Long-term training in endurance activities, such as running, swimming or cycling, may help prevent the stiffening of the heart that occurs with age, an effect that might reduce the risk of heart failure, new research suggests.

Whether less intensive exercise provides any benefit, however, remains to be determined.

When the heart stiffens, it is less able to relax and expand between each beat, and therefore fills with less blood. Then, with each contraction, less blood is pumped to the rest of the body, which can lead to serious problems over time.

Based largely on animal research, “it has been speculated that the heart stiffens with age,” senior author Dr. Benjamin D. Levine, from the University of Texas Southwestern Medical Center in Dallas, told Reuters Health. “But this is the first time that completely healthy older adults have been studied and had their (heart stiffness) measured.”

The study involved 12 healthy sedentary seniors, 12 highly active seniors, and 14 young subjects who led a sedentary lifestyle. Standard heart tests were used to evaluate how easily the heart filled with blood, an indicator of heart stiffness.

“On average, the (highly active seniors) had trained for 23 years” and had run, swum, or cycled an equivalent of 32 miles per week, Levine noted. “Conversely, their sedentary peers did not exercise more than three times per week for more than 30 minutes at a time. We picked these two completely opposite groups so that we could test our hypothesis as cleanly as possible,” he added.

The researchers’ findings appear in the American Heart Association’s journal Circulation.

The highly active seniors were able to pump more blood with each beat of their heart than the sedentary seniors. Moreover, compared with the young subjects, the sedentary seniors showed heart stiffening, whereas the highly active seniors did not.

Because the study involved subjects with such widely different exercise histories, Levine noted that “it doesn’t answer the question of exactly how much exercise is needed to (prevent stiffening) of the heart as you age. I don’t know the answer to that - that is going to be addressed in our next series of studies.”

SOURCE: Circulation, September 13th rapid access issue, 2004.