Abdominal Fat More Significant In Exercise-induced Shortness Of Breath Than Over

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Abdominal Fat More Significant In Exercise-induced Shortness Of

Breath Than Overall Weight

09 Apr 2006

When it comes to being short of breath during exercise, how fat is

distributed on the body is a more significant factor than overall

body fatness or lung function, say researchers at the Institute for

Exercise and Environmental Medicine, Presbyterian Hospital of

Dallas, and the University of Texas Southwestern Medical Center.

They found that women with higher amounts of abdominal fat required

more oxygen during exertion. That finding may have important

implications for helping obese people better tolerate the exercise

they so badly need.

Dr. Tony Babb and Dr. MacDougall, a physician and research

assistant in Dr. Babb's laboratory, presented the findings on April

4 at Experimental Biology 2006 in San Francisco. The presentation

was part of the scientific program of The American Physiological

Society.

More than half of Americans are classified as overweight and more

than 22 percent are obese; obesity contributes to diabetes and

metabolic syndrome; heart disease, hypertension, and stroke; and

some forms of cancer. Last year, approximately 300,000 deaths in the

United States were attributed to obesity, and the annual healthcare

cost related to obesity now runs at $117 billion. Physical activity

and exercise are among the most important components in the

prevention and treatment of obesity, but many obese adults do not

participate in regular physical activity because they simply can't

get enough breath while exerting themselves.

But it's not only their weight per se that's too blame, say the

researchers. In earlier studies in the Babb laboratory, researchers

had measured the oxygen cost of breathing - a unique measurement of

how much oxygen is utilized for breathing -- in mild to moderately

obese women. The oxygen cost was markedly increased in some but not

all of the women, even when their overall body fat was similar. In

the study reported at Experimental Biology, the researchers tested

eight mild-to-moderately obese women to see what caused this

difference.

Age, height, weight, body mass index (BMI), percentage of overall

body fat (as determined by hydrostatic or underwater weighing), and

pulmonary function at rest all were similar among all the women. But

multiple MRI scans of the upper body found significant differences

in fat distribution between the four women who had exertional

dyspnea or shortness of breath on exertion and the four women who

did not have such shortness of breath. There was a significant

correlation between the amount of abdominal fat (fat under the skin

of the abdomen as opposed to visceral fat or fat actually inside the

abdominal cavity where the stomach and other organs are located) and

the oxygen cost of breathing.

It is not yet clear whether increased shortness of breath in these

women is simply the result of increased weight and forces on the

lungs, or if increased fat on the surface of the abdominal area

decreases lung volume, causing the sensation of shortness of breath,

say the researchers. But what is clear, they continue, is that

sending the women to the gym with orders to soldier on through and

get in better condition may not help.

Dr. Babb says these preliminary data show that some obese patients

with breathlessness during exertion do not appear to be

deconditioned as conventionally thought, but rather suffer from

respiratory limitations. Thus the recommendations for these patients

may need to focus on weight loss and use special considerations for

the type of exercise they are prescribed. He adds that it is

important that we obtain more information as to the cause of

breathlessness on exertion in people with high amounts of abdominal

fat.

###

Co-authors of the Experimental Biology study with Dr. Babb and Dr.

MacDougall are McGehee, who is the recipient of the APS 2005

Frontiers in Physiology Professional Development Fellowship and will

be in attendance at Experimental Biology; Trisha Semon, an exercise

physiologist and pulmonary technologist; Laurie Comeau, respiratory

therapist; and medical student Belinda Schwartz.

Support for the research came from the American Heart Association

Texas Affiliate, King Charitable Foundation Trust, and Cain

Foundation.

Contact: Goodwin

ebpress@...

Federation of American Societies for Experimental Biology

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