What does it take to deliver a medal-winning performance in skeleton, which involves racing down a banked track faster than a car on a freeway, with your face mere centimetres from the ice?
It may look like athletes in bobsled, luge and skeleton simply grab a sled and hang on until the bottom, but high-speed physics and tiny motions mean the difference between gold and a crash.
An analysis of 21 former Winter Olympic venues found that only one of them would be suitable and offer safe racing conditions for athletes if greenhouse gas emissions continue to rise.