Respiratory muscle endurance training among patients with chronic diseases: A systematic review of available evidence

This systematic review summarizes the available evidence on respiratory muscle endurance training involving voluntary isocapnic hyperpnoea among patients with chronic diseases. It includes both randomized and non-randomized controlled trials implementing this exercise training modality performed either alone or in combination with other interventions. It was conducted using the following databases: PubMed, Google Scholar, Physiotherapy Evidence Database (PEDro), Embase, CINAHL, CENTRAL, Cochrane and ReeDOC. It was drafted in accordance with the PRISMA guidelines. The final analysis was conducted on 12 studies (n = 257). There was heterogeneity in participants, training modalities and comparators used. The underpowered level of evidence is attributable to the lack of robustness of the original studies, including a lack of description of the intervention, lack of blinding, and missing data. Respiratory muscle endurance training is an exercise training modality that is both safe and feasible, even in the setting of the patient's home. It increases respiratory endurance time. However, its effect on peak oxygen consumption at exercise, maximal work rate, 6-min walking distance, quality of life, dyspnoea and fatigue remains to be confirmed. In conclusion, this systematic review shows that respiratory muscle endurance training increases respiratory endurance among patients with chronic diseases. The populations that benefit the most and the mechanisms involved remain to be investigated. Further high-quality studies are needed to understand its role, whether it is performed alone or as an add-on modality to usual pulmonary rehabilitation programmes.