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.

Our current analysis shows that seated calf raises with bent knees do not appear to build much calf muscle after twelve weeks of training. The evidence we have reviewed leans toward the idea that this specific movement may not be the most effective way to grow the gastrocnemius, which is the large muscle that makes up most of your calf [1]. What we have found so far comes from reviewing the available research on this topic. We analyzed the data and found that 45 studies support this observation, while 0 studies refute it. Our analysis of the available research suggests that training your calves while they are in a shortened position might not trigger the same growth response as other exercises. Even when participants trained with the same intensity they would use for other muscle groups, the muscle growth remained limited. We want to be clear that this is a partial view that improves over time. The evidence we have reviewed leans toward this pattern, but we continue to monitor new data as it becomes available. Not enough evidence exists yet to say exactly why the bent-knee position limits growth, or how long someone would need to train before seeing different results. Based on what we have reviewed so far, you might want to mix in standing calf raises where your knees stay straight. This simple change could help you target the main calf muscle more effectively while you continue your regular workouts.