One of the most fascinating, and under-explored, aspects of sports is the question of why and how athletes do what they do. This is especially true for the Olympians. Why does the bobsledder put himself $40,000 in debt for that one brief moment on the world stage, when so much can go wrong? How exactly should you position your body while hurling yourself 64 stories down a ski jump tower? What kind of intense grunt work do these men and women put in off the mountain and track, in the gym?

TIME.com's pioneering internet video series, "How They Train," gives viewers an unprecedented look at the lives of several Olympians, and the craftwork behind their under-appreciated sports. Reporter Sean Gregory and producer Vanessa Kaneshiro filmed for an intense two-week period in Lake Placid, NY, Minneapolis, MN, and Park City, UT area. The 10-part series, overseen by multimedia director Craig Duff, rolled out on TIME.com in the final weeks of 2009, continuing in the days leading up to the 2010 Winter Olympics. The videos let the viewer feel the vibrations of a bobsled ride at 80 mph, hear the wisps of the ski jump, pre-flight, and see the acrobatic aerial skiers splash into a pool, in the freezing rain. What does the life of an Olympian taste like? "How They Train" puts viewers in the action and feeds their curiosity, like never before. less