"Forget the pollution: it's the heat and humidity of Beijing that pose the greatest concern to athletes this month. Heat chambers have been an integral part of Britain's build-up to the Olympics – but what exactly do they do? 'Exposing an athlete to a hot environment before competition will improve their sweating mechanism and ensure a greater degree of cooling,' says Dr Simon Hodder, tutor of ergonomics at Loughborough University, who has invited me to experience a session.
Five hours before exercise I'm given a pill – actually a microchip – that will measure my core temperature, 'just so things don't get dangerous'. It's purple, large, and difficult to swallow. 'Could be worse,' Hodder says. 'You could have had the rectal probe.' The chamber is set to 32°C and 80 per cent humidity to mimic the conditions in China. 'Picture a sponge,' Hodder says. 'In Britain that sponge would be about 50 per cent full of water. In Beijing it will be 75 to 80 per cent. The sponge that will pick up water more readily is the 50 per cent one.' With sweat it's the same. It is harder for the body to transfer water into an already wet environment, meaning your natural mechanism for heat loss is blocked. 'So just make sure you keep wiping down during the exercise,' Hodder recommends.
I'm weighed so that Hodder can measure how much I liquid I lose through sweating. Probes are attached to my body to monitor my skin temperature, and I strap on a heart-rate monitor. Water bottle in hand, I enter the chamber. The heat hits me straight away but it's the airless atmosphere that really hurts. My breathing rate goes up, my limbs feel heavy. My head is boiling as I start my first paces on the treadmill. A puddle soon forms beneath me.
Twelve minutes in, I'm suffering. After half an hour, I'm woozy and I reach for the stop button. My core temperature has risen 1.5°C to 39°C and I've lost a kilogram . Happily, I'm told by Hodder that elite athletes normally fare better. 'But the human body is unpredictable, so you never entirely know." (Continued via guardian.co.uk, The Observer, James Witts) [Ergonomics Resources]