Uppercuts are awesome punches, particularly useful in close-up combat. Because they target the chin they are knock-out punches. The blow of the uppercut snaps the head back causing concussion and momentarily shutting the brain down. As an exercise uppercuts are great punches to practise because they involve so many different parts of the body. Like most boxing-style punches they are powered by the legs and the twisting power of the body.
What's involved: Shoulders, quads, lateral abs.
Powered by: Quads, lateral abdominals, punching arm (tricep mostly), lower back.
Tip: It's all about coordination. When throwing an uppercut there is a strong temptation to simply scoop the arm. But that is not a good way to punch. Instead, keep your fist close to your chin, as you would for a normal straight punch and then time its release with the straightening of your legs. Punch with your arm in a straight line and twist your body behind the punch bringing the lateral abs and the lower back muscles into play leveraging their power to make the blow devastating.