Concentration Curl
The concentration curl is a seated, one-arm dumbbell curl where your elbow rests against your inner thigh so the arm can't cheat. It isolates the biceps and teaches you to curl with control rather than momentum. It suits beginners learning to feel the biceps working, and experienced lifters who want a strict finishing exercise for arm day.
Muscles worked
The Concentration Curl mainly works your biceps.
Setting up
- Sit on the end of a flat bench with your feet flat on the floor and your knees wide, a little wider than shoulder-width. Keep the dumbbell on the floor between your feet.
- Pick up the dumbbell with one hand and lean forward from your hips, keeping your chest proud and your back flat rather than hunched.
- Rest the back of your upper arm against your inner thigh, just above the knee, so the dumbbell hangs straight down with your arm fully extended. Rest your free hand on your other thigh for balance.
- Choose a light weight to start with. You want to be able to keep the elbow pinned in place for every rep.
How to do the Concentration Curl
- Start with your arm hanging straight, your palm facing across your body or slightly forward, and the back of your upper arm pressed into your inner thigh.
- Curl the dumbbell up towards your shoulder by bending only at the elbow, turning your palm to face up as you lift.
- Keep your upper arm braced against your leg the whole way. Only your lower arm should move.
- Stop when the dumbbell is close to your shoulder and squeeze your biceps hard for a second.
- Lower the dumbbell slowly, taking about 2 to 3 seconds, until your arm is fully straight again.
- Pause briefly at the bottom without letting the weight pull you forward, then start the next rep. Complete all your reps, then swap arms.
Form tips
- Think of your upper arm as fixed in place. If the elbow slides along your leg, the weight is too heavy or you're rushing.
- Squeeze the biceps at the top as if you were trying to bring your fist to your shoulder, but stop just short so the weight isn't resting at the top.
- Lower the weight slowly. The way down is where you can get a lot of work from a light dumbbell.
- Keep your chest still and your torso at the same angle from first rep to last. Don't rock back to help the weight up.
- Match reps on both arms. If your weaker arm manages fewer, stop both sides at that number or start with the weaker arm.
Common mistakes
Swinging or leaning back to lift the weight
Lower the weight until you can keep your torso still. Hold your chest at the same angle for the whole set and lift smoothly.
Elbow drifting away from the thigh
Press the back of your upper arm firmly into your inner thigh and keep it there. If it still moves, reduce the weight.
Dropping the weight on the way down
Count 2 to 3 seconds as you lower the dumbbell. Keep control until your arm is fully straight, without bouncing at the bottom.
Cutting the range short
Start every rep from a fully straight arm and curl until the dumbbell is close to your shoulder. A lighter weight with full range is better than a heavy half rep.
Sets and reps
| Build strength | 3-4 sets of 6-8 reps per arm with a weight you can control, 90-120 seconds rest. Do heavier compound pulling exercises first, then use this as an accessory. |
|---|---|
| Build muscle | 3 sets of 8-12 reps per arm, 60-90 seconds rest. Pick a weight where the last 2 reps are hard but your form stays strict. |
| Fat loss / general fitness | 2-3 sets of 12-15 reps per arm, 45-60 seconds rest, as part of a full-body plan alongside exercises that work the larger muscles and some cardio. |
Pick a weight where the last rep or two of each set is hard but your form stays clean. When every set feels easy, it's time to go up.
Concentration Curl alternatives
Machine taken, or want some variety? These work the same main muscles.
Concentration Curl FAQs
What muscles do concentration curls work?
Concentration curls mainly work the biceps. Bracing your arm against your thigh keeps the effort on the biceps and limits how much you can cheat with momentum.
How heavy should I go on concentration curls?
Start light, often around 4-8 kg depending on your experience, and increase gradually. The right weight lets you keep your elbow pinned and lower each rep slowly. If you have to lean back or swing the weight, drop down.
Are concentration curls better than standing dumbbell curls?
They're different rather than better. Standing curls let you use more weight, while concentration curls are stricter and more controlled. Many people do a standing or other main curl first, then finish with concentration curls.
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