Should You Train a Muscle Once or Twice a Week?

If you want to gain as much muscle as you can as quickly as possible, training a muscle just once a week is not ideal. When you hit a muscle twice a week, it tends to grow faster compared to training it once a week.

Assuming you’re doing the right things in terms of diet and recovery, and your workout volume in the gym isn’t excessive, your muscles don’t need a full seven days of rest before they’re ready for action again.

Is it Better to Train Muscles Once or Twice a Week?

What prompted me to write this was an email that arrived at Muscle Evo HQ this morning. Here’s what it said:

“You’ve explained on your website that training a muscle more than once a week is more optimal for growth and this explains the popularity of full body workouts and upper/lower splits.

“What then confuses me is why are most bodybuilders, whose aim is to be as muscular as possible, training a muscle once a week? Wouldn’t they naturally incline towards a more result producing program to boost their results?”

It’s a good question.

After all, bodybuilders are some of the most muscular people on the planet.

While there’s no universal training template followed by all bodybuilders all of the time, most of their training programs do have a few things in common.

One study I looked at, published in the Journal of Strength and Conditioning Research, surveyed a group of 127 competitive bodybuilders [1].

It shows that 7 out of 10 trained each muscle once a week. The rest did it twice a week.

So why are most of these guys (whose main aim is to be as muscular as possible) hitting each muscle group once a week, and I’m telling you to do it more often?

What’s going on?

Drugs and Muscle Growth

First off, we have the drug factor to consider.

In the survey I just mentioned, almost 8 out of 10 of the respondents who competed in amateur bodybuilding reported using anabolic steroids.

And they were just the ones who admitted it.

If I was on the sauce, and knew that getting caught would land me in trouble, I certainly wouldn’t be telling anyone about it in an online survey.

Anabolic steroids can make a big difference to your results, giving you a skewed picture of the effectiveness of a particular style of training.

If you look at the way bodybuilders trained before drug use was widespread, hitting a muscle more frequently was a lot more popular than it is now.

Even back in the day when Arnold was winning Mr. Olympia contests (when drug use was par for the course) most top bodybuilders were still training their muscles more often than once a week in the gym.

There’s also the “that’s how it’s always been done and it seems to work just fine” line of thinking.

Some guys will always do what they’ve always done, or at least what is commonly accepted practice in bodybuilding circles.

Nothing to say they wouldn’t get better results with more frequent training.

Genetics and Muscle Growth

Next up is genetics, which have a huge impact on your ability to add muscle.

In one trial, researchers looked at the results of men who built the most muscle (high responders) and those who built the least muscle (low responders) after a 12-week training program [2].

To their surprise, they found roughly four times greater growth in the high versus the low responders.

In other words, let’s say that two guys start out lifting weights. Both follow the same training routine and eat the same diet for three months. The high responder adds eight pounds of muscle. The low responder, on the other hand, puts on just two pounds.

If someone has great genetics, they can often get away with training (and nutrition) methods that are less than optimal.

Even if the low responder were to follow the greatest training and diet program ever devised in all of human history, the high responder may still end up building muscle more quickly.

Since there are so many factors that affect how muscular someone is, you shouldn’t automatically try to copy what a particular group of people are doing simply because of the condition they’re in.

The Bro Split: Is Training Each Muscle Once a Week Enough?

Training programs that involve hitting each muscle group directly just once a week are often known as bro splits.

Although training a muscle just once a week is less popular than it used to be, research shows that it’s still an effective way to add muscle mass.

A good example comes from a study published in the Journal of Strength and Conditioning Research, where scientists put two groups of trained men through an eight-week training program [3].

Both groups did the same exercises, in the same order, in the same rep range, for the same number of sets. The only difference was in how often each muscle was trained.

• Group one hit each muscle once every seven days, squeezing all their training for the week into just two gym workouts.
• Group two spread their training volume across four rather than two workouts, hitting each muscle twice a week rather than once.

Here’s what the training routine in the once-a-week group looked like:

Monday

• Bench Press 8 sets x 8-12
• Dumbbell Flyes 8 sets x 8-12
• Cable Pressdown 8 sets x 8-12
• Squats 8 sets x 8-12
• Leg Extension 8 sets x 8-12

Thursday

• Lat Pulldown 8 sets x 8-12
• Straight Arm Pulldown 8 sets x 8-12
• Biceps Curl 8 sets x 8-12
• Seated Leg Curl 16 sets x 8-12

This wasn’t a typical bro split routine, in the sense that it didn’t involve training 4-6 days a week, with each workout focused on one or two body parts.

However, it does incorporate one of the main tenets of a bro split, namely that the major muscle groups are trained directly just once per week.

