Doing bicep curls with one arm makes that arm stronger for one-arm curls, but doesn’t make you stronger for two-arm curls or the other arm.

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Evidence from Studies

Supporting (1)

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Small muscle mass exercise enhances muscular adaptations? Effects of unilateral and bilateral biceps curl on maximum strength and muscle size changes.

Randomized Controlled Trial

Human

2025 Dec 8

People who trained one arm at a time got stronger in that arm, but not much stronger in the other arm or when using both arms together — so training one side doesn’t automatically help the other side or both sides at once.

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No contradicting evidence found

Source Study

Small muscle mass exercise enhances muscular adaptations? Effects of unilateral and bilateral biceps curl on maximum strength and muscle size changes.

Score: 61

DOI: 10.1007/s00421-025-06033-4

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