One of the biggest debates in bodybuilding has been about whether a higher or lower training frequency is better. Early studies that compared training a muscle only once a week to twice a week seemed to suggest twice a week builds more muscle and that’s what most trainers heavily promoted. But more recent studies that were better designed have increased our understanding of this subject. We now know that if you manage your training volume right, you can achieve similar muscle gains regardless of whether you work each muscle once a week, twice a week or three times a week. Unfortunately, the ideal lifting frequency debate is still raging and causing much confusion.
It’s crazy how many arguments I still see about this, and below is an example of the kind of questions (and confusion) about training frequency that I still hear on a regular basis:
“Tom, I was wondering if there anything wrong with doing a 4-day body part split where each muscle gets worked only once a week? The reason I’m asking is because I’ve done the upper lower split with 4 workouts a week and I like training 4 days a week in total, but I don’t like training every muscle so often (twice a week) because I don’t feel like my muscles fully recover, especially my legs.
I’d like to keep training 4 days a week and use a 4 day split but I keep hearing trainers say working each muscle only once a week is too low a low frequency and telling me I’m wasting my time. My question is, isn’t that what most bodybuilders have done for years to build so much muscle? If training each muscle only a once a week worked so well for the best bodybuilders, wouldn’t it be a good option if building muscle is my primary goal?”
What’s being asked here is about the ideal training frequency to build muscle, but it’s also about training volume (how many sets per week). As you’ll see in a minute, these two topics of frequency and volume are so closely related, they have to be discussed together or you’ll miss the big picture.
In this post I’ll revisit and clear up once and for all the question about training frequency, based on the newest research. I’ll also answer the question about working each muscle with a low frequency of only 1 time per week, such as with the 4 X 4 routine (4 day split with 4 workouts a week).
Training Each Muscle Twice A Week: A Popular Method
It’s true that a lot of coaches today strongly lean on the side of more frequent training being better for muscle growth. The most popular and still accepted recommendation today is to work each muscle twice a week.
Of course, that raises the question, “Have bodybuilders using body part splits (“bro splits”) been doing it wrong if they train each muscle only once a week? Or, at the very least, did they leave results on the table?” If so, how do we explain their amazing physiques?
It’s undeniable that some of the most successful bodybuilders in the world use body part splits – 3-day splits, 4 day splits and even 5 day splits. Some of them also work each muscle only once a week, or at least they lean toward the lower frequency side.
In a 2013 study by Hackett, a research group followed 127 competitive bodybuilders to assess their training and nutrition practices. They found that twice a week (3-day split/6 workouts a week) as well as once a week (5 day split/5 workouts a week) frequencies were both used by the athletes with success. But they noted that 7 out of 10 (elite level) bodybuilders in their sample reported working each muscle once per week.
Many top bodybuilders in the trenches appear to have not followed the most widely accepted training frequency advice, yet they are built to the hilt. There’s an explanation for this apparent paradox. I’ll get to it in a minute.
But first, what is the scientific rationale behind so many trainers recommending higher frequency training? The initial idea was the protein synthesis hypothesis.
Why Train Each Muscle With A Higher Weekly Frequency? The Protein Synthesis Hypothesis
Lifting weights stimulates muscle protein synthesis, which may peak around 48 hours after a workout. For this reason, advocates of more frequent training say that the more often you stimulate or spike protein synthesis (giving at least 48 hours of recovery time), the more muscle you grow. The longer you wait after that 48 hour period, the more you simply de-train and delay the opportunity for more growth.
In other words, they’re arguing that if you work a muscle only once a week, you only get one protein synthesis spike per week. If you work a muscle twice a week, you get two protein synthesis spikes. That’s two opportunities per week for muscle growth versus one. Some say that three times a week is even better still.
Some trainers have gone as far as saying that when you work each muscle twice a week (two protein synthesis spikes per week), you could gain twice as much muscle. There’s no evidence for this.
Other say that if you only train each muscle once a week, by the time your next workout for a specific muscle rolls around, you’ve not only been fully recovered for days, your muscles are already starting to shrink. This is also false. Muscles don’t start to atrophy after even two weeks of total layoff, let alone just one week, where you’re still training.
This protein synthesis hypothesis sounds logical, and it may be one small part of the puzzle, but it’s not the only piece. There are other variables that influence how much muscle you gain at different frequencies. The most important beef those is weekly volume.
