Researchers found that a 9-12 reps zone workout each workout resulted in greater gains in muscle mass than a % 1-RM-based strength training. The 9-12 reps zone workout resulted in greater volume progression than the % based strength training.


  • The study found that those that used a fasted volume progression has better muscle gains.
  • Researchers found that a 9-12 reps zone workout each workout resulted in greater gains in muscle mass than a % 1-RM-based strength training.
  • The 9-12 reps zone workout resulted in greater volume progression than the % based strength training.


When trying to increase muscle size, there are many options that a lifter must consider for increases in lean muscle tissue.  The critical factors for gaining muscle are:

  •       A progressive overload training program is needed (i.e., increasing the number of sets or increasing the number of reps)
  •       Sets must be taken close to the proximity of failure.
  •       A certain amount of volume must be performed (i.e., the number of sets is related to increased muscle fiber size).
  •       A calorie surplus is needed.


Training volume (i.e., sets x reps x load) has been proposed as a major determinant of gaining muscle. (Schoenfeld et al., 2019) Comprehensive studies have suggested a dose-response relationship between the number of weekly sets and muscle strength and mass gains.  (Ralston et al., 2017) Most beginner workout programs recommend 3 sets per bodypart, which is a good starting point.

One of the most compelling arguments for performing multiple sets to enhance muscle growth was a study that muscle growth was the greatest in those that did 2-3 sets versus 1 set; furthermore, 4-6 sets had a slightly better increase in muscle growth than the 2-3 sets. (Krieger, 2010)

The same authors later reviewed the literature and found a relationship between sets and muscle growth.  Less than 5 sets per week per bodypart resulted in the least muscle growth (5.4%), whereas more sets, 5-9 sets (6.6%), and 10+ sets (9.8%) resulted in greater increases in lean muscle mass. (Schoenfeld et al., 2017)

The general recommendation for muscle growth is anywhere between 10 to 20 sets per week for muscle growth.  However, doing more sets does not always mean more muscle growth (Aube et al., 2022) Why don’t we know the exact number of sets to perform for each muscle group to gain muscle size?

volume progressionEach person has a unique capability to recover from a workout; therefore, an individualized amount of sets (i.e., some people need more sets while others need less) is required.  A landmark study found that when adding weekly sets, some subjects had better muscle growth by reducing the sets, whereas others had better gains in muscle growth by increasing their sets.(Scarpelli et al., 2022)


Many lifters will ask, “What is the best rep range for muscle growth?” Traditionally, you have been recommended to perform 4-6 reps for mass; however, many bodybuilders advocate 20 rep sets for hypertrophy.

Based on the research, muscle growth can occur in a wide range of reps per set (i.e., 6-30 reps) as long as the high rep ranges are taken to failure.  Traditionally, 15 reps or greater per set were considered muscular endurance training, but we now know that higher reps are equally effective for gaining muscle. Gaining muscle is more related to the level of effort rather than a specific rep range.

The most common method by athletes to gain size is to use % base rep ranges for hypertrophy.  % based training is used in a wide variety of sports, such as football, track, volleyball, etc. For example, 60-80% of a 1-repetition maximum is recommended for muscle growth. (Schoenfeld et al., 2021)

When starting a training cycle, gradually increasing the training volume (i.e., increasing the weight or reps) is often recommended.  A new study raises some eyebrows because faster volume progression resulted in more muscle growth. This is contrary to the traditional recommendations of slowly increasing volume over the course of training.

The study also showed that % based training was inferior to 9-12 reps for gaining muscle.  A secondary analysis of two different studies.  The study compared leg extension muscle growth between the two studies.


To be clear, this study used untrained subjects, so well-trained athletes’ responses may differ.  Both groups completed 24 sessions, but the training frequency was different.  The % based training group trained two times per week, whereas the rep zone training group trained three times per week.  Both groups trained to muscular failure.

The % based group trained with 80% of their 1RM, whereas the RM zone group trained to failure with a weight corresponding to their 9-12RM.  This means that the weight increased or decreased with each workout depending on whether they stayed in the prescribed rep range. For example, if the subjects were only able to complete 8 reps during the second set, the weight was lowered so they could complete 9 reps the next set.

Both groups completed an equal amount of volume; it was achieved at a different pace. In the % based group, the weight was adjusted after the 1RM retest on week 6 in an attempt to optimize muscle adaptations to the protocol.  So, the volume progression rate was slower; the 8-12 RM zone training had a much faster rate of progression.


