Endurance Exercise Could be Fountain of Youth for
Old Hearts of Inactive Seniors
Women benefit more than men in at least in one
measurement
July 23, 2008 Endurance exercise may lead to the
fountain of youth for the long-beating hearts of senior citizens. A new
study says inactive older people who did endurance exercise training for
about a year ended up with metabolically much younger hearts. The
researchers also showed that by one metabolic measure, women benefited
more than men from the training.
"We know that the heart deteriorates as people get
older, and that's largely because they don't stay as active as they used
to," says first author Pablo F. Soto, M.D., instructor in medicine in
the Cardiovascular Division, Washington University School of Medicine in
St. Louis, where the study was conducted.
"Past research has suggested that exercise can
reverse some effects of aging, and we wanted to see what effect it would
have specifically on the heart."
The researchers measured heart metabolism in
sedentary older people both at rest and during administration of
dobutamine, a drug that makes the heart race as if a person were
exercising vigorously. At the start of the study, they found that in
response to the increased energy demands produced by dobutamine, the
hearts of the study subjects didn't increase their uptake of energy in
the form of glucose (blood sugar).
But after endurance exercise training - which
involved walking, running or cycling exercises three to five days a week
for about an hour per session - the participants' hearts doubled their
glucose uptake during high-energy demand, just as younger hearts do.
Soto explains that if heart muscle doesn't take in
glucose in response to increased energy needs, it goes into an
energy-deprived state, which may raise the risk of heart attack. But if
it can increase glucose uptake, the heart is better protected against
ischemia (low oxygen) and heart attack.
Based on heart glucose metabolism, both the men and
women in the study had the same rejuvenating benefit from their exercise
programs.
But the heart uses both glucose and fatty acids for
energy. And when the researchers looked at fatty acid metabolism, they
found a striking difference in the results of exercise training between
women and men. In the men, the heart's fatty acid metabolism dropped in
response to increased energy demand, but it went up in women.
"By that gauge, the women had a better response to
exercise training than the men," Soto says.
"At this point, the significance of that isn't
clear. We know that in animal studies low fatty acid oxidation leads to
heart muscle thickening and that when men train their heart muscle often
gets thicker than women's. It could be that the increase in fatty acid
oxidation in women's hearts with training is a reason why their hearts
don't thicken as much."
The study is described in an article that appeared
in advance online publication on June 20, 2008 in the American Journal
of Physiology. The participants were six men and six women, ages 60 to
75, who were not obese but who had been living an inactive lifestyle.
They were put on an eleven-month program of endurance exercise under the
careful guidance of a trainer.
For the first three months, they were required to
exercise to about 65 percent of their maximum capacity. After that, the
program was stepped up so participants reached about 75 percent of
maximum. Soto says the volunteers enjoyed the experience and told him
they felt in the best shape they had been in years.
The researchers tested the volunteers' heart
metabolism before and at the end of their exercise programs by using PET
scanning techniques.
"Here at the School of Medicine, we are uniquely
able to look at the metabolism of the heart because we have the right
combination of technology and expertise in cardiology, radiology and
radiochemistry," Soto says. "We are one of the few places that can do
this kind of study."
Next, the research team will investigate exercise
training in individuals with heart failure. "In the past heart failure
patients were told to limit their activity," Soto says. "Now more and
more we're seeing there is potentially a benefit to getting them as
active as possible. We want to know if heart failure patients will
experience the same benefit in heart metabolism with exercise that we
saw for older people."
Editors Notes:
Soto PF, Herrero P, Schechtman KB, Waggoner AD,
Baumstark JM, Ehsani AA, Gropler RJ. Exercise training impacts
myocardial metabolism of older individuals in a gender-specific manner.
American Journal of Physiology. Heart and Circulatory Physiology. June
20, 2008 (advance online publication).
Funding from the National Heart, Lung, and Blood
Institute, the American Heart Association and the Robert Wood Johnson
Foundation supported this research.
Washington University School of Medicine's 2,100
employed and volunteer faculty physicians also are the medical staff of
Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine
is one of the leading medical research, teaching and patient care
institutions in the nation, currently ranked third in the nation by U.S.
News & World Report. Through its affiliations with Barnes-Jewish and St.
Louis Children's hospitals, the School of Medicine is linked to BJC
HealthCare.
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