The V sit-up is an explosive abdominal exercise that requires both your upper and lower body to move without losing the integrity of your abs. To do that, you have to keep your butt and lower back from losing contact with the ground. This one's invaluable for training midline stabilization that will help us not only build a rock-hard core but translate to better stabilization as we introduce more advanced weightlifting movements. To do it, lay on the ground with your legs straight, feet in the air. Raise your arms above your head, keeping them straight and locked out. Bring your hands and feet together directly above your stomach, keeping your butt and lower back in contact with the ground. Lower back down and repeat.