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.

We analyzed the available evidence on incline curls versus preacher curls and found that 49 studies suggest incline curls may lead to more growth in the main bicep muscle, while 40 studies suggest preacher curls may lead to more growth in the forearm muscles that help bend the elbow [1]. What we’ve found so far leans toward the idea that these two exercises might target different parts of the arm in slightly different ways, but we cannot say one is definitively better for building bigger biceps overall. The evidence does not show that incline curls cause greater bicep size compared to preacher curls — only that they may place more emphasis on the bicep itself, while preacher curls may involve the forearm muscles more. We don’t have enough data to say whether this difference translates to noticeable changes in muscle size over time. The studies we reviewed don’t measure long-term results, nor do they compare total arm growth between the two movements. Our current analysis shows the difference may be in muscle activation patterns, not final size outcomes. For someone looking to build their biceps, this suggests that including both exercises could help engage different muscle fibers, but we can’t say one will produce bigger arms than the other. If you’re trying to vary your routine, trying both might help you feel the work in different places — but don’t assume one is the clear winner.