The Claim
Resistance training of the biceps performed with the shoulder in an extended position (lengthened muscle state) may lead to slightly greater hypertrophy, particularly in the proximal to mid regions of the biceps brachii, compared to resistance training performed with the shoulder in a flexed position (shortened muscle state).
What the research says
Challenges is higher
Challenge is ahead, but a single strong supporting study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
Working your biceps with your arms stretched back might grow the upper part of the muscle a bit more than doing curls with your arms already in front of you.
See the scientific wording
Resistance training with the biceps in a lengthened position (shoulder extended) may induce slightly greater hypertrophy, particularly in the proximal to mid regions of the biceps brachii, compared to training in a shortened position (shoulder flexed).
When the biceps is stretched while under load, the muscle fibers near the top get pulled tighter and longer than usual, which may cause more tiny damage and signaling that leads to more muscle growth in that area over time.
What the research says
2 studiesStudy: The effects of shoulder extension angle on elbow flexor hypertrophy in the cable curl exercise
Scientists tested whether doing bicep curls with your arm stretched back grows the top part of your bicep more than doing them with your arm in front — and found no difference. Both ways worked the same.
Related videos
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 2 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.