Both a human story and an intriguing scientific exploration of the way our bodies respond to intense exercise demands, this episode follows 13 novices as they take the first steps toward running in the 2007 Boston Marathon.

What does it take for the average person to run one of the world's toughest races? NOVA finds out in a program that's both a human story and an intriguing scientific exploration of the way our bodies respond to intense exercise demands. Filmed in cooperation with the Boston Athletic Association, NOVA was granted unprecedented access to the Boston Marathon course and takes viewers on a unique adventure inside the human body. Every year thousands of athletes from across the globe flock to Boston to run the city's marathon, known worldwide as the ultimate test of stamina and endurance. In the summer of 2006, NOVA began following 13 novices as they took the first step toward completing the 26.2-mile race in April 2007. The group of participants includes people of diverse backgrounds - a young woman running in memory of her mother, who died in a tragic car accident; a working single mom; even a former NFL linebacker. Not one of them is currently a runner. Over the nine-month training period, exercise and nutrition scientists and doctors at Tufts University use sophisticated technology to monitor the physical transformations that the participants undergo. Intimate interviews reveal the highs and lows along the way. The experience demands a transformation of mind and body; NOVA cameras are there, following every step.