The V-up is an ab exercise that works the entire rectus abdominis which is what most people refer to as the “6 pack”. It basically involves folding your legs and upper body into a V shape in order to engage all your ab muscles.
To perform a V-up, simply lay flat on the floor with your legs flat and your arms extended over your head. lift your chest and legs up off the ground in unison. Your chest should be led by your arms. Your goal should be to touch your toes at the top of each repetition. As you’re touching your toes, the top of your butt/tail bone should be the only thing in contact with the ground.
Don’t make the mistake of raising your leg, but not your upper body. That will do little for your abs.
To make it easier, simply reach for your shins or knees instead of your toes. You can also bend your knees to make it easier. To make it more difficult hold onto a weight, like a medicine ball, but go through the same exact motion.