Do you know where real punching power is generated and released? It is in the final inch or two of motion. Legendary martial artist, Bruce Lee, was known for demonstrating this fact with his famous "one inch punch." Lee would position his fist just one inch in front of the abdomen of a subject and without moving his hand backward whatsoever would unleash a punch that would lift the subject off his feet and launch him into a waiting chair several feet behind him.Many boxing and martial arts techniques involve intercepting or redirecting an opponent's punch or kick before it reaches full extension. These techniques are only possible because of the reduced power contained in a punch or kick before it reaches full extension.
Any serious boxer or martial artist will throw thousands of punches over his training career. A pro will throw millions. These repetitions build efficiency into the neuromuscular pathways between the brain and muscles. It is these many repetitions that make throwing a fast, accurate and effective punch second nature. However, all those repetitions do virtually nothing to develop strength in the muscles.
If you want big power…you are going to have to pump some iron - heavy iron. Think of that "one inch punch"; it is not merely hand speed or delivery technique that launches the opponent into the air. It is muscle power anchored on the ground by leg muscles and transmitted through the muscles of the shoulders and arms.