How Often Should You Train a Muscle Group?
My goal of this site is to use the knowledge I’ve gained over the years as a trainer and lifting enthusiast to answer the common questions I used to ask and now get asked by my clients. "How often should you train a muscle group?" is definitely a question I had and was confused about for a while.
This article covers what I have discovered through research and personal experience. I am basing around muscle hypertrophy.
Training to be stronger at certain movements or for sports will have a different set of recommendations.
But, if you want to gain more muscle, the answer to how often you should train each muscle is written below.
What happens when you train a muscle?
Before you can make any judgements or plans based on how often you should train a muscle, it’s important to understand the process that your muscles undergo as a result of training.
The process is best illustrated by the SRA curve. SRA stands for stimulus recovery adaptation. As a visual representation, the curve is a nice way to explain the stages your body goes through as you train, recover and grow.
Definitions as they relate to your own training
A bunch of lines and squiggles might not mean a great deal to you right now. Here is a list of definitions for each piece of the SRA curve and how they relate to training.
Baseline: Your current level of performance. The level of performance you are at as you enter the gym for a workout.
Stimulus: Refers to the activity that you perform in order to stimulate your muscles. A stimulus can be as little as one set of squats or an entire leg workout.
Fatigue: The drop that you see in performance and energy levels as an immediate result of a workout. Each set during your workout getting harder than the previous one or you being sore the next day. Both of those fall into this “fatigue” phase.
Recovery: Period of time where the muscles are growing and you are actually adapting to the workout. It’s the period of time where muscle protein synthesis is elevated, more on that later.
Super-compensation: All of the gains you make as a result of the initial training stimulus. After you have fully recovered, your body has finished making adaptations to the initial stimulus. The adaptations are realised through an increase in performance above your baseline level. For you, this performance increase should be bigger, stronger muscles.
Involution: Sometimes called de-training. It shows the gradual return to baseline levels after the super-compensation effect has occurred.
Applying the SRA curve to your training
As you can now see, your body goes through a whole journey of adaptations as a result of a workout or training stimulus. I bet never thought the question, "how often should you train a muscle group?" would have such a complex answer. So, what do you do with this curve?
You need to be able to optimize each phase in order to get the best return on your training. It is very difficult to do exactly but I will try my best to give you some guidelines to follow.
Just quickly, to sum up the curve: You need to stimulate (train) a muscle, you fatigue that muscle during the workout and your performance level decreases, you then need time to let that muscle recover and grow, when you are recovered, your body super compensates by pushing your performance above your old baseline. You now need to restart the curve before de-training occurs.
If you are not stimulating the muscles again around the peak of that super-compensation phase, then you will begin to de-train and regress. Not good!
You need to allow time for that recovery cycle to finish you hit the gym and work the same muscle group again.
How long does each phase last?
That is the million-dollar question right there. I’m sorry to say that it’s near impossible to tell.
There are simply too many factors that can affect and adjust each phase of the curve.
Each phase also has a knock-on effect for the next phase. For example, a greater training stimulus will increase initial fatigue and delay the start of the recovery phase.
Poor recovery, as a result of inadequate sleep, will delay and limit the supercompensation effect.
It’s all very dependent on you as an individual.
The important phase of the curve for actual muscle growth is the recovery phase. As you now know, the recovery part of the curve is where the actual adaptations and gains are happening.
To be a bit more exact and scientific, the recovery phases is where muscle protein synthesis (MPS) is elevated as result of your workout.
MPS is the rebuilding of the muscle tissue that has been broken down as a result of the training stimulus.
You can look at it like this: elevated MPS is muscle repair and growth (as long as nutrition, sleep etc. are on point).
Using recovery time and MPS elevation to determine how often you should train a muscle
The actual amount of time it lasts for does depend on a few different factors. For the purpose of hypertrophy, the two that I think are most important to you are the size of the initial training stimulus and your experience level.
For example, A greater training stimulus/harder workout can increase the length of time MPS is elevated.
A newer trainee will require less of a training stimulus to elevate MPS for the same amount of time as a more advanced lifter.
