Shifting Your Shoulder Makes Your Biceps Work Harder

Original Title

The Effects of Varying Glenohumeral Joint Angle on Acute Volume Load, Muscle Activation, Swelling, and Echo-Intensity on the Biceps Brachii in Resistance-Trained Individuals

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Summary

When you do bicep curls while moving your shoulder up and down, your biceps muscles fire more — even if you lift the same total weight.

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Surprising Findings

Varying joint angles increased muscle activation by up to 23.3% without increasing volume load.

Common training wisdom says you need to lift more weight or do more reps to stimulate growth. This shows you can boost neuromuscular demand purely through movement variation.

Practical Takeaways

During bicep curls, alternate shoulder positions: 3 sets with shoulder extended (-30°), 3 neutral, 3 flexed (90°) to boost muscle activation by up to 23%.

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