Effects of inspiratory muscle training in cystic fibrosis: a systematic review

Objective: We performed a systematic review to determine the effect of inspiratory muscle training (IMT) on inspiratory muscle strength and endurance, exercise capacity, dyspnoea and quality of life for adolescents and adults living with cystic fibrosis. Data sources: MEDLINE, EMBASE and CINAHL electronic databases were searched up to January 2008. Review methods: We performed a systematic review using the methodology outlined in the Cochrane Collaboration protocol. Articles were included if: (1) participants were adolescents or adults with cystic fibrosis (>13 years of age); (2) an IMT group was compared to a sham IMT, no intervention or other intervention group; (3) the study used a randomized controlled trial or cross-over design; and (4) it was published in English. Data were abstracted and methodological quality was assessed independently by two reviewers. Results: The search strategy yielded 36 articles, of which two met the inclusion criteria. Both studies used a targeted or threshold device for IMT. Meta-analyses were limited to forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC), which showed no difference in effect between the IMT group and the sham and/or control group. Individual study results were inconclusive for improvement in inspiratory muscle strength. One study demonstrated improvement in inspiratory muscle endurance. Conclusion: The benefit of IMT in adolescents and adults with cystic fibrosis for outcomes of inspiratory muscle function is supported by weak evidence. Its impact on exercise capacity, dyspnoea and quality of life is not clear. Future research should investigate the characteristics of the subgroup of people with cystic fibrosis that might benefit most from IMT.