To continue to grow, your muscles need to be challenged in different ways. One way to vary the stimulus you place on a muscle is to change the “lifting tempo,” or the speed with which you do a rep. You’re probably familiar with super-slow training where you reduce the speed or tempo of a rep to maximize the time the muscle is under tension. At the other end of the spectrum, you can increase the speed and make the movement faster and more explosive, thereby stimulating the muscle in a different way. What role does rep speed play in muscle gains and is one rep speed more effective than another?
What Rep Tempo is Best for Strength and Muscle Hypertrophy?
According to one small study, fast rep speeds may be more effective for building strength than slow reps. In this study a group of young males did 4 sets of bench press, completing 12 reps with each set. One group used a fast rep tempo, completing each rep in 1.5 seconds, while the other used a slow rep speed, finishing a rep in 6 seconds. At the completion of the study, researchers measured one-rep max on the bench press exercise and compared them to values measured before training. How did they fare? Participants who used a fast rep tempo experienced greater strength gains than those who used a slow one – not surprising since a fast rep tempo maximizes recruitment of fast-twitch fibers, those optimized for strength and power.
What about muscle hypertrophy? What’s most important for muscle growth is exposing muscles to progressive overload AND maximizing time under tension. With high-velocity reps, your muscles spend less total time under tension compared to when you slow down the speed of your reps. Because you’re moving the weight quickly and using more momentum, you can use more resistance. This is beneficial for developing strength, but it also comes with a price – less time under tension due to the speed of the movement. For this reason, a fast rep speed works well for developing strength and for increasing power – but slow rep speeds are better for muscle hypertrophy.
Varying the Rep Speed
As you might have guessed, there isn’t a right or wrong rep speed. The rep speed you use will depend upon your short-term and long-term goals. If your primary goal is to become stronger, become more powerful or improve your performance in sports that involve power, fast rep speeds will help you accomplish that. If muscle hypertrophy is your main goal, average rep speed and super-slow training maximizes the time your muscles spend under tension, giving your muscles a strong stimulus to grow. Fortunately, you don’t have to choose between the two. Alternating rep speeds, by doing slow reps during one training cycle and fast, explosive reps during another cycle, will help you avoid a plateau.
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