Background: Inspiratory muscle training (IMT) is a rehabilitation technique aiming to improve inspiratory muscle strength and endurance.

Aim: This Cochrane systematic review (published on 06 January 2023) aims to explore the effect of IMT as a stand-alone intervention and when combined with pulmonary rehabilitation (PR) for patients with COPD.

Methods: We conducted a comprehensive literature search (last update 20 October 2022). We included RCTs that compared (PR+IMT vs PR) and (IMT vs control/sham) except those that used resistive devices without controlling the breathing pattern or a training load less than 30% of PImax. We used the new Cochrane tool of risk of bias assessment (ROB 2.0) and the five domains of GRADE to assess the certainty of the evidence.

Results: 22 RCTs (1446 participants) compared (PR+IMT vs PR). We did not find an improvement in dyspnea (Borg scale, moderate certainty of evidence), exercise capacity (6MWD, very low certainty of evidence) and quality of life (SGRQ, low certainty of evidence).

37 RCTs (1021 participants) compared (IMT vs control/sham). There was a trend towards improving Borg and the SGRQ (very low certainty of evidence) and a better effect with the 6MWD (moderate certainty of evidence).

For both comparisons, we did not find a larger effect with longer training durations and in participants with respiratory muscle weakness.

Conclusion: Future research should focus on participants with respiratory muscle weakness, explore whether IMT may be a start intervention for patients unable to undergo PR, compare different training protocols and consider training with higher inspiratory flow rate and at high lung volume.