How do cardiorespiratory fitness improvements vary with physical training modality in heart failure patients? A quantitative guide

Background: Peak oxygen consumption (VO₂) is the gold standard measure of cardiorespiratory fitness and a reliable predictor of survival in chronic heart failure patients. Furthermore, any form of physical training usually improves cardiorespiratory fitness, although the magnitude of improvement in peak VO₂ may vary across different training prescriptions. Objective: To quantify, and subsequently rank, the magnitude of improvement in peak VO₂ for different physical training prescriptions using data from published meta-analyses and randomized controlled trials. Methods: Prospective randomized controlled parallel trials and meta-analyses of exercise training in chronic heart failure patients that provided data on change in peak VO₂ for nine a priori comparative analyses were examined. Results: All forms of physical training were beneficial, although the improvement in peak VO₂ varied with modality. High-intensity interval exercise yielded the largest increase in peak VO₂, followed in descending order by moderate-intensity aerobic exercise, functional electrical stimulation, inspiratory muscle training, combined aerobic and resistance training, and isolated resistance training. With regard to setting, the present study was unable to determine whether outpatient or unsupervised home exercise provided greater benefits in terms of peak VO₂ improvement. Conclusions: Interval exercise is not suitable for all patients, especially the high-intensity variety; however, when indicated, this form of exercise should be adopted to optimize peak VO₂ adaptations. Other forms of activity, such as functional electrical stimulation, may be more appropriate for patients who are not capable of high-intensity interval training, especially for severely deconditioned patients who are initially unable to exercise.