Illustration of a bodybuilder doing an Arm Day workout to build bigger arm muscles.

The Best Arm Day Workout for Building Muscle

Arm Day is an entire workout routine focused purely on arm exercises. It’s what allows the Bro Split to stimulate more arm growth than almost any other workout routine.

Arm Days are simple in theory. Arm muscles aren’t hard to train. But you still need a fruitful combination of exercises. If you’re doing more than one type of biceps curl or triceps extension, you’d best have a good reason for it. We’ll explore those reasons.

You also need to watch out for putting too much stress on your elbow joints. It’s common for barbell curls, skull crushers, and overhead triceps extensions to hit the elbows pretty hard. We’ll teach you how to navigate those perilous waters.

A skinny guy building muscle. Illustrated by Shane Duquette for Outlift.

What’s Arm Day?

Arm Day is a workout focused on your arm muscles. It’s part of a Bro Split routine, where you divide your body into different muscle groups, allowing you to train 4–5 days per week while still giving each muscle plenty of time to recover.

Bro Splits and Push/Pull/Legs (PPL) Splits have much in common. Push Day is nearly the same as Chest Day, Pull Day is somewhat like Back Day, and they each have Leg Days. What makes the Bro Split unique is its greater emphasis on arm training.

Arm exercises are usually pushed to the back of a workout. By the time you get to your biceps curls, you’ve already done deadlifts, pull-ups, and rows. You’re already tired. Your biceps don’t get your best effort. Your forearms might not get any deliberate attention whatsoever. That isn’t always a problem, but it can be. It’s common for arms to lag behind. Arm Day is the answer.

Muscles Worked During Arm Day

Arm Day works both heads of your biceps and all three heads of your triceps. It also works your brachialis, brachioradialis, forearm flexors, and sometimes shoulders.

Diagram showing which Arm Day exercises work different arm muscles.

You may want to sneak in some chest and back work, too. By default, Bro Split routines train each muscle once per week, which isn’t quite enough to maximize your rate of muscle growth. You can solve that by including some arm-focused pushing and pulling exercises, such as close-grip bench presses and chin-ups.

Be warned, though: adding too many compound lifts to Arm Day will sap it of its magic, making it little more than a generic upper-body workout. We need to keep the emphasis on your arms.

The Best Arm Day Exercises

The Best Biceps Exercises

Your biceps cross your shoulder joint, pulling your arms forward. Most back exercises pull your arms backward. That interference prevents the long head of your biceps from fully engaging (study). That’s why biceps curls are so important.

Illustration showing the biceps, brachialis, and brachioradialis muscles.

However, your biceps aren’t your only elbow flexors. Your brachialis and brachioradialis are simpler muscles that can work incredibly hard during pulling movements. You can emphasize your brachialis by using a neutral grip. You can focus on your brachioradialis by lifting with an overhand “reverse” grip.

  • Chin-ups are the biggest vertical pulling exercise. They’re great for your lats and upper back, but they also work your biceps, brachialis, and brachioradialis. A narrower, neutral grip makes for a great default.
  • Pulldowns are great for beginners. You can do them with an underhand, neutral, or overhand grip.
  • Barbell Curls are simple, stable, and easy to progressively overload. You can do them with a straight barbell or an angled curl-bar (aka EZ-Bar).
  • Dumbbell Curls train your biceps in the same way as barbell curls. They aren’t quite as stable, but they tend to be easier on your elbow joints.
  • Lying Dumbbell Curls challenge your biceps through a deep range of motion, stimulating a tremendous amount of muscle growth, especially in the long head. This is my favourite biceps exercise.
  • Incline curls demand less shoulder stability than lying dumbbell curls, but they also don’t challenge your biceps under as deep of a stretch.
  • Preacher curls have the same resistance curve as lying dumbbell curls, and they’re quite stable, which is great. However, the biceps are shortened at the shoulder joint. That’s fine for your short heads but less so for your long heads.
  • Hammer curls are great for your brachialis and brachioradialis.
Illustration of a muscular weight lifter doing the lying dumbbell biceps curl exercise.

The Best Triceps Exercises

You can bulk up the lateral and medial heads of your triceps with pressing exercises. The long head crosses the shoulder joint, interfering with pressing movements. Better to train it with triceps extensions (study).

Illustration showing which exercises work which triceps heads.
  • Close-grip bench presses are fantastic for emphasizing the medial and lateral heads of your triceps. Building these into my arm routine is what finally helped my triceps grow. You can get similar benefits from push-ups, dips, and overhead presses, but they don’t put quite as much emphasis on your triceps.
  • Triceps pushdowns are easy to learn, easy on the elbows, and don’t require much shoulder mobility, making them a great exercise for beginners.
  • Overhead extensions stimulate the most muscle growth (study). If you have the shoulder mobility to lift your arms fully overhead, overhead extensions are ideal. Stretching your triceps at the shoulder joint works them through a deeper range of motion, improving muscle growth (study).
  • Skull crushers are famous as an assistance exercise for the bench press. They’re great for building bigger triceps, too.

The Best Forearm Exercises

Most of the muscles in your forearms get worked during pulling exercises and biceps curls, but you can probably benefit from devoting some extra attention to your forearm flexors. They’ve got great potential for growth, and they aren’t always challenged enough during biceps curls.

