 Ultimately, that additional strain that's placed on the body will cause a decline in their performance. But it can also be perhaps more fatal conditions like heat stroke, where we will see certainly athletes becoming very unstable on their feet, sometimes collapsing and falling to the ground. So how are some of the world's top Olympians training to beat the heat? 20 seconds, Phil. Join me, Kasa Alam, for the climate question, right after the BBC World Service News.