Mind telling us what ab work outs you have done thus far in detail? How long have you been doing these exercises anyway?
You seem to drive for soreness as an indicator of you having done a proper ab work out, they may correlate, but are not necessarily a true indication of whether or not you worked it out properly.
Naturally, your body hits a peak and it grows ever more difficult to improve your strength after a certain point, this limit is more evident if you continue to do the same exercises over and over again, your body undergoes habituation and adapts. Obviously, there is always a limit to the human strength, but changing around your work out methods on a completely different schedule, with completely different exercises, will help considerably to reach that limit.
So what is it that you do in your gym class?
