How Exercise Lowers Cardiovascular Risk
It is well
known that physical activity can improve cardiovascular health. But
it's the impact exercise has on specific known risk factors that
accounts for about 60 percent of that improvement, researchers reported
in Circulation: Journal of the American Heart Association.
In a major
study of over 27,000 women in the Women's Health Study, researchers
assessed a variety of risk factors and different levels of exercise in
women who were followed for 11 years for new diagnosis of heart attack
physical activity is enormously beneficial in preventing heart attack
and stroke," said Dr. Samia Mora, lead author of the study and
instructor of medicine at Harvard Medical School in the divisions of
preventive and cardiovascular medicine at Brigham and Women's Hospital,
Boston Mass. "We found that even modest changes in risk factors for
heart disease and stroke, especially those related to
inflammation/hemostasis and blood pressure, can have a profound impact
on preventing clinical events. This study is the first to examine the
importance of a variety of known risk factors in explaining how
physical activity prevents heart disease and stroke."
ranged from 45 to 90 years old (average age 55) and were assessed for a
full range of risk factors and different levels of exercise. There was
a 40 percent reduction in heart attack and stroke between the highest
and lowest exercise groups. The women self-reported physical activity,
weight, height, hypertension and diabetes.
benefits of exercise start at a relatively low level, 600 kilocalories
per week, equivalent to about two hours of physical activity per week,
measured levels of a variety of traditional and novel risk factors to
help understand the mechanisms that reduce risk for heart attack and
stroke. Novel risk factors are emerging clinical, biochemical, and
genetic markers that researchers have studied in order to better
understand the development of a disease, to improve disease risk
prediction, and to identify new targets for treatment.
and hemostatic biomarkers -- fibrinogen, C-reactive protein and
intracellular adhesion molecule-1 -- together made the largest
contribution to lower risk, 33 percent.
pressure was the next major contributor to lower risk, 27 percent,
followed by lipids, body mass index, glucose abnormalities, with
minimal contribution from measures of renal function or homocysteine.
and hemostatic biomarkers are novel risk factors that relate to blood
vessel function and inflammation of the arteries.
and hemostatic factors as a group have overlapping functions and roles
and, in our study, had the biggest effect in mediating exercise-related
cardioprotection, more so than blood pressure or body weight," Mora
said. The study population was divided into four groups by levels of
level expended greater than or equal to 1,500 kilocalories per week
(kcal/week) representing greater than five hours of moderately intense
physical activity (such as brisk walking) per week.
The next group expended from 600 to 1,499 kcal/week which reflected about two to five hours of physical activity per week.
A third group
represented an expenditure of 200 to 599 kcal/week, which is about one
to two hours of physical activity per week.
The reference group had less than 200 kcal per week (less than one hr per week).
The risk of
cardiovascular disease events decreased with higher levels of physical
activity. Compared to the reference group, relative risk reductions
were associated with -- 1,500, 600 to 1,499, 200 to 599 kcal/wk of 41
percent, 32 percent and 27 percent, respectively.
For more information on the American Heart Association, visit www.americanheart.org.