Forearm Flexor and Extensor Hypertrophy: Wrist Curls, Reverse Curls, and Grip Girth

A good forearm workout for hypertrophy trains three separate targets: the wrist flexors on the palm side, the wrist extensors on the back, and brachioradialis near the elbow. Wrist curls cover the first two, and reverse or hammer curls cover the third. Aim for 15-25 controlled reps on wrist work, stay 1-3 reps from failure, and train two days a week.

That is the practical answer. The honest caveat is that almost no research measures forearm size directly, so much of this is borrowed from what we know about muscle growth in general. This guide is part of our complete arm and forearm training guide, and it covers the forearm belly (the muscle you can see), not grip strength, which gets its own treatment in grip strength types: crushing, pinching and supporting.

What are the forearm flexors, extensors and brachioradialis?

Think of the forearm as a bundle of small muscles with different jobs. For hypertrophy you only need three groups.

• Wrist flexors: on the palm side. They curl the wrist toward you and do the squeezing when you grip a bar.
• Wrist extensors: on the back of the forearm. They lift the hand back and keep the wrist stable under load.
• Brachioradialis: a thumb-side muscle that starts on the upper arm, near the elbow, and runs down the forearm. It helps bend the elbow.

Most people overtrain the flexors and ignore the other two. The flexors are bigger and get hit by every row and deadlift, so it feels like forearms are covered. The extensors are smaller and get far less work.

How do you build bigger forearms?

There is no forearm-specific hypertrophy trial that I could find to anchor the answer. What we have is indirect: when muscle growth is compared across rep ranges, it looks surprisingly similar. A 2017 meta-analysis of 21 studies, with all sets taken to failure, found that gains in 1RM strength favoured heavy loads, while changes in muscle hypertrophy were similar between low and high loads (Schoenfeld et al., 2017). A later review argued that muscular adaptations can be obtained across a wide spectrum of loading zones, rather than only in a narrow “hypertrophy range” (Schoenfeld et al., 2021).

Those reviews mostly looked at big muscles like the quads and elbow flexors, not wrist flexors. So the 15-25 rep range for wrists is a judgement call, not a finding. Why choose it? Wrists and elbow tendons dislike heavy, jerky loading. Lighter loads taken close to failure let you feel the muscle work without grinding the joint.

Volume matters too. A meta-regression of 15 studies found that more weekly sets were associated with greater muscle growth, with each extra set linked to about 0.37% more gain in muscle size (Schoenfeld et al., 2017). That analysis was not about forearms either, and one extra set per week is a small effect, so this is not a licence to pile on endless sets. Still, it supports the idea that a handful of hard sets a week beats a token set at the end of the session.

Wrist curls vs reverse curls: which one should you do?

Both, because they do different things. This is the most common confusion with the query “wrist curls vs reverse curls,” since the names sound alike.

Exercise	Main target	Grip	Suggested reps
Seated wrist curl	Wrist flexors	Palms up	15-25
Reverse wrist curl	Wrist extensors	Palms down	15-25
Reverse EZ-bar curl	Brachioradialis, elbow flexors	Palms down	8-15
Hammer curl	Brachioradialis, brachialis	Thumbs up	8-15

How to do a seated wrist curl

Sit on a bench, rest your forearms on your thighs with the wrists hanging past your knees, palms up. Let the bar roll down to your fingertips, then curl it up and squeeze at the top. Go slowly on the way down.

The most common mistake is letting the forearms lift off the thighs and using the biceps to heave the weight up. Pin them down. Use a load you can control for the full range, which for most people is lighter than the ego wants.

How to do a reverse wrist curl

Same setup, palms down. Lower the bar until the wrists drop, then lift the back of the hand up. The weight will feel embarrassingly light, because the extensors are small. Let it be light.

How to do a reverse EZ-bar curl

Grab an EZ bar overhand, hands just inside shoulder width, elbows pinned at your sides. Curl up without swinging. This is an elbow-flexion exercise, so it behaves more like a biceps curl with a forearm emphasis than a wrist exercise. If an EZ bar bothers your wrists, the comparison in barbell vs EZ-bar curls explains why the angle matters.

Does grip change how hard brachioradialis works?

This is where the research gets messy, so here is the fair version.

Study A. In a surface EMG study of 10 competitive bodybuilders doing 6-rep sets with an 8-rep-max load, brachioradialis excitation during the lifting phase was higher with a supinated grip than with a pronated grip (+5%) or a neutral grip (+6%). Biceps excitation differed far more: +19% versus pronated and +12% versus neutral (Coratella et al., 2023). A separate EMG study in 15 young men doing maximal isokinetic elbow flexion also found brachioradialis very active in all three forearm positions, slightly higher in supination (Caufriez et al., 2018).

