A Cochrane review included 21 studies with a total of 772 subjects. Eight studies included adult-aged subjects, while 13 examined children. Physical training consisting of whole body aerobic exercise (lasting for at least 20–30 min 2–3 times weekly) was well tolerated with no adverse effects or worsening of asthma symptoms reported. Physical training improved cardiopulmonary fitness as measured by a statistically and clinically significant increase in maximum oxygen uptake (4.92 ml/kg/min, 95% CI 3.98 to 5.87; 8 studies, n=267). No statistically significant effects were observed for forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), minute ventilation at maximal exercise (VEmax) or peak expiratory flow rate (PEFR). Meta-analysis of 4 studies detected a statistically significant increase in maximum heart rate, and following a sensitivity analysis and removal of 2 studies significance was maintained (MD 3.67 bpm, 95% CI 0.90 to 3.44). Although there were insufficient data to pool due to diverse reporting tools, there is some evidence available to suggest that physical training may have positive effects on health-related quality of life, with four of five studies producing a statistically and clinically significant benefit.
Comment: The quality of evidence is downgraded by study limitations (unclear allocation concealment and lack of blinding) and by inconsistency (unexplained variability in results).