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Exercises

Concentration curl: how to do it and where it fits in your arm day

Published October 19, 2026

A concentration curl is a seated, one-arm dumbbell curl with the back of your upper arm braced against your inner thigh. Bracing the arm takes your shoulders and hips out of the lift, so the biceps does nearly all the work and cheating is almost impossible. Use a lighter dumbbell than for standing curls, curl until your forearm is upright, and lower all the way down.

Your last concentration curl set

How to do the concentration curl

With your arm pinned against your leg there is no way to swing the weight, which makes this the cleanest way to finish your biceps after heavier curls. Working one arm at a time also shows you quickly if one side is weaker.

Steps

  1. Sit on the end of a bench with your feet wider than your hips and flat on the floor.
  2. Pick up a dumbbell, lean forward slightly from the hips and set the back of your working upper arm against the inside of the same-side thigh, just above the knee.
  3. Let the arm hang straight with the dumbbell near the floor, palm facing the other leg, and rest your free hand on your other knee.
  4. Curl the dumbbell up toward your shoulder while your upper arm stays pressed against your leg, and squeeze for a second at the top.
  5. Lower slowly until your arm is straight again, finish the set, then switch sides.

Cues

  • Arm stays on the thigh
  • Pinky turns up at the top
  • Slow on the way down

Common mistakes

  • Lifting the elbow off the thigh: once the arm leaves your leg the shoulder starts to help. Keep the contact for the whole set.
  • Rocking the torso up to finish the rep: if you have to sit up to complete it, stop the set there or use a lighter dumbbell.
  • Stopping short of a straight arm: the bottom of the rep counts, so let the elbow open fully before each curl.

Swap for: Preacher Curl, Spider Curl, Dumbbell Curl

Muscles the concentration curl works

The concentration curl works the biceps, with the brachialis and forearm flexors helping to bend the elbow. Because your upper arm is fixed and slightly in front of your body, it is a strict biceps isolation movement. Your free arm and torso only steady you.

Sets, reps and reps in reserve for the concentration curl

GoalSets × repsRIRRest
Build muscle 2–3 per arm × 10–15 1–2 60 s
Go straight from one arm to the other; the rest of the other arm is the rest.
Finisher 2 per arm × 12–20 0–1 45–60 s
Use it last on arm day, after a heavier two-arm curl.
Fixing a weaker arm 3 per arm × 8–12 2 60 s
Start with the weaker arm and match its reps with the stronger one.

Concentration curl variations

  • Kettlebell Concentration Curl start position

    Kettlebell Concentration Curl

    Use a kettlebell when that is what you have; the handle position makes the top of the curl a bit harder.

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  • Spider Curl start position

    Spider Curl

    Lie face down on an incline bench and curl both dumbbells when you want the same strictness on both arms at once.

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  • Preacher Curl start position

    Preacher Curl

    Rest your arms on a preacher pad with an EZ bar when you want a braced curl you can load heavier.

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Concentration curl alternatives

Two-arm curls

  • Dumbbell Curl start position

    Dumbbell Curl

    Stand and curl both dumbbells when you want to move more total weight.

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  • EZ-Bar Curl start position

    EZ-Bar Curl

    Curl an EZ bar when you want a heavy main biceps exercise to do before concentration curls.

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Stretched biceps

  • Incline Dumbbell Curl start position

    Incline Dumbbell Curl

    Curl lying back on an incline bench when you want the biceps loaded at a long stretch.

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  • Cable Curl start position

    Cable Curl

    Use a cable when you want steady tension through the whole rep.

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Concentration curl vs preacher curl

Both brace your upper arm so you cannot swing. The preacher curl rests your arm on a pad angled in front of you, which makes the bottom of the curl hardest and lets you use an EZ bar with both arms. The concentration curl hangs your arm straight down from your thigh, which makes the top of the curl harder and needs only one dumbbell and a bench.

Use the preacher curl as a heavier two-arm exercise and the concentration curl as a lighter one-arm finisher, or pick whichever your gym has free.

Where it fits in your arm day

Put it near the end of the workout, after a two-arm curl like the EZ-bar or dumbbell curl. Your biceps are already tired, so a lighter dumbbell for strict reps is enough to finish the session without needing heavy loads.

Questions

What's the difference between concentration curls and preacher curls?

Both pin the upper arm. A preacher curl uses an angled pad and is hardest at the bottom; a concentration curl braces the arm on your thigh and is hardest near the top. Preacher curls are usually done with a bar, concentration curls with one dumbbell.

What muscles do concentration curls work?

Mostly the biceps, with help from the brachialis under it and the forearm flexors.

Are concentration curls good for building biceps?

Yes. They are strict and easy to take close to failure, which makes them a good second or third biceps exercise after a heavier two-arm curl.

How heavy should concentration curls be?

Lighter than your standing curls. Choose a dumbbell you can curl for 10 to 15 strict reps with the arm on your thigh and one or two reps left.

Should you do concentration curls standing?

The standard version is seated, which keeps the arm braced. Standing bent over with the arm hanging works too, but it is easier to swing, so the seated version is the better default.

What are the top three biceps exercises?

A heavy two-arm curl such as the EZ-bar or barbell curl, a curl that stretches the biceps such as the incline dumbbell curl, and a strict braced curl such as the concentration or preacher curl cover the biceps well.