Mixed
Long-duration static stretching (1 hour daily for 6 weeks) induces significant increases in maximal strength, muscle thickness, and range of motion in the plantar flexors for both males and females, with males demonstrating superior magnitude of adaptation.
If you want to increase calf strength and size without heavy weights, you can try static stretching for 1 hour daily using a device that holds your ankle at a stretched position. You need to feel significant discomfort (7-8/10) at the start, but it will subside. Do this for 6 weeks. Note that men will likely see bigger gains than women, but both sexes will improve strength, size, and flexibility.
Statistically significant increases in MSt of 6%–15%... ROM of 6%–21%... and MTh of 4%–14%... from pre-to post-test were observed, considering both sexes and both legs. Furthermore, there was a significant higher increase in MSt, MTh and ROM in male participants.
Why this rating
Randomized controlled trial with active control (contralateral leg), clear metrics, and statistical significance, though limited to healthy, active young adults.
Source
Sex differences in stretch-induced hypertrophy, maximal strength and flexibility gains
Konstantin Warneke et al. · Frontiers in Physiology · 2023
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