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Dallas Researchers Investigate Connection Between Obesity, Shortness of Breath

DALLAS — Researchers at the Institute for Exercise and Environmental Medicine (IEEM) at Texas Health Presbyterian Hospital Dallas are working to unlock the secrets of breathing problems in overweight adults, a prevalent medical problem that keeps millions of obese Americans from exercising and enjoying active, healthy lifestyles. Scientists hope to learn how overweight and obese people can recover healthy lung function, lose weight and improve their overall health.

Researchers at Texas Health Dallas
Researchers at Texas Health Dallas are (from left): Todd Bassett, MS; Santiago Lorenzo, Ph.D; Tony G. Babb, Ph.D., primary investigator; Raksa Moran, BSN, RN; and Sarah Haller, BS.
Click photo to download hi-res image

Shortness of breath during exercise, called exertional dyspnea, is an obstacle to losing weight and reducing related medical conditions. The condition produces a sensation of not being able to “get enough air” and a feeling of being “out of breath.”

The IEEM researchers, led by Dr. Tony G. Babb, director of the institute’s cardiopulmonary laboratory, will investigate what causes the breathing discomfort and how best to improve the condition, especially in women.

Some scientists think a reduction in fitness or overall cardiovascular conditioning may cause the breathing difficulties, while Babb and his team theorize it could be something else. They’ll investigate whether a layer of fat on the chest wall or other physical effects of being obese may change the mechanics of breathing.

The results of their work could change how doctors and their patients prevent and treat obesity.

“It’s true that people often get into weight problems because of a lack of exercise and physical activity,” Babb said, “but the formidable, sometimes impassable hurdle for them is that when they do try to get moving again, many of them are unable to exercise as recommended.”

Babb and his team will try to uncover one of the central mysteries of obesity and exertional dyspnea: whether losing weight first, before tackling an exercise routine, might be a better way for obese adults to recover lung function and build a strong foundation for a long-term return to healthy living.

“We theorize that breathing problems will not improve with endurance exercise training alone since our initial research tells us that obese adults with exertional dyspnea are not deconditioned,” said Babb, who holds the Effie and Wofford Cain Foundation Chair in Cardiopulmonary Research and is an associate professor of internal medicine at UT Southwestern Medical Center at Dallas. “Exercise training alone is unlikely to decrease obesity-related respiratory limitations, specifically the increased oxygen cost of breathing.”

Obesity is an epidemic problem in the United States and is among the most important health challenges of the 21st century. The consequences of obesity are devastating: sickness and death from heart disease, hypertension, diabetes, sleep-disordered breathing and metabolic syndrome. More than 55 percent of Americans are classified as either overweight or obese. The prevalence of obesity has doubled since 1980 at a cost of $117 billion, with more than 300,000 deaths a year in the United States attributed to obesity.

Shortness of breath during exercise, called exertional dyspnea, is an obstacle to losing weight and reducing related medical conditions.
Shortness of breath during exercise, called exertional dyspnea, is an obstacle to losing weight and reducing related medical conditions.
Click photo to download hi-res image

“When obese individuals decide to get active to address their weight problems, many are faced with the unsettling sensation of not being able to get enough air when they’re exercising, even when they’re walking or doing other low-impact exercises,” said Dr. Benjamin Levine, director of the IEEM and holder of the S. Finley Ewing Jr. Chair for Wellness at Texas Health Presbyterian Hospital and the Harry S. Moss Heart Chair in Exercise and Environmental Medicine. “The consequences are profound: it’s a major roadblock to losing weight for millions of Americans, which is the reason so many obese adults can’t simply ‘get going again’ and don’t get back to a healthy weight.”

Levine, a professor of internal medicine and cardiology at UT Southwestern Medical Center and co-investigator of the research project with Babb, added: “It leads to numerous health problems in overweight children and adults and greatly diminishes their quality of life.”

Although most obese adults with shortness of breath during exercise are generally considered to have a compromised cardiovascular systems, preliminary data by Babb and his colleagues challenge this conventional wisdom. Babb said it’s unclear if exertional dyspnea in obesity is due to cardiovascular deconditioning, in which exercise training would be dramatically beneficial, or to obesity-related changes in respiratory mechanics.

“If we find that changes to the breathing function are affected by the obesity itself — not other cardiovascular problems,” Babb said, “then aggressive weight loss measures may be necessary before exercise training can be tolerated for some obese patients.”

To qualify to be a study participant, a person must be 20 to 45 years old, obese (BMI 30 to 45), and be a non-smoker without asthma or diabetes. The subject must also have no pulmonary or cardiac diseases and must not currently be participating in a weight loss program or regular exercise training. Those who participate in the study will receive individualized diet counseling, personalized resistive exercise consultation, and weekly progress log reviews by the exercise specialist assigned to the program. The study subjects also receive information regarding their lung function, body fat, and exercise tolerance. For more information or to apply to participate in the study, call 214-345-6574.

About the Institute for Exercise and Environmental Medicine
The Institute for Exercise and Environmental Medicine (IEEM) was founded as a joint program between Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center at Dallas. Its mission is to promote basic and clinical research, education, and clinical practice in defining the limits to human functional capacity in health and disease, with the objective of improving the quality of life for human beings of all ages. The IEEM includes ten major laboratories tightly integrated and organized intellectually along the “oxygen cascade” — the path that oxygen must follow through the body from the external environment through the lungs, heart, and skeletal muscle to perform cognitive function and physical activity. The IEEM is among the only research centers in the world that fosters the fusion of basic science and clinical medicine in a program designed specifically to study human physiology.

About Texas Health Presbyterian Hospital Dallas
Texas Health Presbyterian Hospital Dallas is an 866-bed acute care hospital and recognized clinical program leader, having provided compassionate care to the residents of Dallas and surrounding communities since 1966. U.S. News and World Report has ranked Texas Health Dallas among the nation’s best hospitals in digestive disorders, orthopedics, and neurology and neurosurgery. An affiliate of the faith-based, nonprofit Texas Health Resources system, Texas Health Dallas has approximately 4,000 employees and an active medical staff of more than 1,000 physicians. For more information, call 1-877-THR-WELL, or visit

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