Effects of Different Exercise Interventions on Cardiorespiratory Fitness, as Measured by Peak Oxygen Consumption in Patients with Coronary Heart Disease: An Overview of Systematic Reviews.

Background: Exercise is an important component of rehabilitation care for people with coronary heart disease (CHD).

Objectives: The aim of this study was to critically analyze and summarize the existing evidence from published systematic reviews (SRs) and meta-analyses of randomized controlled trials (RCTs) that have evaluated the effects of different types of exercise interventions on cardiorespiratory fitness, as measured by peak oxygen consumption in people with CHD.

Methods: Electronic databases (Cochrane Library, Medline/PubMed, EMBASE, and PEDro) were searched for SRs of exercise interventions of people with CHD. Two reviewers assessed the quality of SRs using the AMSTAR-2 tool and evaluated the strength of evidence quality with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system for relevant outcome measures. Mean difference (MD) and 95% confidence intervals (CIs) were calculated.

Results: Thirty-one SRs (with 125 RCTs) met the study criteria, including 33,608 patients. Compared with usual care, continuous aerobic exercise produced an improvement in peak oxygen consumption, MD of 3.8 mL kg^-1 min^-1 (95% CI: 3.204.4, I² = 67%); high-intensity interval training, MD 6.1 mL kg^-1 min^-1 (95% CI: 0.4-11.8, I² = 97%); resistance training, MD of 2.1 mL kg^-1 min^-1 (95% CI: 0.98-3.2, I² = 60%); combined aerobic and resistance training, MD of 3.0 mL kg^-1 min^-1 (95% CI: 2.5-3.4, I² = 0%); and water-based exercise, MD of 4.4 mL kg^-1 min^-1 (95% CI, 2.1-6.7; I² = 2%).

Conclusion: Exercise interventions improve peak oxygen consumption in people with CHD. However, there was moderate to very-low certainty for the evidence found.