Should you do high or low reps to build muscle?

You go to the gym with the goal of getting jacked: you want big arms, tree trunks for thighs, and a chest that makes it hard to clasp your hands together.

You know what exercises you need to do to hit these areas: some tricep extensions to smash the tri’s, leg extensions for quads, and as long as you get to the gym before 5pm, the bench press will be all yours for working the pecs.

Everything is set for a ‘Gain Dat Size’ workout, except for one thing: how many reps should you do?

You’ve always followed between 8-12 reps for each exercise (as that’s what you’re supposed to do), but your body still looks pretty similar to when you first started. So is 8-12 actually the right amount of reps?

In this blog I’m going to explain why there are different rep ranges for building muscle, and which range is the best for you. Let’s dive in and find out how you can transform your workouts to get the improvements you want.

The Conventional Approach To Deciding Reps


Most people will decide the amount of reps they are going to do based on something similar to the below image.

Rep range
  • 1-5 reps – Focuses on strength 
  • 6-12 reps – Builds muscle size
  • 12-20+ reps – Works on the endurance of the muscles


These definitions, on paper, are accurate.

When performing 1-5 reps the muscles will be producing the highest amounts of force due to the energy of the muscle being at its most fresh.

6-12 reps still produces force, but to a lesser extent. However, there is increased tension within the muscle as it is placed under tension for longer. This causes increased damage of the muscle, leading to greater potential for regrowth.

While 12-20+ will produce far less force in the muscle, it will be able to produce the force for longer periods of time.

Why The Rep Ranges Fall Apart


These rep ranges won’t have the desired effect if you don’t account for one of the most overlooked training variables…  intensity.

If you perform 4 reps with ease, your muscles will not produce high amounts of force.

When performing 10 reps and it feels like you could perform 10 more, there is not much tension being placed on the muscle.

You could perform 20 reps effortlessly, you would be training the endurance of the muscle, but it would be to such a low level that you would receive minimal benefits.

It’s a common mistake that people will perform 1-5 reps with the intensity of 6-12 reps, or perform 6-12 reps with the intensity of 12-20 reps.

By doing so, your muscles are not being fatigued enough to allow for adaptation. Essentially it’s like your muscles are being taught a math equation they learn during the class but is forgotten once class finishes.

To get the most out of the different rep ranges you have to ensure that you train at the optimal intensity for the particular rep range. This means if you are going to perform 10 reps, you shouldn’t finish the exercise thinking you had 5 more left.

In The Strength Lab Free 7-Day Trial, we use the Reps In Reserve (RIR) method to find the optimal intensity for you with each exercise. RIR provides a numerical figure based on the number of reps you should feel you have left at the end of a set. To learn more, click here to join The Strength Lab Free 7-Day Trial.

Which Reps For Which Exercise?


So training at higher intensities is important, but you always feel like you work hard enough!

How do you work at the right intensity so you don’t become exasperated with your results?

Feeling like you’re training hard and not seeing improvements is a sign that you’re getting the intensity wrong. To get the intensity right, and feel like you’re making real progress, we need to look at what reps range you’re doing for what exercises.

Although technically you can perform any exercise with any rep range, These 2 simple tips can change your training frustration to triumph :

The heavier an exercise becomes, the fewer reps you should perform.

This is because the more reps you perform, the higher risk that you begin to alter your technique. Common exercises for using heavy weights are squats and deadlifts. These exercises are generally known as compound exercises.

The easier an exercise is, the more reps you should perform.

When performing exercises that focus on only one muscle or joint, the risk of compensating technique is low. Common exercises that are easier to perform include calf raises and arm curl. These exercises are generally known as isolation exercises.



There are a variety of ways to use the rep ranges, and each will train the muscle in a different way. But if we only use the same intensity for each rep, we will stop seeing our muscles develop, and fast!

Next time you’re in the gym about to perform some heavy back squats, ask yourself ‘what would the right number of reps be to train hard, but not change my form’. Go through your program and make sure you know the right intensity for the right rep range.

If you’re looking for a guaranteed way to develop your muscle size, without worrying about whether the rep range is right, click here to join The Strength Lab Free 7-Day Trial.




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