The Study
Influence of Long-Lasting Static Stretching on Maximal Strength, Muscle Thickness and Flexibility
This study is a controlled experiment where people were split into groups to see if stretching makes muscles stronger and bigger. Because it compares a stretching group to a non-stretching group, it gives us good clues about cause and effect, but we can't be 100% sure because the people and researchers didn't hide which group was which.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Researchers tested if stretching your calf muscles for an hour every day for six weeks could make them stronger and bigger, similar to weightlifting.
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 555 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes, these are substantial gains typically associated with heavy resistance training, showing that extreme stretching can trigger real muscle and strength adaptations.
- 2The stretched leg got 16.8% stronger in static holds, 25.1% stronger in lifts, 15.2% thicker, and 27.3% more flexible.
- 3The other leg also got 11.4% stronger without being stretched.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Frontiers in Physiology
Year
2022
Authors
K. Warneke, Anna Brinkmann, M. Hillebrecht, S. Schiemann
Related Content
Claims (6)
Doing one hour of static stretching every day for six weeks can actually make your calf muscles grow bigger, not just more flexible. This shows that holding stretches puts enough tension on the muscle to make it build new tissue, which goes against the old idea that stretching only helps you bend better.
Doing one hour of calf stretches every day for six weeks can make your leg muscles significantly stronger, almost as much as if you were lifting weights. This shows that just stretching a lot can build muscle strength just like traditional exercise.
Stretching your calf muscles for an hour every day for six weeks can make your ankle bend up to 27% further. This happens because your brain gets used to the discomfort and your muscles actually grow new parts, not just because they get looser.
If you only stretch one leg, your other leg actually gets stronger too. This happens because your brain and nervous system adapt to the stretching, which could be really useful for physical therapy and preventing injuries.
Doing a lot of long static stretches can actually build up and strengthen your calf muscles just as much as traditional weightlifting. It means stretching isn't just for flexibility—it can also help you get stronger and bigger muscles.
Doing a lot of stretching can make you stronger without necessarily making your muscles bigger. This suggests the strength gains come from your nervous system and muscle structure working better together, rather than just from building more muscle mass.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.