Doing strength exercises with your muscle stretched out for 8 weeks can make the muscle fibers longer, but doing them with your muscle bunched up doesn’t change their length.

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Against

Evidence from Studies

Supporting (1)

46

Community contributions welcome

46

Differential changes in muscle architecture and neuromuscular fatigability induced by isometric resistance training at short and long muscle-tendon unit lengths.

Randomized Controlled Trial

Human

2020 Jul 1

This study found that doing isometric exercises with the foot stretched out (long muscle length) made the muscle fibers longer by about 4%, but doing the same exercises with the foot bent (short muscle length) didn’t change the fibers — just like the claim said.

Contradicting (0)

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No contradicting evidence found

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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

Differential changes in muscle architecture and neuromuscular fatigability induced by isometric resistance training at short and long muscle-tendon unit lengths.

Score: 46

DOI: 10.1152/japplphysiol.00280.2020

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