What is Better for Hypertrophy? 2 or 3 Days per Week?

When it comes to building muscle and designing a workout and fitness routine there are a lot of different variables you must consider.

What your goals are. What resources you have at your disposal. What you enjoy doing. What challenges you. What your capabilities are. What your anatomy calls for. What injuries you may have or had. Or HOW MANY DAYS PER WEEK YOU SHOULD WORK A CERTAIN MUSCLE GROUP.

Now, given the fact that VOLUME and INTENSITY are the first and largest determining factors of your muscle growth potential. You might automatically assume that training a muscle group 3 times a week would be the better way to go if your goals are hypertrophy.

But as we know with most things in the fitness world, not everything is straight forward, black, or white. Most things in this world exist in some shade of gray.

There are four different training variables that determines an individual’s muscle building success. There is a simple acronym used to remember these four variables.

L.E.A.F.

• L- LOAD or the actual weight lifted (light, moderate, or heavy weight).
• E- EFFORT or the “INTENSITY” of work done, your proximity to failure during training.
• A- AMOUNT or the “VOLUME”, how much work you did during training (load x reps x sets).
• F- FREQUENCY or how often you stimulate a muscle group per week.

Today we are going to focus on FREQUENCY or how often you should be training a muscle group per week for the best hypertrophy results.

There aren’t many known absolutes about frequency. At this time, the only thing that exercise scientists agree on is that you shouldn’t do all your training for a body part or muscle group one day per week.

But what about the workouts that the huge bodybuilders post in the magazines and the internet? Don’t they do all their training for a body part on a specific day of the week? It would look something like:

• Monday- Chest
• Tuesday- Back
• Wednesday- Quads
• Thursday- Shoulders
• Friday- Arms
• Saturday- Hamstrings
• Sunday- Rest

Whether or not some of the more famous bodybuilders still train like this is uncertain, but the current scientific evidence (of which there is very little at this time) does not support this type of training. Rather, the limited amount of the current evidence that does exist suggests that it’s best to structure your program such that each muscle group/body part is being trained at least two times per week.

Let’s say you want to grow your hamstrings. Based on the limited scientific evidence that’s available at this time, it appears that you don’t want to do all your hamstring work only one day per week.

So, what’s best? Should you train your hamstrings 2 days per week? 3 days per week? 7 days per week?

Unfortunately, we don’t have a clear-cut answer to this. The research that has been done on this topic has yet to identify an optimal or best training frequency for a particular muscle group.

The research study I looked at compared the effectiveness of training a muscle group two times per week vs. three times per week. It’s one of the most recent investigations on this topic of training frequency to maximize muscle mass.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6724585/pdf/hukin-68-135.pdf

So, who did this study look at? The study looked at 28 resistance trained males in their early 20’s with at least 3 years of resistance training experience. Which is good because we know they won’t just be experiencing newbie gains.

The researchers split the participants into 2 groups:

• 2 Days/week: each muscle group was trained 2 times per week
• 3 Days/week: each muscle group was trained 3 times per week

A very important consideration that the researchers made was to make sure that the total lifting volume was the same for the two groups. Regardless of whether the subjects trained a muscle group 2 or 3 days per week, at the end of each week they performed the same total volume.

This is very important! If you don’t equalize the total amount of volume completed by the two different groups, you really can’t answer the question that you are wanting to answer. For example, if one group did gain more muscle mass than the other group, you can’t be sure if this increased muscle mass was due to the difference in the number of days training the muscle group or if it was due to the fact that one group did more or less total training volume during the study!

The training program was 10-weeks long. All subjects (regardless of the group they were assigned to) started each set of their workouts with a 10RM load (this means that the weight they selected on each exercise allowed them to complete exactly 10 repetitions—if they attempted an 11th repetition, they would not be able to complete it).

During the study, as the subjects got stronger, if they were able to complete more than 12 repetitions, the weight was increased by 2.5% on that exercise. Likewise, if they were not able to complete 8 reps on a set, the load was reduced by 2.5%. Also, the rest interval between sets was 90 seconds.

All sets were carried out to the point of momentary muscular failure. This means that they took each set until they could not complete another repetition. This is also very important! Requiring the subjects to take each set to failure makes sure that all subjects (regardless of group) are lifting with the same effort on every set and every exercise during the study. While I wouldn’t recommend that the average person take every set to failure in their own workouts, I do recommend that each set is taken to near failure—within 2-3 repetitions of failure for each set).

All subjects (regardless of the training frequency group they were assigned to) were advised to maintain their usual and regular eating habits during the study period. Stated differently, the subjects were not to attempt to gain weight or lose weight during the study. The subjects recorded their food and macronutrient intake for seven days prior to starting the training program and then again during the last week of the training program. The subjects were also told to avoid consuming any muscle-building supplements during the study.

The researchers measured muscle thickness at the beginning of the study and at the end of the 10-week training program. B-mode ultrasound was used to measure the changes in muscle mass of the upper body and lower body at these locations:

• Upper Body: biceps and triceps
• Lower Body: quadriceps/front of leg

In addition to these physique-related variables, the researchers also tested the subjects' maximal strength on the bench press and smith squat.

So, what were the results?

For both groups, muscle thickness increased significantly in the triceps and quadriceps, but not the biceps.

From the ‘Muscle Thickness Gains’ figure provided by the authors, it clearly looks like training a muscle group two times per week is much better than training it three times per week! In fact, the authors also stated that effect size differences (another way to statistically analyze data) were observed in favor of training muscles two versus three days per week for every hypertrophy outcome measure studied.

If you take this study as a stand alone (meaning that you ignore all of the other research conducted in this area), I would say you should structure your training program to stimulate each muscle group two times per week (rather than three times per week).

However, I don’t think it is time to crown ‘Two Days/Week of Training a Muscle Group’ as “best” of all weekly training frequencies. There are other published studies reporting that whole-body training approaches (similar to the 3-Day/Week Group in this study, up to 5 times a week) was superior to other training frequencies.

It is possible that training a muscle group two days per week is the best strategy for maximizing muscle hypertrophy. But, until they do more studies and provide more data, I would not feel comfortable making this claim. What I would claim is that training a muscle group only one day per week is not optimal for maximizing muscle hypertrophy. In order to maximize muscle hypertrophy, the current evidence suggests that each muscle group be stimulated two or more times per week.

Ultimately, as long as programming allows you to stimulate a muscle group at least twice per week, it doesn’t much matter how you divide up your days. If it is a split or program that you enjoy and can stick to consistently, you work to a close enough proximity to failure, and fuel and recover your body appropriately.

YOU WILL BUILD MUSCLE!!

The world of fitness, nutrition and health is an incredibly individualized one.

Experiment.

Try things.

FIND OUT FOR YOU!!

The problem with relying on research is the fact that they are working on an AVERAGE. We are not averages. We are individuals, with individual needs, likes, abilities, anatomies, schedules, and LIVES!

The best thing you can do is to experiment with different methods and tactics.

As one of my mentors Cody Mcbroom has said, “Methods are many, principles are few. Methods often change, principles never do.”

Meaning, how you go about your journey to a better, stronger, healthier you can change, can be adapted to suit you and your needs. As long as those methods apply to the certain concrete principles.

Don’t think that just because some scientist or researcher says so that it is an absolute.