The Study
Comparison Between High- and Low-Intensity Static Stretching Training Program on Active and Passive Properties of Plantar Flexors
This study is like a controlled experiment where some people stretch hard and others stretch lightly to see what happens. It can show that hard stretching likely makes your muscles more flexible and less stiff, but it can't prove it works for everyone or over a long time.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Researchers tested whether stretching to the point of discomfort improves flexibility and reduces muscle stiffness more than gentle stretching.
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 549 / 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, high-intensity stretching is highly effective for improving joint flexibility and reducing stiffness, but it should not be used as a substitute for strength training or hypertrophy programs.
- 2Stretching hard (6-7/10 discomfort) three times a week for a month boosted ankle flexibility by 40% and reduced muscle stiffness by 57%, while gentle stretching only improved flexibility by 15% and stiffness by 24%.
- 3Neither method made muscles stronger or bigger.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Frontiers in Physiology
Year
2021
Authors
M. Nakamura, Riku Yoshida, Shigeru Sato, Kaoru Yahata, Yuta Murakami, Kazuki Kasahara, Taizan Fukaya, Kosuke Takeuchi, J. Nunes, A. Konrad
Related Content
Claims (6)
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.
If you stretch your calves hard enough to feel a 6 or 7 out of 10 in discomfort three times a week for a month, you'll gain much more flexibility in your ankles than if you stretch lightly. Basically, how hard you push during stretching directly controls how much your muscles loosen up.
Doing static stretches, whether hard or easy, won't make your calf muscles stronger or more powerful over a month. Your strength and jumping ability stay exactly the same because stretching doesn't actually force your muscles to work hard enough to build strength.
Doing intense static stretches for four weeks makes your calf muscles much more flexible and less stiff than doing gentle stretches. This happens because the harder stretching changes how the muscle and tendon stretch, making them more pliable without causing damage.
Doing static stretches for four weeks won't actually make your calf muscles bigger or change their shape. Unlike lifting weights, gentle holding stretches don't create enough pull on the muscle fibers to trigger real growth or structural changes.
Doing intense static stretches for a month makes your body more comfortable with being stretched further, mainly because your brain and nerves get used to the discomfort rather than your muscles actually changing. Light stretching doesn't trigger this response, so you won't see the same flexibility gains.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.