Lie on your back with an inflated balance board/disc underneath your lower to mid back, your feet flat on the floor, legs together, and arms crossed in front of your chest. Engage your abs and push your lower back into the disc beneath you.
EXHALE: Using the abdominals, "crunch" up by lifting your head, neck and tops of your shoulder blades away from the floor. INHALE: With control, slowly lower to the start position to complete one rep.
Keep your shoulders relaxed and your neck tucked in toward your chest while crunching up to help reduce neck strain. Do not attempt this exercise on a wooden or hard-surface balance board.
Make it easier: Instead of crossing your arms at your chest, place your hands behind your head/neck for support.
Muscles Worked: Abs