Performing different types of biceps curls, such as hammer curls or preacher curls, leads to different amounts of muscle growth and strength improvements depending on how the movement is performed.

We analyzed the available research on biceps curl variations and found that different ways of performing curls may lead to small differences in muscle growth and strength gains, but the evidence is not consistent across all studies. What we’ve found so far suggests that how you perform a curl — whether it’s a hammer curl, preacher curl, or standard barbell curl — can influence which part of the biceps is activated and how much strength improves for that specific movement [1]. Fifty-four studies support the idea that these variations produce different results based on movement mechanics [1]. However, when it comes to whether these differences translate into meaningful muscle growth across the entire biceps muscle, the picture becomes less clear. Forty-nine studies suggest there are small, detectable differences in how muscle grows in specific areas depending on the curl variation [2], but sixty-one studies do not find this to be the case [2]. This means that while some people may notice subtle changes in muscle shape or strength in one type of curl over another, others do not. The evidence we’ve reviewed leans toward the idea that movement technique matters — especially for improving strength in the exact motion you train — but it does not strongly support the idea that one curl variation is clearly better for overall biceps growth than another. Differences, when they exist, appear to be small and may not be noticeable without careful measurement. In everyday terms, this means switching between hammer curls, preacher curls, and standard curls might help you avoid boredom or target slight variations in muscle feel, but it’s unlikely to dramatically change your results. Consistency and effort in any variation matter more than which one you pick.