Effects of exercise on muscle fatigability in COPD: a systematic review and meta-analysis

This systematic review aims to summarise the impact of exercise training on peripheral muscle fatigability in people with COPD, addressing different assessment methods and exercise interventions (i.e. endurance, resistance and combined training).PubMed, CENTRAL, CINAHL and PEDro databases and trial registers were searched from inception to September 2024. We identified randomised and nonrandomised trials assessing pre-to-post-training changes in muscle fatigue resistance, assessed as a reduction in volitional or non-volitional measures of muscle strength or muscle total work output during standardised fatiguing protocols. The Cochrane Risk of Bias 2 (RoB 2) and Risk of Bias in Non-randomized Studies - of Interventions (ROBIN-I) tools were used for assessing risk of bias in randomised controlled trials and nonrandomised studies of interventions, respectively, and meta-analyses were performed.A total of 20 studies (574 participants from 14 randomised controlled trials and 217 from six nonrandomised studies of interventions) were included. Overall, combined endurance and resistance training appeared to improve muscle fatigue resistance. While results varied by study design, type of training and fatiguing protocols, similar improvements were observed in quadriceps fatigue resistance regardless of the assessment method. In contrast, no significant improvements were observed in the fatigue resistance of the arm muscles. However, the presence of moderate to high risk of bias in several included studies may have influenced the results.The findings of this systematic review suggest a positive effect of exercise training in improving muscle fatigue resistance, particularly in the leg muscles, in people with COPD. Future research should establish standardised protocols for assessing muscle fatigability and explore alternative tools to facilitate the clinical implementation of muscle fatigability outcomes into COPD rehabilitation.