Physical activity: Can there be too much of a good thing?

It is widely acknowledged that physical activity in some way, shape, or form is beneficial to a person’s health, a concept that has been around for >2 millennia, having been first espoused by Hippocrates: “Eating alone will not keep a man well; he must also take exercise.”1 Therefore, it should come as no surprise that in this issue of Circulation, Armstrong and colleagues present findings from The Million Women’s Study that highlight the beneficial effects on the risk of coronary heart disease, cerebrovascular disease, and venous thromboembolism that regular moderate physical activity confers among active healthy, middle-aged women in the United Kingdom.2 Findings from the current study have brought some clarity with respect to the questions of how much, how often, and how hard, middle-aged women need to do physical activity to accrue the greatest vascular benefits.