Building Your Arms: Biceps, Triceps & Forearms

Start Here

Bigger arms come from three muscle groups, not one. The biceps bend the elbow. The triceps straighten it, and they're the bigger muscle on the upper arm. The forearms run your grip and your wrists. If you only curl, you're training the smallest part of the job.

Your arms also get work from everything else you do. Rows train the biceps, presses train the triceps, and heavy holds train the forearms. Direct arm work fills in the rest.

Think of your arm like a crane. The biceps lift the load up, the triceps push it away, and the forearms are the hook. A crane with a weak hook doesn't lift much, no matter how strong the arm is.

Your First Step: Add one overhead triceps extension to your next upper-body day. Three hard sets, full stretch at the bottom, full squeeze at the top.

The Breakdown

How the Arm Works

• Biceps. Two heads on the front of the upper arm. They bend the elbow and turn your palm up.
• Brachialis. Sits under the biceps and bends the elbow no matter which way your palm faces.
• Brachioradialis. Runs into the forearm and works hardest with a thumbs-up grip.
• Triceps. Three heads on the back of the arm. All three straighten the elbow. The long head also crosses the shoulder, so it's stretched most when your arm is overhead.
• Forearm flexors and extensors. Run your grip and your wrists.

Biceps & Brachialis

Curls are the base. Arm position and where the hardest part of the rep sits change the stimulus.

• Supinated curls (palms up). The classic. Biceps do most of the work.
• Hammer curls (thumbs up). Shift more work to the brachialis and brachioradialis.
• Incline dumbbell curls. The arm hangs behind you, which puts the biceps on stretch at the bottom.
• Preacher curls. The pad locks your upper arm in place and makes the bottom of the rep hard.

For anything biceps, I like a preacher bar. There's a time and a place for a straight bar, but the preacher bar is my go-to. I set my grip about shoulder width. Not too narrow, not too wide.

Isolation work helps people understand the movement. An angled bench, or any bench you can brace your arm on, stabilizes the upper arm and shows you where the bottom-out position is. From there you can lock out the elbow and force the stretch.

That bottom range matters. In one study, women trained one arm on preacher curls through only the first half of the range (arm nearly straight to about halfway) and the other through only the second half. After 8 weeks, the first-half arm gained more strength across the full range and more muscle near the elbow end of the biceps. Total growth across the two spots they measured was similar (Pedrosa et al., 2023).

My takeaway isn't "only do half reps." The stretched bottom of a curl is too valuable to skip. That's one of the Five Essentials: train the entire strength curve. If you add partials at the end of a set, keep them in that stretched range with constant tension, not swinging the weight up.

Triceps

Pushdowns are fine. As your only triceps exercise, they leave growth on the table.

In a 12-week study, adults trained one arm with overhead cable extensions and the other with pushdown-style extensions with the arm at their side. The overhead arm always used lighter weight, yet grew more in every head of the triceps, with the biggest difference in the long head. Strength gains were similar (Maeo et al., 2023).

The practical move: have at least one overhead triceps movement in your week. Good options:

• Overhead cable extensions (facing away from the stack, rope or bar).
• Dumbbell overhead extensions.
• Pushdowns as a second movement, for the squeezed position.

I don't like a V-bar for pushdowns. It's too narrow for me. I'd rather use a preacher bar so I can go reverse grip, or do wider pushdowns. Palm up, I get a better contraction because I'm not throwing more of my arm into it.

Attachments matter too. A short rope works well for pushdowns. A longer rope is better for overhead work. For single-arm cable extensions, I'll put a fat grip on the handle, because you don't always want to be holding that little ball above the carabiner.

Forearms & Grip

Forearms get trained every time you hold something heavy, but they still benefit from direct work. On arm day, forearms usually finish the session: wrist curls and wrist extensions, barbell, cable or whatever feels better that day. I don't always do them, but when my arm workout needs something different, I like to prime it with strongman carries like farmer's walks. It's an add-on. They also get their own time on Sundays, along with core, calves and tibialis.

• Wrist curls and wrist extensions (barbell, cable or dumbbell) for the flexors and extensors.
• Reverse curls (palms down) for the brachioradialis and the top of the forearm.
• Heavy holds and carries, like farmer's walks, for grip that lasts.
• A power pin (a loading pin with a T-handle; a single 2.5-, 5- or 10-pound plate held on with a barbell clip). Pronation and supination (turning the palm down and up) with the forearm on a bench. Radial deviation (tilting toward the thumb side) on a 45-degree preacher pad. Ulnar deviation (tilting toward the pinky side) standing with the arm at your side.

My go-to grip cue on curls: supinate toward the pinky. Turning the pinky up gets you the squeeze in the biceps. I don't wrap my thumb. I keep a thumbless grip and squeeze hard.

A fat grip forces a better connection with the working muscle on some exercises. For forearms, I don't feel it does much unless I'm doing farmer's walks with them. Then it just kills.

Do You Even Need Direct Arm Work?

In one study, trained men did 8 weeks of either compound upper-body lifts only, or the same lifts plus curls and triceps extensions. Both groups got stronger and grew their arms, with no significant difference (de França et al., 2015).

That's worth knowing, but it has limits. It was short, the groups were small, and arm size was measured with a tape, not a scan. It doesn't tell you much about someone who has trained for years and needs targeted work to keep progressing.

Compounds first, isolation to finish the job. I use mostly machines for compound lifts and free weights for isolation work like curls and extensions. The rows in Building Your Back and the presses in Building Your Chest do a lot of the heavy lifting for your arms. Direct arm work fills in the stretch and the squeeze those lifts miss.

Bro Science Check: "Pushdowns are all you need for big triceps."

What the Research Says: Over 12 weeks, overhead extensions grew every head of the triceps more than extensions with the arm at the side, even with lighter weight (Maeo et al., 2023). Both arms still grew.

Verdict: Keep. Pushdowns build muscle. Pair them with an overhead movement so the long head gets fully stretched.

How to Pair Them

Biceps and triceps work in opposite directions, which makes them easy to pair. While one rests, the other works. That saves time.

My arm days are mostly supersets: a biceps movement, then a triceps movement, back and forth. I like keeping the pump going on both sides. Forearms finish the session.

I don't have a set weight. I play around with the movements a lot. My arms are about 19.25 inches, and I don't want much more size. Arm day is more of a pump workout for me: I focus on the pump and the squeeze. What I want is grip strength, a little more fine motor control, and consistent performance from week to week.

Execution: Where Arm Training Goes Wrong

Arm exercises are simple, which is why people get sloppy with them. My cues all come back to setup. Run every rep through S.S.I. (Setup, Stabilize, Initiate) and the Five Essentials:

• Initiate with the working muscle. The curl starts at the elbow, not with a hip swing.
• Keep continuous tension. Don't rest at the top of a curl with the weight stacked over the elbow.
• Get the full squeeze. Lock the triceps out hard. Curl until the biceps can't shorten any more.
• Train the entire strength curve. Let the weight all the way down into the stretch.
• Maintain proper posture. Upper arms stay still on curls and pushdowns. If your elbows drift, the shoulders are taking over.

Common Mistakes

• Curling ego weight. If you need your back to get it up, it's too heavy for your biceps.
• Ignoring forearms until grip fails. A few burnout sets keep them from being the weak link.

Elbow pain that sticks around isn't something to train through. See a doctor or physical therapist. Not medical advice.

Round out your upper body with Building Your Shoulders. Next: Building Your Back.