Green Means Go … Physical Activity and the Prevention of Heart Failure.

U p until the late 1990s, questions about the safety and benefit of exercise in patients with heart failure (HF) were common. As a result, patients with HF were not routinely asked to engage in regular exercise training. However, over time, much evidence emerged such that regular exercise now represents guideline-based care for patients with HF with reduced ejection fraction (1). In addition to improvements in functional capacity and quality of life and partial reversal of the many physiologic abnormalities that develop in patients with HF (e.g., endothelial function), regular exercise also reduces the risk for clinical outcomes (2–4). Also, the potential benefits of exercise training in patients with HF with preserved ejection fraction are now emerging (5,6). The previously cited effects of exercise in patients with HF are also consistent with observational studies that evaluated the effects of physical activity or cardiorespiratory fitness on the development of HF (7–9). These studies uniformly report more favorable outcomes with a higher dose (volume) of exercise; however, exercise dose was usually qualified (e.g., low/high or active/inactive) rather than quantified (e.g., kilocalories or metabolic equivalent [MET] hours per week).