It’s important to note that protein synthesis is a short term marker of potential muscle growth (a proxy for growth), it’s not actual muscle growth that’s been measured over time. Long-term studies that compare muscle growth using different training frequency and volume tell us a lot more.
The truth is, how soon you’re ready to train a muscle group again isn’t based on a single factor like protein synthesis rates. Some people need more recovery time, and working each muscle hard twice a week leaves them feeling beat down. Also, not many people, save a handful of elite bodybuilders, want to lift 6 days a week. That will leave most recreational lifters feeling burnt out eventually .
While everyone is different and even personal preferences must be considered when choosing a program, if we look at all the new science as well as real world results today we can now make more informed recommendations for frequency and volume. We now know that you don’t have to train each muscle twice a week to make gains.
New Research Explains How People Get The Same Gains Whether They Train 1X 2X, or 3X Per Week
One study (Schoenfeld, 2019 went a long way in settling the argument. This meta analysis was published in the Journal of Sports Science and it gathered data from all the research from 25 of the most important studies on training frequency and muscle growth.
The main finding was that as long as the weekly volume was matched, the training frequency did not seem to matter – twice a week, once a week, or any point in between (once every 4, 5 or 6 days) – in every case, muscle growth was about the same.
This helps us understand why so many bodybuilders have been successful even when only working each muscle once a week. If you train with a lower frequency (once every 5 to 7 days), it can still work great, but only if you’re doing the same weekly volume as you would have if you trained with a higher frequency. Sometimes when you switch to a higher frequency, you end up doing more weekly sets (you may or may not even realize it) and that is where the extra growth comes from.
Here’s the major take-away lesson: whatever training split and frequency you use, you must keep track of your total weekly sets, make sure it reaches the benchmarks for optimal muscle gain and make sure it doesn’t drop if you switch to a lower frequency.
Studies show that up to about 10 sets per muscle per week, there is a direct relationship between the number of sets and increased muscle growth. Up to about 20 sets per muscle per week there is usually additional muscle growth, but at a diminishing rate of return. More is better, but only up to a point where overtraining kicks in.
Advanced lifters typically require more volume but response is individual and depends on a person’s ability to tolerate a workload and recover from it. Therefore, most people are advised to aim for between 10 to 20 sets per muscle per week and adjust it within that range based on their recovery and results.
Consider this example:
Schedule A: 2 day split, train 4 days a week, do 6 sets per body part on big muscles each workout = 12 sets per week
Schedule B: 4 day split, train 4 days a week, do 6 sets per body part on big muscles each workout = 6 sets per week
Who gains more muscle, lifters following schedule A or schedule B? This is easy. The group that did more total work per week – the 12 sets per week group, which in this case was the twice a week schedule. They did double the weekly workload. Furthermore, 12 sets per week is in the optimal range, while 6 sets a week is sub-optimal. It’s not even fair to compare these schedules for the effect on growth because weekly volume was not equalized.
Ironically, this is how some of the early comparisons of training frequency were done – they only looked at frequency and didn’t consider volume.
The increased gains didn’t come from training each muscle more often (twice a week), the increased gains came because training more often led to more total sets being done per week.
Now take a look at this second example:
Schedule A: 2 day split, train 4 days a week, do 6 sets per body part on big muscles each workout = 12 sets per week
Schedule B: 4 day split, train 4 days a week, do 12 sets per body part on big muscles each workout = 12 sets per week
In this case, if we look at what bodybuilders have seen in practice and also consider the newest research that equalized for weekly volume, we can predict that both of these schedules will produce similar results.
Total Body 3 X Per Week Training Vs 4-Day Split Training
In 2021 a similar study (Bartolomei) compared the effects of a 4-day bodybuilding-style split routine to a total body routine on strength and muscle growth. Both routines were matched for volume (number of sets per week).
The overall finding was that in experienced, trained male lifters, age 18 to 35, after 10 weeks, both programs had significantly increased the subject’s muscle mass and maximal strength when volume was equated. The higher frequency group did slightly better on strength, but there was no difference in muscle gain.
In 2022, another study (Neves) confirmed that when weekly volume is matched, there is little to no difference in strength or muscle size gains regardless of whether you hit each muscle once a week or three times a week.
