The soleus muscle is a flat, broad muscle located in the lower leg, beneath the gastrocnemius muscle. It plays a crucial role in walking, running, and maintaining balance by helping to lift the heel off the ground. The soleus is primarily responsible for plantar flexion, which is the movement that points the toes downward. This muscle is essential for activities that involve standing or moving, especially during activities like jogging or jumping. It is also important for maintaining posture and stability while standing still. Strengthening the soleus can improve overall leg function and athletic performance.