The heart of a 75-year-old "superjock" can outperform that of an average 25-year-old, a researcher said last week, dispelling the idea that the cardiovascular system inevitably declines with age.

"Older individuals benefit at least as much from exercise as younger people," said Dr. Jerome Fleg at a press briefing at the National Institute on Aging. Fleg is a cardiologist at the institute's Gerontology Research Center. Some of his studies currently focus on top senior athletes, whom he referred to as "superjocks."

Fleg said earlier research had concluded that the heart system declines more than is actually the case. He said the earlier studies failed to screen out people with heart disease.

But Fleg's studies of healthy men and women showed "the heart of a normal 80-year-old can pump blood as effectively under stress as that of a normal 30-year-old."

Fleg said age does cause some changes in the heart system, including stiffening of the arteries, and changes in the aorta and left ventricle -- lower chamber -- of the heart. He said the left ventricle fills more slowly with blood in older people, but said the body compensates for this with more vigorous contraction of the upper heart chamber.

He said the superjocks in his studies -- winners of the senior divisions of running, bicycling and swimming races -- maintained muscle mass and a high rate of oxygen consumption.

In general, Fleg said, "Regular aerobic exercise such as rapid walking, jogging, bicycling and swimming increases the body's maximal oxygen consumption, improves metabolic function and enhances psychological well-being in older subjects."