A study on rats has shown that moderate exercise has positive benefits on the hearts, holding out promising implications for humans.
Several human studies in the last 10 to 20 years have shown that moderate exercise does not appear to harm people suffering from congestive heart failure.
However, the positive benefits of such exercise have not been found to be statistically significant.
In the new study rats carrying the genetic characteristics for spontaneously developing heart failure exercised moderately on a treadmill. They significantly lived longer, the science portal EurekAlert reported.
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.
"Assuming the results are applicable to humans, low-intensity exercise is likely to have benefits for humans in early stages of congestive heart failure," said Russell Moore, a researcher of the University of Colorado who led the study.
The intensity of exercise in the study was a crucial factor affecting longevity in the rats used in the study, said Moore.
Early in the study, several of the rats that began exercising at nine months of age died after the locomotion speed was increased from 10 metres per minute to 17.5 metres per minute, he said.
The speed was subsequently reduced to 14 metres per minute for the duration of the study, and no additional rat deaths occurred, he said.
"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."
"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.