Watch James May Documentaries online: Episode 3 20th Century: Body Fantastic

James sets out to discover how far he can push his body and finds out about some of the most remarkable medical advances over the last hundred years. He begins by testing himself in a centrifuge – a machine that can make fighter pilots and astronauts break out in a cold sweat. He wants to find out what would happen to his body when it is subjected to high forces. As he reached 4.4 g – he passed out: "There was no doubt that I’d clearly reached my limit. The blood was forced from my head to my feet and I passed out." He then tries out anti-g trousers, and manages to get to 5.4 g without passing out. Next stop is New York where James meets a group of athletes that have pushed their bodies to the limit to get extraordinary results. These elite sportsmen and women have each lost a leg – but are able to run long distances at high speed thanks to hi-tech prosthetic replacements. They are now winning against able-bodied competitors, a success which has brought the remarkable complaint that the disabled athletes may have a competitive advantage because of their artificial limbs. Back in the UK James is invited to watch open heart surgery - and sees a man’s heart come to a complete stop during the operation. But James’ biggest surprise came when he looked at one of the 20th century’s greatest medical breakthroughs – the discovery of DNA. He had his DNA tested: "To be honest I’m so English that I’m assuming I’m descended from a piece of fruit cake and cricket bat, but let’s see." The results, however, were not at all what he expected.

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