A new University of Colorado at Boulder study involving laboratory rats that indicates low-intensity exercise may significantly delay the onset of congestive heart failure appears to have some promising implications for humans.

According to Professor Russell Moore who led the study, lab rats carrying the genetic characteristics for spontaneously developing heart failure were shown to live significantly longer if they exercised moderately on a treadmill.

The exercise protocol, the equivalent of daily, leisurely strolls in humans, extended the life expectancy of the rat study group by at least 10 percent to 15 percent, according to the study.

"Assuming the results are applicable to humans, low-intensity exercise is likely to have benefits to humans in early stages of congestive heart failure," he said.

"Our study, coupled with several human studies conducted elsewhere, shows a definite trend indicating that moderate intensity exercise has a potential role in stemming the downward spiral in heart failure," he said.

Moore said a unique feature of the CU-Boulder study was that the delay in the onset of CHF (congestive heart failure) in the rats through moderate exercise was accomplished without reducing hypertension, or high blood pressure, in the animals.

Most people in the early stages of development of heart failure also have hypertension, which is regularly treated to help improve the prognosis of CHF sufferers, said Moore.

Although several human studies in the last 10 to 20 years have shown that moderate exercise does not appear to harm CHF sufferers, the positive benefits of such exercise have not been found to be statistically significant, he said. Such studies are difficult to evaluate because participants often are taking a number of different medications, he said.

The intensity of exercise in the study was a crucial factor affecting longevity in the rats used in the study, said Moore.

"The bottom line is if the animals are exercised too hard, they will die," he said. "But when exercised moderately, in this case at barely more than a walk, the results were striking."