To me sprint means what it does in swimming... GO HARD. HARDER. DON"T SLOW DOWN. (It's a little easier on the bike because I can breathe whenever I want, harder because there's not a wall to charge and be done at. )
I'm on the road but on a flatbar bike. I don't even get out of the seat but I think most people would. Mainly I am pulling up a lot more with my hands. I prefer sprinting up hills 'cause I'm not coordinated enough to *move* that fast; the hill lets me get all out of breath without crashing :-)