Freed of its ice, the antarctic would be a BETTER training ground, comparatively speaking. Of course, we would have a hard time in general since the ocean level would be ridiculously high, but I don't get the impression that they blasted the entire polar cap to the melting point.
I don't suppose you've ever watched the anime: Battle Atheletes Daiundokai? The whole thing involves athletic training that takes place in Antarctica after aliens blasted Earth and its axis rotated so that the continent is now along the equator. Athletic training in a competition against the warfaring aliens as a proxy battle as to prevent them from conquering earth...