Maybe what they were talking about was sitting up, and every time you come up, you punch on the bag. I don't think those were V-ups...

is boxing training routine and iunno if it was on here or another website but it had a warmup session and a workout for your abs and other stuff involving a heavy bag and a sparring partner. But NEways one of the ab workouts was called a
" V - SIT"
WTF is that and how is it done?!?!?