When untrained men perform cable curls, the amount of muscle growth in the biceps does not change significantly whether the shoulder is extended to increase tension on the muscle, as long as the...
Mechanism
Synthesis from 1 study
Your biceps grow when you lift heavy enough and push hard — it doesn’t matter if your arm is stretched back or relaxed, as long as the weight and effort are the same. The muscle responds to how tired and stressed it gets, not to how far back you pull your shoulder.
Most probable mechanism
When you lift the same weight as hard as you can, your biceps muscle gets tired and breaks down a little bit, and the cells inside it sense that stress. This triggers signals that tell the muscle to build more protein and get bigger, no matter how much you stretch your shoulder back — as long as the effort and weight are the same.
Mechanical tension on the biceps brachii reaches a threshold sufficient to activate intracellular signaling pathways related to protein synthesis, regardless of shoulder position, when resistance and effort are matched.
Metabolic byproducts such as lactate and hydrogen ions accumulate during high-effort contractions, activating mTOR and other growth-related pathways.
Microtears in muscle fibers and associated cellular stress responses initiate satellite cell activation and myonuclear accretion.
Evidence from Studies
Supporting (1)
Community contributions welcome
The effects of shoulder extension angle on elbow flexor hypertrophy in the cable curl exercise
Contradicting (0)
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Gold Standard Evidence Needed
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