I repeat: Asking horses to move faster than their natural cadence is likely to cause some bad side effects. Another one of them is damage to the hind limb joints.  When the forelimbs are on the ground too long, too far back, the hind limbs have to adapt to avoid striking the front. They have many choices but all of them will interfere with the synchronization of the joints’ rotations creating asynchronous joint rotations. Unfortunately repeating these motions creates a new pattern of movement that becomes habit. To correct this requires creating healthy locomotion patterns (also know as central pattern generators). This calls for many many repetitions of correct kinematics to create the stronger preference for the new motor patterns than for the old.