If you are attending a "a strength- and core-training circuit" or "bootcamp" class with the expectation of actually growing stronger (or strong enough to push a significant amount of weight overhead), you are performing exercises in futility. Real strength isn't attained that way. Powerlifters and olympic weightlifters aren't going to be found training at some bootcamp class, and they certainly can move a lot of weight. You'd be much better off with a cheap gym membership and a good training program. But, I digress. Best of luck pressing a man over your head.