Tim Fitzhigham meets the humans who defy science and puts their powers to the test - against himself. Tim meets Dean Karnazes, a man who has run 350 miles without stopping and completed 50 marathons in 50 days without breaking a sweat. But does Dean's extraordinary stamina make him a real-life Captain America?

Tim challenges Dean to three super tests in order to prove, or disprove, these amazing superhuman powers. Can Tim and Dean run and run all day in Death Valley - one of the hottest and driest places on the planet? This is exactly as dangerous as it sounds, so Tim uses state-of-the-art technology, real medical science and his very own mission doctor, Dr Megan John, as he prepares for his challenges.

Is Dean Karnazes a real-life Captain America? Be prepared to be amazed by Super Human Challenge! Show less