for fun may lower the risk of high blood pressure, but heavy lifting on the job
does not offer the same benefit, according to a new review of the evidence.
looking at studies that followed nearly 137 000 people found that recreational
exercise for more than four hours a week was linked to a 19% lower risk of
developing high blood pressure compared to doing little or no leisure-time exercise.
with similar levels of physical activity in the course of work had about the
same risk as those in less strenuous jobs.
makes sense that occupational physical activity is not associated with reduced
risk of hypertension," said Dr Martha Daviglus, a professor of medicine at
the University of Illinois in Chicago and a preventive medicine specialist.
Work environment different
People experience more stress at work, and the
kinds of physical activity individuals do in the work environment is different,
said Daviglus, who was not involved in the study. "When you exercise, you
have to be completely relaxed."
with predictions that the total number of adults in the world with high blood
pressure will reach 1.56 billion by 2025, researchers are taking a serious look
at factors that can lower the risked.
Wei Ma from Shandong University in Jinan,
China, and his colleagues combined the results of 13 studies that followed 136 846
healthy individuals for at least two years and up to 45 years to see what types
of physical activity were linked with a person's risk of developing high blood pressure.
The studies included in the review were
conducted in North America, Europe and Asia, and 15 607 of the individuals
followed eventually developed high blood pressure.
In addition to the heaviest weekly exercisers
having a 19% lower risk, those who exercised for between one and three hours a
week had an 11% lower risk than those who did less than an hour's worth of exercise.
jobs such as industrial, farm or forestry work with comparable levels of
lifting, walking, climbing and other activities had a slightly lower risk of
high blood pressure than those in sedentary jobs. But the difference was so
small it could have been due to chance, Ma's team reports in the journal
found that occupational physical activity could not decrease the risk of
hypertension in the present study," he told Reuters Health in an email.
The researchers also looked at the effects of physical activity in the course
of commuting to work on foot or by bicycle.
studies included data on that kind of exercise, and one found a large benefit,
the other found nearly none.
Variety of movement
speculates that the nature of the activities at work, which tend to consist of
"heavy lifting, prolonged standing and highly repetitive work," may
explain the lack of apparent health benefit. Recreational exercise often works
large muscle groups in a more varied way that increases the metabolism and
cardiac output of the whole body, they write. In addition, individuals who
exercise during leisure time can rest when they are tired.
been known for a long time that exercise can help prevent the development of
hypertension," said Dr David Jacobs, an epidemiologist at the School of
Public Health at the University of Minnesota.
study is good in that it has nailed the relationship down a little better and
formalised it in a large body of information.
shows that a wide variety of studies produced the same answers," he told
Reuters Health. Jacobs agreed that the kinds of physical exercise individuals
perform in a work environment do not actually involve a variety of movement.
do leisure time exercise are also different in other ways from people who
don't, he pointed out, and a study like this cannot precisely identify the difference.
there is strong evidence that physical activity is an important factor to help
prevent a range of chronic diseases like hypertension, the missing piece is what
kind of activity and the level of physical activity needed, Daviglus said.
is no prescription of one kind of exercise for everybody," she said.
Rather, the recommendation is to incorporate physical activity into your life.