The Study
Efficacy of passive repetitive stretching of skeletal muscle on myofiber hypertrophy and genetic suppression on MAFbx, MuRF1, and myostatin
This study watched what happened to mouse leg muscles when they were stretched regularly. It saw that the muscle fibers got bigger and some genes changed, but we don’t know for sure if the stretching caused it because there was no comparison group mentioned. It’s like saying ‘I ate apples and felt better’ — maybe the apples helped, or maybe something else did.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Scientists stretched mice legs without making the muscles work, just by moving the ankle. They did this many times a day for two weeks and then checked the muscles.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 57 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This suggests passive stretching might help keep or grow muscle even in people who can’t actively exercise, like those who are paralyzed or unconscious.
- 2The muscle fibers got bigger.
- 3Genes that help build muscle were turned up.
- 4Genes that break down muscle were turned down.
- 5The number of muscle repair cells stayed the same.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Muscle Research and Cell Motility
Year
2021
Authors
Yumin Wang, Satoshi Ikeda, K. Ikoma
Related Content
Claims (6)
You can grow muscle not just by lifting weights, but also by stretching—just as long as the muscle feels enough tension, no matter how it's created.
Stretching mouse leg muscles regularly seems to turn on genes that help build muscle and repair muscle cells.
Stretching mice's leg muscles didn't change the number of muscle repair cells, suggesting their muscles still grew without using more of these cells.
Stretching mouse leg muscles regularly for two weeks seemed to make the muscle fibers grow bigger, which could mean the muscles got stronger at a microscopic level.
Stretching mice passively over time might help reduce the activity of genes that break down muscle and block muscle growth, suggesting it could help protect against muscle loss.
Stretching mouse leg muscles repeatedly seems to turn on a key switch inside the muscle cells that helps build new muscle protein.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.