How do you desensitize the body during imprinting?

Desensitizing the body — the barrel, ribcage, back, and loin of the foal — during imprinting prepares the horse for the sensations that will be most constant and most significant throughout its riding career: the weight and movement of a saddle on the back, the pressure of a girth or cinch around the barrel, leg contact from the rider on both sides, and the movements a rider's body transmits through the saddle. A foal whose body has been thoroughly desensitized during imprinting accepts saddling, girthing, and leg pressure with a foundational familiarity that makes these early riding preparations smoother and less anxiety-producing. Begin body desensitization by rubbing firmly along the top of the back — from the withers along the entire spine to the croup — using a pressure that approximates the weight of a hand pressing down on the back, which is a rough analog to the pressure a saddle tree will later produce. Work the hands back and forth across the back repeatedly, establishing firm contact tolerance along the length of the spinal area. Many horses that were not imprinted show sensitivity to back touching or saddling that traces to insufficient early desensitization of this area. Move to the ribcage and barrel — the areas on both sides of the body where a rider's legs will rest and where the girth will encircle. Run hands firmly over the entire barrel from the girth area behind the elbow to the flank, paying particular attention to the highly sensitive flank area which many horses protect instinctively. A foal that has had the flank area firmly rubbed and kneaded during imprinting is a horse that is significantly less reactive to the rider's leg in this area, less likely to buck in response to spur or leg pressure near the flank, and more accepting of girth tightening in the flank girth position. Rub along the back and loin firmly, establishing acceptance of hand pressure over the lumbar and sacral area — the region that carries the most significant loading from a rider's weight. A horse that associates firm pressure on the loin and back with calm human contact from its earliest neurological experience is better prepared for the physical reality of carrying a rider than one whose first experience of back pressure is the weight of a saddle and then a person settling into it.