Why Rep Speed Matters for Size and Strength

Why Rep Speed Matters for Size and Strength

If you’re an avid weight lifter, you probably periodize your training with different rep schemes and splits. But do you always train every exercise at the same rep speed? If so, you might be selling yourself short. That’s because the more time a muscle is under tension, the better the stimulation.

Let’s break it down by looking at the anatomy of a rep.

A rep involves two moves: The negative, or eccentric part of the move, and the positive, or concentric part of the move. In a barbell curl, for example, the negative happens when you lower the barbell, and the positive happens when you lift it.

Most of us perform both the eccentric and concentric portions of a rep at the same speed–1-2 seconds up and 1-2 seconds down. But in a 2005 University of Sydney study, researchers found that participants performing slower reps made significantly greater gains in biceps muscle size than those doing faster reps.

According to the study, the best rep speed for muscle gain is to perform the negative portion of the rep in 2 seconds, and the positive one in 1 second. But training for pure strength requires a slightly different approach.

In the same study, researchers compared two groups for their ability to increase muscle strength with the bicep curl. One group performed slow reps (1 second each on the positive and negative portions of the rep) while the other group performed fast reps (1 second each on the positive and negative portions of the rep). After six weeks, the group performing fast reps made 10 percent greater strength gains.

So if you’re training for explosiveness, you will want to train with faster speed in order to condition your muscles and nervous system to produce power faster.

Why does this matter to you? Because you want to maximize muscle stimulation! To do so, periodize your program to include training for both size and strength. Using slower and faster reps will stimulate your muscle fibers differently.