A Cochrane review included 13 studies with a total of 402 adults and children with a wide range of disease severity. There was some limited evidence from both short- and long-term studies that aerobic or anaerobic physical training, or a combination of both has a positive effect on primary outcomes (exercise capacity, strength and lung function, health-related quality of life). Although improvements are not consistent between studies, the most consistent effects of the heterogeneous exercise training modalities and durations were found for maximal aerobic exercise capacity (in four out of six studies).
Comment: The quality of evidence is downgraded by imprecise results (limited study size for each comparison), by inconsistency (variability in results across studies) and by indirectness (mixed study populations, short duration of studies, questionable clinical significance of results).