so to answer your question in your first post, the opinon you ACTUALLY ASKED FOR, on how to have shot these better.
first off you have a few things working against you.
shooting in a poorly lit area without using a flash is hard enough, then you add the fact that your trying to shoot things that are moving. your fighting an uphill battle thats for sure.
what type of equipment are you working with? a digital slr?
can you use flash next time or is that not cool in this situation?
if you are using an slr, i would invest in a lens that can go down to f 2.8 this will help you alot in all lower light situations. it will allow you to use higher shutter speeds to better capture the motion. ever see sports photographers with the huge lenses? thats how they capture fast paced action.
try using a monopod if possible.
higher iso’s will be more grainy i wouldnt go more than iso400 if possible.
try to plan/anticipate the shots, it will allow for less “trigger jerk” as i like to call it. have the camera focused where they skater will end up, have it prefocused and shutter release partially depressed, squeeze off the shot easy while breathing out slowly.
im not a profesional by any means, i hope to be someday, but i do like to shoot in low light alot though. i love the challenge.
hope some of this will help you.