Working out the exact length of time MPS is elevated for you is going to be basically impossible. Therefore, I think going off of an average of 48 hours will suit the vast majority of people.
If you say that MPS and the “recovery” phase is going to last about 48 hours, then you know that you should probably be looking to restart the curve again around that time.
Starting the curve by training the same muscle again, before the recovery phase is fully finished can eat into your muscle repair and growth time.
Waiting for too long to train a muscle again after MPS returns to baseline, could mean you enter the de-training phase of the curve.
How often should you train a muscle group then? - Real world application
From the information above, it would seem very easy to suggest that full body workouts performed about 48 hours apart are going keep MPS elevated constantly and will produce the best results.
That may or may not be the case. Again, a number of factors come into play.
As I mentioned earlier, the main one that will be of concern to you now is your training experience.
If you are a novice trainee, the training stimulus from a full body workout will probably be large enough to elevate MPS for that 48-hour period. Maybe even longer in some cases.
For you guys and gals, a 3 day, full-body split is going to work very well.
A more advanced lifter will need a greater training stimulus to keep MPS elevated for around 48 hours. A full-body workout probably won’t provide enough total work to achieve it. Unless, you have the time and energy to spend 3-4 hours in the gym.
To account for extra recovery needed, a 4-day upper/lower split is what I would suggest. This still allows you to train all of your muscles twice per week, with enough work load in each session to keep MPS elevated and enough recovery time to adapt to the higher work load.
Training a muscle twice per week has been shown to be better for muscle growth than training just once. (Schoenfeld et al., 2016).
Things aren't quite as simple as just training harder to elevate MPS for longer. The recovery process involves many more factors than just elevating MPS and the rebuilding of muscle tissue.
Connective tissue breakdown and nervous system fatigue are part of the process as well.
Training harder impacts these, which means spending longer in the “fatigue” phase of the curve.
In simple terms, doing a high amount of work in one workout is likely to leave you too sore and worn-out to restart the curve before de-training occurs.
If you’re training is consistently making you sore to the point of decreased performance, you probably need to adjust your program.
As a general rule, if you’re training is consistently making you sore to the point of decreased performance for much more than 48 hours, you probably need to adjust your program.
I say “consistently making you sore” because a change in exercise, or an increase in work load might leave you sore for longer than recommended after the first few sessions.
How often should each muscle be trained – My suggestions
If you are a very new trainee, then you can get away with less total workload to cause adaptations.
Breaking down your training into 3 full body sessions each week is my suggestion.
Each session will include a lower total amount of work for each muscle, 5 sets maximum. That should be enough to keep MPS elevated for a while after each workout but should also be fairly easy to recover from.
Focus on progression over time. Progression can be more weight, more reps, less rest, better technique or a whole range of different things. The bottom line is that getting better and doing more work over time will lead to growth.
My previous point leads me nicely on to the more advanced lifters. You need to do more work over time to keep triggering growth.
At some stage, those 5 sets in the full body workouts aren’t going to trigger enough of a response to elevate MPS very much. You need to do more work.
It’s fine to increase workload and still perform full body workouts but there will come a point where your recovery is impacted.
Once you increase your work load to a certain point, your body will struggle to recover enough to train every other day. You might need to split your training up further when you get to that point.
Training split for more advanced trainees
A great way to break your training down is an upper/lower split performed for 4 days each week. It would look like this:
Day1 – Upper
Day 2 – Lower
Day 3 – Rest
Day 4 – Upper
Day 5 – Lower
Day 6 – Rest
Day 7 – Rest or repeat the cycle
You can do more work in the same amount of time each workout by focusing on just your upper or lower body.
The extra work should elevate MPS sufficiently but will incur more fatigue.
Not a problem, there’s an extra day, sometime two for each muscle group to recover.
I hope that all made sense and has given you a better insight into how often you should train each muscle. I tried, as always, to keep it basic and not too science-y.
If you are still following the once-per-week splits, try training each twice per week. I think you will be pleasantly surprised by the results.
Have friends or gym-pals that are still training their muscles once per week? Share this article so they can maximize their gains alongside you.
Unless you want to be bigger than all of them. In, which case, share with no one.