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Claim
Strong Support
descriptive
Analysis v3

In men who are new to strength training, doing cable curls until muscle fatigue for 10 weeks leads to about the same increase in bicep muscle size whether the shoulder is kept straight back or pulled...

60
Pro
0
Against

Mechanism

Synthesis from 1 study

How it works

When you lift a weight until you literally can't move it anymore, your muscle gets a strong signal to grow — and that signal doesn't change whether your arm is straight back or relaxed, as long as the weight feels just as hard. The total amount of force your muscle produces at the point of failure...

Most probable mechanism

In Simple Terms

When someone lifts a weight until they can't do another rep, the muscles are stretched and pulled with enough force to activate signals that tell the body to build more muscle tissue. It doesn't matter if the arm is held straight back or relaxed at the side — as long as the weight feels just as hard to lift and the person pushes until they truly can't move it anymore, the muscle gets the same strong signal to grow.

Causal chain
1

Resistance applied during elbow flexion generates mechanical tension across the biceps brachii muscle fibers, stretching them under load.

Verified by multiple studies
which leads to
2

Mechanical tension activates intracellular signaling pathways, including mTORC1 and MAPK, which initiate the translation of mRNA into new contractile proteins.

Supported by evidence
which leads to
3

Muscle fibers reach a threshold of metabolic stress and fiber recruitment at momentary failure, maximizing the activation of satellite cells and protein synthesis machinery.

Supported by evidence
which leads to
4

The total volume of tension applied over time, not the joint angle at which it is applied, determines the cumulative stimulus for muscle growth.

Verified by multiple studies

Evidence from Studies

Supporting (1)

60

Community contributions welcome

60

The effects of shoulder extension angle on elbow flexor hypertrophy in the cable curl exercise

Randomized Controlled Trial
Human
2026

Contradicting (0)

0

Community contributions welcome

No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

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Source Study

The effects of shoulder extension angle on elbow flexor hypertrophy in the cable curl exercise

Score: 60
DOI: 10.3389/fphys.2026.1750722

Similar Assertions

In untrained men performing cable curls with the same resistance, movement range, and effort, changing the shoulder angle between neutral and fully extended positions leads to similar increases in elbow muscle thickness after 10 weeks of training.

60
0
91%

If new guys do a specific arm curl workout for 10 weeks — going until their muscles are totally tired — their arm muscles get about 7% to 9% thicker, no matter how their shoulders are positioned, as long as the movement and resistance stay the same.

60
0
90%

If you're new to lifting and do cable curls the same way each time, it doesn't really matter whether your arms are stretched far back or in a neutral position — your biceps will grow about the same amount after 10 weeks.

60
0
89%

If you're new to lifting, changing your arm position during cable curls doesn't make one part of your biceps grow more than another — both positions give you the same kind of muscle growth over 10 weeks if everything else is kept equal.

60
0
88%

If you do cable curls the same way every time except for where your shoulders are, it doesn’t really matter for building arm muscle—even if you can lift heavier when your arms are stretched out.

60
0
86%