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Does Maxing Out Build Muscle? (Explained)

Updated: Oct 10, 2021

TL;DR: A 1-rep max set may be effective for strength training, but it does nothing to build muscle. A 5-35 rep range is effective for building muscle, providing you train to failure.

Regularly maxing out on a 1-rep max isn’t uncommon. Maxing out may be useful for strength training due to improved motor learning with heavier loads and greater neural adaptations.

But, what about muscle growth? We often hear 8-12 reps being effective for muscle building. But could 1-rep max training still be effective for muscle growth?

In this article, I'll discuss the research surrounding 1-rep max training and muscle growth.

bodybuilder bicep curling his 1-rep max

The Research

In this section, I'll discuss two studies research whether maxing out (1-rep max sets) can help build muscle.

2017 Study

One arm was allocated to a one-rep max workout and the other arm to a volume workout in a study of five men with at least one year of training experience. (1)

They worked on both arms for a total of 21 days.

With the 1-rep max arm, every day, they worked their way up to a 1-rep max on the unilateral dumbbell biceps curl.

Their backs and shoulders were pressed against a wall to prevent momentum from assisting them. They also used a dynamometer to achieve a maximal isometric contraction of the biceps at 60° of elbow flexion. This was repeated again for a total of two 3-second contractions.

They accomplished the same thing with the volume arm that they did with the 1-rep max arm (working up to a one-rep max on the unilateral dumbbell biceps curl and performing the maximum isometric contraction).

In addition, the volume arm did three sets of 10 repetitions with a 70% load on the unilateral dumbbell biceps curl.


It was measured at 50%, 60%, and 70% of upper arm length before, during, and after the session.

The training regimen itself measured 1-rep max and maximum isometric contraction strength on the dynamometer.


Both arms gained strength in 1-rep max and maximum isometric contraction. Throughout the 21 days, the volume arm had thicker elbow flexors than the 1-rep max arm.

If we look closely at the data, we can see that the 1-rep max arm grew very little in size. So, 1-rep max training on the dumbbell biceps curl for 21 days does not seem to develop muscle.

3 sets of 10 repetitions on the dumbbell biceps curl seemed to be required for muscular size development.

Now, this study had subjects train daily and the study was only 21 days in duration.

2017 Randomised Controlled Trial

Untrained men and women, totalling 17 men and 21 women, were divided into two groups: testing and hypertrophy. (2)

For eight weeks, both groups exercised twice a week on unilateral knee extension (both legs) and chest press.

For each exercise, the hypertrophy group did four sets to failure with an 8-12 rep-max load and 90 seconds of rest between sets.

Each session, the testing group warmed up and had a maximum of 5 tries to lift the most weight feasible on each exercise, with 90 seconds of rest in between. Every session, they basically assessed their 1-rep maximum for each activity.


Before and after, both groups 1-rep max on unilateral knee extension (both legs) and chest press was measured. It was also measured in both groups at 50%, 60%, and 70% of the thigh length before and after.

This would have encompassed the vastus medialis and rectus femoris in the anterior thigh.


Both groups had statistically comparable increases in unilateral knee extension 1-rep max for both legs and chest press one-rep max.

The hypertrophy group outperforms the testing group in all measures of anterior and lateral thigh thickness.

The variations in all of the leg measurements for the lateral thigh, however, were not classed as statistically significant. Similarly, changes were not categorised as statistically significant at 60% and 70% of the anterior thigh for the dominant leg.

Regardless, it is clear that the hypertrophy group grew much faster than the testing group. This is also supported by the before and after adjustments for each group.

Looking at the findings of the testing group, we can observe that for almost all metrics, there were no increases, and in some cases, small reductions.

The hypertrophy group, on the other hand, saw gains in essentially every area, as shown below.

Muscle & Measurement Length

Hypertrophy Group

1-Rep Max Group

Anterior Thigh 50% (Dominant Leg)



Anterior Thigh 50% (Non-Dominant Leg)



Anterior Thigh 60% (Dominant Leg)



Anterior Thigh 60% (Non-Dominant Leg)



Anterior Thigh 70% (Dominant Leg)



Anterior Thigh 70% (Non-Dominant Leg)



Lateral Thigh 50% (Dominant Leg)



Lateral Thigh 50% (Non-Dominant Leg)



Lateral Thigh 60% (Dominant Leg)



Lateral Thigh 60% (Non-Dominant Leg)



Lateral Thigh 70% (Dominant Leg)



Lateral Thigh 70% (Non-Dominant Leg)




To summarise, the findings of these two studies seem to indicate that, although 1-rep max training is beneficial for increasing strength, it is not effective for increasing muscle size and mass.

These results support the theory that 1-rep max training generates substantial strength increases through improving neural and motor abilities rather than by increasing physical muscle size.

Current research suggests that reps between 5 and 35, roughly 85% and 30% 1-rep max loads, generate comparable muscular development when repetitions are completed to failure. (3)


Written by Billy White

billy white

Billy White is a qualified Kinesiologist and Personal Trainer. He is an aspiring bodybuilder, fitness enthusiast, and health and fitness researcher.

He has multiple years of experience within the fitness, bodybuilding and health space. He is committed to providing the highest-quality information.



This section contains links to research, studies, and sources of information for this article, as well as authors, contributors, etc. All sources, along with the article and facts, are subjected to a series of quality, reliability, and relevance checks.

Real Muscle primarily uses high-quality sources, such as peer-reviewed publications, to back up the information in our articles. To understand more about how we fact-check and keep our information accurate, dependable, and trustworthy, read more about us.

This evidence based analysis of 1-rep max sets for muscle growth features 3 references, listed below.

1. Dankel SJ, Counts BR, Barnett BE, Buckner SL, Abe T, Loenneke JP. Muscle adaptations following 21 consecutive days of strength test familiarization compared with traditional training. Muscle Nerve. (2017, Aug) ✔

2. Mattocks KT, Buckner SL, Jessee MB, Dankel SJ, Mouser JG, Loenneke JP. Practicing the Test Produces Strength Equivalent to Higher Volume Training. Med Sci Sports Exerc. (2017, Sep) (Randomised Controlled Trial) ✔

3. Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. Strength and Hypertrophy Adaptations Between Low- vs. High-Load Resistance Training: A Systematic Review and Meta-analysis. J Strength Cond Res. (2017, Dec) (Review) ✔

Citations with a tick indicate the information is from a trusted source.


The information provided in this article is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the guidance of a physician or other competent professional before following advice or taking any supplement. See our terms and conditions.

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