Background: Physical training may form an important part of the care package for people with cystic fibrosis. Objectives: To determine whether a prescribed regime of physical training produces improvement or prevents deterioration in physiological and clinical outcomes in cystic fibrosis compared to no training. Search strategy: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches and hand searches of relevant journals and abstract books of conference proceedings. Date of the most recent search: 29 November 2010. Selection criteria: All randomised and quasi-randomised controlled clinical trials in which a prescribed regimen of physical training is compared to no physical training in people with cystic fibrosis. Data collection and analysis: Two authors independently selected studies for inclusion, assessed methodological quality and extracted data. Main results: Of the 28 studies identified, seven studies which included 231 participants, met the inclusion criteria. This review does provide some limited evidence from both short- and long-term studies that aerobic or anaerobic physical training has a positive effect on primary outcomes (exercise capacity, strength and lung function) but improvements are not consistent between studies.Authors' conclusions: Conclusions about the efficacy of physical training in cystic fibrosis are limited by the small size, short duration and incomplete reporting of most of the studies included in this review. Physical training is already part of the care package offered to most people with cystic fibrosis and there is a lack of evidence to actively discourage this. The benefits obtained from including physical training in a package of care may be influenced by the type of training programme. Further research is needed to assess comprehensively the benefits of exercise programmes in people with cystic fibrosis and the relative benefits of the addition of aerobic versus anaerobic versus a combination of both types of physical training to the care of people with cystic fibrosis.