I'm averaging 38 right now after 400 races on typeracer (I would add a screen shot of my progress but i dont now how to attach things on here) and all of a sudden I start feeling pain in my right thumb. I use the space bar with my right thumb and i think this may have to do with the fact that colemak uses more hand alternation (as opposed to 15% favored on the left hand with qwerty) so im using my right hand more then i'm used to.
you think i should keep typing for a few days, and see if the pain goes away, if it does then good, if it doesnt then maybe i should first try using my left thumb for spacebar, and if that doesnt work then maybe i go buy a microsoft 400 natural keyboard (if you don't know what that is then google it its an ergonomic keyboard)?