 Most of the energy required to clear an obstacle is produced by the hind legs.The longer the hindlegs are in contact with the ground, the greater their capacity for producing power; the further forward the hindlegs are placed under the body, closer to the obstacle, the longer this stance phase.Power is produced by the compression of the hindleg, which flexes at the hip, stifle, hock, and fetlock, and then releases energy like a spring.