Muscle hypertrophy, a scientific term for muscle growth, can be achieved with correct training program and some persistence. You might have heard the age-old rule for hypertrophy, which says:

“Do 3 – 5 sets of 8 – 12 repetitions and you will grow.”

This definitely isn’t wrong, but it lacks information about how often and how heavy you should train. To make things easy for you, this article shortly summarizes the current evidence-based knowledge of optimal volume, load and frequency for muscle hypertrophy.

Volume

Resistance training volume means the total amount of work done in a given time period. Easiest and most common way to express volume is as total sets done weekly per muscle group. To be more accurate you can multiply sets with repetitions and load (sets * reps * load).
[kuva volume report]

So how much volume then? In their review article Schoenfeld et al. (2017b) analyzed 15 studies and found out what the relationship is between weekly volume and hypertrophy. Simply put, more volume equals more muscle mass. At least until you get to 10 sets or more per week.

The relationship between weekly volume and hypertrophy (Schoenfeld et al. 2017b).

From this data, it can’t be said if the effect still increases after 10 weekly sets. Also, almost all the included studies had untrained population as subjects with no real resistance training background which makes it less reliable to apply this data to more advanced athletes. It would be logical to think that more advanced lifters need even more volume to make their muscles adapt to training.

Load

Load in this context means the load you’re lifting relative to your one repetition maximum (1RM). The usual answer you get from anyone involved in lifting about growing muscles is to use relatively high loads between 65 and 80 % of 1RM. Is low load training then useful only for strength-endurance and bodypump-class?

Schoenfeld et al. (2017a) investigated if there were a difference in hypertrophy between groups which trained with low loads (<60 %) or high loads (>60 %). They found that mean muscle mass gains were similar between low and high load groups (7.0 % versus 8.3 %, respectively) and there wasn’t a statistical difference between groups, although the effect was slightly in favor of high loads. In all the 21 analyzed studies, every set was performed to failure (the point when you can’t do more reps) which makes these kinds of training programs very impractical to use in real life.

If we simplify things a bit, when lifting relatively low loads you are actually using only a portion of your muscle at a time. As the working portions of your muscle get tired during a set, new portions start firing until all the capacity is used and you reach failure. With higher loads, all portions of the muscle start to fire earlier in the set and you don’t have to reach failure to activate the whole muscle. Mechanical loading is an important signal for muscle growth and with low loads, you have to go to failure to load the whole muscle. Both ways clearly work, but with higher loads, you don’t probably have to go to failure to reach sufficient loading on the muscle which would make high loads a more practical way to gain muscle.

Frequency

Finally, how often should you train for maximal hypertrophy? Most typical training frequencies per muscle group are once or twice a week but some go to three or even beyond that.

Schoenfeld et al. (2016) analyzed 7 studies in their review to compare the hypertrophic effect of training frequencies from 1 to 3 times per week in mainly untrained subjects. Results were in favor of higher frequencies (mean increase 6.8 % vs 3.7 %) but due to a low number of studies included, they couldn’t analyze the effect between 1, 2 and 3.

Zaroni et al. (2018) compared the hypertrophic effect of training programs with 1-2 and 5 weekly sessions with trained subjects. Results were in favor of higher frequency training group although the difference on triceps wasn’t statistically significant.

Hypertrophy in high- and low-frequency groups (Zaroni et al. 2018).

In both articles, the weekly volume of training (sets * reps) was equal between compared groups. One reason that might explain the difference is that the volume is actually higher in high-frequency groups because they are able to lift higher loads (volume = sets * reps * load). Subjects on the low-frequency group are undoubtedly too fatigued to lift high loads after doing 12 sets to failure in one session and having three more sets to go.

You can successfully increase muscle mass by training a muscle group only once a week but it would seem to be more effective to train at least twice a week. For advanced lifters, it might be beneficial to go even beyond that. In contrast, Yue et al. (2018) found that on untrained subjects there was a slight trend in favor of lower frequency group when the volume was equal (1-2 versus 2-4 times a week). Biggest benefits of training more often seem to be that fatigue is lower and you can manage more volume.

In summary with my recommendations:

• Start from 8 – 10 weekly sets and slowly progress towards higher amounts (beginners could start with only 4 – 6 sets to get used to volume).
• Reduce volume every 3 – 6 weeks to remove fatigue. 4 weekly sets are enough for most to maintain muscle mass (Bickel et al. 2011). Don’t reduce load!
• Use loads between 60 and 85 % of your 1RM (loads much over 85 % aren’t sustainable when doing high volume).
• Train each muscle group at least twice a week.
• Variate your training every 8 – 12 weeks with new exercises.

References:

Bickel, C. S., Cross, J. M. & Bamman, M. M. 2011. Exercise dosing to retain resistance training adaptations in young and older adults. Medicine & Science in Sports & Exercise 43 (7), 1177-1187.

Schoenfeld, B. J., Ogborn, D. & Krieger. J. W. 2016. Effects of Resistance Training Frequency on Measures of Muscle Hypertrophy: A Systematic Review and Meta-Analysis. Sports Medicine 46 (11), 1689-1697.

Schoenfeld, B. J., Grgic, J., Ogborn, D. & Krieger. J. W. 2017a. Strength and hypertrophy adaptations between low- versus high-load resistance training: A systematic review and meta-analysis. Journal of Strength and Conditioning Research 31 (12), 3508-3523.

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

Yue, F. L., Karsten, B., Larumbe-Zabala, E., Seijo, M. & Nacleiro, F. 2018. Comparison of 2 weekly-equalized volume resistance-training routines using different frequencies on body composition and performance in trained males. Applied physiology, nutrition and metabolism 43 (5), 475-481.

Zaroni, R. S., Brigatto, F. A., Schoenfeld, B. J., Braz, T. V., Benvenutti, J. C., Germano, M. D., Marchetti, P. H., Aoki, M. S. & Lopes, C. R. 2018. High Resistance-Training Frequency Enhances Muscle Thickness in Resistance-Trained Men. The Journal of Strength & Conditioning Research (DOI: 10.1519/JSC.0000000000002643)