17 Objective Assess the role of exercise intensity on changes in cardiorespiratory fitness (CRF) in 18 patients with cardiac conditions attending exercise-based cardiac rehabilitation. 19 Design Systematic review with meta-analysis. 20 Data sources MEDLINE, Embase, CINAHL, SPORTDiscus, PsycINFO and Web of Science. 21 Eligibility criteria for selection Studies assessing change in CRF (reported as peak oxygen uptake; 22 VȮ2peak) in patients post-myocardial infarction and revascularisation,

more »

... ng exercise-based 23 cardiac rehabilitation. Studies establishing VȮ2peak via symptom-limited exercise test with ventilatory 24 gas analysis and reported intensity of exercise during rehabilitation were included. Studies with 25 mean ejection fraction <40% were excluded. 26 Results 128 studies including 13,220 patients were included. Interventions were classified as 27 moderate, moderate-to-vigorous or vigorous intensity based on published recommendations. 28 Moderate and moderate-to-vigorous intensity interventions were associated with a moderate 29 increase in relative VȮ2peak (standardised mean difference ± 95% CI = 0.94 ± 0.30 and 0.93 ± 0.17, 30 respectively), and vigorous-intensity exercise with a large increase (1.10 ± 0.25). Moderate and 31 vigorous intensity interventions were associated with moderate improvements in absolute VȮ2peak 32 (0.63 ± 0.34 and 0.93 ± 0.20, respectively), whereas moderate-to-vigorous intensity interventions 33 elicited a large effect (1.27 ± 0.75). Large heterogeneity among studies was observed for all analyses. 34 Subgroup analyses yielded statistically significant, but inconsistent, improvements in CRF. 35 Conclusion Engagement in exercise-based cardiac rehabilitation was associated with significant 36 improvements in both absolute and relative VȮ2peak. Although exercise of vigorous intensity 37 produced the greatest pooled effect for change in relative VȮ2peak, differences in pooled effects 38 between intensities could not be considered clinically meaningful. 39 Registration Prospero CRD42016035638. 40