Exercise can stave off ageing

Getting older was not an excuse to slow down for masters swimming champion Mabel Leung Yuen-ying. She took up competitive swimming in her 40s, learned how to ski in her 50s, and tried scuba diving and skydiving, during her 60s.

Now 70, and fresh from competing at the World Masters Championships in Riccone, Italy, she has set her sights on completing the 1.5-kilometre cross-harbour swim in Hong Kong.

"When you reach a new milestone in your life, I think it's really good to do something challenging," says Leung, who trains for up to 90 minutes every day. "Being active makes you focused."

Keeping active is known to add years to a person's life. A study by Sweden's Karolinska Institutet, published in August in the British Medical Journal, tracked 1,800 people aged 75 years and older for more than 18 years.

It found that those who maintained a healthy lifestyle - that is, those who didn't smoke or drink, participated in a leisure activity and maintained a social network - lived, on average, five years longer for women and six years longer for men. Of the leisure activities, physical activity was most strongly associated with survival. On average participants who swam, walked, or did gymnastics regularly lived two years longer than those who did not.

Globally, life expectancy has risen in the past 30 years, according to World Health Organisation statistics. In 2009, global life expectancy at birth was 68 years, four years higher than in 1990. High-income countries tend to have higher life expectancy; in Hong Kong it's now 86.7 years for women and 80.5 years for men, according to the latest government figures.