Stability ball ab crunches

Stabilize your body on a stability ball by finding your balance point for performing a crunch movement (your lower back will be on the top of the ball). Then simply crunch your upper body up while keeping your fingers on the sides of your head, chin up, and feet planted flat on the floor.
To make this exercise more challenging, you will see that my programs progress on this movement as you advance through the levels by incorporating moving your arms straight out behind your head, and then further progressing by holding a weight or medicine ball out behind your head while completing the crunch.
The modifications to the crunch add resistance to the exercise making it more effective, since a standard crunch does not provide enough resistance for someone who is past the initial strengthening phases.
As a tip to make all of your crunches much more effective, try to hold the top of the crunch for 2 seconds while forcefully exhaling and holding a tight contraction of the abdominals.