From Heartwire
August 2, 2011 (Boston, Massachusetts) — The first meta-analysis to specifically examine the dose-response relationship between physical activity and risk reduction for coronary heart disease (CHD) has found that those engaging in the equivalent of 150 minutes of moderate-intensity exercise per week--the basic minimum as recommended by 2008 US federal guidelines--had a 14% lower CHD risk, and those who achieved 300 minutes per week had a 20% lower risk of CHD, compared with those who were sedentary.
Dr Jacob Sattelmair (Harvard School of Public Health, Boston, MA) and colleagues report their findings online August 1, 2011 in Circulation.
"Although it is well-established that physical activity helps prevent CHD, a lot of the literature compares active vs inactive individuals or qualitative concepts, such as 'high,' 'medium,' and 'low' amounts of exercise," Sattelmair explained to heartwire .
"We wanted to look at studies done recently that assessed physical activity quantitatively. Generally, the 'industry-standard' quote is that if you are physically active, you will lower your CHD risk by 20% to 30%. We wanted to see, if you follow the US federal guidelines, what does that mean? What are the risk reductions for CHD?
The conclusion is that even a little bit
of physical activity is beneficial and more is better, but the biggest
bang for your buck happens at the lower end of the spectrum.
The majority of the
population in the US is inactive, so if you start by doing something,
that's a great first step, and you'll start to realize the benefits. If
you're doing nothing, you don't have to start by running a marathon to
see the benefit; even walking briskly for 15 minutes a day was
associated with a significant reduction in CHD risk," he observes. This
is, he says, in line with the US guidelines, which encourage any amount
of activity for those unable to meet the minimum recommended.
Findings Support US Federal Physical-Activity Guidelines
Sattelmair and colleagues included in their review 26 studies published in English since 1995, nine of which allowed for quantitative estimates of leisure-time physical activity. The researchers performed initial analyses comparing high and low physical activity, which included all 26 studies, and the findings were similar to those of the primary analysis, which included only the nine studies.
As well as the 14% and 20% CHD risk reduction observed with the minimum and advanced recommended amounts of exercise, the researchers found that those who were physically active at levels lower than the minimum recommended also had a significantly lower risk of CHD, compared with those who did nothing.
So although meeting the basic guideline "is associated with a lower risk reduction than that which is generally ascribed to being physically active, meeting the advanced guideline--300 minutes of moderate-intensity exercise per week--is associated with a risk reduction that is pretty much in line with the benefit that has generally been ascribed to physical activity," he notes.
And those who engaged in more than the advanced amount of exercise saw additional benefits--those able to participate in 750 minutes per week of moderate intensity exercise (five times the minimum recommended amount) had around a 25% reduction in risk of CHD, Sattelmair said.
The researchers also found that the cardiovascular benefits of exercise appeared to be stronger in women than in men but say they don't have any plausible explanation for this finding.
And there were insufficient data to examine the effect of age at baseline or race on the relationship between physical activity and CHD risk.
Nevertheless, "These findings provide quantitative data that support the 2008 US physical-activity guidelines," they say, and indicate that the most benefit for CHD risk occurs at the lower end of the activity spectrum--ie, very modest, achievable levels of physical activity.
Future studies that quantitatively assess the dose-response relation between leisure-time physical activity and CHD risk will help clarify the upper end of the dose-response curve, they note, "and enable additional quantitative evaluations in future reviews, such as exploring potential differences by age and race."
No comments:
Post a Comment