A Johns Hopkins study should ease the concerns held by
many older adults with mild high blood pressure about the
strain or harm exercise could cause their hearts. Results
of the research on 104 men and women ages 55 to 75 showed
that a moderate program of physical exertion has no ill
effects on the heart's ability to pump blood, nor does it
produce a harmful increase in heart size.
In this study, "moderate" translated to sustained
exercise for about an hour three times a week. Researchers
say that people's concerns stem from the fact that during
each workout blood pressure can rise on average from 40
millimeters to 60 millimeters of mercury. The Johns Hopkins
study is believed to be the first to evaluate the effects
of exercise on the heart's ability to function, to pump and
to fill up with blood.
"While having high blood pressure at rest is a
well-established risk factor for heart problems, older
people should not fear the effects of moderate exercise on
the heart, despite short-term bump-ups in blood pressure
during their workout," said lead study investigator Kerry
Stewart, a professor of medicine and director of clinical
and research exercise physiology at the Johns Hopkins
School of Medicine and its
Heart Institute. "Exercise is a highly effective means
of increasing the heart's efficiency and reducing body fat,
factors that may ward off future health problems, such as
heart disease and diabetes."
A report on the Johns Hopkins study, published in the
July issue of the journal Heart, showed that after
six months of aerobic exercise on a treadmill, bicycle or
stepper, plus weightlifting, participants showed no overall
ill effects in 11 measures of diastolic heart function,
when the organ's main chamber fills with blood between
beats. The researchers also found that exercise produced no
increase in eight measures of heart size, including left
ventricular mass and wall thickness. In contrast, a
long-term effect of hypertension, even when the body is
relaxed, is hypertrophy, an enlargement of the heart that
eventually stiffens and weakens the muscle.
Not only were there no ill effects sustained despite
periodic increases in blood pressure during the workout,
Stewart and his team reported, but results also suggest
that the exercise producing these effects benefited the
hearts of those who made the most gains in physical fitness
and for those who lost the most abdominal fat.
And, researchers say, unlike the increased heart size
that results from high blood pressure, any increase in
heart size observed in the active group was similar to what
athletes experience when their hearts get bigger and
stronger not stiff.
For a six-month period, the Johns Hopkins team
assessed the benefits of a supervised program of exercise
training in a group of 104 older men and women, measuring
heart function, body fitness and fat levels at the start
and end of the study. All the participants were in general
good health except for untreated mild hypertension. Half
were randomly placed in a widely recommended moderate
exercise program, while the rest maintained their usual
physical routine and diet.
The active group participated in a supervised series
of exercises for 60 minutes three times per week. The
combination of exercises was designed to work all major
muscle groups, including the heart, with substantial
improvements observed in active participants' body fat, and
muscle and fitness levels.
Aerobic fitness, as measured by peak oxygen uptake on
a treadmill, increased by 17 percent, as did average
strength. The average weight loss in this group was only
four pounds because much of the loss of fat was offset by
increased muscle mass. The fat in the abdominal region,
measured by magnetic resonance imaging, was reduced by 20
percent among exercisers. The group that was not exercising
had either no or significantly less improvement than the
exercising group. Special scans using an X-ray machine were
used to assess total body fat.
"Making gains in body fitness and losing abdominal fat
are truly important to the long-term health of the heart,"
said study co-author Edward Shapiro, a professor of
cardiology. "Our results confirm that
moderate-intensity exercise can have many health benefits,
including gains in heart function that are linked to
increased fitness and reduced fatness.
"Our study also shows that the vast majority of older
people with mildly elevated blood pressure can benefit from
moderate exercise, and they should talk about it with their
physician to determine an appropriate exercise and any
other options for treatment," he said.
The Johns Hopkins study's exercise program followed
current guidelines from the American College of Sports
Medicine. The study was part of a larger ongoing trial
called the Senior Hypertension and Physical Exercise study,
or SHAPE. It is believed to be the first detailed
examination of the guidelines' effectiveness and the
separate effects of exercise on blood pressure, heart
structure and cardiovascular function, with nearly an equal
number of men and women enrolled.
A study published last year by the Johns Hopkins
scientists showed that exercise reduced by more than 20
percent the number of people who develop metabolic
syndrome, a clustering of three or more risk factors for
developing heart disease, diabetes and stroke. Risk
factors include high blood pressure, elevated blood glucose
levels, excess abdominal fat and abnormal cholesterol.
Funding for the study was provided by the National
Institute of Diabetes and Digestive and Kidney Diseases,
part of the National Institutes of Health, with additional
assistance from the Johns Hopkins Bayview General Clinical
Research Center, also funded by the NIH. In addition to
Stewart and Shapiro, researchers who took part in this
study were Pamela Ouyang, Anita Bacher and Sandra Lima, all
of Johns Hopkins.