Writing from both the cutting edge of scientific discovery and the front-lines of elite athletic performance, National Magazine Award-winning science journalist Alex Hutchinson presents a revolutionary account of the dynamic and controversial new science of endurance.

An endurance athlete and coach reveals how the marathon transforms the lives of everyone who attempts it - and how it has helped his own family cope with serious adversity.

Isolated by Mexico's deadly Copper Canyons, the blissful Tarahumara Indians have honed the ability to run hundreds of miles without rest or injury. In a riveting narrative, award-winning journalist and often-injured runner Christopher McDougall sets out to discover their secrets. In the process, he takes his readers from science labs at Harvard to the sun-baked valleys and freezing peaks across North America, where ever-growing numbers of ultra-runners are pushing their bodies to the limit.

New York Times best-selling author and ultramarathoning legend Dean Karnazes has pushed his body and mind to inconceivable limits, from running in the shoe-melting heat of Death Valley to the lung-freezing cold of the South Pole. He’s raced and competed across the globe and once ran 50 marathons, in 50 states, in 50 consecutive days.

When Chris McDougall agreed to take in a donkey from an animal hoarder, he thought it would be no harder than the rest of the adjustments he and his family had made after moving from Philadelphia to the heart of Pennsylvania Amish country. But when he arrived, Sherman was in such bad shape he could barely move, and his hair was coming out in clumps. Chris decided to undertake a radical rehabilitation program designed not only to heal Sherman's body but to heal his mind as well - and so Chris decided to teach Sherman how to run.