Copyright 2005 Daily News
Central
Quantity may beat quality
when it comes to exercise
and heart health. Adults who
engage in mild exercise --
such as walking briskly for
12 miles or exercising moderately
for 125-200 minutes over the
course of a week -- can improve
their aerobic fitness significantly
and reduce their risk of cardiovascular
disease, according to a study
published in Chest.
"The classic exercise regimen
has a component of intensity
up to 80 percent of someone's
maximum for health benefits,"
says lead author Brian D.
Duscha of Duke University
Medical Center in North Carolina.
"Our study demonstrates that
you can exercise at an intensity
much less than that and still
achieve fitness benefits,"
he notes.
"People find exercise 'hard'
and few people want to exercise
at an intensity higher than
they have to. Walking briskly
for 12 miles a week per week
is realistic and does not
require anyone to incorporate
a hardcore training regimen.
Increasing your mileage or
intensity will give you even
greater health benefits,"
Duscha says.
Improved Oxygen Consumption
A Duke Medical Center research
team examined the effects
of different exercise training
regimens on 133 patients aged
40 to 65 years. All were sedentary,
overweight nonsmokers who
had abnormal levels of fat
in their blood.
The participants were divided
into four exercise groups:
- high-amount/high-intensity
(HAHI), the equivalent of
jogging 20 miles per week
at 65 to 80 percent peak Vo2
(maximum oxygen consumption);
- low-amount/high-intensity
(LAHI), the equivalent of
jogging/walking up an inclined
treadmill approximately 12
miles per week at 65 to 80
percent peak Vo2;
- low-amount/moderate intensity
(LAMI), the equivalent of
walking approximately 12 miles
per week at 40 to 55 percent
peak Vo2; and
- a control group of nonexercising
patients.
All patients underwent cardiopulmonary
exercise testing twice at
baseline and after seven to
nine months of exercise training.
All exercise groups significantly
improved their absolute and
relative peak oxygen consumption
and time to exhaustion (TTE)
compared to baselines scores.
Increasing Intensity May Help
Too
Although the HAHI group showed
the greatest improvements
in peak Vo2 overall, increasing
exercise intensity from 40
to 55 percent to 65 to 80
percent (at a controlled amount
of 12 miles/week) did not
significantly improve peak
oxygen consumption. However,
increasing the amount of exercise
did produce improvements.
An increase in exercise amount
also demonstrated a graded
increase in TTE between groups,
although data were not statistically
significant.
"Although our results did
point toward amount being
more important, it is very
likely fitness levels can
be improved by increasing
either amount or intensity,"
says Duscha.
"This is illustrated by the
tiered effect the exercise
dose had on fitness improvements
across our groups. We believe
with more people in the study,
increasing intensity would
also have been significant,"
he explains.
Losing Weight Not Essential
Body mass index (BMI) was
reduced in the LAHI and HAHI,
groups but remained unchanged
in the LAMI group. All exercise
groups lost an average of
2.87 pounds after exercise.
Baseline characteristics of
age, BMI, weight, peak and
relative Vo2, and TTE were
not different between the
groups.
"A second very important message
is that subjects enjoyed fitness
benefits in the absence of
weight loss. Many people exercise
with the purpose of losing
weight. When they do not lose
weight, they do not think
the exercise is benefiting
them and they stop exercising,"
notes Duscha.
"The truth is, you can improve
your cardiovascular fitness
and reduce your risk for heart
disease by exercising without
losing weight. Even if individuals
do not lose weight, it is
likely that they will lose
body fat and increase lean
muscle mass while reducing
other risk factors," he points
out.
12 Miles a Week
Adherence to exercise requires
motivation and making exercise
a priority, the researchers
stress. They advise those
who are beginning an exercise
regimen to start slowly, choose
an enjoyable activity, and
make exercise a social activity.
Individuals with medical problems
should consult a physician
before starting an exercise
program.
"If you distill our results
down, the public health message
is: You only need to walk
briskly for 12 miles per week
or for approximately 125 to
200 minutes per week to improve
your health. This sheds more
light on the question, 'What
is the minimum amount of exercise
I need to do to get a health
benefit?'" says Duscha.
"Regular exercise is an important
part of a well-balanced lifestyle,"
adds Paul A. Kvale, MD, FCCP,
President of the American
College of Chest Physicians.
"Physicians and other healthcare
providers should encourage
their patients to engage in
regular exercise in order
to obtain pulmonary and cardiovascular
benefits."
About the Author
Rita Jenkins is a health journalist
for Daily News Central, an
online publication that delivers
breaking news and reliable
health information to consumers,
healthcare providers and industry
professionals: http://www.dailynewscentral.com
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