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

Abstract

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. Article see p 721 The key findings from this article relate to the frequency, intensity, and total amount of physical activity that were associated with optimal vascular benefits among middle-aged women. Interestingly, the relationship between the frequency of activity (either strenuous or any) and vascular risk was not linear but rather U-shaped; in women who engaged in strenuous activity (defined as “enough to cause sweating or a fast heart rate”), the optimal frequency of activity in terms of vascular risk reduction was 2 to 3 times per week which was associated with significant relative risk reductions of 17% to 19% in comparison with the rarely/never group. Any further increase in the frequency of strenuous exercise beyond that point was associated with an increased vascular risk. For any activity, which mainly included walking, gardening, and housework, the optimal frequency was 4 to 6 times per week (in comparison with rarely/never), which was associated with a slightly greater 17% to 25% reduction …