The twice-a-week group did the same number of sets, but spread them across four rather than two workouts. Wednesday, Saturday and Sunday were rest days. Here’s what their routine looked like:

Monday

• Bench Press 4 sets x 8-12
• Dumbbell Flyes 4 sets x 8-12
• Cable Pressdown 4 sets x 8-12
• Squats 4 sets x 8-12
• Leg Extension 4 sets x 8-12

Tuesday

• Lat Pulldown 4 sets x 8-12
• Straight Arm Pulldown 4 sets x 8-12
• Biceps Curl 4 sets x 8-12
• Seated Leg Curl 8 sets x 8-12

Thursday

• Bench Press 4 sets x 8-12
• Dumbbell Flyes 4 sets x 8-12
• Cable Pressdown 4 sets x 8-12
• Squats 4 sets x 8-12
• Leg Extension 4 sets x 8-12

Friday

• Lat Pulldown 4 sets x 8-12
• Straight Arm Pulldown 4 sets x 8-12
• Biceps Curl 4 sets x 8-12
• Seated Leg Curl 8 sets x 8-12

So, which group gained the most muscle?

Ultrasound scans showed no significant difference in results between the two groups. Whether a muscle was trained once or twice a week, the amount of muscle hypertrophy was very similar.

You can see the full set of results below:

Triceps
Group One + 5.5 %
Group Two + 5.7 %

Biceps
Group One + 6.1 %
Group Two + 5.7 %

Vastus Lateralis (quads)
Group One + 9.2 %
Group Two + 9.6 %

Rectus Femoris (quads)
Group One + 9.2 %
Group Two + 10.9 %

When the researchers calculated volume load (sets x reps x weight), the twice a week group ended up doing the most work, which is exactly what you’d expect to happen. 

Over a longer period of time, the increase in volume load with the higher training frequency may well lead to a faster rate of muscle growth.

To quote the researchers directly:

It is plausible to hypothesize that this greater [volume load] achieved through high frequency protocol if executed for a longer time frame (more than 8 weeks) may possibly culminate in a significantly greater increase in strength and hypertrophy compared with a single-session per muscle group.”

All things considered, I’d still recommend hitting each muscle more often than once a week.

But that doesn’t mean you won’t see results with just one weekly training session per muscle group. It’s not like leaving seven days between each body part produces zero results.

As long as the total weekly volume (number of sets per muscle group) and intensity (amount of weight you lift) is equated, a lower training frequency can still build an impressive amount of muscle.

However, if you want to maximize your rate of growth, I think you’re better off training each muscle at least twice every seven days.

That might mean an upper/lower split performed four times a week, where you split your training into upper and lower body days, and do two upper and two lower body days per week.

Or it might mean a push/pull split, which involves training the major muscle groups in two different workouts – a push workout and a pull workout.

The push workout revolves around the pushing movements for the upper body, which involve the chest, shoulders and triceps, along with the quads.

The pull workout is based around pulling movements for the upper body, which involve the back and biceps, as well as the hamstrings.

Why does hitting a muscle group twice a week work better than training it once a week?

One of the key driving forces behind muscle growth is muscle protein synthesis, which refers to the creation of new muscle protein. And it’s the gradual accumulation of this new muscle protein that makes your muscles bigger [4].

After you train, protein synthesis goes up. But it’s back to normal a couple of days later [5]. And creating more muscle damage doesn’t appear to make the rise in protein synthesis last any longer [6].

Put differently, there’s an upper limit on the amount of stimulation your muscles can respond to in any given workout.

In other words, when you train a muscle once a week, it might spend a few days growing after the workout. But leaving seven days before you train that muscle again means missing out on several additional opportunities to stimulate muscle hypertrophy.

The Law of Individual Differences

Working a muscle 2-3 times per week may, on average, produce a faster rate of muscle hypertrophy than training it once a week.

However, no two people respond to the same training program in exactly the same way, and we can’t exclude the possibility that there may be a set of people who thrive on a training program that involves training less frequently.

We know, for example, that people with a specific variant of the ACE gene gain just as much strength with single versus multiple-set training programs, while people with another variant make faster progress with multiple sets [7].

The same may hold true for training frequency. Some people may make equal or faster progress working a muscle once a week compared to twice or three times a week.

In one study, roughly 3 out of 10 subjects put on more muscle when they followed a training routine that involved working a muscle five times per week [8].

Another 4 out of 10 saw faster results when they trained that same muscle 2-3 times each week. The others made similar progress irrespective of how often they trained.

Even after training volume was taken into account, some folks gained muscle faster on the higher training frequency [9].

I will always recommend an approach to training and diet that I think will work for most people, most of the time.

But most people, most of the time doesn’t mean all people, all of the time, and there will always be exceptions and outliers.

There is no universally correct training frequency that works equally well for everyone, nor are there rigid guidelines that determine exactly what your training routine should look like.

All of which means you’ll need to be willing to experiment. By that, I mean testing out different training frequencies with the aim of finding the one that works best for you.

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