Building muscle works best when you stretch it out during your exercises. For example, doing standing calf raises stretches the calf muscle more than seated ones, which leads to bigger muscle growth.

Working your muscles while they are fully stretched builds more muscle than working them while they are shortened. This stretching advantage is especially noticeable in muscles that cross two joints, like the back of your lower leg, but doesn't seem to matter for muscles that only cross one joint.

Doing calf raises while standing up with your knees straight builds more calf muscle than doing them while sitting down with your knees bent. Research shows that keeping your legs straight during the exercise leads to much bigger muscle growth over a few months.

Doing calf raises with your knees straight builds more of your main calf muscle than doing them with your knees bent. This happens because keeping your knees straight puts the muscle in a better position to handle more tension and stretch, leading to bigger growth.

Doing calf raises with your knees bent for 12 weeks doesn't seem to build much calf muscle, even if you train just as hard as you would for other muscles. This suggests that working your calves while they're shortened might not be the best way to make them grow.

Doing seated calf raises while keeping your knees bent (short muscle length) twice a week for three months won't really build up your calf muscles. Research indicates this specific method only leads to tiny, unnoticeable muscle growth.