Weighted V-UPS

Anyone here ever do weighted v-ups(with ankle weights), i did them one time to see how they felt and i felt i got a pretty good lower abdomen workout. But felt they put too much strain on my lower back. i did 3 sets of 10 with about 2.5 pound weights on each leg.

Anyone else here get good results doing these?

Yea they freakin hurt if you do a ton. I did weighted ones awhile back and it was a pretty nice ab workout, but not extremely necessary toward my goal at the time. So I guess incorporate them as you see fit my friend!