How to Do It
- Sit on the edge of a flat bench with your legs spread comfortably wider than shoulder-width and feet flat on the floor.
- Grip a dumbbell with one hand and brace the lower back of your tricep against the inside of your same-side inner thigh.
- Let your arm hang straight down with your palm facing forward or slightly inward, ensuring the elbow stays firmly against the thigh.
- Curl the dumbbell upward toward your shoulder by bending only at the elbow, keeping your upper body completely stationary.
- Squeeze your bicep firmly at the top of the range of motion for a brief pause without rolling your shoulder forward.
- Lower the dumbbell under steady control back to full extension before beginning the next repetition.
Common Mistakes
- Resting the point of the elbow on top of the thigh instead of bracing the back of the tricep against the inner thigh.
- Swinging the torso backward or using shoulder momentum to initiate the upward curl.
- Allowing the wrist to curl excessively upward or collapse backward under load.
- Cutting the bottom range short instead of allowing full elbow extension.
- Letting the working shoulder drop or hunch forward during the contraction.
The concentration curl is a classic single-arm biceps exercise built around a strict, braced position. Anchoring the back of your working arm against your inner thigh makes it hard to use momentum, so the elbow flexors, mainly the biceps brachii and brachialis, do the lifting.
Seated Setup & Arm Anchor Matrix
Proper execution depends on where and how your arm is anchored against your leg.[1][2]
| Setup Component | Proper Placement | Common Error | Correction |
|---|---|---|---|
| Bench Position | Edge of flat bench, torso inclined ~45° | Sitting too far back | Slide forward to allow full arm hang |
| Foot Stance | Wide stance, feet flat on floor | Narrow feet crowding arm | Widen feet so elbow clears opposite knee |
| Arm Anchor | Flat tricep against inner thigh | Olecranon (elbow point) on knee | Move the contact point slightly down the inner thigh |
| Non-Working Hand | Braced on opposite knee for stability | Hanging loosely | Firmly grip opposite knee to lock torso |
Step-by-Step Execution Guide
- Establish the Stable Base: Sit on the edge of a flat bench with your feet planted wider than shoulder-width. Hold a dumbbell with an underhand (supinated) grip in your right hand.[1][2]
- Anchor the Tricep: Lean forward from the hips and press the lower tricep of your right arm against the inside of your right thigh. Place your left hand firmly on your left knee to steady your torso.
- Hang to Full Extension: Allow the dumbbell to hang straight down toward the floor between your legs. Let your arm straighten fully without forcing the elbow.
- Initiate Strict Flexion: Without moving your torso or shoulder, contract your right bicep to curl the dumbbell up toward your chest. Keep your wrist neutral.[1][2]
- Peak Contraction: Squeeze your bicep hard at the top of the movement for a 1-second pause. Ensure your elbow remains anchored to your inner thigh.[1][2]
- Controlled Eccentric: Lower the dumbbell under control along the same path over 2 to 3 seconds until your arm reaches full extension. Complete all prescribed repetitions before switching arms.[1][2]
Programming & Quality Stop Rules
Concentration curls usually fit best as a secondary or later exercise on pull or arm days.
- Hypertrophy starting point: 3 sets of 10–12 repetitions with a 2-second lowering phase.
- Form Failure Boundary: Terminate the set immediately if your torso rocks backward to yank the weight up, or if your elbow slips off the inner thigh during the concentric phase.[1][2]
References
See our exercise methodology for how this evidence is applied and its limits.
Frequently Asked Questions
- What is a concentration curl?
- A concentration curl is a seated single-arm dumbbell curl where the back of the upper arm is braced against the inner thigh. Bracing the arm this way makes it hard to swing the weight up, so the elbow does the moving and the biceps do most of the work.
- What muscles do concentration curls target?
- Concentration curls mainly train the biceps brachii, which both bends the elbow and turns the palm up. The brachialis and brachioradialis also help bend the elbow. Some lifters feel the inner part of the biceps more with the arm in front of the body, but the whole muscle works.
- Where should your elbow be placed during concentration curls?
- Place the flat lower portion of your tricep against the inside of your inner thigh, just above the knee. Avoid resting the point of the elbow on top of the knee or thigh, where it tends to slip and press uncomfortably.
- Are concentration curls better than standard standing curls?
- They are stricter rather than better. The braced arm stops you from swinging, which makes it easy to feel the biceps and to train each arm on its own, but you will use lighter dumbbells than in a standing curl. Many lifters use a heavier standing curl first and concentration curls afterward for controlled higher-rep work.
- When should I stop a set of concentration curls?
- End the set as soon as you cannot reach full contraction without leaning your torso backward, when your elbow lifts off your inner thigh, or when you can no longer lower the weight under control.