Women could be living longer than men because they have stronger hearts, a study says.
Women live on average five years longer than men
A team from Liverpool John Moores University found men's hearts lose up to a quarter of their pumping power from 18 years old to 70.
But there was little change in women's hearts from 20 to 70, the study of 250 people said.
The researchers said the difference may explain why women live on average up to five years longer than men.
Each volunteer in the research underwent five hours of tests focusing on body composition, blood pressure and heart performance.
The study found large arteries became stiffer and less elastic with age, causing blood pressure to increase both at rest and during exercise.
Blood flow to the muscles and skin of limbs also progressively decreased, the team found. This occurred earlier in men, but women soon caught up after menopause.
But lead researcher Professor David Goldspink said it was the difference in heart strength that was most interesting.
"This dramatic gender difference might just explain why women live longer than men."
But he said related-research showed that men had the potential to improve their health.
He found that the hearts of veteran athletes were as strong as those of an inactive 20 year-old.
He said: "If men work at it, they can preserve the power and performance of their ageing hearts."
Professor Goldspink added people needed more information about what benefits they can gain in response to different levels of physical activity.
But Dr Suzanne Wait, director of research for think-tank the International Longevity Centre UK, welcomed the research but pointed out that women were still dying from heart disease.
One in six deaths in women are from coronary heart disease, the main form of cardiovascular disease, according to British Heart Foundation statistics.
Dr Wait said: "What is important to keep in mind is that even if this study is true what is often not recognised is that women get cardiovascular disease too.
"It is still the biggest killer among women."
And Belinda Linden, head of medical information at the British Heart Foundation, cast doubt on the study.
"The authors discuss the issue of inactivity among men and yet in the UK population overall, women are less active than men.
"The number of men and women investigated may not be adequate to provide a conclusive interpretation of the findings.
"Women tend to develop coronary heart disease about 10 years later than men - the differences noted between men and women in this research may be linked with the UK trends in heart disease."