Does knee flexion reduce medial gastrocnemius force transmission due to pennation angle?

What we have found so far points to a clear pattern. When the knee is flexed, the muscle fibers sit at a different angle relative to the tendon. This arrangement, which we call pennation angle, changes how efficiently the muscle can transfer energy. Our review suggests that this angled position reduces the direct line of pull. As a result, the calf cannot move force as effectively during that bent-knee position. We want to be clear that this is a partial view. Our analysis is based on the research available to us right now, and it may improve as new data emerges. The evidence we have reviewed leans toward a reduction in force transmission when the knee is bent, but we do not claim this is a final answer.

If you are training or rehabbing, this means your calf might not push as hard when your knee is deeply bent. You may notice less power output during movements that require a ninety-degree knee bend. Adjusting your joint angles or focusing on straight-leg calf work could help you work around this mechanical limitation. We will keep tracking new research to update our findings as they become available.