Overview: The human body is engineered for strength, power and endurance. Bone is sturdy as concrete but flexible enough to resist breaking and light enough to allow us to be quicker off the mark than a racehorse. Our muscles, ligaments and joints have far greater strength and endurance than we know. In this episode, we feature extraordinary tales of human strength told with stunning see-through "anatomy in motion." * A young man is sucked up into a tornado, only to be spat out a quarter of a mile away, unharmed. * Pinned by a massive boulder, a climber finds the strength to lift it off in a seemingly impossible muscular feat. * A college football player sustains what would normally be unbearable injury and pain, yet has the mental stamina to continue playing at full output. Plus, how does a swimmer tap the remnants of our distant ancestors' extraordinary stamina to swim across the English Channel in 14 hours? How do marathon runners keep the pace on their grueling 26-mile run?