Bending your knee to 90 degrees makes your soleus calf muscle work better than keeping it completely straight. This happens because of how the muscle is built and how its length changes with different knee angles. So, if you want to activate this muscle most effectively during movements like calf raises, keeping a slight bend in your knee is best.

When you point your toes while keeping your knee straight, your inner calf muscle works much harder than the muscles around your shin and ankle. This happens because straightening your knee naturally changes how your body activates different leg muscles during exercises.

Bending your knee changes which calf muscle does more work when you push off the ground. Straight legs make the outer calf muscle work harder, while bent knees shift the effort to the deeper calf muscle.

Changing the angle of your knee changes which calf muscles work the hardest when you push off your toes. Bending your knee more shifts the effort to the deeper soleus muscle, while keeping it straight moves the workload to the outer calf and side muscles. This shows that your leg position directly controls how the effort is split among different calf muscles during exercise.

When you do calf exercises like heel raises, the electrical activity in the outer part of your calf muscle stays about the same no matter how bent your knee is. This is different from the inner calf muscles, which change their activity depending on your knee angle.

When your knee is bent at 30 or 60 degrees, moving your ankle faster doesn't make your calf muscles work any harder. This suggests that bending the knee acts like a stabilizer, keeping your calf muscle activity steady even when you change how fast you're moving.