Physical Activity and Cardiorespiratory Fitness in Heart Failure

Recognition of the importance of physical activity in patients with heart failure is relatively recent. Historically, these patients were discouraged from participating in exercise programs due to concerns regarding safety and the perception that exercise might further harm an already damaged myocardium. This perception gradually changed over the last three decades based on numerous studies evaluating physiological, functional, and outcome benefits of exercise in patients with heart failure. Even small increases in fitness level, such as 1-2 ml O₂kg^-1min^-1 changes in peak VO₂, are associated with significant reductions in mortality and heart failure-related hospitalizations. While the impact of training on central mechanisms (e.g., cardiac contractility) remains mixed, the physiological benefits of exercise training include multiple physiological systems, including skeletal muscle, vascular, ventilatory, and autonomic. A growing body of data has demonstrated that heart failure patients randomized to exercise-based rehabilitation programs have lower short- and long-term mortality and fewer heart failure-related hospitalizations. These benefits have been shown to be consistent regardless of gender, type of heart failure (reduced vs. preserved ejection fraction), and cardiac rehabilitation program characteristics (exercise training dose, program duration, exercise only vs. comprehensive rehabilitation, risk of bias, and publication date). There remains a gap in understanding the value of exercise therapy for patients with HF across the medical community, and a major challenge going forward is to improve the referral and participation rates in cardiac rehabilitation.