COLUMBUS, Ohio -- People suffering from diseases such as chronic bronchitis and emphysema can benefit from high-intensity exercise of their chest muscles and diaphragm, according to a recent study.

In fact, the sickest patients are the ones who appear to benefit most from high-intensity respiratory muscle exercise.

Researchers at the Ohio State University College of Nursing looked at the effect of this specialized exercise on 22 patients with chronic obstructive pulmonary diseases (COPD). These diseases, which include chronic bronchitis and emphysema, are the fourth leading cause of death in the United States.

The scientists found that COPD patients who exercised their respiratory muscles three times a week for three months -- both those who trained at a high-intensity level and those who trained at a lower level -- showed significant improvement in respiratory muscle endurance, combined strength and endurance, and walking speed.

Further, they found that these improvements were greatest among those patients with poor lung function who participated in

high-intensity training.

"With high-intensity training, there was some concern about injury, a concern that you could overtrain and perhaps cause a patient to have more problems," said Thomas Clanton, associate professor of physiology, internal medicine and allied medical professions at Ohio State and one of the authors of the study. "These results show that patients can tolerate it well and that even low-intensity training can have beneficial effects."

The study, which appeared in a recent issue of the journal Chest, is among the first to demonstrate the benefits of high-intensity respiratory muscle training for COPD patients. Respiratory muscle training itself -- during which patients must generate enough inhaling power to pop open a pressure-loaded valve, yet maintain a regular breathing pattern -- is fairly controversial, Clanton said.

"Probably only about 50 percent of people involved in pulmonary rehabilitation believe that it's a great part of a comprehensive rehabilitation program," he said. "The other half think it's not of as much value as other components."

Despite the controversy, study results suggest that high-intensity respiratory muscle training could become a way for the most seriously ill COPD patients to improve their quality of life, Clanton said.

"There are not a lot of treatments available for people who've lost lung tissue to these diseases," he said. "The idea behind respiratory muscle training is that if we can exercise these muscles and make them less susceptible to fatigue, patients will be able to exercise more and may have the 'reserves' necessary to stave off respiratory failure and stay out of the hospital."

Clanton conducted the study with former nursing doctoral student Barbara Preusser and former Ohio State professor of nursing Maryl L. Winningham.

For their study, the scientists measured the lung function, respiratory muscle strength, endurance, combined strength and endurance, and walking speed of the COPD patients. They then assigned the patients to either a high-intensity or low-intensity respiratory exercise group and had them exercise three times a week for three months using a threshold trainer -- a respiratory testing device that measures patients' ability to generate inhaling power and pop open a pressure-loaded valve. Patients in the high-intensity group had a higher pressure load to inhale against.

During the study, the researchers increased the size of the load, the length of the training session and the work-to-rest ratio. In the first week, the training session took five minutes; in the last, 18 minutes. At the end of the study, the scientists measured each patient's respiratory muscle strength, endurance, combined strength and endurance, and walking speed.

The results:

_ Respiratory muscle endurance, combined strength and endurance and walking speed improved for both the high-intensity and low-intensity groups over the course of the study, indicating no significant difference between the two training regimens.

"This suggests that both high- and low-intensity training are effective in conditioning the respiratory muscles," Clanton said.

_ However, respiratory muscle strength, endurance, combined strength and endurance, and walking speed improved most among very ill patients who participated in high-intensity training and least among very ill patients who participated in low-intensity training.

"Patients who have the most severe lung disease are constantly 'training' just through their everyday living. Because of this, they probably need a higher load in order to show a training effect," Clanton said.

_ Respiratory muscle strength, endurance, combined strength and endurance, and walking speed did not significantly improve during the third month of the study in either group.

"This suggests that the optimal length for this particular training regimen is two months," Clanton said. Currently, however, some third-party health insurance providers won't even pay for that many weeks, he said.

Clanton said he hopes this training regimen will eventually be evaluated in a multi-center trial with a larger group of patients.

Also, he hopes researchers will address the question of whether respiratory muscle training reduces health care costs -- over and above regular pulmonary rehabilitation.

"If you add respiratory muscle training to the overall pulmonary rehabilitation program, are patients less likely to end up in the hospital? Will spending a little extra on this element ultimately lower patient costs? That's a question we need to answer in a statistically defendable way."

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Contact: Thomas Clanton, (614) 293-4936

Written by Kelly Kershner, (614) 292-8308