He took up running aged 70. He’s run a sub-4-hour marathon. What’s this Chinese senior’s secret?

• Liang Huguo never smoked or drank and did a lot of swimming. He took up cycle racing after retirement, and hiked to Everest base camp
• Two years ago, the 72-year-old from Yunnan switched to running, and has since finished 23 marathons. He tells us about his simple diet and training