INCREASE THE ROM
If you’re smart, you can use the gym ball to increase your range of motion (ROM) for some abs and lower back exercises. This is useful because working through a greater range of motion will present more of a challenge to your muscles, leading to greater size and strength increases.
KEY MOVE GYM BALL CRUNCH
Lie with your mid-back on the ball, your knees bent at 90° and your feet planted firmly on the ground. Place your fingers to your temples and lean back over the ball to stretch your abs. Exhale, then contract your abs to bring your torso up. Pause at the top. This move is about the quality of muscle contraction so keep the tempo slow and controlled.