This exercise is a great alternative to traditional floor crunches. The stability ball sit-up is done in much of the same way as a regular sit-up. The difference is that it is done against resistance. The rubber resistance tube is simply used to make the sit-up more challenging.

Start by positioning the middle of the back on the ball. The resistance tubing must be affixed around a stationary object, preferably low to the ground. Tightly grasp the resistance tubing handles and place them on the chest as shown in the demonstration. Slowly contract the abs by sitting completely upright. You can also go past the upright position, as the abs will still have to work against resistance. Be sure to exhale as you sit up. Hold the position for 2 or 3 seconds and repeat the exercise.