The basic building blocks will be familiar to you by now. First off, you should recognize that a serious punch (as opposed to a jab, meant only to distract) will involve much more than just the arm. While the fist is the "delivery system" (as it were) for the attack, the force of the attack is generated from the entire body. It is a truism in animation that any powerful movement starts in the hips, and this is no exception.
If it is sounding to you like the punch is going to start with a pivot, you would be absolutely right. Since there's already a large tutorial on pivots, I won't bother repeating it. You should animate a pivot with the "power foot" (the foot on the same side of the body as the punching fist, generally the right foot) stepping forward.
So now you've got
some power developing in the pelvis. If you didn't animate the torso seperately,
it would be like the torso was passively transmitting this power to the
arm. Of course, that's not how a punch works out: the torso
contributes power too. It is the combination of the power of the
pelvis, the torso, and the arm that makes the attack so devestating.
The torso probably won't start to move until the pelvis is already in
motion. This makes the torso movement a type of Overlapping motion,
but not the same as the type we looked at in the Bowing tutorial.
So what type of overlap is it? Move on to the next page to find out!