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Home » How To Get Bigger Arms | Science Explained

How To Get Bigger Arms | Science Explained


Probably one of the most sought after goals in the gym is building bigger arms.

They’re a signature of strength and muscularity.

And the second most attractive part of the body according to research (resource).

So, how do you get bigger arms?

You just lift heavy and eat enough protein, right?

Well, if it were that easy, everybody would be walking around with big muscular arms.

The reality is that in order to get bigger arms there’s a lot of technique and knowledge that needs to be applied. Just like any other muscle.

By the end of this article you’ll know the science and technique and how to successfully reach your goal.

Let’s get into it.

How To Get Bigger Arms

Arm Anatomy


Most associate arm size with the biceps. When in reality that’s not the case at all.

The biceps only makes up  25% of the total muscle mass in your arms.

The brachialis (which we’ll discuss in more depth later) makes up 18%. And the triceps makes up over 52% of your arms.

What this should show you is how important the triceps is for arm size.

So if you want to get bigger arms, you must be training the triceps.

That being said, your biceps and brachialis should not be avoided.

So what is the brachialis exactly?

how to get bigger arms brachialis

The brachialis is a muscle located right underneath the biceps. It’s the main muscle responsible for elbow flexion – actively decreasing the distance between the forearm and the biceps (curling).

Yeah, it’s not the biceps.

Because the biceps does cross the elbow joint, it is also doing a lot of work during elbow flexion.

However, the brachialis muscle is the primary muscle being worked when doing exercises such as curls.

Don’t let the smaller size of the brachialis fool you though!

While the brachialis has the smallest involvement in the total muscle mass of the arms, it is indirectly responsible for their size.

The bigger the brachialis muscle grows, the more it pushes your biceps and triceps out. Giving you the appearance of bigger arms.


Eccentric Contraction

The eccentric contraction is one of the main signals and drivers of muscle growth.

It is where you apply weighted resistance to a stretched or stretching muscle.


how to build bigger arms


For example, when lowering the barbell during barbell curls.

Many find this portion of the exercise a good time to rest. When in reality it should be when you’re focusing on contracting the muscle and controlling the weight.

Don’t just swing or drop the weights. Rather control them.


Arm Workout Breakdown

A workout geared towards bigger arm size should look something like this:

3:2:1 ratio – 3 triceps exercises, 2 biceps exercises and 1 brachialis exercise.

Not all exercises are built equal.




For your triceps you want to make sure you’re adding exercises that target all three heads of the muscle – the long head, lateral head and medial head.

The triceps has one main functionality that all three heads are involved in – forearm extension from the elbow. This is where you’re actively increasing the distance between the forearm and the biceps.

But because the long head of the triceps is connected to the shoulder blades, that means that it is best targeted when the shoulders are at a 90 degree flexion.

In other words with exercises where the arms are more overhead.

So adding exercises such as skullcrushers, overhead extensions and cable overhead skullcrushers to your workout program is a good idea.

Also, because of its connection, the long head is responsible for shoulder extension – bringing the arm closer to the body when it’s out in front.

Hyperextended triceps kickbacks are a great exercise for targeting the triceps through this functionality. It is where your triceps’ long head is at its strongest possible contraction.




As we discussed, the biceps is largely involved in curling movements. But so is the brachialis.

So how do we make sure that we increase biceps activation?

Through supination twisting your palm up (leading with the pinkie finger).

The biceps is the prime mover of forearm supination. Which is why it is incredibly important to use it during curls as the brachialis cannot contribute to supination.

So the biceps will have to handle the load.

While most would argue that supination is best achieved through dumbbell exercises, I would argue to opposite:

Barbell exercises such as the barbell curl are better at contracting the biceps during supination.

This is because you can actively put the majority of the pressure on your pinkie and ring finger to drive the weight up.

And because the long head of the biceps crosses the shoulder joint, it assists during shoulder flexion.

So, when performing barbell curls make sure that you don’t just drive the weight straight up, but rather out in front of you in an arc.



So, if supination targets the biceps better, lack of supination targets the brachialis better.

A neutral grip, such as that of hammer curls, will cause the brachialis to handle the majority of the curling movement.


Progressive Overload


Progressive overload is regarded as the most important driver for muscle growth.

It’s what will make or break your muscle building progress.

It’s so important in fact that researchers are calling progressive overload:

… a critical prescription component, deemed necessary to elicit chronic adaptation

If you want to get your arms bigger, you’ll have to make sure that you apply progressive overload to your workouts.

What is progressive overload?

It is where you gradually increase the demand and stress of your muscles.

This can be done through a number of ways:

  1. More reps with the same weight;
  2. More weight for the same reps; or
  3. More sets with the same or higher weight.

A good example would be:

If you can only do 7-8 reps with a certain weight, next week increase your rep range to 8-9.

The following week, keep the increased rep range, but also add one extra set where you lift a heavier weight for 6-7 reps.

The third week, increase the weight and carry out 7 to 8 reps.

Repeat the whole process again and watch your gains explode.


Muscle Protein Synthesis

protein synthesis

Muscle protein synthesis (MPS) is the physiological process of building muscle.

It’s a signaling process and it involves two signals – exercise induced and nutritional.

Weight training has a greater simulative impact on MPS.

The problem is that it lasts for about 48 hours.

If your workout program consists of hitting your arms only once per week, you’re only activating muscle protein synthesis to the three muscles involved only once.

You’re leaving a lot of potential muscle growth on the table.

Make sure that you’re targeting your arms at least twice a week. And make sure that you give your muscles sufficient amount of time to rest before training them again.

A really good split for that is a push/pull/legs. You can check out this 6 week muscle building workout plan that follows the same split.


Bottom Line

Building bigger arms takes a bit of know-how and technique.

Something really important about this article is that it’s mostly workout focused.

I really wanted to focus on the proper technique and breakdown behind bigger arms.

A good workout is only one part of the equation. Your diet is the rest.

Make sure that you’re eating enough protein – about 1g per 1lbs is enough as a safety net. And make sure that you’re getting enough calories from carbs and fats to fuel your workouts.

Now that you know what it takes to get bigger arms it’s your turn now to put in the work at the gym.

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