The researchers found that muscle growth was much higher in the 9-12 rep range group compared to the % based training.  The muscle growth was 2X higher for the 9-12 reps zone training!  A faster progression of volume could explain 24% of the increases in muscle growth.  What is a shocking discovery was that the total volume was similar between the group, and both groups were trained to failure. What differed was how fast the volume was increased.

hypertrophy training progressive overload training how many reps should i do how many reps to build muscle hypertrophy workout hypertrophy rep range how many reps for hypertrophy rep range for hypertrophy best rep range for muscle growth 4-6 reps forAnother shocking finding was that the % RM group trained for 12 weeks, whereas the 9-12 reps zone group trained for 8 weeks.  So, the 9-12 reps zone gained more muscle in a shorter time frame.  It shows muscle growth was greater with fewer training sessions but with similar training volume.


Volume progression adds a new piece of the puzzle to factors influencing muscle growth; volume progression is important for muscle growth.  For each set, the 9-12 rep zone adjusted the weight so that they were training at an intensity that was a near-optimal range for their individualized capacity.  The authors suggest that a slow progression of volume may negatively influence muscle growth.

The authors of the study concluded, “The present findings suggest that exercise professionals and coaches, when prescribing an resistance training regimen for untrained individuals and beginners, should opt for programs prescribed with RM Zone models rather than programs prescribed with %1RM carried out to concentric muscle failure, as the former results in muscle hypertrophy of greater magnitude, with a potential benefit on muscle strength.”

The results are something surprising, most coaches will recommend a slow progression in training volume over the course of a training cycle, but this study shows that a faster progression in training in training volume resulted in more muscle growth despite both groups’ training to failure.

The gains in muscle mass are contrary to the research with linear vs. undulating periodization, in which when the volume was equated, both groups experienced similar increases in muscle growth.  (Grgic et al., 2017)

This study should be read cautiously because it collected data from two studies.  They also only looked at leg extension muscle growth; we don’t know if other exercises would result in differences in muscle growth.  The other part of the equation was the calories between the groups were not examined.  Maybe the 9-12 rep zone group consumed more protein and calories.


Aube, D., Wadhi, T., Rauch, J., Anand, A., Barakat, C., Pearson, J., Bradshaw, J., Zazzo, S., Ugrinowitsch, C., & De Souza, E. O. (2022). Progressive Resistance Training Volume: Effects on Muscle Thickness, Mass, and Strength Adaptations in Resistance-Trained Individuals. J Strength Cond Res, 36(3), 600-607.

Grgic, J., Mikulic, P., Podnar, H., & Pedisic, Z. (2017). Effects of linear and daily undulating periodized resistance training programs on measures of muscle hypertrophy: a systematic review and meta-analysis. PeerJ, 5, e3695-e3695.

Krieger, J. W. (2010). Single vs. multiple sets of resistance exercise for muscle hypertrophy: a meta-analysis. J Strength Cond Res, 24(4), 1150-1159.

Ralston, G. W., Kilgore, L., Wyatt, F. B., & Baker, J. S. (2017). The Effect of Weekly Set Volume on Strength Gain: A Meta-Analysis. Sports Med, 47(12), 2585-2601.


Scarpelli, M. C., Nóbrega, S. R., Santanielo, N., Alvarez, I. F., Otoboni, G. B., Ugrinowitsch, C., & Libardi, C. A. (2022). Muscle Hypertrophy Response Is Affected by Previous Resistance Training Volume in Trained Individuals. J Strength Cond Res, 36(4), 1153-1157.

Schoenfeld, B. J., Contreras, B., Krieger, J., Grgic, J., Delcastillo, K., Belliard, R., & Alto, A. (2019). Resistance Training Volume Enhances Muscle Hypertrophy but Not Strength in Trained Men. Medicine and science in sports and exercise, 51(1), 94-103.

Schoenfeld, B. J., Grgic, J., Van Every, D. W., & Plotkin, D. L. (2021). Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum. Sports (Basel, Switzerland), 9(2), 32.

Schoenfeld, B. J., Ogborn, D., & Krieger, J. W. (2017). Dose-response relationship between weekly resistance training volume and increases in muscle mass: A systematic review and meta-analysis. J Sports Sci, 35(11), 1073-1082.

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