Can anyone run a marathon? How do you run 26.2 miles if you have trouble making it around the block? With good coaching, discipline, and lots of group support, as NOVA shows when it follows 13 generally sedentary people through a training regimen designed to prepare them for an ultimate test of stamina and endurance. Produced in cooperation with the Boston Athletic Association®, which granted NOVA unprecedented access to the 111th Boston Marathon®, and Tufts University, "Marathon Challenge" takes viewers on a unique adventure inside the human body, tracking the physiological changes that exercise can bring about.