Written by Justin Harris and Team 1D

What is the bro split routine?

By definition, the bro split workout routine is a weightlifting program that involves working out different muscle groups on different days of the week. The term "bro split" comes from the fact that this type of workout is often associated with "gym bros" who frequent most public gyms.

You know the ones.

The bro split typically involves working out one or two muscle groups per day, with a typical weekly (7-day) routine looking something like this:

• Monday: Chest
• Tuesday: Back
• Wednesday: Rest
• Thursday: Shoulders
• Friday: Arms
• Saturday: Legs
• Sunday: Rest

Each workout typically involves several exercises targeting the specified muscle group for muscle gains. For example, a chest workout might include exercises such as bench presses, incline presses, flys, and dips, while a back workout might include exercises such as rows, pull-ups, and lat pulldowns.

Now that we have definitions out of the way, let's talk about it.

The truth about the bro split workout routine.

It would seem that way, but it's never worked that way in practice.

Bro split gives enough full attention to the arms and shoulders muscle groups, which I don't think you can get with any other split. You're not going to get 20 sets of arm work in on a push/pull/legs program, and you're not going to get 20 sets of shoulder work on it, but you can and probably will, with warm-ups of a bro split.

You have to remember what "training" is to a muscle group.

On a bro split routine, your triceps are getting hit directly on arm day, but they're also getting taxed indirectly on chest and shoulder day. So you’re already getting more total stimulus moments with 5x per week training on a bro split than 6x per week training on push/pull/legs where triceps are only given any activation on push day.

Is the bro split routine most effective for building muscle?

Many people have tried to find the perfect abbreviated split where things are hit more frequently, but at the end of the day, every top 10 Olympia competitor of the last 30 years has done a bro split.

And even amongst people highly focused on training and developing the most optimal program for muscle growth, the people who focus on higher frequency splits like Dr. Scott Stevenson and Jordan Peters, while very solid bodybuilders are far from the top 10 of the Olympia stage. 

How much of that is genetics?

Who knows, because the top 10 Olympians definitely have better genetics, but I don't believe you could argue that the top 10 at the Olympia would be even better with a different program because they've all tried it (no one is going to just miss out on the best method if it's out there)

I think the biggest part is that the studies are on protein synthesis. Synthesized muscle proteins don't make up much of your muscle mass. About 30% of it, and if you're on gear, it's going to be even less than someone who isn't because you'll hold more intramuscular water, and probably even less than that if you're someone who does a lot of sarcoplasmic 

You can imagine a pound of steak and how big it is. 

Now, imagine that steak dehydrated to beef jerky; it's a small rock-hard mass of contractile tissue. 

The beef jerky is part of the muscle affected by protein synthesis. 

The steak is the muscle with everything else.

And you can affect the "everything else" far more than the contractile tissue, which is what bodybuilding is and what the bro split workout routine improves through all the blood volume stuff related to the pump.

Myofibrillar growth vs. Sarcoplasmic work.

Larry Wheels is what you get when you focus on contractile tissue. Thick chest and back, but lack of arms, delts, and legs. That's what a heavy powerlifting training routine does. 

Phil Heath is what you get when you focus on sarcoplasmic work. VERY round muscles, especially the arms, delts, and legs. 

The bro split is (probably) just much better at maximizing the sarcoplasmic growth that affects >70% of what makes up a muscle.

Other programs may be more effective at maximizing myofibrillar growth that affects <30% of what makes up a muscle, but being better at 30% while worse at the other 70% will lose to being better at the 70% every time.

That and smaller body parts just get the shaft in terms of output and progressive overload when they come last, so you're getting a hell of a lot more stimulus and growth potential by dedicating one day to them vs. training them 2-3x per week after bigger muscles.

Plus, I would argue that arms, shoulders, and legs have FAR more sarcoplasmic potential than back or chest. 

Accepting reality for muscle growth.

I think powerlifting plays this out, and it makes sense evolutionarily, also. If we were birds, our chest muscles would be built for high-volume work where blood needs to be moved around very well.

But we're not birds. We walk with our legs and use our arms for daily tasks. We use our chest to push something heavy and our backs to lift something heavy, which all makes sense when you wonder why Larry Wheels has a freaky back and chest but small legs and arms, and it's because of that sarcoplasmic work he's not getting, that the muscles of the arms and legs have evolved to thrive on.

This is not something most bodybuilders obsess over when it's clearly worked well for decades, but I find it interesting.

Why do people do the bro split?

I think most people who are really into learning the sport go through at least a brief "why does everyone do this when the studies show that?" phase, but I think it's because the studies aren't looking at the whole picture. You need more myofibrillar growth, but you won't win a bodybuilding show unless you emphasize sarcoplasmic growth.

Interestingly, this is also why research shows that GH isn't good for muscle growth, but every bodybuilder knows it is. GH doesn't increase the protein structures of the contractile tissue, which is what the research will look at. But it does increase the intracellular fluid volume, as anyone who's used GH will tell you. 

And whether you increase the cross-sectional area of a muscle by 5% from new protein structures or more water in the muscle, it looks the same on the outside. And since there's probably 2.5x as much potential for growth from the water version of muscle, you can see why GH is a great "muscle" builder

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