Should physicians prescribe physical training to improve symptom control and quality of life for patients with asthma?
Physical training lasting for at least 20 to 30 minutes, two to three times a week for at least six weeks, improves physical fitness in patients with asthma. Physical training is not associated with worsening of asthma symptoms, and it improves health-related quality of life. (Strength of Recommendation: B, based on inconsistent or limited-quality patient-oriented evidence.)
Asthma affects 300 million persons worldwide.1 In the United States, the prevalence of asthma increased from 7.3 percent in 2001 to 8.2 percent in 2009, affecting nearly 25 million persons.2 Despite being treatable, asthma was responsible for 10.5 million missed school days and 14.2 million missed work days in 2008, and was responsible for 1.75 million emergency department visits and 456,000 hospitalizations in 2007.3
This Cochrane review examined the effect of medically supervised physical training on the health of persons with asthma. Training programs consisted of aerobic and strength training lasting 30 to 90 minutes, two to three days per week for six to 16 weeks. Outcomes included physiologic measurements, exercise capacity, and measures of asthma severity and health-related quality of life. Although 19 studies with 695 patients eight years and older were included, different outcome measures limited the ability to pool results. In comparison with those in education-only control groups, patients who participated in physical training programs improved their cardiopulmonary fitness as measured by maximum oxygen uptake (mean difference = 5.57 mL per kg per minute; 95% confidence interval [CI], 4.36 to 6.78; six studies with 149 participants). Physical training also improved maximum expiratory ventilation (mean difference = 6.0 L per minute; 95% CI, 1.57 to 10.43; four studies with 111 participants); there was no effect on resting lung function. Four out of five studies demonstrated a positive effect on health-related quality of life. No adverse effects of training on asthma symptoms were reported.
The improvements in cardiorespiratory parameters are clinically significant. An increase in maximum oxygen uptake of 5.57 mL per kg per minute is equivalent to the difference between being limited to light activities (e.g., desk work) to tolerating moderate activities (e.g., walking or biking).4,5 Also, the improvements in quality of life are considered to be clinically significant.6,7
The physical training regimens in this study were conducted under controlled conditions and may not be generalizable. On the other hand, because none of the programs in this review were associated with adverse effects, it would seem reasonable for physicians to recommend that patients with asthma take advantage of locally available physical training programs.
Although clinical practice guidelines note that exercise is a potential trigger of asthma, the National Asthma Education and Prevention Program advocates promoting physical activity,8 and the Scottish Intercollegiate Guidelines Network suggests that physical training be viewed as part of the general approach to improving the lifestyle of patients with asthma.9