Application of the whip requires great reserve and good judgment if the learning situation is to be constructive for the horse. Using the whip on the shoulders of a running horse will tighten the shoulder muscles and shorten its stride. Application near the flank or directly along the ribs may cause a move sideways. Probably the most pain horses have to bear is from ill-fitting saddles. We can't have a saddle for each horse or one for different conditions in which it is used, but most of us can do a better job than we do of fitting saddles to horses.
Horses vary greatly in skin sensitivity.
They love to be groomed and have their backs scratched. Selecting mild grooming equipment is necessary for some thin-skinned horses. Saddling is a bruising experience for some horses, whereas others seem immune to any feeling when a saddle is thrown on them. If your horse humps up and tries to avoid the saddle, see if it is being hit by flapping cinches and stirrup. Turn these items back over the seat and place the saddle on gently, with both hands.