Are Hammer Curls or Reverse Curls Better For Forearms? (3 Forearm-Curling Facts)

I bet you’re curious, “Which is superior for my forearms: Hammer Curls or Reverse Curls?”

I would hazard a guess that you’ve done a lot of curling in your time in the gym.

We all know that in order to produce a great set of biceps we have to curl.

However, there are curl variations that tend to focus on different areas of the arms.

So, it makes sense to use these other exercises when it comes to great all-round arm development.

But, when it comes to forearms, are you better off using hammer curls or reverse curls?

Allow me to reveal all.

Hammer Curls or Reverse Curls For Forearms

Hammer curls will work the biceps, brachioradialis, and brachialis at the same time. However, reverse curls don’t allow for any wrist supination, so they won’t work the biceps as effectively. Therefore, you will typically lift more weight with hammer curls, so this will allow for greater strength gains in your arms. With that being said, reverse curls allow you to isolate the forearms to far greater effect, whereas hammer curls are a better all-round arm exercise.

1. Hammer Curls are a Better All-Round Exercise

If I had to choose just one exercise then I would go with hammer curls.

For me, they’re just a better all-round exercise.

By this I mean that hammer curls work more of the overall arm infrastructure.

Plus, hammer curls allow you to go heavier than reverse curls, which means that you can experience better strength gains with hammer curls.

Firstly, hammer curls provide some form of wrist supination which means that your biceps will automatically get worked as well.

Okay, your biceps won’t get stimulated as well as with a standard curl where your wrists are fully supinated and your palms are pointing to the ceiling.

But still, hammer curls will activate the main long head and short head of the biceps.

Unfortunately, you cannot say the same for reverse curls, as your wrists will not go through supination at all, and your palms are always facing the ground.

Hammer curls will also work the brachioradialis and the brachialis.

The brachioradialis is the main muscle that allows the forearm to flex at the elbow.

Whereas, the brachialis is a muscle of the upper arm, located just beneath the bicep, and also allows for flexion at the elbow.

However, when the wrist is either in a neutral or palms facing down position this puts the biceps at a mechanical disadvantage.

The brachioradialis will take up the slack when your hands are in this position (this is good if you want to specifically train the forearms).

The brachialis will always be active regardless of your grip.

That said, in the same vein, if you put your biceps at a mechanical disadvantage (neutral or palms facing down grip) then you’ll work the brachialis to greater effect as well.

So, both exercises work the main muscles of the forearms extremely well.

But, hammer curls also bring the biceps into the equation, and they allow you to lift heavier weights.

Therefore, as I’ve mentioned, if I had to choose one exercise, and one alone, then I would have a preference for hammer curls.

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2. Reverse Curls Isolate the “Forearms” More

Now, it probably sounds like I’m giving reverse curls a hard time.

But, nothing could be further from the truth.

In fact, reverse curls are a fantastic exercise to build both size and strength in the forearms.

Plus, one of the main advantages they hold over hammer curls is that they isolate the forearms much more.

Anyone who specifically trains for hypertrophy will know exactly how much of an impact isolation exercises can have.

We all typically start out training with the big, heavy, compound lifts, and in truth, this is how it should be.

Your main aim when you initially start training, for at least the first 6-12 months, is to become proficient at the big lifts.

By this I mean that you should be able to perform the main compound lifts, e.g., squats, deadlifts, bench press, overhead press, rows, pull ups, dips, etc. safely and effectively.

Furthermore, you should also be progressing in terms of reps and weight regularly.

It’s only once you start stalling in weight progression that you know that you are potentially close to your maximum strength gains.

The way forward from here is to eat more and train each specific muscle group to a greater extent – enter isolation exercises.

And this is exactly what reverse curls are.

I’ve mentioned how the main forearm muscle, the brachioradialis, is worked harder when your biceps are at a mechanical disadvantage.

Therefore, when your grip is neutral or palms facing down you’ll hit this muscle much better.

However, reverse curls are definitely better for building the brachioradialis than hammer curls.

There are those who disagree, but there is enough scientific research and evidence to prove that reverse curls are the better brachioradialis exercise.

So, if you want to focus on the brachioradialis, and really bring this muscle to the fore, then reverse curls should be your exercise of choice.

3. Fast Twitch vs Slow Twitch Conundrum

Something else to consider is the type of muscle fibres that each specific muscle is made up of.

Whether a muscle is fast or slow twitch will help you to decide which exercise is best, as well as the preferred training protocol.

Firstly, the biceps are 60% fast-twitch muscle fibres.

This means that they will respond better to low to medium reps.

However, as 40% of the biceps muscle fibres are slow-twitch this will mean that they also respond fairly well to high reps and slow negatives.

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As for the brachioradialis, these are mainly fast-twitch muscle fibres.

So, in effect, the main forearm muscle will respond better to low to medium reps and a heavier weight.

As hammer curls allow you to go heavier than reverse curls this should mean that they potentially train the brachioradialis better.

However, as I’ve mentioned, I personally think that the brachioradialis responds better to reverse curls.

Finally, the brachialis is a slow-twitch dominant group of muscle fibres.

This means that the brachialis typically responds better to higher reps.

So, in effect, even though you’re lifting less weight with reverse curls, they could actually be the better exercise as you’ll be performing a higher number of reps.

With that being said, irrespective of which curl variation you decide to use, the brachialis responds extremely well to slow tempos.

Therefore, I would recommend some extremely slow negatives (up to 5 seconds) to properly train the brachialis.

Fast Twitch vs. Slow Twitch – Muscle Fibre Specific Training

Final Thoughts

Personally, I’ve never believed there should be an either/or scenario when it comes to training.

Clearly, both hammer curls and reverse curls both work the forearms extremely well.

So, I see no problem with training both exercises on a regular basis.

With that being said, hammer curls will work a greater overall area of the arms.

Hammer curls will stimulate the biceps, brachioradialis, and the brachialis.

So realistically, you’re getting more bang for your buck with hammer curls, as you’re training more muscles.

However, due to the fact there is no wrist supination, reverse curls won’t stimulate the biceps anywhere near as well as hammer curls.

But, this will mean that reverse curls isolate the forearms much better than hammer curls.

Finally, it’s also important to take into consideration the types of muscles fibres each muscle is made up of.

This will help you to determine the best overall reps, sets, and tempos you should be using to train each individual muscle.

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