As if running a marathon weren't challenging enough, long-distance runners in Beijing this August will be contending with extremely poor air quality. The Chinese government plans to control air pollution as best it can, but conditions will be far from perfect.
Some athletes are taking extreme measures, like practicing inhaling exhaust. Not American Olympic marathon runner Deena Kastor.
"I want to stay in the cleanest air possible for as long as possible," she says. Training in the hottest parts of the day and wearing excess clothing are the simple training tools she's using.