Illustration of a bodybuilder doing forearm curls to build bigger arms on Arm Day.

The best exercise for building bigger forearm flexors is the forearm curl. It’s a small exercise. It won’t take much time or effort.

The Best Shoulder Exercises (Optional)

If you have a Shoulder Day, you don’t need to include shoulder exercises on Arm Day. That’s even more true if you’re already doing close-grip bench presses and chin-ups, both of which work your shoulders.

Illustration of a weight lifter doing the lateral raise exercise to build bigger side delts and broader shoulders.

Still, you could make a case for including lateral raises. They’re quick and simple, and they work your wrist extensors along with your side delts.

How to Calculate Training Volume for Arms

You need around 9–18 sets per muscle per week to maximize your rate of muscle growth. This can be confusing, though, because arms get so much ancillary volume from compound exercises. How are you supposed to count volume for your arms? Do the compound exercises count? Sort of.

If your chest limits you on presses, your triceps might not work hard enough to get an optimal growth stimulus. If your lats limit you on pull-ups, your biceps and forearms might not get a chance to work hard enough.

A better way to count volume for your arms, then, is to ignore the volume coming from those compound exercises. Only count direct arm work. But set a lower target. Maybe you’d aim for 4–8 sets of isolation exercises for your biceps and triceps. This is especially important if you have stubborn arms.

So, what we’ll do in these workouts is give your arms muscles around 4–8 sets. We’ll also sneak a few sets of curls and extensions into Back Day and Chest Day, giving your arms the frequency they so desperately desire.

Arm Day Workouts

Classic Arm Day

Neutral-Grip Chin-Ups4 sets6 reps
Close-Grip Bench Press4 sets8 reps
Lying Dumbbell Curls4 sets10–15 reps
Overhead Triceps Extensions4 sets10–15 reps
Seated Wrist Curls3 sets10-15 reps
Lateral Raises3 sets10-15 reps

Chin-ups work your biceps, brachialis and forearms, along with your rear delts and back muscles. Close-grip bench presses work your triceps along with your front delts and chest. If you want, you can superset these two exercises together. You could even swap the close-grip bench presses for diamond-grip push-ups if that makes the superset easier.

Lying dumbbell curls and overhead triceps extensions train your biceps and triceps under a tremendous stretch, stimulating a fearsome amount of muscle growth. You can superset them together if you want.

Seated wrist curls work your forearm flexors. Lateral raises work your side delts. You can superset them together if you want.

Purist Arm Day

Curl-Bar Curls4 sets6–8 reps
Skull Crushers4 sets8–12 reps
Lying Dumbbell Curls3 sets10–15 reps
Overhead Triceps Extensions3 sets10–15 reps
Hammer Curls3 sets10–15 reps
Seated Wrist Curls3 sets10-15 reps

This Arm-Day workout foregoes the compound pressing and pulling movements to free up more room for pure arm work. If you have stubborn arms and want to emphasize them, this can be a powerful approach.

It’s relatively common for heavier triceps extensions to be hard on the elbows. If the skull crushers bother your elbow joints, you can swap them out with close-grip bench presses. That should help to warm your elbows up. The lighter overhead extensions should go smoothly afterwards.

Since you aren’t doing neutral-grip chin-ups, we’ve added hammer curls for your brachialis and brachioradialis.

Illustration of a lifter doing biceps curls on Pull Day of his 6-day workout split.

Arm Day Training Guidelines

Arm Days are part of the bodybuilding tradition. They’re designed to stimulate muscle growth, they train a single body part, and they often use relatively short rest times. Here are some basic training guidelines:

  • Exercise SelectionChoose exercises that suit your body and your goals. If barbell curls hurt your elbows, feel free to use dumbbells or cables.
  • ProgressionThe goal is to get progressively stronger over time. The first two exercises of each workout are perfect for this. Try to add weight and reps.
  • Rest times: Classic Arm Day workouts use short or moderate rest times. You could rest for 2 minutes between sets on the first exercise, then 30–90 seconds between sets for the other exercises.
  • Reps in Reserve: Leave 1–2 reps in reserve on the first 2 exercises. Take every other exercise to the cusp of failure. Arm muscles grow best when you push them hard.
  • Muscle-Building Diet: You need enough food to fuel muscle growth. If you’re skinny-fat or overweight, you can get extra energy from your body fat. If you’re thin or lean, you may need to gain weight to make progress.

Alright, that’s it for now. If you have any questions, drop them below. I’ll answer all of them. If you want the latest research and methods in your inbox, we have a free muscle-building newsletter.

Shane Duquette is the co-founder and creative lead of Outlift, Bony to Beastly, and Bony to Bombshell, and has a degree in design from York University in Toronto, Canada. He's personally gained 65 pounds at 11% body fat and has ten years of experience helping over 10,000 skinny people bulk up.

Marco Walker-Ng is the co-founder and strength coach of Outlift, Bony to Beastly, and Bony to Bombshell, and is a certified trainer (PTS) with a Bachelor's degree in Health Sciences (BHSc) from the University of Ottawa. His specialty is helping people build muscle to improve their strength and general health, with clients including college, professional, and Olympic athletes.

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