Study B. A fine-wire EMG study in 10 healthy people found no difference in brachioradialis activation across neutral, pronated and supinated forearm positions during elbow flexion. The authors concluded its main role is as a consistent elbow stabiliser during flexion (Boland et al., 2008). A 2025 study of 36 healthy men under a 1 kg isometric load suggested biceps appeared more active in supination and brachioradialis in pronation, and the authors called for further controlled studies (Chen et al., 2025).

Why might they differ? Different tools (surface versus fine-wire electrodes), different tasks (isometric, isokinetic, or loaded reps), different loads and small samples. None of these studies measured muscle growth, and EMG amplitude is not the same as hypertrophy.

The cautious takeaway: do not hunt for one magic grip. Brachioradialis works in every position, so rotating through hammer curls and reverse curls across your training weeks is a safe way to hit it. For the hammer curl specifics, see hammer curls for brachialis and brachioradialis.

Do forearms grow from indirect work?

Partly. Rows, pull-downs and deadlifts load your grip and wrist muscles, so they are not asleep. In the fat-grip study, 15 resistance-trained men did deadlifts, bent-over rows and pull-ups with and without thick grip attachments. Forearm EMG rose with the thicker grip, while 1RM strength and pull-up reps dropped (Krings et al., 2021). That tells us forearm muscles work during these lifts, but it does not tell us they grow from them.

A different kind of clue: in professional tennis players, MRI scans of 8 players showed 11-15% more muscle volume in the dominant arm’s forearm superficial flexors (and the deltoid, triceps and arm flexors) than in the non-dominant arm (Sanchis-Moysi et al., 2010). It is an observational comparison of a sport, not a training trial, so treat it as a sign that forearm muscle can enlarge with years of heavy use, not a recipe.

What I would do: let your pulling work count as a base, and add a few direct sets once your forearms look like the weak link. If you use straps on heavy back work, as covered in lifting straps for back hypertrophy, keep a couple of lighter sets strap-free, and add direct wrist work. How much arm work to count directly or indirectly is covered in direct vs indirect arm volume.

How many sets and how often?

Start small. A reasonable plan is 2-3 sets of wrist curls and 2-3 sets of reverse wrist curls each week, split across two days, plus your normal hammer or reverse curls in arm training. That is about 4-6 direct sets a week for the wrist muscles. It is a modest dose on purpose: your pulling work already adds indirect volume, and you can add sets later if your forearms respond well and your elbows stay happy.

Keep reps in the 15-25 range, stop 1-3 reps before failure, and add a rep or a small plate every week or two. If you want to check how this fits your overall weekly volume, our training volume calculator can help, and a pull day template shows where forearm work fits. Pairing wrist curls with your biceps and triceps work in supersets also saves time, which we cover in antagonist arm supersets.

What about wrist rollers?

Wrist rollers are popular as a burnout, and many lifters like the pump. I could not find a trial testing them for forearm size, so I would not build a plan around them. If you enjoy them, use a light load, a few slow rolls up and down at the end of the session, and treat them as a finisher.

Genetics, tendons and realistic expectations

Forearm appearance depends on muscle belly length, tendon length and bone structure, and none of those can be trained. Two people with the same forearm circumference can have very different muscle mass. Be patient: forearms are small muscles, so progress is measured in months, not weeks.

Measure the same spot on the forearm every 4-6 weeks, and judge progress by reps and load too. If you have a stubborn forearm, keep tracking before you change plans.

When to see a doctor

Forearm work loads the tendons at the inner and outer elbow. If you get sharp pain, tingling or numbness in the hand, or elbow pain that lasts more than a couple of weeks, stop the offending movement and see a doctor or physiotherapist. Our guide to golfer’s elbow and distal biceps tendon issues covers what that can look like. This article is education, not diagnosis.

The bottom line

Bigger forearms mean training three targets: flexors, extensors and brachioradialis. Use wrist curls and reverse wrist curls for 15-25 slow reps, hammer and reverse curls for brachioradialis, and let your pulling work cover the base. The research on forearm size specifically is thin, so treat these numbers as sensible starting points, not laws, and adjust to what your tape measure and logbook show.

Want a plan that places all of this? Start with the push, pull and legs plans and work out your protein with the protein calculator.