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Concentration Curl

A seated, single-arm curl that isolates the bicep fully by removing any possibility of using momentum or other muscles to assist.

Setup

Sit on the edge of a bench, legs spread. Hold a dumbbell in one hand, leaning slightly forward.

Movement

Brace your elbow against your inner thigh. This is what locks the upper arm in place and removes momentum from the equation. Curl using only your forearm. Bring the dumbbell up toward your shoulder, keeping the upper arm completely still against your leg.

Return

Lower with control. Extend fully before starting the next rep, maintaining the brace against your thigh throughout.

Common Mistake to Avoid

Letting the elbow lift off the thigh. If the elbow comes off your leg, you've lost the isolation that makes this exercise valuable.

Equipment Dumbbell, bench
Primary Muscles Biceps
Secondary Muscles Forearms

Why it matters

By bracing your elbow against your inner thigh while seated, the concentration curl removes almost every way to cheat the movement — no swinging, no shoulder assistance, no momentum. What's left is close to a pure test of bicep strength and control, which makes it useful both as a strength-builder and as a way to genuinely feel which arm is weaker if there's an imbalance.

How to do it

  1. Sit on the edge of a bench, legs spread. Hold a dumbbell in one hand, leaning slightly forward.
  2. Brace your elbow against your inner thigh. This is what locks the upper arm in place and removes momentum from the equation.
  3. Curl using only your forearm. Bring the dumbbell up toward your shoulder, keeping the upper arm completely still against your leg.
  4. Lower with control. Extend fully before starting the next rep, maintaining the brace against your thigh throughout.

Common mistakes

  • Letting the elbow lift off the thigh. If the elbow comes off your leg, you've lost the isolation that makes this exercise valuable.
  • Rushing the rep. Because there's no momentum available, rushing just means sloppier form — slow down and feel the muscle working.
  • Using too much weight. This exercise typically uses less weight than a standing curl, since there's no assistance available from the rest of the body.
  • Leaning too far forward or back. Find a stable, balanced position rather than contorting to manage a weight that's too heavy for strict form.

Sets & reps by level

Beginner

3 sets of 10–12 reps per arm with light weight, prioritizing the strict, braced position.

Intermediate

3–4 sets of 8–10 reps per arm at a moderate weight.

Advanced

4 sets of 8–10 reps per arm, often used to finish an arm workout with maximum isolation.

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