This claim suggests that the physical stretching of your calf muscles, whether from holding a stretch or lifting weights, builds strength and muscle size in similar ways. It proposes that both methods trigger the same internal muscle-building signals, meaning passive stretching might work almost as well as active weight training for this specific muscle group.

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.

Holding a stretch for a long time might build muscle and strength in your calves by triggering the same biological signals that weightlifting does. Researchers think this happens because the stretch creates tension that activates growth pathways in your muscles, though we haven't directly proven this in humans yet.

Adding long static stretches to your regular weightlifting routine might help competitive bodybuilders build stronger calf muscles. Over three months, this extra stretching could boost their leg strength by about 11%, making it a useful addition to their normal workout plan.

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.

Adding a short, weighted stretch between your workout sets might give your calf muscles a small strength boost compared to just resting, without hurting your overall workout progress.