Barbell Curl.
The barbell curl is the standard bilateral biceps exercise. Arms start fully extended with the bar against the thighs, elbows pinned to the sides, and the forearms curl the bar to shoulder height while the upper arms stay completely stationary.
Step by step.
Stand tall with your feet about hip width apart and grip the bar with your palms facing forward, hands roughly shoulder width. A straight bar keeps the wrists fully supinated; an EZ bar lets them sit at a friendlier angle.
Let the bar hang against your thighs with the arms straight. Pin your elbows to your sides and keep them there for the whole set.
Curl the bar up by bending only at the elbows, lifting the forearms while the upper arms stay still. The elbows must not swing forward to help.
Bring the bar to shoulder height and squeeze the biceps at the top. If you cannot reach the top without the elbows drifting or the torso rocking back, the weight is too heavy.
Lower the bar under control over about three seconds, resisting it the whole way down until the arms are fully straight again.
Reset against the thighs and keep your wrists neutral, not bent back, before starting the next rep.
Elbows pinned to the sides is not a suggestion. The moment the elbows drift forward at the top of the curl, the front deltoid takes over and the biceps stops working through its full contraction. You've turned the last few inches of a curl into a partial front raise. Pinning the elbows means the upper arm literally doesn't move. The forearm is a lever, the elbow is the hinge, and the bicep is the motor. If you can't reach shoulder height without the elbow swinging forward, the weight is too heavy for strict form.
The "no torso lean or swing" instruction is the other half of the same problem. Swinging the torso backward to generate momentum for each rep (body English, or cheating curls) turns the exercise into a partial hip hinge plus partial curl. Cheating curls are a legitimate advanced technique when done intentionally: you cheat the weight up to do a slower, heavier eccentric. Cheating because the weight is too heavy is just sloppy. Pick a weight where you can feel the biceps working from full extension to full contraction, and the speed is under your control on both the way up and the way down.
The eccentric (lowering) phase is where most of the muscle damage and growth signal comes from. Three seconds down is a productive target. A lot of lifters drop the bar back to the start without controlling the descent. That's leaving the second half of the exercise on the floor.
One practical note: straight bars can cause wrist discomfort for some lifters because the fixed pronation/supination angle doesn't suit everyone's forearm structure. An EZ curl bar (cambered bar) reduces that stress by letting the wrists sit at a more natural angle. It's not a weaker version of the exercise. The biceps work just as hard.
Supinated curls like this one bias the long head of the biceps. To round out the arm, add a hammer curl on another day. The neutral grip shifts work onto the brachialis underneath, and a thicker brachialis pushes the whole upper arm wider.
Common questions.
Either works. The straight bar keeps the forearm in full supination throughout the curl, which is theoretically optimal for the biceps brachii long head. But full supination on a straight bar can cause wrist and elbow discomfort (particularly at the lateral epicondyle) in some lifters, especially those with narrower grip widths. The EZ bar's angled grip puts the wrist in a semi-supinated position, which reduces that stress at a small cost to peak bicep activation. If your wrists or elbows bother you on straight bar curls, switch to the EZ bar. If straight bar feels fine, keep using it.
The best weight for curls is the heaviest one you can control through a full range of motion without swinging, elbow drift, or torso lean. For most lifters that's going to be somewhere between 30-60% of their bench press weight, not because there's a formula, but because that's the range where the technique stays honest. Ego loading on curls is common and counterproductive. A 90 lb barbell curl with a 3-inch elbow swing and a body-rock produces less biceps stimulus than a 65 lb curl done strictly, because the strict version keeps the load on the muscle rather than distributed across momentum and hip extension.
Usually wrist extension under load. If the wrists are bending backward (knuckles dropping toward the forearm) at the top of the curl as the weight gets heavy, the wrist extensors are failing under the load. Keep the wrists neutral (straight) throughout the movement. This often requires dropping the weight. Another cause is the fixed supination angle of a straight bar not matching your natural wrist alignment. An EZ curl bar resolves most cases of straight-bar wrist irritation.
The biceps respond well to direct work and the barbell curl covers the movement pattern effectively. But the biceps has two heads (long and short), and the brachialis underneath it also contributes to arm size significantly. The barbell curl trains both, with emphasis on the long head at a supinated grip. Adding a neutral-grip exercise (hammer curl) trains the brachialis more directly, which adds thickness to the outer arm. Chin-ups and rows provide additional bicep work through heavier compound pulling. A program that includes curls, hammer curls, and regular pulling movements covers the arm development bases well.
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