April 19, 2002
Guess what? Exercise is good for you. Okay, you already knew that. But what is news is that any type of aerobic exercise, of any frequency or duration, measurably reduces blood pressure, according to a study by Jiang He, associate professor of epidemiology and medicine, that appears in this month's Annals of Internal Medicine.
"The data confirms what we've known all along," said He. "Any level of activity is good for the heart and can have long-term benefits for health. This is an inexpensive way to prevent or reduce high blood pressure, and could help some people get off the medicines they use to control the condition."
The study is based on a meta-analysis of 54 randomized, controlled clinical trials that included a total of 2,419 participants. The subjects were at least 18 years old and had previously been sedentary. They participated in aerobic exercise programs of at least two weeks that involved walking, jogging, bicycling or swimming. Although all of the studies analyzed were published in English, they include trials conducted in Europe, Asia, Africa, Australia and New Zealand.
Blood pressure was shown to go down whether the subjects started with normal blood pressure or high blood pressure, whether they were normal weight or overweight, and no matter what their gender or ethnicity. All frequencies, intensities and types of aerobic exercise lowered blood pressure. It didn't even matter if the subjects lost weight in the process. It was necessary, however, to continue exercising in order to maintain lower blood pressure.
The overall pooled net effect of aerobic exercise on blood pressure was a reduction of systolic blood pressure by 3.84 mm Hg and diastolic blood pressure by 2.58 mm Hg. This is significant because previous studies have shown that a decrease of as little as 2 mm Hg in mean population diastolic blood pressure could significantly reduce the risk of cardiovascular diseases associated with elevated blood pressure.
High blood pressure, which currently affects almost 50 million Americans, is a major risk factor for stroke, coronary heart disease, heart failure and kidney disease. So the results of the study have implications for individuals who want to reduce their blood pressure, but they also have broader public-health implications.
The prescription of exercise along with or instead of medication could significantly reduce incidence and mortality from cardiovascular disease, which has long been the leading cause of death in the United States and necessitates hundreds of billions of dollars in expenditures each year. Of course, the results of the study weren't exactly a surprise.
Several recent clinical trials have demonstrated that exercise reduces blood pressure. But the value of pooling together the results from a large number of trials allowed for more precise and definite information about exercise-related reduction in blood pressure, in the population at large and among different subgroups. What's significant about the study is that it shows how universal that reduction is and how little exercise is needed to bring it about.
He's coauthors on the study include Seamus Whelton, an undergraduate student at Princeton University, and Ashley Chin and Xue Xin, graduate students at Tulane's School of Public Health and Tropical Medicine.
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