The Claim
The shear modulus of the biceps brachii increases when the shoulder is extended from 45° of flexion to 45° of extension in resistance-trained males, indicating greater passive stiffness at longer muscle lengths, irrespective of regional or head-specific variations.
What the research says
Supports is higher
Support is ahead, but a single strong opposing 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.
In men who regularly lift weights, the biceps muscle becomes stiffer when the shoulder is moved from a bent position to a straightened position, due to the muscle being stretched longer.
See the scientific wording
Shear modulus of the biceps brachii increases with shoulder extension from flexion (45°) to extension (−45°) in resistance-trained males, indicating greater passive stiffness at longer muscle lengths, regardless of regional or head-specific differences.
When you stretch your arm back at the shoulder, your biceps muscle gets pulled longer, like stretching a rubber band. This stretch pulls on the internal parts of the muscle fibers and the connective tissue around them, making the whole muscle feel stiffer. This happens even before you move your elbow, and it’s the same no matter which part of the biceps you look at.
What the research says
1 studyStudy: Biceps brachii regional shear modulus following elbow flexion exercises at different muscle lengths.
When you stretch your biceps by pulling your arm back at the shoulder, the muscle naturally gets stiffer — like a rubber band pulled tight — even before you lift anything. This study proved that happens in trained guys, no matter which part of the biceps you look at.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.