Most successful track athletes who started late.

[doug5321]

jack foster started running at age 33 ran 2:11 at 41 and 2:20 in the marathon at age 50. http://stevequick.blogspot.com/2010/02/ ... leage.html

[Conor Dary]

jack foster started running at age 33 ran 2:11 at 41 and 2:20 in the marathon at age 50. http://stevequick.blogspot.com/2010/02/ ... leage.html

Already mentioned Foster.

[Spickard]

Not sure if you are limiting this to track-only athletes, but Donald Thomas learned to high jump in 2006 and was World Champion in 2007. Not too shabby.