The plank exercise is a simple, yet difficult exercise that will work on the stabilization of the abdominal muscles. Hold yourself on your elbows and toes, keeping your body in a straight line. Do not let your back over arch or round out. Make sure to keep your hips down as well and not let them rise up, especially as you fatigue.
The easiest way to do this is to attach the band to a power rack as shown. Place yourself underneath the band so the band runs across your lower back. Perform the plank and hold for time. The band will put resistance on your body making the exercise harder. To increase the resistance, use a larger band. You can also place a weight on your back.