StrengthBeginner

Concentration Curl

A single-arm seated curl that pins the elbow against the inner thigh, eliminating cheat and isolating the biceps under a clean stretch-to-peak arc.

GIF · Demo Concentration Curl

What is the concentration curl?

The concentration curl is a strict isolation move that has dominated bodybuilding biceps work since the seventies. You sit on a bench, lean forward, brace the working elbow against the inside of the same-side thigh, and curl a dumbbell from a fully extended position to peak contraction. Pinning the elbow removes hip and torso assistance and forces the biceps to do all the work. Multiple EMG studies have ranked it as the highest biceps activation lift, especially for the long head and peak.

How to do the concentration curl

Sit and set the angles

Sit on a flat bench, knees wide, feet flat. Lean forward from the hips, holding the dumbbell in one hand with palm up.

Pin the elbow inside the thigh

Brace the back of the working upper arm against the inside of the same-side thigh, just below the knee. Free hand rests on the other knee.

Curl with intent, supinate at the top

Lift the dumbbell in a slow arc, twisting the pinkie up at the peak to drive supination. Squeeze hard at the top.

Lower under control

Take 3 seconds to lower to a fully extended elbow. Pause one beat at the bottom stretch, then go again.

Coach tip

Cut the weight in half from what you'd swing on a barbell curl. Concentration curls are about feel and squeeze, not load. If the elbow leaves the thigh, the set's over.

Common mistakes

Swinging the dumbbell up. If the shoulder rocks back to start the lift, the load is too heavy. Drop weight and curl strict.
Elbow lifting off the thigh. The whole point is the elbow stays glued. Lift it, you cheat the biceps. Re-rack and reset.
No supination at the top. If you don't rotate the pinkie up at the peak, you skip the strongest biceps contraction.
Bouncing out of the bottom. Using stretch reflex to start the next rep robs the eccentric. Pause one second at the bottom.

Variations & progressions

Easier

Cable concentration curl

Same posture, low-pulley handle. Constant tension and easier to control the arc with light loads.

Harder

1.5-rep concentration curl

Curl up, lower halfway, curl up again, then lower fully. Counts as one rep. Murderous for the peak.

No bench?

Spider curl on incline bench

Lie chest-down on a 45-degree incline, arms hanging straight. Same isolation, both arms at once.

How to program it

Three protocols by goal. Pick one per cycle and aim for progression on load or distance.

Goal	Sets × Distance	Load	Rest
Hypertrophy	4 × 10-12 each arm	Light to moderate	60 s
Peak builder	3 × 12 with 2 s squeeze	Light	45 s
Pump finisher	2 × 15-20	Very light	30 s

Log every rep

Add the concentration curl to your ZON program

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Concentration Curl FAQ

Is it really the best biceps exercise?

A 2014 ACE-sponsored EMG study by Bret Contreras ranked it first for biceps activation, ahead of barbell curls and chin-ups. That said, EMG is one signal among many. Concentration curls are excellent for peak feel and mind-muscle connection, but they cannot be loaded as heavily as barbell curls. Use both, compound first when heavy, concentration second for finishing isolation.

Should I do both arms together or one at a time?

One at a time is the classic, and it has two advantages. Total focus on a single arm, and the ability to drag the rest period out without losing pump (working arm rests while the other arm goes). Doing both at once turns it into a spider curl, which works but loses the deep elbow pin against the thigh.

How heavy should I go?

Most lifters do well between 30 and 60% of their barbell curl working weight per arm. The cue is simple. If you can do twelve clean, strict reps with elbow glued and supination at the top, the weight is right. If reps 6 to 8 already need swing or elbow lift, drop a notch and earn the reps clean.