Viktor Roethlin is well aware his health may never be the same if he runs in the marathon at this summer's Beijing Olympics. But for the Swiss medal hope, the potential rewards are well worth the risks.

Fears that a combination of the city's notorious air pollution and the sweltering August heat could wreak havoc for the athletes have been carefully noted by Roethlin.

"You always hear that it is stupid to go there to run and even that you could have problems for the rest of your life," he said.