On a bright afternoon in Jiangsu, China, Xin Yin plays personal trainer for some mice. One by one, he puts the rodents on a miniature treadmill that starts slowly and gradually speeds up. These littermates are athletes who can run farther with less lactic acid accumulation than the average lab mouse.
The secret of their speed is not in their genes – the animals come from the same genetic pool as a group of control mice. And they have not received any special training. Instead, their fitness appears to stem from their father’s exercise habits even before conception. This is a finding that suggests running can be beneficial not only the athlete, but also his unborn children.
“I was very surprised when I first saw the data,” says Yin, a biochemist at Nanjing University.
