The 'Tetsujin' or Iron Man category at RoboGames doesn't have a lot of competitors, but the few builders that do participate in building human assisting and enhancement robotic systems do it with a real passion.
The 'sport', if we can call it that, requires long term dedication and the willingness to invest large amounts of personal time and money. Building linkages, actuators, and control systems that are human sized, and sometimes larger, is not for the faint of heart or pocketbook.
Monty Reed, the defacto RoboGames Tetsujin guru and founder of the They Shall Walk organization, got involved out of personal need. In 1986 he was injured in a parachute accident while serving as a US Army Airborne Ranger. During his recovery in the hospital he sketched out ideas for his first power suit to help the disabled and elderly recover as much functionality and mobility as possible.
He hasn't stopped since. His current version of the power suit, number 12 in the series, only weighs 75 pounds and enables walking, climbing stairs, lifting heavy objects, and even jumping, as you can see Monty demonstrate in the video below from RoboGames 2007 last month.