Optimizing Outcomes in Cardiac Rehabilitation: The Importance of Exercise Intensity

Figures

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  Figure 1. Physiological adaptations from exercise training that may contribute to improvement in VO2peak in patients with cardiovascular disease or heart failure. Cardiac adaptations contribute to VO2peak improvements primarily through increases in stroke volume. Pulmonary adaptations contribute to VO2peak by optimizing arterial oxygen content and therefore oxygen delivery. Muscle adaptations contribute to VO2peak improvements through increased exercise tolerance and enhanced oxygen extraction. Vascular adaptations contribute to oxygen delivery by reducing arterial resistance, increasing capillary density, and enhancing blood flow distribution, which in turn enhances function of the cardiac, pulmonary, and muscle systems. Increases in plasma volume can occur within days of commencing exercise training. Adaptations within skeletal muscle and to the vasculature can occur within weeks of training. Current evidence supports greater adaptations in mitochondrial content, vascular vasodilatory function, and stroke volume following HIIT compared with MICT, although the precise cardiac mechanisms that lead to increased stroke volume remain unclear. VO2peak, peak oxygen uptake; SV, stroke volume;…

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  Figure 2. Example of a HIIT progression model within a cardiac rehabilitation program. Exercise intensity remains constant for each HIIT protocol with high intensity intervals eliciting 85-95 %HRpeak and RPE 15-18, and the low intensity intervals involving recovery at 50-75 %HRpeak or RPE 11-14. CR, cardiac rehabilitation; HIIT, high intensity interval training; HRpeak, peak heart rate; MICT, moderate intensity continuous training; RPE, rating of perceived exertion on 6-20 Borg scale; VO2peak, peak oxygen consumption. This figure has been adapted from the previously published work of (158); with permission of Mayo Foundation for Medical Education and Research, all rights reserved.