Exercise Capacity in Chronic Respiratory Diseases in the Context of Multimorbidity: A Systematic Review and Meta-analysis

Chronic respiratory diseases (CRD) are accompanied by coexisting chronic conditions, which may occur individually or as multimorbidity burden or patterns. These conditions may contribute to exercise intolerance, a determinant of prognosis. However, their association with exercise capacity remains unclear. This study aimed to evaluate, in individuals with CRD, the association between one or more other chronic conditions (multimorbidity) and exercise capacity and to quantify this relationship through meta-analysis.

Searches were conducted in PubMed, Scopus, Embase, Web of Science, Virtual Health Library, and CINAHL until July 2025. Observational studies evaluating exercise capacity in adults with CRD, with coexisting chronic conditions, using field- or laboratory-based tests were included. Methodological quality was assessed using Joanna Briggs Institute checklists. Meta-analyses were performed using random-effects models.

A total of 49 studies were included in the qualitative synthesis (n=28,972 participants), and 23 contributed to the quantitative synthesis. Most studies involved individuals with chronic obstructive pulmonary disease. Sensitivity analyses excluding outliers yielded clinically meaningful reductions in six-minute walk distance for metabolic (MD -34.26 m; 95% CI -46.98 to -21.53; I²=5.91%), cardiovascular (MD -27.18 m; 95% CI -39.59 to -14.78; I²=16.19%), and mental health conditions (MD -29.52 m; 95% CI -54.89 to -4.15; I²=0%).

In individuals with CRD, multimorbidity is associated with reduced exercise capacity, with clinically meaningful reductions particularly in the presence of metabolic and cardiovascular conditions. Although the certainty of evidence is very low, these findings highlight the importance of considering multimorbidity when interpreting exercise limitation in CRD.

PROSPERO, identifier CRD420251125343.