The bent knee calf stretch, or standing soleus stretch, is a simple variation of the straight leg calf stretch that targets the smaller but equally important soleus muscles that make up the calves along with the larger gastrocnemius.
Maintaining and improving soleus flexibility is vitally important in helping us maintain and improve our posture and movement especially when running and when performing major exercises such as the deadlift or squats, which require full ankle dorsiflexion (shin moves towards foot) to perform correctly.