Always thought it was only ab/curlbros who did it, but then I saw a couple of really strong PLers doing it, so I did my research on them.
Did them for the first time today, and my core was on FIRE!
Definitely felt the burn, and I actually feel like my core got stronger today.
For anyone who hasn't tried them (I'm assuming all of you have, haha), I highly suggest you do.
I need all the core work I can if I want to have visible abdominals at 220