Think you got a strong core? Try These

[Spartacus Sully]

I find that these in order to so them well requires both a strong core and a strong back if not even more so a strong back where your core is supporting your legs and helping to keep your body straight your back is pretty much supporting your whole body from the shoulders down.

if you cant do a decent amount of sit ups and pull ups your going to have problems with these.

[Kiid Dynamite]

rocky does these

[MANIAKO]

damn i want to f.uck that girl in the back of that vid....