Both rep schemes can be beneficial, depending on the individual as well as the training goal.  In the present article, we will touch on how each rep scheme affects injury risk, joint health, muscle gain, strength gain, fat loss, and which one should be used for single-joint versus multi-joint exercises.  In this way, I avoid turning the article into click-baity-“The Best Exercise YOU Should Be Doing…” bullshit, and instead focus on educating you, dear reader, so that you may make the best-informed decision for yourself, based on your own individual biology and training goals!  However, before we begin I need to lay out three assumptions as to what kind of exercise we are talking about…

  1. The tempo of each repetition we are talking about is one second up, one second down.  If we were to dive deep down the rabbit hole of tempo-based training, we would discover that high reps and low reps may accrue the same amount of time under tension, thus making the essence of this question pointless.
  2. Each set is performed to near-failure.  Otherwise high-reps performed to near-failure would always trump low-reps performed with minimal effort, and vice versa.
  3. High reps will be defined as 15-25 reps, while low reps will be defined as anything under 6 reps.

Now that we’ve got that out of the way, here we go…



High rep sets will generally be safer for individuals with a low training age – individuals who do not have much experience in the weight room.  Low rep sets generally require a ton of neural drive, ability to brace, and tissue resiliency, all three of which can only be developed through many months, or even years in the gym.  But if you are one of those veteran lifters, well then have at it with the low rep training!


High rep sets are tremendous for rehabilitating tendon or ligament strains.  Blood flow is one of the keys to healing injured tendons and ligaments, and high rep sets lead to the pooling of blood in and around the working muscle.  Some of this blood is able to diffuse into the area of injury and help clear away inflammation while simultaneously introducing new “good” cells into the area.  On the flipside, low rep sets are fantastic for building up the tensile strength of tendons and ligaments before injury ever occurs! Without getting too deep into the minute details, high reps are good for injury rehabilitation, while low reps (when dosed appropriately) are good for injury prevention.


Both high rep and low rep sets are not the most optimal way to build muscle.  The real sweet spot for hypertrophy (if we keep to the one second up, one second down, and performing each set to near-failure rules laid above) is the 8-12 rep range.  Anything that falls closer to that rep range will be better for muscle building. So a high rep set of 15 reps, and a low rep set of 6 reps would be more effective than a high rep set of 25 or a low rep set of 1.


Low rep sets better stimulate the energy system needed for building maximal strength (i.e. the ATP-PCr system).  Low rep sets also do a better job of remodelling tissue in a way that allows the body to better tolerate near-maximal loads.  Low rep sets are better for strength gain, period.


This is a trickier topic.  While technically, high rep sets stimulate the two metabolic energy systems most important for fat loss (i.e. the aerobic and glycolytic systems), the real key to fat loss is total amount of work performed in the gym.  Much more work can be performed when an individual possesses high levels of absolute strength, which is best increased through low rep sets.  To keep things short and simple, I’ll say this: Spend most of your time performing high rep sets for fat loss, but make sure to incorporate low rep sets to increase absolute strength so that your high rep sets can eventually be performed with higher loads/weights in order to do more work and burn more calories.


As a general guideline for injury prevention, low rep sets should not be performed often with single-joint exercises such as bicep curls or tricep extensions.  Low rep sets are better suited for multi-joint compound lifts such as squats, deadlifts, and rows, to name a few examples. High rep sets can be performed with both single-joint and multi-joint exercises.


As always, if you’d like to know more about, and start taking responsibility for your own health, fitness, and wellness, please reach out to Crux Fitness Richmond for any of your personal training needs.

Patrick Koo – Personal Trainer at Crux Fitness Richmond

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