Concentration curl

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A seated single-arm curl braced against the thigh, the strictest curl there is.

What it is

Sitting with the elbow resting inside the thigh, you curl one dumbbell at a time. The braced elbow removes swing entirely, so the biceps works through a clean range.

Muscles worked

Primary: Biceps. Secondary: Brachialis, Forearms.

How to perform it

  1. Sit on a bench with the legs apart and a dumbbell in one hand.
  2. Brace the back of that upper arm against the inside of the same-side thigh.
  3. Curl the dumbbell up toward the shoulder, turning the palm up as you go.
  4. Lower slowly to a full stretch without letting the elbow leave the thigh.

Common form faults

  • Leaning back to swing the dumbbell up. Keep the torso still; if it moves, drop the weight and let the arm work.
  • Stopping short of straight at the bottom. Straighten fully each rep. The stretched position is where much of the growth stimulus lives.

Programming

10 to 15 reps a side, usually at the end of an arm session where strict form beats load.

Variations & substitutions

Frequently asked questions

Does it build the biceps peak?
Peak shape is genetic. The concentration curl builds the biceps well, but no exercise changes where the muscle attaches.
Why one arm at a time?
It lets you brace the elbow and keeps attention on one side, which often evens out a strength difference between arms.