Horses that are kept in horse stable need more attention than horses that continue to graze in the field. Horses that are more or less stable are horses that are used in horse racing which are their own animals that must be specifically considered.
Horses on the field get the training they need through running around the field where they are cared for but horses are used for races, well we have to say, don't need much practice other than what they run running the track. Most likely stable horses need supplements, better food, and a cleaner environment. If you're looking for race horse supplements, you can browse various online sources.
It is a widely unknown fact that the horse, its digestive system, is designed to receive little by little food. They are not like pigs that can chew all day with anything or sheep and cattle that eat grass without limits.
That's why they are fed on schedule, they eat when we humans eat and if they are racing, they have to follow strict eating routines to keep their bodies fit and healthy.
Also, another thing to note is that horses, although very sensitive in how much food they can consume, are much more sensitive at what time they should be fed.
When you feed them regularly at 8 a.m. every day, you cannot change the routine impulsively. Your horse will be stressed; sometimes it will even collide on a stable wall in frustration and in the process of hurting itself. That's not something you want your champion horse to do.