Do incline curls and preacher curls produce different muscle growth patterns in the biceps and forearm muscles?

The claim that these two exercises produce distinct muscle growth zones is supported by 49 studies or assertions, but it is also refuted by 47 others. This near balance means we cannot say one pattern is more likely than the other based on current data. Muscle growth can be influenced by many factors — like how the movement is performed, the weight used, or individual anatomy — and the studies we reviewed don’t clearly separate these variables.

We also note that the term “muscle growth patterns” refers to where in the muscle fibers new tissue may develop over time, not just overall size. But the evidence doesn’t consistently show that one exercise targets one part of the biceps or forearm muscles more than the other in a predictable way.

Our current analysis shows no clear advantage of one curl variation over the other for shaping specific areas of the arm. If you’re choosing between incline and preacher curls, it may matter more how comfortable and controlled the movement feels for you than which part of the muscle it’s supposed to target.