Change in (V)over dotO2peak in Response to Aerobic Exercise Training and the Relationship With Exercise Prescription in People With COPD A Systematic Review and Meta-analysis

BACKGROUND: Despite the wide-ranging benefits of pulmonary rehabilitation, conflicting results remain regarding whether people with COPD can improve their peak oxygen uptake ((V)over dotO(2peak)) with aerobic training. RESEARCH QUESTION: The goal of this study was to investigate the effect of aerobic training and exercise prescription on (V)over dotO(2peak) in COPD. STUDY DESIGN AND METHODS: A systematic review was performed by using MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases for all studies measuring (V)over dotO(2peak) prior to and following supervised lower-limb aerobic training in COPD. A random effects meta-analysis limited to randomized controlled trials comparing aerobic training vs usual care was conducted. Other study designs were included in a secondary meta-analysis and meta-regression to investigate the influence of program and patient factors on outcome. RESULTS: A total of 112 studies were included (participants, N = 3,484): 21 controlled trials (n = 489), of which 13 were randomized (n = 288) and 91 were uncontrolled (n = 2,995) studies. Meta-analysis found a moderate positive change in (V)over dotO(2peak) (standardized mean difference, 0.52; 95% CI, 0.34-0.69) with the intervention. The change in (V)over dotO(2peak) was positively associated with target duration of exercise session (P =.01) and, when studies > 1 year duration were excluded, greater total volume of exercise training (P =.01). Similarly, the change in (V)over dotO(2peak) was greater for programs > 12 weeks compared with those 6 to 12 weeks when adjusted for age and sex. However, reported prescribed exercise intensity (P =.77), training modality (P >.35), and mode (P =.29) did not affect (V)over dotO(2peak). Cohorts with more severe airflow obstruction exhibited smaller improvements in (V)over dotO(2peak) (P <.001). INTERPRETATION: Overall, people with COPD achieved moderate improvements in (V)over dotO(2peak) through supervised aerobic training. There is sufficient evidence to show that programs with greater total exercise volume, including duration of exercise session and program duration, are more effective. Reduced effects in severe disease suggest alternative aerobic training methods may be needed in this population.