A diagnosis of multiple sclerosis hasn't stopped an elite teen runner from winning races, even though her legs get so numb that she collapses at every finish line.

Kayla Montgomery, 18, spoke with CBC Radio's As It Happens about how she became a high school state champ in North Carolina.

"When I stop running, I will fall, because the momentum of having been running keeps me running when my legs are numb," she tells host Carol Off. "But as soon as I stop, there's no momentum."

Listen to the full interview by clicking the embedded audio player.