The Bicycle Crunch
This move not only targets your abdominal muscles, but also the ones the run alongside it, your internal and external obliques. Researchers over at the San Diego University Biometrics Lab, found that the bicycle crunch activated your abdominal muscles more so than other exercises, including the traditional crunch.
How to do it:
Start of by lying on your back on a mat, keeping your back pressed to the ground and knees bent. Take a deep breath in; place both hands behind your head while contracting your abdominal muscles. At the same time lift your head, upper back and right shoulder, and bring it across to your left knee while breathing out. Your right leg will be straight. Repeat with the opposite side (left shoulder to right knee), which makes one complete rep. Make sure you keep moving continuously and have both legs off the ground, like you're pedaling a bicycle. Don't strain your neck by pulling at the back of it. Stop to correct your form, and then start over.