You Don't Have to Strain for Cardio Fitness Gains

By: Rita Jenkins

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