Collection (horse)

Collection occurs when a horse's center of gravity is shifted backwards. Energy is directed in a more horizontal trajectory with less forward movement (limbs generate higher vertical impulses). Biomechanical markers include: increased flexion in the lumbo-sacral joint, stifle, and hocks of the horse; increased engagement of the thoracic sling muscles resulting in the withers rising relative to the horse's scapula; and reduced ranges of limb protraction–retraction.