There are three ways in which the horse's hind legs work: thrusting power, reach and carrying power (engagement). A good dressage horse must be well developed in his ability and strength to utilize all three. Well-developed hind legs
There are three ways in which the horse's hind legs work: thrusting power, reach and carrying power (engagement). A good dressage horse must be well developed in his ability and strength to utilize all three. Well-developed hind legs also require a strong, supple back to create the suspension bridge that connects the horse from back to front. The three ways in which the hind legs work are interrelated because each continuously builds on the other. The educated rider understands which of the three he is asking the horse to do and how to ask for it.
Thrust (Pushing Power)
Thrust refers to the horse's ability to push himself forward off the ground. The hind leg that thrusts does so from a position of engagement in which it is solidly on the ground with the three joints of the leg bent equally carrying the weight. The horse then pushes against or off the ground with a powerful thrust that either propels him forward (in extended trot, for example) or up (as in passage) or to an extreme leap into the air (such as to a capriole).
To influence thrusting power, we ask the horse to go forward or we drive him when the desired hind leg is on the ground. In practical terms, this means that we would ask for a canter depart, for example, when the horse's outside hind is on the ground at the first step of a canter stride, or we might ask for an extended trot when the inside hind is on the ground so that the horse can propel himself forward by pushing against the ground.
When the horse's weight is on the outside hind, the rider can influence the inside hind to create greater closing--or articulation--of the joints and greater reach. When asking for greater reach, we influence the flight pattern of a hind leg when it is at its highest point and is articulated the most. At this moment, the opposite hind leg is on the ground and engaged, preparing for the moment of thrust. Movement within the horse's stride happens rather quickly but as the rider is finding the rhythm of his horse, we want him to find the definite moment in time at which the leg is at its highest point--when it's easiest to influence the flight pattern. In leg yielding, for example, we ask the horse to enlarge the circle at this moment so he can move his inside hind leg farther under his body toward the outside of the circle--either directing his inside hind foot into the hoof