Using a fitness ball for abdominal exercises gives you a greater range of motion than doing them on a hard, flat surface. As a result, you can exercise your core muscles more thoroughly. Try these fitness ball crunches:
1. Lie face-up with the fitness ball under your middle or lower back. Keep your feet flat on the floor, shoulder-width apart.
2. Place your hands behind your ears.
3. While keeping your hips and lower body still, tighten your abs and lift your chest up in a crunching motion. Don't bend your neck to initiate the crunch.
4. When your mid-back loses contact with the fitness ball, hold your position for 1 second, then slowly return to the starting position.
5. Perform three sets of eight to 12 repetitions, resting for 60 seconds between sets.