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 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 one hour of static stretching every day for six weeks might make your calf muscles just as strong as doing traditional weightlifting three times a week. This suggests that long stretching sessions could be a surprisingly effective way to build strength, not just improve flexibility.

Doing one hour of static stretching every day for six weeks might make your calf muscles significantly stronger. In fact, the strength gains could be similar to those from traditional muscle-building workouts that only take 15 minutes three times a week.

Adding a short, weighted stretch between your workout sets can actually help your calf muscles get a little stronger over two months. This extra stretching boosts your muscle power without slowing down your regular strength training progress.

Holding stretches for a few weeks in a row can actually make your muscles a little stronger and bigger, even if you don't do traditional weightlifting. This happens because keeping the muscle under tension for a long time signals it to adapt and grow.