When you lift heavy weights regularly, your muscles get bigger because the individual muscle fibers inside them grow thicker and more numerous.

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Pro

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Against

Evidence from Studies

Supporting (1)

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Community contributions welcome

1

Morphological and Neurological Contributions to Increased Strength

Narrative Review

2007

This study shows that lifting heavy weights makes muscles bigger by increasing the number and size of the tiny contractile parts inside muscle fibers, which is exactly what the claim says.

Contradicting (0)

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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.

Source Study

Morphological and Neurological Contributions to Increased Strength

Score: 1

DOI: 10.2165/00007256-200737020-00004

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