The study was well designed. For example, to measure the increase in muscle cross sectional area (size), the researchers used magnetic resonance imaging (MRI) which is more accurate than the body composition methods used in previous studies. In addition, they used only trained subjects in their experiment.
This study also used a within subject design. That means each participant went through a phase where they trained with a three times a week frequency and the same participant also used the once a week frequency. Older studies used a between subject design where one group trained each muscle three (or two) times per week, and different group did the same.
Because individuals vary in their response to training, the latter type of study was less accurate at figuring out which protocol worked better. These newer studies with the superior design have given us a lot of confidence in the conclusion that muscle growth is similar regardless of the frequency, as long as the weekly volume is the same.
Weekly Volume (Sets) Matters The Most For Muscle Gains
There is some evidence that strength gains might be a bit better with training a muscle more than once a week. Even if your goal is physique / hypertrophy, not maximum strength, this is worth considering.
But at this point, we now have numerous studies showing that 1X, 2X or 3X per week training frequencies can all produce similar results in muscle gain if weekly volume is the same. In some of the older research 2X and 3X frequencies produced more muscle or strength. But we’re now certain that the reason is because training more often led to more total sets being performed per week. (Also, older study designs had flaws).
We also have lots of anecdotal evidence and there are countless examples of bodybuilders who got jacked training each muscle only once a week (or with a somewhat low frequency like hitting each muscle once every 5 or 6 days, which is what I often do).
What did those bodybuilders do differently to produce such great gains while working each muscle only once a week? They did more sets for each muscle in each workout. And because it’s a body part split routine, it’s more practical to do. When you’re only working a couple muscles per session, you have plenty of time for a lot of sets without making it a marathon workout. But you do have to be aware of one thing.
Downsides Of Lower Training Frequency
How you spread a certain amount of training volume across the week is an important question to ponder. And it’s still being debated. In spite of what the recent research has revealed, a lot of coaches still insist that twice a week is the best practice for frequency for most people, so don’t be surprised if you keep hearing that.
For example, an upper / lower split done 4 days a week where each muscle is worked twice a week may look ideal on paper, it does work and it’s great for recreational lifters. However, not everyone enjoys training their entire upper body in one session and doing that twice a week. Many people enjoy body part splits much more. (Especially bodybuilders). A lot of people also don’t want to train 5 or 6 days a week, they want to stick with 4 sessions a week because that’s realistic for them.
Given the way the research shows weekly volume is what matters most for muscle gains, your decision on a training frequency is probably going to come down to personal preference, what you enjoy, what fits your time available and what works best for you. If you want to train each muscle only once a week, give it a try and see how it goes for you.
Simply be aware that there are pros and cons to this approach. For one thing, training a muscle more often than once per week may indeed help build more muscle if it helps you do more sets per week. It can also help you spread your training volume across the week so you’re not doing so many sets in a single workout.
The researchers who did some of the newer studies point out that doing a very high number of sets for one muscle in a single workout (more than 10 to 12) might be detrimental. Some people say the whole reason they chose a lower frequency is they wanted more recovery time. But if you do an exorbitant number of sets for one muscle in one workout, it can cause a lot of (micro) muscle damage and it also demands a lot of recovery.
For this reason, some coaches suggest that if you want to do a high volume of 14, 16, 18, even 20 sets a week for a single body part (which is a ton), then go for it, but in their opinion, it’s better to spread that large number of sets out across the week more. For example, do 8 or 10 sets per session twice a week instead of trying to cram 16 or 20 sets for one muscle in a single workout. Personally, I would argue that 12 sets for a large muscle in one workout is manageable and advanced bodybuilders could probably handle a little more than that with no detriment.
The Bottom Line
The bottom line here is that if you do the same number of weekly sets per muscle, and you’re hitting optimal volume benchmarks, then whether you train each muscle once, twice or even three times a week, the muscle gains will be similar. So yes, it’s okay to work each muscle only once a week.
We have to admit, training each muscle only once a week is a really low frequency. If I train chest on Monday, I don’t feel like I need to wait until the following Monday to hit it again. I feel like I could train it again on Friday, fully fresh and recovered. That’s why my personal preference is to set up bodybuilding-style split routines where I train each muscle about once every 5 days. For me, that’s a sweet spot for frequency.
