STABILITY BALL LEG CURL

Anything that you can do lying on your back doesn't sound too hard, does it? Just try out these stability ball leg curls. Your hamstrings will be screaming for you to stand up.

1. Lie flat on the back on the ground. Place the heels on top of a stability ball. Rest the arms by the sides.
2. Tighten the abs, dig the heels into the ball, bend the knees, and roll the ball toward the butt.
3. Straighten the legs to roll the ball back to the starting position.
4. Make this exercise more challenging by doing a hip extension and holding the hips up while you roll the ball, or by performing the exercise unilaterally.