New Study on Periodization and Muscle Growth

A new review has just been published ahead of print on the effects of periodized resistance training (RT) on muscle hypertrophy (1).

As a brief overview, periodization can be defined as a cyclic training structure designed to maximize performance, manage fatigue, and minimize plateaus (2).

This can include the manipulation of numerous training variables, including: volume, intensity, and training frequency (3).

The goal of most periodized training programs is to obtain the benefit of each variable at the most opportune time (4).

Now, as some of you may know, a while back I wrote an article which argued why periodized RT should be utilized for those looking to maximize muscle growth.

While it is relatively established that periodized RT routines are superior to non-periodized routines for optimizing strength gains (5, 6), the question has always remained whether periodization could influence gains in muscle growth.

In my previous article on the topic, I highlighted some studies which showed that periodized RT provided superior gains in muscle growth compared to non-periodized RT.

One of these studies lasted 9 months in duration (7), and is one of the few periodization studies that have actually been conducted over a decent time period.

Unfortunately, no reviews or meta-analyses had been conducted to compare periodized to non-periodized RT protocols as it pertains to muscle growth.

Until now.

Let’s look at what was found.



Any form of periodized RT was included in the review. This included: linear periodization, block periodization, daily undulating periodization, weekly undulating periodization, etc.

Each study must have used at least some form of measurement to assess changes in muscle mass.

Each study must have lasted a minimum of 6 weeks.



The authors evaluated a total of 1483 studies, and found that 12 met the inclusion criteria.

A total of 337 participants (mostly male) were included in the studies.

The average training duration of each study was 15.4 weeks, and the majority of studies assessed were rated as moderate to excellent quality.

7 of the 12 included studies equated training volume between groups.

To my surprise, the authors found that both periodized and non-periodized RT appear similarly effective for eliciting gains in muscle mass.



As the authors note, there were several limitations found in the body of literature analyzing this topic.

First, the authors note that some studies did not equate training volume between groups, and that this does not provide a proper assessment of the topic given the influence that volume has on muscle growth (8, 9).

Second, the authors state that only 3 of the 12 studies used a direct measurement of muscle hypertrophy (MRI or ultrasound).

Third, the authors found that the majority of the studies that fit the inclusion criteria used untrained participants.

While research has suggested that periodized RT can greatly benefit untrained lifters (5, 6), whether this would be the case for muscle growth is unknown.

And finally, the authors suggest caution in interpreting these findings, given the small number of studies analyzed, in addition to only 3 of them using a direct measurement of muscle hypertrophy.



While I was surprised to see that there were no differences found between conditions for muscle growth, a few things come to mind.

First, the limitations outlined by the authors warrant caution in interpreting the results.

But aside from that, it is interesting that most studies show a benefit of periodized RT for strength, however, this one does not show a benefit of periodized RT in regard to muscle growth.

This may be for a few reasons.

First, training for strength and training for hypertrophy are not the same thing.

While muscle size is correlated to strength (10), someone can be stronger than their muscle size would suggest (11), which indicates an influence of neural adaptations being responsible for strength increases (12).

Therefore, while a periodized training structure may be optimal for eliciting strength increases, this structure may not be necessary for optimizing hypertrophy.

Furthermore, an important point in regard to these findings (and periodization research as a whole) is the use (or lack thereof) of deload weeks or ‘taper periods’.

Deload weeks / taper periods are a trademark of periodized training (13), as they consist of systematic reductions in training load (via volume, intensity, frequency, etc.) to allow the body to recover and optimally adapt to the training stimulus.

Deload weeks can be implemented at the end of each training cycle, and they can (and should) be used immediately before a competition (3).

While it is suggested that this form of recovery will allow for maximal performance in terms of strength and endurance, whether it would influence muscle growth is unknown.

I say that it is unknown because for whatever reason, the majority of periodization studies do not incorporate the use of deload weeks.

Instead, the researchers simply equate ‘variation’ as being ‘periodization’, which is not an accurate representation of periodized training (14).

Hopefully, future studies analyzing this topic address this limitation in the research, as well as the other limitations brought up by the authors in the review.

See you next time.



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9. Schoenfeld BJ, Ogborn D, Krieger JW. Dose-response relationship between weekly resistance training volume and increases in muscle mass: a systematic review and meta-analysis. J Sports Sci. 2017 Jun;35(11):1073–82.

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13. Turner A. The science and practice of periodization: a brief review. Strength Cond J. 2011 Feb;33(1):34–46.

14. Afonso J, Nikolaidis PT, Sousa P, Mesquita I. Is empirical research on periodization trustworthy? A comprehensive review of conceptual and methodological issues. J Sports Sci Med. 2017 Mar;16:27–34.