exam to assess the efficacy of his or her current therapy.

Whether or not they also have chronic asthma, individuals who have EIA are likely to benefit from treatment with an inhaled short-acting beta-agonist 15 to 30 minutes before exercise. For athletes who expect to compete over the course of several hours (or children who may be active throughout the school day), a long-acting beta-agonist may be preferable.

Warm-up exercise at a level below the EIA threshold, such as light aerobic activity, before a regular workout may reduce the severity of symptoms but is unlikely to make pretreatment unnecessary (3). Patients should also be taught strategies to minimize EIA, such as avoiding exercise in cold, dry air.

Patients who are discouraged from activity by EIA might take heart from the experience of Olympic athletes: A survey (4) of participants in the 1984 Los Angeles Games found that 67 of 597 athletes had EIA—and won 41 medals.

References

  1. Rice SG, Bierman CW, Shapiro GG, et al: Identification of exercise-induced asthma among intercollegiate athletes. Ann Allergy 1985;55(6):790-793
  2. Mellion MB, Kobayashi RH: Exercise-induced asthma. Am Fam Physician 1992;45(6):2671-2677
  3. Storms WW, Joyner DM: Update on exercise-induced asthma: a report of the Olympic Exercise Asthma Summit Conference. Phys Sportsmed 1997;25(3):45-55
  4. Voy RO: The US Olympic Committee experience with exercised-induced bronchospasm, 1984. Med Sci Sports Exerc 1986;18(3):328-330


Dr Disabella is the assistant director of primary care sports medicine and the primary care sports medicine fellowship program for Crozer-Keystone Health System in Springfield, Pennsylvania. Mr Sherman is a freelance writer in New York City. Dr DiNubile is an orthopedic surgeon in private practice in Havertown, Pennsylvania, specializing in sports medicine and arthroscopy. He is the director of Sports Medicine and Wellness at the Crozer-Keystone Healthplex in Springfield, Pennsylvania; a clinical assistant professor in the department of orthopedic surgery at the University of Pennsylvania in Philadelphia; the orthopedic consultant to the Philadelphia 76ers basketball team and the Pennsylvania Ballet; and a member of the editorial board of The Physician and Sportsmedicine. Address correspondence to Vincent Disabella, DO, 196 W Sproul Rd, Suite 110, Springfield, PA 19064; e-mail to [email protected].


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