Exercise-based pulmonary rehabilitation for individuals with chronic obstructive pulmonary disease: What is the potential role of biomarkers? A narrative review.

Chronic obstructive pulmonary disease (COPD) is a prevalent, complex, and heterogeneous respiratory condition characterized by cough, dyspnea, exercise intolerance, and persistent airflow limitation. Despite its common features, COPD encompasses a variety of phenotypes-including airflow obstruction, emphysema, chronic bronchitis, asthma-COPD overlap (ACO), and frequent exacerbations-each driven by distinct pathophysiological mechanisms. Over the past three decades, pulmonary rehabilitation (PR) including exercise training has emerged as a cornerstone non-pharmacological intervention for COPD management. However, individual responses to exercise training are highly variable. This variability may stem from both patient-related factors-such as disease severity, comorbid conditions, and motivational levels-and program-related aspects, including session frequency, exercise intensity, and program duration. Consequently, there is a pressing need for reliable predictive and monitoring biomarkers that can identify people most likely to benefit from PR, and guide personalization of treatment protocols regarding intensity and duration. Such biomarkers are essential not only for improving clinical outcomes but also for optimizing the use of limited healthcare resources. Despite their potential, the association between biomarkers and PR outcomes remains underexplored. In this narrative review, we aim to synthesize current evidence on the role of specific biomarkers in predicting and evaluating the effectiveness of PR in individuals with COPD.