Its called a Kip-up. All the power is in the legs. It takes some practice, and you will bust your ass a few times, but mostly its about timing more than power. It took me a few days, but I have it down now. Also if you get that pancakes are sure to follow.
-Basically what you want to do is get on the ground sitting.
-Practice rolling yourself from toe to head in a ball back and forth to warm up your spine a little.
-Then roll back putting your arms/hands behind your head for bracing. Fingers towards shoulders.
-Honestly you could not even use your hands, remember that, they are for a tiny extra help and balance.
-While rolled back kick legs together in a forward/diagonal type motion. It is tricky and hard to explain. Once you see your vertical movement though you will understand the physic method of it.
-AFTER you kick, this is very important, THEN use your hands to fuller yourself along. Its a Kick push thing.
-When you come up to land, land with your knees bent and then stand up. This gets you braced and ready, soon after some practice it will be fluid and effortless.
Again not about brute strength or arms. Its about timing and leg force. Just remember when you kick out, really kick.
Also practice some with a small pillow under you spine/tail bone area. It really can hurt when you land wrong.
here is a link to a few videos of them.
