Hey Michael... sorry, I'm clueless.

In thailand you run for miles on concrete and do endless situps, chinups, pushups, etc. so we end up doing a lot of the same here - it's primitive but it's proven. Some of the people in my club use gym mats beneath them to do situps and whatnot, they seem to prefer it. We try and stay real loose, foam rolling a lot, stretching, etc and that helps a bit too. But hey, if you feel something slipping in your back or whatever, find another way.

Have you started sparring yet? I have a feeling once you get going, the aches and pains from hard sparring will make these discomforts seem trivial; not that I'm minimizing them at all, it's just that you might see them differently. I don't wanna say too much, everyone is different and you know more than anyone else what your thresholds are and whether or not the things that are bothering you are just uncomfortable or potential injuries waiting to happen.