In a meta-analysis published this week in Circulation, investigators have attempted to quantify how much exercise you really need in order to reduce your cardiovascular risk.
The authors included 33 studies on exercise and cardiac risk published since 1995. From their analysis, they conclude that (compared with being completely sedentary) exercising, at a moderate intensity, for 150 minutes per week (about 20 minutes per day) reduces your cardiovascular risk by 14%; and that exercising 300 minutes per week (about 40 minutes per day) reduces your risk by 20%.
These findings are consistent with the 2008 Federal guidelines for exercise, which recommends at least 20 minutes per day.
Sources:
Sattelmair J, Pertman J, Ding EL, et al. Dose response between physical activity and risk of coronary heart disease. A meta-analysis. Circulation 2011; DOI: 10.1161/CIRCULATIONAHA.110.010710.
DrRich:
I think that there may be a typo. With 150 min/week, the abstract says that the relative risk reduction was 14%, not 1%. Also, it appears that this number comes from 9 studies, not 26:
“Among the 33 studies, 9 allowed quantitative estimates of leisure-time physical activity. Individuals who engaged in the equivalent of 150 min/wk of moderate-intensity leisure-time physical activity (minimum amount, 2008 US federal guidelines) had a 14% lower coronary heart disease risk (relative risk, 0.86; 95% confidence interval, 0.77 to 0.96) compared with those reporting no leisure-time physical activity. ”
It also says that the risk reduction was significantly lower for men than women. Since I can’t afford to purchase the full article, what were the separate relative risk reductions for men and women?
Also, did they control for other risk factors that are interrelated with exercise? For example, regular exercise tends to lower weight, modify biochemistry, etc. which also affects the endpoints that they were examining. In this case, counterintuitively, it may have been proper NOT to control for these factors, because they are affected by the exercise?
Thanks.
S. Nelson
S. Nelson,
Thanks for pointing out the typo.
This meta-analysis was complex, and they actually wound up using all 33 studies, even the non-quantitative ones, to reach their conclusion.
The risk reduction for low and high exercise levels for men was 9 and 18%, and for women was 20 and 28%. They could offer no explanation for this difference, but speculated it might have been due to a difference in unmeasured additional risk factors. They were unable to relate the exercise benefits to the presence or absence of other risk factors. Gender, apparently was the only risk factor they could tabulate reliably among these studies.
Dr.Rich -
The difference between men & women could also be a function of how the majority studies defined/tabulated “exercise.” Logically, people consider this to be physical activity outside of occupational activity.
It could be that men are, on average, are more physically active at work, so their baseline is effectively different?
S. Nelson
DrRich -
Since the average of 9% & 20% for the low exercise level is 14%, that suggests to me that there were about equal numbers of men & women in the meta-analysis at the low level. But since the weighted average of 18% & 28% is 20% at the high level, that means there were about 4 men for every 1 women at the high exercise level, right?
S. Nelson
Hello
The notion that a given amount of exercise is necessary to improve health by some measure or other, is preposterous. Exercise is desirable, necessary, etc., not a 20 min or 30 min or 60 min., regimen, etc. If you exercise within your physical and health restraints, even if it falls far below what the experts are recommending, you’ll be improving your lot tremendously. If all you can “do” is walk at a crawl, say 1 mph, then, by all means do that. The important thing with exercise is doing it, not doing it according to some preordained, ideal, plan or measure, forced on you be an exercise freak. The problem with what we loosely call science, is that it falls too easily into arrogance and orthodoxy. Arrogance and orthodoxy is not science. Consideration of the realities that people face in their lives, and taking it into account, is science. Do what you can, and, in time, doing what you can will almost inevitably, help you do more. The body wants to exercise, and it doesn’t need you to “urge” and “coax” it along. It doesn’t need you to loudly pant and profusely sweat and fall on your couch with utter exhaustion and a feeling of defeat. However, it does need you to “continue” to respond to the tiniest encouragement that will almost certainly arise, one morning, in your body.
You do point out that it can be chalenging to exercise for an hour a day but doing it troughout the day makes easy and feasable and doesn’t affect family life. Morning walk 20 minutes either at home or by going to work a little earlier. Noon another 20 minutes during lunch time or half an hour or 40 minutes depending on the posibilities. Ariving from work at night another 20 minutes walk an it is done. Thanks for your regular good advices.
Wonderful! but is better to advise people on how to balance food intake and expenditure, this is due to the fact that the major challenges that people face are dietary ammandments and meal planning