hi
I know what you mean about underswings . I spent all year last year with my level 4's working them. I use a jump rope and tie it across from each side of the bar and when they dismount they have to go over the rope with out touching it. I also spot a lot of them. I also did levers for conditioning thats when they start with their chin at the bar without touching the floor and hold then lean back to thighs on the bar hold then back to chin, we did 5 in a row 3 times. one more thing i used to tie a baloon from the high bar and have them dismount and try to kick the baloon. i hope i was of some help!!!