A long awaited MMA-related post. Striking is all about the hips. When punching, movement generated should begin at the hips with a triple extension of the hips, knees and ankles to generate the force.
Studies have shown that in elite fighters, movement of their punches come from this triple extension of the lower limb and gets transferred from the torso to the shoulders then the arms. In amateur fighters, they found that majority of the movement generation is from the arms which makes the movement less efficient and tires you out alot faster from punching.
So next time when you are training your punches or doing your boxing classes, remember to focus on generating the movement for your punches from your hips to become a more efficient striker!