This Exercise complex is mine, but I give it to you, be grateful!
It is called the bug, bugs are strong, bugs on their backs are desperate to right themselves. This exercise is good for everybody, and everything, I have watched babies doing this exercise. If you use this complex well, it will improve your core strength dramatically, and increase your ability to climb. Every kind of climber can use this, boulderers, ice climbers, even hill runners. It is also safe, and I think fun.
One of the problems of stomach and trunk/core exercises is that they can irritate the Sciatic nerve. This complex, or super set, attempts to be safe, and easy to do, but with the biggest pay off.
Lie on your back with your knees raised to the side like a frog. The important bit, which is very natural in this position, is that your pelvis is tilted up and not back.
With your hands folded behind your head touch your elbows to your knees, or behind the knees, without taking your back off the floor. Squeeze tight, very tight. Alternate each side.
Now do the same but with your back curved in the crunch position.
First part over, rest if you like in the yoga Corpse position. Resume Bug, and do the same thing but using the legs, and not the arms. So your knee comes up, alternately to touch your elbow. If you cant do this just do Crunchies, with your head as far over your crutch as possible. Remember squeeze,
Corpse out, if you want.
Now fingers touch toes alternately
Corpse out, if you want
Now both hands touch toes together.
Repeat, and numbers, as much as you want, but quality, and range of motion over volume. Add resistance for more power. If doing it for the first time, watch out, the Bug bites.