I know that for a lot of injuries, you want to ice it right when it happens to help supress the inflammation/swelling. After the first day or so, you want heat to help loosen everything up and relax it. I messed up my knee a few weeks ago, reallllly bad cramp that somehow swelled up and I couldn't bend my leg backwards. Kept using ice, then figured it out, and the heat helped much more. Get an IcyHot pack.