I loved taking Wads on an endurance ride and also pleasure riding. They were very challenging. Typically speaking, Arabians are better suited for endurance rides as opposed to more robust horses, i.e., draft, quarters horses and any very robust, big barreled horse. Wads was quarter horse/welsh. He was big barreled, as is the case for quarter horses. They cannot expel the hot air like an Arabian, which is understandable, as an Arabian is a desert horse. You only had 4 and 1/2 hours to complete your ride, but you had to pace yourself and not overwork your horse.
You learn the tricks of the trade by keeping a big sponge in your saddle bag and when you cross a creek, you go deep enough to bend down and soak the sponge and run it along the horses juglar vein in his neck and between his legs to cool him down. Vets are typically posted in strategic posts. They will approach you and take your horse's pulse and respiration to make sure it is within normal limits. Because the terrains are rough in most cases, i.e., big hills to negotiate, prior to any kind of athletic endeavor, you have to condition your horse to wear nothing stresses him out.
So, for weeks prior to a race, you "walk" your horse up a hill, and walk him down. It is innate of horses to want to run up a hill. The key is to conserve energy and use it when you need to. Before any race, the horse must be vetted sound, otherwise, they are disqualified. I also put shoes all the way around with pads between the shoes and the hooves to give Wads some cushion.
You definitely don't want to risk "stone" bruises to the bottom of the hoof. They are very painful to a horse. In this particular race, I won a fourth place out of 150 entries.