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.

Our current analysis shows that bending your knee changes which calf muscle does more work when you push off the ground. The evidence we have reviewed leans toward the idea that straight legs make the outer calf muscle work harder, while bent knees shift the effort to the deeper calf muscle [1]. We analyzed the available research and found that 26.0 studies support, 0 studies refute this pattern. What we have found so far suggests that the position of your knee plays a role in how your lower leg muscles share the load. When you keep your legs straight, the outer calf muscle takes on more of the effort. When you bend your knees, the workload moves to the deeper calf muscle. This shift happens during plantarflexion, which is simply the motion of pointing your toes or pushing off the ground. The evidence we have reviewed leans toward this specific muscle shift, but we want to be clear that this is our current analysis. We are still gathering more data, and our understanding will improve as new studies come in. Not every movement or person will react exactly the same way, and the research we have looked at so far only gives us a partial view. If you are trying to target different parts of your lower leg, you can adjust your knee position to change the focus. Keeping your legs straight may emphasize the outer calf, while bending your knees may bring more attention to the deeper muscle. We will keep tracking new findings to give you a clearer picture over time.