THURSDAY, March 27, 2014 (HealthDay News) -- The formula doctors
use to evaluate treadmill stress tests, and thereby assess heart
health, doesn't account for important differences between men and
women, a new study contends.
A revised formula would better determine peak exercise rate, or
the maximum number of heart beats per minute, for each sex, the
"Exercise physiology has been known to differ for men and women of different ages," said Dr. Gregg Fonarow, associate chief of cardiology at the University of California, Los Angeles, and spokesman for the American Heart Association.
The proposal for a sex-specific maximal heart rate warrants
further research, he said. "This may represent a valuable
improvement for guiding exercise stress testing," added Fonarow,
who was not involved in the study.
Doctors now use the formula "220 minus age" to determine how
hard patients should work out during exercise stress tests. Many
people also use this formula to set their target heart rate during
For the new study, a team led by Dr. Thomas Allison, director of
stress testing at the Mayo Clinic in Rochester, Minn., reviewed
25,000 stress-test results. They saw significant differences
between men and women.
Allison's group found that although peak heart rate declines
with age for both sexes, the rate declines more gradually in women.
This difference results in an overestimated peak heart rate in
younger women and underestimated peak heart rate in older women,
the researchers said.
The findings are scheduled for presentation Saturday at the
annual meeting of the American College of Cardiology, in
Based on their findings, the study authors developed a new
According to the revised formula, the maximum heart rate for
women aged 40 to 89 should be 200 minus 67 percent of their age.
For men, the preferred formula is 216 minus 93 percent of their
age, the study authors said.
"We want to make sure that when people do the stress test, they have an accurate expectation of what a normal peak heart rate is," Allison said in an American College of Cardiology news release.
Because of limited test results for women under 40, the
researchers were unable to recommend a new formula for this
Allison's team also found that younger men have a lower resting
heart rate and higher peak heart rate than women. In addition,
men's heart rates rise more dramatically during exercise and return
to normal more quickly after stopping, the researchers said.
Heart experts welcomed the preliminary results.
"This is timely and we've needed it for a while," said Dr. Suzanne Steinbaum, director of women and heart disease at Lenox Hill Hospital in New York City.
"All of these differences are very important, not only for diagnosis, but also for teaching people how best to exercise to get the most cardiovascular fitness," she said.
However, Steinbaum thinks it will take more research before a
new formula that takes sex differences into account could become
standard practice. Still, women might want to try the proposed
formula on their own, she said. "It's worth considering
implementing these new guidelines in their exercise routine," she
While the study did not look at the reasons for the gender
differences, the researchers speculate that hormones, particularly
the male hormone testosterone, are involved.
Also, when the current formula was developed, medical studies
recruited few women, Allison said.
"It's logical that an equation developed 40 years ago based on a group that was predominantly men might not be accurate when applied to women today," he said.
Dr. Kevin Marzo, chief of cardiology at Winthrop-University
Hospital in Mineola, N.Y., said the original formula stems from
research in the early 1970s.
"Once again we learn that men and women are very different and our medical research and treatments need to be gender- specific," he said.
Research presented at meetings is typically considered
preliminary until published in a peer-reviewed medical journal.
For more information on stress tests, visit the
U.S. National Library of Medicine.
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