In this fascinating book based soundly in medical science, Mike Stroud - of BBC Television's The Challenge and SAS: Are You Tough Enough? - sets out the genetics, diet and exercise that enable humans to perform at their peak. Dr Stroud - polar explorer, practising hospital physician, and a former adviser to the Ministry of Defence - analyses individual feats of survival and athletic prowess that illustrate the way the body functions at its best. He dissects his own challenging experiences of crossing Antarctica with Ranulph Fiennes, running marathons in the Sahara and participating in gruelling cross-country endurance races in the United States and gives some tips on how to stay fit for life for those of us who find walking the dog an endurance challenge... This revised edition includes the story of Dr Stroud and Sir Ranulph Fiennes' incredible 2003 global marathon challenge - seven marathons on seven continents in seven days - in aid of the British Heart Foundation.