How to Properly do a Bicycle Crunch
Lie on your back on a mat with knees bent, feet on the floor, and hands behind your head (dont clasp your fingers). Press your lower back into the mat and tighten your ab muscles as you lift your head, shoulders, and upper back off the floor and simultaneously move your right elbow and left knee toward each other while straightening your right leg (dont let it touch the ground).
Draw your right knee back up and immediately move your left elbow and right knee toward each other while straightening your left leg; thats one rep. Continue to move continuously, as if pedaling a bicycle. Do 3 sets of 15 reps 2-3 times a week.