Abstract
Exercise based cardiac rehabilitation (CR) is recognized internationally as a class 1 clinical practice recommendation for patients with select cardiovascular diseases and heart failure with reduced ejection fraction. Over the past decade, several meta-analyses have generated debate regarding the effectiveness of exercise-based CR for reducing all-cause and cardiovascular mortality. A common theme highlighted in these meta-analyses is the heterogeneity and/or lack of detail regarding exercise prescription methodology within CR programs. Currently there is no international consensus on exercise prescription for CR, and exercise intensity recommendations vary considerably between countries from light-moderate intensity to moderate intensity to moderate-vigorous intensity. As cardiorespiratory fitness [peak oxygen uptake (VO2peak)] is a strong predictor of mortality in patients with coronary heart disease and heart failure, exercise prescription that optimizes improvement in cardiorespiratory fitness and exercise capacity is a critical consideration for the efficacy of CR programming. This review will examine the evidence for prescribing higher-intensity aerobic exercise in CR, including the role of high-intensity interval training. This discussion will highlight the beneficial physiological adaptations to pulmonary, cardiac, vascular, and skeletal muscle systems associated with moderate-vigorous exercise training in patients with coronary heart disease and heart failure. Moreover, this review will propose how varying interval exercise protocols (such as short-duration or long-duration interval training) and exercise progression models may influence central and peripheral physiological adaptations. Importantly, a key focus of this review is to provide clinically-relevant recommendations and strategies to optimize prescription of exercise intensity while maximizing safety in patients attending CR programs.
Highlights
Exercise-based cardiac rehabilitation (CR) is a class 1A recommendation for patients with select cardiovascular diseases (CVD) and heart failure with reduced ejection fraction (HFrEF), as it leads to significant improvements in exercise capacity, CVD risk profile, and reductions in hospital readmissions, cardiovascular (CV) events, and mortality [1,2,3,4,5,6]
Common intensity prescription of HIIT and moderate intensity continuous training (MICT) used in patients with coronary artery disease (CAD) and HF are outlined in Table 2, devised from studies included in reviews by Pattyn et al [52] and Taylor et al [53]
HIIT Progression Model Example In Figure 2 we provide an example of how HIIT commencement and progression could occur during a CR program
Summary
Exercise-based cardiac rehabilitation (CR) is a class 1A recommendation for patients with select cardiovascular diseases (CVD) and heart failure with reduced ejection fraction (HFrEF), as it leads to significant improvements in exercise capacity, CVD risk profile, and reductions in hospital readmissions, cardiovascular (CV) events, and mortality [1,2,3,4,5,6]. Over the past decade, results from RAMIT (Rehabilitation after Myocardial Infarction Trial) [7] and subsequent systematic reviews [8, 9] questioned the effectiveness of exercise-based CR for reducing recurrent CV events [7, 9], CV mortality [9], and all-cause mortality [7,8,9] This generated substantial debate within the scientific community [10,11,12], with speculation that low exercise training intensity and dose may be responsible [13]. This review will discuss how increasing the duration of intervals and training volume may improve physiological adaptations; and will discuss practical applications and progression models to optimize exercise prescription in CR programs
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