Greyhounds and hares can both reach top speeds of 20 metres per second and change direction very easily, despite the obvious differences in size. However, there are important differences in the structure of their muscles, which is what gives the hare the advantage over its adversary: the hare's hind-limb hip-extensor muscles are more exaggerated relative to the greyhound's, as are its adductor muscles. "The hip-extensors are most likely used to act as the propulsors of the animal and are important for tasks such as accelerating and jumping, while the adductor muscles enable rapid changes in direction", explains Williams.