The Study
Effects of a high-volume static stretching programme on plantar-flexor muscle strength and architecture
This study looked at whether stretching makes leg muscles stronger by comparing one leg to the other before and after a 5-week program. Because it didn't randomly assign people to groups and only had 16 participants, it can only show a possible connection, not prove that stretching definitely caused the strength gain.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Researchers tested if doing long, high-volume static stretches for five weeks could make calf muscles stronger or bigger.
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 545 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The strength gains are meaningful for everyday movement and athletic performance, but the stretches alone did not build muscle mass.
- 2Calf strength improved by about 6-8%, but muscle size and structure did not change.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
European Journal of Applied Physiology
Year
2021
Authors
Kaoru Yahata, A. Konrad, Shigeru Sato, R. Kiyono, Riku Yoshida, Taizan Fukaya, J. Nunes, M. Nakamura
Related Content
Claims (4)
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 static stretching for five weeks won't actually make your calf muscles bigger or change their shape. This happens because the stretch itself doesn't put enough physical stress on the muscle to force it to grow or adapt.
Doing static stretching for five weeks, twice a week for half an hour, can slightly but noticeably make your calf and ankle muscles stronger. This happens because stretching helps your nerves and muscles work together better, rather than actually making the muscle tissue itself bigger.
Doing long static stretching sessions with gentle stretches doesn't actually change the physical structure of your muscles. Any strength improvements you get from stretching come from your nervous system working better, not from your muscles physically growing or changing shape.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.