Design and control of legged robots is a popular field in the pursuit of building robots that can be as mobile as humans. While much effort is put into understanding how to control the dynamics of these legs, less effort is focused on designing and controlling robot ankles. Ankles on legged robots are often not used beyond balancing during standing and making small corrections to the gait during walking. Meanwhile, work in biomechanics has shown ankles to be beneficial to the energetics of human walking, which indicates that ankles have the potential to improve the energy efficiency of robots. To investigate this potential, this thesis focuses on ankle torques and the resulting center of pressure profiles while the foot is at on the ground. Through optimization of a reduced order model of legs and ankles, this work finds that in general ankle actuation during mid-stance does not contribute to the energy economy of locomotion.