ASPEN, Colo. — On a cold and sunny morning, Kevin Pearce stood at the bottom of the massive halfpipe at Buttermilk Mountain wearing a grin and black-framed glasses with thick lenses as his friends and former competitors practiced their runs for the Winter X Games. Riders kept zipping up the wall of the 22-foot pipe Thursday and launching into a bright, blue sky, working their way toward Pearce.

“There’s nothing I would rather do than ride this pipe right now,” said Pearce, a two-time medalist in the event at the X Games. “You don’t realize what it is till you lose it.”

Pearce, 23, has not been able to strap into a snowboard since falling and striking his head on the edge of the halfpipe Dec. 31, 2009, while practicing in Park City, Utah. He was attempting a double cork, a difficult inverted maneuver that only a handful of riders had started landing in advance of the Vancouver Olympics. He had been expected to qualify for the United States snowboard team and contend for a medal.

Although he was wearing a helmet, Pearce sustained a traumatic brain injury. He spent a month at the University of Utah Hospital before transferring to the Craig Hospital in Denver for rehabilitation. In May, he returned to his parents’ house in Norwich, Vt., where he is continuing his physical therapy.