听美文故事记6级单词07-04（在线收听）

4. Why Hearty Women Outlive Men?

The age-old riddle of why many women live longer than men has been solved. It's their pumping power, British researchers have found.

On average, women live five years longer than men and women over the age of 60 are now the fastest-growing section of the British population.

The average male heart becomes weaker with age, and by the age of 70 its power to pump blood around the body could have decreased by up to a quarter of its youthful strength.

David Goldspink, Professor of Cell and Molecular Sports Science at Liverpool John Moores University, said yesterday that women's longevity is linked to the strength of their hearts. Unlike men, they pump just as strongly at 70 as they do at 20.

"We have found that the power of the male heart falls by 20-25 per cent between 18 and 70 years of age," Professor Goldspink said. "In stark contrast, over the same period there was no age-related decline in the power of the female heart, meaning that the heart of a healthy 70-year-old woman could perform almost as well as a 20-year-old's."

The dramatic difference between the sexes might explain why women live longer. The good news is that men of any age can improve the health of their heart simply by taking more regular exercise.

The results are based on the findings of a two-year study of a cross-section of the British population, which examined the effects of ageing on the cardiovascular system.

Professor Goldspink and a team of scientists at the university's Research Unit for Human Development and Ageing examined more than 250 men and women between 18 and 80.

None of the volunteers had a weekly exercise routine and all were considered to have low fitness levels, but were otherwise healthy. Each volunteer underwent five hours of tests to measure their blood pressure and the performance of their heart while at rest and while they exercised on a treadmill.

The researchers found that the large arteries in the body became stiffer and less elastic with age, causing increased blood pressure. Blood flow to the muscles and skin of the limbs was also found progressively to decrease. These changes were found to occur earlier in men, but women caught up soon after the menopause.