But everyone is different, especially with regards to recovery. Like everything else in training and nutrition, you need to customize your training to suit your body, accounting for genetics, recovery ability, injuries and personal preference. To do that you need to know yourself and you need to fully understand this concept of weekly volume and frequency.
Also, don’t be afraid to experiment with different training schedules and training volumes. You may have stumbled onto one schedule that works like a charm for you and stick with it all the time. But there’s evidence supporting the idea that if you change your training frequency over the course of a year instead of always sticking to the frequency you’re used to, it might produce better gains. It doesn’t hurt to train each muscle twice a week at times, once a week at times, and somewhere in between at other times.
You might do a 2-day split for a few months, then switch to a 3-day, and later to a 4-day split. Then you might try one of our hybrid splits. You might even try a full-body workout (no split) even if you’re advanced. Full body workouts hitting each muscle 3 times a week are not just for beginners.
If you’ve heard advice before to “mix things up,” we now may want to extend that beyond simply changing exercises and lifting techniques, but also changing up your lifting frequency regularly rather than looking for one “best” way. This doesn’t mean program hopping, but it might mean trying a new training schedule as often as every three months or so.
This is one of the reasons that we offer multiple training program options for our members at Burn the Fat Inner Circle. In fact, we have over a dozen flagship training plans and this year have been adding new ones every quarter.
Best part is, we have memberships for as little as 10 bucks and change per month, and you can access as many of the training plans as you want. Compare that to most sites charging near 100 bucks for each workout.
Our newest training program is a 4 day split with 4 workouts per week. You can see that means each muscle is worked only once per week. We call this the 4 X 4 Muscle and Physique program.
If you’re not a member yet and you want 24-7-365 access to a wide variety of different split routines designed by an all-natural bodybuilder for optimizing muscle gains and physique transformation without ever being pitched to buy supplements, you can learn more on the pages below:
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There’s a new post here at Burn the Fat Blog every Friday. Until next week…
Train hard and expect success!
Tom Venuto, Author of Burn the Fat, Feed the Muscle Guide To Flexible Meal Planning
Founder and CEO, Burn the Fat Inner Circle,
The support community for all-natural, no-BS body transformation
PS. Check out the new 4 X 4 Muscle & Physique Program Here:
Tom Venuto is a natural bodybuilding and fat loss expert. He is also a recipe creator specializing in fat-burning, muscle-building cooking. Tom is a former competitive bodybuilder and today works as a full-time fitness coach, writer, blogger, and author. In his spare time, he is an avid outdoor enthusiast and backpacker. His book, Burn The Fat, Feed The Muscle is an international bestseller, first as an ebook and now as a hardcover and audiobook. The Body Fat Solution, Tom’s book about emotional eating and long-term weight maintenance, was an Oprah Magazine and Men’s Fitness Magazine pick. Tom is also the founder of Burn The Fat Inner Circle – a fitness support community with over 52,000 members worldwide since 2006. Click here for membership details
Bartolomei, S, et al, A comparison between total body and split routine resistance training programs in trained men. J Strength Cond Res 35(6): 1520-1526, 2021.
Hacket D et al, Training Practices and Ergogenic Aids Used by Male Bodybuilders, Journal of Strength and Conditioning Research, Volume 27 – Issue 6 – p 1609-1617, 2013.
Hwang, The Effects of Short-Term Detraining and Subsequent Retraining on Body Composition and Muscle Performance in Males Consuming a Whey Protein or Carbohydrate Supplement, Intl J Exer Sci, vol 2: 8, 2016.
McDougall JD, et al, The time course for elevated muscle protein synthesis following heavy resistance exercise. Can J Appl Physiolo. 20(4): 480-486, 1995.
Neves R, et al, Effect of different training frequencies on maximal strength performance and muscle hypertrophy in trained individuals – a within-subject design, PLOS ONE, 17:10, e0276154, 2022
Schoenfeld BJ, Grgic J, Krieger J. How many times per week should a muscle be trained to maximize muscle hypertrophy? A systematic review and meta-analysis of studies examining the effects of resistance training frequency. J Sports Sci. 2018 Dec 17:1-10.
Schoenfeld BJ, et al, Effects of resistance training frequency on measures of muscle hypertrophy: A systematic review and meta-analysis, Sports Medicine, 46(11), 1689-1697, 2016
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