The revelation that doing sets at different speeds can increase mass and strength has stirred up controversy. Many say faster reps are too dangerous. Others contend that if properly performed, faster reps can activate different growth fibers—the type 2Bs that heavy training can call to action.
I think “speed” reps can be very effective for growth, strength and variety—change to gain, but you can’t throw the weights. You must still stay in control of them. I like to go about 1.5 seconds per rep.
Speed reps are excellent to use as part of a drop set on the last set of an exercise. For example, say you get six reps on your last set of dumbbell bench presses. Immediately grab dumbbells that are about half the weight, and crank out a speed set—as many as you can do. You’ll really feel it, augmenting the pump considerably with new growth stimulation.
One caveat: Do not use speed sets on dangerous exercises like behind-the-neck moves or direct lower-back moves—or any exercises that produce the least bit of joint pain for you.