There is no evidence to suggest that martingales provide any benefit to horses, and in fact, some experts believe that they can actually be harmful. Martingales can restrict a horse's movement, which can lead to discomfort and pain. They can also interfere with the horse's natural balance and coordination. In addition, martingales can create a false sense of security for riders, who may rely too heavily on the martingale to control the horse instead of using proper riding techniques.