This is a cut and paste from a question about punching answered over at dave tate's site. Elitefts
The response is from Tom Myslinski. Tom knows his stuff.
"The punch is characteristically very similiar to other movements (such as benching, throwing a shot, baseball, fencing prick, etc.), but what make it different is that is an unloaded movement. Thus, tension has to generated by the body, surprisingly, not in a rapid manner, but displayed at brief intervals using intense muscular contractions. These intrinsic properties categorize the punch as a true speed-strength movement, which incidently lies between 0-20% of one maximum.
Since maximal strength (80-100%) and speed-strength are not correlated (different neurological regimes), max strength doesn't effect initial muscular tension or max force when the external resistance is low. Speed-strength thus correlates highly with starting strength (20-40%). Thus, starting-strength which is displayed isometrically against an external resistance, is displayed dynamically in an unloaded movement, but barely (100-500 ms of conscious initiation).
1- Training for relative body strength, you don't need hypertrophy. The success of your other regimes depend upon this.
2- Train the appropriate energy systems. Shift that lactate curve to the right (speed-endurance).
3- Train in a relaxed, but heightened state. This will increase your reactionary times as well as your auogenic inhibition (eliminate co-contraction).
4- Train through incorporating different regimes. Use extreme isometrics, SUB-maximal eccentrics, starting strength (20-40%), and maximal speed (0-20%). For example, for starting strength, use suspended chain bench presses with 20-40% of your max for time. For maximal speed, utilize 1-5# DB's, weighted gloves, or mini-bands, in various positions.
5- Continue your DE day. This is acceleration strength (40-60%). Together maximal speed + starting strength + acceleration strength + relative strength = explosive strength.
And remember, your punching success depends upon your speed of execution. In order to be fast, you must train fast"
I hope you found this helpful