Rate of Force Development (RFD)
Many martial artists work hard to improve their absolute (or maximum) strength, but this is not the type of strength they need. In the martial arts, the amount of time to develop maximum muscular force is limited to only a fraction of a second. While high levels of absolute strength are for the development of speed strength, too much lifting of heavy weights at slow speeds, without making the conversion to speed strength later in the training cycle, results in slow athletes.
The ability to apply muscular force rapidly is called rate of force development, or RFD. Training with heavy weights significantly improves absolute strength, but RFD remains largely unchanged. Only when speed strength methods, such as plyometrics or ballistic training, are used is the RFD significantly improved. However, absolute strength declines during this period, and, if absolute strength is allowed to degrade too much, RFD will suffer. For this reason, many coaches alternate between maximum strength and speed strength phases during the competitive period.
While constant resistance is the most conventional form of weight training used by athletes, it has one distinct disadvantage: deceleration. For example, in the bench press, you lower the bar to your chest, and then ram it to arms length. You may think this is an explosive movement, but as your arms reach extension, the antagonists, lats, biceps, rhomboids, and medial traps, begin to contract in an effort to decelerate the bar before it leaves your hands. This disadvantage may be overcome by strengthening the antagonists and stabilizers and using ballistic training.