The answer to this question has proven harder to find than I first thought it would be, so I decided to ask it here.

My question is, what is the optimal rep duration in a resistance training regime designed for maximum muscle growth (so not for strength or endurance).

If you can provide a reference to original research, that would be beyond awesome.


3 Answers 3


For maximising muscle growth(Hypertrophy) you need to make sure that you're keeping higher time under tension which will incorporate more muscle fibre against the resistance and incur in a much better growth.

A prolonged muscle time under tension, only when fatigue leads to full motor unit recruitment, affects the acute amplitude of muscle protein synthesis and mediates a delayed effect on rates of synthesis during 24–30 h recovery. Provided your protein intake is to the point. Time under tension Reference

Therefore, increasing your time under tension to about 40-45s will be optimum. The reason you shouldn't look for reps as a rule of thumb is exemplified here. Consider these three cases for Bicep curl(This is applicable to almost every exercise):

Case1:- 1 rep: 1second concentric(lifting the weight up)+ 1 sec pause for squeezing the muscle + 2 sec eccentric(lowering the weight) Time per rep = 4sec. Reps required for optimum time under tension = 10

Case2:- 1 rep: 1 second concentric + 2 second eccentric Time per rep = 3 sec. Reps required for optimum time under tension = 13(~12)

Case3:- 1 rep: 1 sec concentric + 1 sec pause + 3 sec eccentric Time per rep = 5sec. Reps required fo optimum time under tension = 8

On a personal level, I have experienced more satisfying workouts after incorporating these techniques.

Hope this helps.


In general when you are talking about fitness here are the 4 areas that you have to look at with exercises:

  1. Frequency - How often do you exercise or perform the movement. Ex: Are you working out 3 times a week or 6 times a week. This of course does have a cap on it as over training is a real thing.
  2. Duration - How long do you perform the movement for. Ex: Are you lifting weights for 20 minutes each time you work out or for 60 minutes.
  3. Intensity - How intense is your workout each time. Ex: In the case of weight lifting are you benching 145 pounds 10 times or are you benching 160 pounds 10 times. As the weight increases the intensity will naturally increase.

So the answer about are more reps better should be framed withing this context. As each one of these 3 factors increases, your strength and fitness levels will generally increase (all other factors being equal, ie diet, sleep, stress).


This is a loaded question. First off, Everyone's body responds differently to different rep ranges. I'm going to give your a broad answer and say all rep ranges are good. The reason is because you never want to let your muscles get into a routine.

Another point to be made is that heavier weight recruits more of the muscle to perform the movement. So doing 6x5 is technically better for building muscle than 4x12.

I like heavier weight and lower reps on compound movements like bench press and rows, but I add more reps on isolated movements like bumbell flies for inner chest and preacher curls.

  • 1
    I think he asked for the duration
    – Sebas
    Mar 28, 2017 at 13:50