PA and Exercise in Patients With Asthma
Several population-based studies have shown patients with asthma engage in less PA and are more sedentary than their non-asthmatic counterparts.[8,9] The decreased levels of PA are related to the fear of triggering asthma symptoms, weather affecting asthma, time constraints, and the belief that PA should be avoided in asthma and not because of their degree of airway obstruction.
In up to 90% of patients with asthma, exercise is a trigger of asthma symptoms such as cough, wheezing, or shortness of breath. During exercise, there is a net loss of heat, water, or both, due to hyperventilation of air that is cooler and dryer than the lung, which leads to bronchoconstriction. With proper premedication before exercise and the use of warm-up and cool-down exercises (15 minutes each), the incidence of exercise-induced asthma symptoms is low. Extensive literature exists supporting the safety and benefits of exercise conditioning on cardiopulmonary fitness, asthma symptoms, and asthma-related quality of life. Both the American College of Sports Medicine (ACSM) and American Thoracic Society (ATS) recommend regular exercise for patients with asthma.[11,12]
Currently, the ACSM recommends engaging in aerobic exercise at least 2–3 days per week, yet < 50% of patients meet this recommendation. Aerobic exercises, such as walking or exercises that use large muscle groups, are recommended for patients with asthma, whereas other exercises, such as running, cycling, and basketball, may be more likely to cause symptoms of exercise-induced asthma. Currently, there is no consensus on the optimum intensity of exercise, but exercising at 50% of peak oxygen uptake or at limits as tolerated by symptoms is recommended. The optimal duration of exercise is 20–30 minutes of continuous activity, although patients starting an exercise program may need to work up to this goal gradually. The ACSM guidelines endorse the use of exercise prescriptions for patients with asthma, although most existing data are in patients with COPD.
Although a formal pulmonary rehabilitation (PR) program is frequently recommended in patients with COPD (see below), there have been few trials evaluating PR among adults with asthma. Thus far, existing data suggest that exercise training and rehabilitation improve exercise tolerance and/or health status/quality of life in persons with asthma. The ATS recommends PR for patients whose lung disease (including asthma) results in loss of independence; anxiety or breathlessness with activities; or limitations in social, leisure, indoor, or outdoor activities. It is important to distinguish between formal exercise defined by objective physiologic changes and routine gradual, moderate-intensity physical activities, such as walking or playing.
It is possible that a more frequent (ie, daily) moderate-intensity activity like walking is what confers the protective effects in asthma. Walking interventions in patients with asthma can improve quality of life and asthma control. Whether other outcomes are impacted, such as reduced health care utilization, needs further study.
About half of asthma may be triggered or worsened by exposure to allergens, such as house dust mites, molds, pests (cockroaches, rodents), animal dander, and pollen. Moreover, these allergens may also cause rhinitis, inflammation in the nasal passages that makes it difficult for patients to engage in physical activity. An evaluation by an allergist/immunologist should be considered before starting an exercise program, to help identify triggering allergens, review avoidance measures, and consider addition of pharmacologic treatments if necessary (see Table 1 for additional practical tips for patients).
The National Asthma Education and Prevention Program guidelines for the management of asthma recommend that clinicians advise patients to avoid, to the extent possible, exertion or exercise outside when levels of air pollution are high. The relationship between increased levels of air pollution and asthma risk and impairment are well documented, with increases in asthma exacerbations and emergency care visits. The relationship between PA, exercise, and air pollution is not as clear. One foundational epidemiologic study found that heavy outdoor exercise in a high ozone concentration was associated with a higher risk of asthma in school-aged children. Air pollution should be taken into consideration when asthma patients engage in PA, especially in outdoor urban environments. To limit the effects of poor air quality during PA and exercise, patients should be advised to check air pollution levels (Table 1). On poor air quality days, patients should be instructed to avoid outdoor PA and exercise, engage in indoor PA and exercise, or reduce the intensity and duration of the outdoor activity. Further, patients should be advised to avoid engaging in PA and exercise in high-pollution areas, such as within 50 feet of a road, and when pollution levels tend to be highest, often midday or afternoon.
In addition to engaging in aerobic exercise, other alternative exercises, such as yoga or breathing exercises, should be considered. Both yoga and diaphragmatic breathing exercises have been shown to lead to improvements in asthma-related quality of life and asthma symptoms.[16,17] The mechanistic pathways of how these exercises improve asthma are not fully elucidated, and randomized, controlled trials with larger samples sizes and high reporting quality are needed to confirm these preliminary effects.
Journal for Nurse Practitioners. 2017;13(1):41-46. © 2017 Elsevier Science, Inc.