If you do hamstring holds with your knee almost fully bent, you might get stronger at that angle more than if you do the same exercise with your knee only slightly bent—even if you're pushing with the same total force.

Even though people push with the same total force during hamstring holds whether their knee is bent or straight, their muscles are actually working less hard when the knee is more bent.

Doing strength exercises with your knee bent further back makes your muscles weaker and harder to activate for up to two days afterward—even when you’re testing them at different knee angles—compared to doing the same exercise with your knee less bent.

If you do leg exercises with your knee only slightly bent, your muscles stay strong at that angle—even right after the workout—but if you do them with your knee fully bent, your muscles get weaker at that angle and also at other angles.

Even if you're not pushing very hard, doing short muscle holds at different knee angles for eight weeks can make your hamstring muscles bigger and stronger, no matter if your knee is mostly bent or almost straight.

When untrained men get stronger in a static leg press, the main reason is that their thigh muscle near the hip gets bigger and its fibers angle more, which helps push harder.