The instability of the ball increases the work of a basic crunch, making it feel more concentrated in the upper abs.
- Lie on your back with your feet together and knees opened in a butterfly position.
- Place the ball at the bottom of your shoulder blades, and then place your hands behind your head.
- Exhale, pulling your abs to your spine, and contract your upper abs as you perform a crunch. Continue this motion with small, concentrated pulses.
- Do 25 pulses for a set, and do two to three sets.