I respect Dabney's opinion and her endurance record speaks for itself as she is very successful. I agree with Dabney that it is easier to control or direct energy then try to create it in a horse. I also like a horse that wants to go. But just to give a different perspective from two horses I have worked with that were "hot" horses.
One horse, Red, I put 4-5 years into. He loved to run in front, he never learned to pace, he would be so excited at vet checks he refused to eat and just stared at the horses leaving the vet check. This was not just the first vet check but EVERY vet check. I tried letting him run in front....he just ran faster, I tried pacing him, starting him behind the pack, in the middle of the pack and he fought the whole time and still was not eating at the vet checks. I took him to a multiday as I was told that should settle him down.....the only thing that came out of that Mt Carmel 3 day was that I was exhausted and had gone through three pairs of gloves. In other words, some horses are hard wired this way and their personalities may not be suited to endurance riding. I would get concerned about the not eating at a vet check and low gut sounds. It may have been normal for him BUT how would I know when the eating and low gut sounds were going to result in a metabolic crash?
The second horse, Ben, I have also put around 5 years into. This one is off the track and I got him as a 4 year old. If he had his way he would gallop in front the entire ride. I have worked on legging him up and pacing for the 5 years I have had him. THIS HORSE HAS NEVER LOST HIS DESIRE TO RUN!!!! He has gone to 4 or 5 endurance rides in this time so I could learn to deal with his behaviors around other horses. The good thing about this horse is he does relax at vet checks and does take care of himself as far as eating and drinking so I felt there was hope for him as an endurance prospect so I continued working with him. At his first ride this season, he broke his running martingale because he was fighting so much to go. I honestly believe that if I had let him go at that ride he never would have slowed down and would not have been able to finish the ride. I decided after that ride that I would put him in a 100 as a training exercise and see how far he could go. The next month he finished his first 100. During that entire ride, I could never ride on the buckle and always had to have contact with his mouth or he would speed up. For this horse, it seems that the 100 mile distance settled him a bit as the last few group training rides I have done with him since he gives up the fight a little sooner when horses pass on the trail. This is a huge improvement. Throughout the time I have worked with him I have concentrated on teaching him to pace, walk, and trot. He has never lost his desire to RUN, gallop or canter!! In fact, last weekend, I took him out by himself and put him in a hand gallop for a bit and when I tried to bring him back he fought me for the rest of the 20 mile ride.
I guess my advice to you is -
1. Be honest when you evaluate your horse to make sure that he has the mind and metabolics to be an endurance horse. Just because they want to run doesn't always mean they should or that they can.
2. If you are going to compete with a hot horse make sure he is fit enough to do what is asked. That means if you are going to run in the front because he doesn't pace make sure you have done your homework and conditioning. You have to condition the tendons, bone, etc which take longer then muscle. In my opinion, the fitness level of a hot horse should be at an even higher level then a calm horse because of the added stress both physical and mental. A horse like this will waste a lot of energy in a competition setting.
3. Some horses seem to have the desire to run bred into them and I don't think that any amount of training for pacing, walking, trotting, will ever erase that desire.
Kim
I know the prevailing wisdom is to slow your horse down, and do so for a good long time. The following advice is based only on my own experience, and probably also my love of going fast on fast horses. So, please don't listen to me! (LOL)
As long as there are no soundness or safety issues, I'd say let him go as fast as he wants--but keep him out there until he asks to slow down on his own, however long that takes. Once your guy gets over the "kid in the candy store" attitude about going fast that he has now, he'll learn to cool his jets when it's asked for.
I've used this method with my real hotheads and IMHO it works much better than the constant fighting of forcing them to walk all the time. Also, I do believe you can ruin their forwardness with that method.