The barbell preacher curl isolates the biceps by eliminating momentum and ensuring strict form. Performed on a preacher bench, it emphasizes the lower part of the biceps, enhancing muscle definition and strength.

1. Sit on a preacher bench and rest your arms on the pad, holding a barbell with an underhand grip.
2. Curl the barbell towards your shoulders, keeping your upper arms on the pad.
3. Squeeze your biceps at the top of the movement.
4. Slowly lower the barbell back to the starting position.