Different ways of performing biceps curls lead to small but detectable differences in how much muscle grows in specific areas and how much strength improves for that movement.

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.

Just because a study doesn’t find a clear difference in arm muscle growth between two curl types, it doesn’t mean there isn’t a real difference — the study might just be too small to catch it.

If you're a guy new to lifting and do bicep curls with a cable machine for 10 weeks, your biceps grow evenly from top to bottom — not more in one spot — no matter how your shoulder is positioned.

For guys new to lifting, doing bicep curls with your arms in front of your body works just as well for building arm muscle as doing them with your arms behind you — both give about the same 6% to 9% growth in 10 weeks.

If young women do bicep curls on an incline bench, they’ll likely grow the upper part of their biceps more, but if they use a preacher curl bench, they’ll grow the lower part more — the way you curl matters for where your muscle grows.