Doing preacher curls might build more muscle in a specific lower part of your upper arm than incline curls do.

Different bicep curl exercises lead to different patterns of muscle growth: incline curls cause more growth near the shoulder end of the biceps, while preacher curls cause more growth in the brachialis and brachioradialis muscles along the forearm side of the upper arm.

When performed by the same person, incline curls lead to more growth in the main bicep muscle, while preacher curls lead to more growth in the forearm muscles that help bend the elbow.

After ten weeks of preacher curls using either a cable machine or a barbell, young adults who had never trained before gained the same amount of biceps muscle thickness, regardless of whether the exercise placed more resistance at shorter or longer muscle lengths.

Doing bicep curls on an incline bench builds more muscle in the upper part of your biceps than preacher curls do.

Whether you do preacher curls with a cable machine (harder when your arm is bent) or a barbell (harder when your arm is straight), your biceps grow about the same amount after 10 weeks of training.