Do Slow Reps for Increased Size and Strength

ez bar curls

We have told you before that time under tension is the key to muscle building. We were not kidding either.

I know many of you out there think slow reps are boring or you don’t like having to use less weight to do a slower controlled rep. I can’t lie, I feel the same way sometimes myself. This article might change your mind and have you putting in those nice slow reps to reap the benefits they provide.

A recent study proves this point in a big way. The study by Pereira, et al. found that increasing the time-under-tension was not only beneficial for increase size but it was also beneficial for increased strength as well. Not only is the study just about time under tension but the slow portion of the rep focused on the negative portion of the lift rather than the part of the lift where you raise the weight. So you could say it’s about slow negatives as well.

Let’s take a look at the study and see how it was performed and the results.

The Study

For this study, they used 12 male weightlifters and had them do Scott Curls twice a week for 12 weeks.

Half of the men performed slow reps where they would raise the weight for one second and then lower it for 3 seconds.

The other half of the group would do regular or “fast reps” where they lifted the weight for one second and lowered the weight for one second.

They would perform 3 sets of 8 reps with the 8th rep going to failure.

For testing, they used ultrasound examination of a cross-sectional area of the brachialis biceps muscle along with 1 rep curl max for each participant.

The Results

Larry Scott Curl

When the 12-week study was over the slow rep group showed almost 5 times the progression in strength over the slow rep group and also built three times as much muscle as the fast rep group.

A Little Skepticism

It should be noted that some of the reason for the gains could be from simply switching from one way of training to another, this will usually lead to new gains all by itself. I would imagine if you always trained using slow reps that going to faster and heavier reps would shock your muscle and lead to new gains as well. Just some food for thought.


While I wouldn’t do every single rep of every exercise in the slow rep fashion you can see that slow reps definitely have their place in both muscle and strength building. Find a way to use both slower and faster reps into your workout and get the best of both worlds. You may have to check your ego at the door but it’s worth it.

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  1. Pereira, et al. “Resistance training with slow speed of movement is better for hypertrophy and muscle strength gains than fast speed of movement,” International Journal of Applied Exercise Physiology, Vol. 5, No. 2.