Function of the legs.—The legs act on the hind quarters. Their business is to communicate the rider's will to the horse in order to move him straight to the front, to make him extend or increase his gaits, and to start him in movements of all kinds. It is also their special business to control the haunches, to restrict them to the direction pursued by the shoulders or to swing them in reference to the shoulders. Finally, they are used to collect the horse by bringing his hind legs closer to the center of gravity.
To recapitulate, the legs have three effects:
- (1) To produce a forward movement.
- (2) To swing the haunches in reference to the shoulders.
- (3) To bring the hind legs under.
The simultaneous action of both legs produces a double pressure to which the horse should respond by moving to the front.
The action of a single leg, while it incites motion, forces the weight of the hind quarters toward the opposite side. Thus, for instance, if the rider closes his left leg, he produces two effects: a general forward movement of the mass and a right lateral movement of the haunches.
Unison of the legs.—Whenever one leg acts to swing the haunches, the opposite leg must receive the mass in order to limit and rectify the movement. The legs, therefore, should always be close enough to the horse to act without sudden jolts and to lend mutual assistance.