Back and teeth check and very importantly his back.  Think when he started it and see if there is a pattern to change of feed.  How old was he when saddle fitted? His shape and muscle will be different now matured in age and tack not fitting may affect him.  Horse walker will NOT get rid of energy a damn good gallop will but not possible everyday and not the solution either. How much outdoor time does he get? Can he be turned out 24/7. Does he do it in walk, trot, canter or only when he sees a jump and gets excited. Does he do it in company?  So many factors to take in consideration......

Good luck.  I do recommend Sam Kemp she is a horsewhisperer and trainer

Have a look at what you are feeding him, then mabe you could give him a gallop if you have somewhere to do so, or lunge him and let him have a buck and a fart if he wants to, failing that you might just have to ride him through it, i have just started to ride a friends horse who does the same thing, but she always brought him to a halt to stop him but he learned that when he bucked, she stopped him and he got out of it, what started out as excitment developed into a problem, since i have been riding him he has not bucked once because when he did i just kept my leg on and pushed him through it and let him have a gallop untill he calmed down.

Strikes me this bucking is probably related to tension in you as well as your horse. A restraining hand is going to exacerbate the problem. If we were all brave riders and we had the space the best thing you could do when you feel the excitement mounting is to let him run....forward, into a non-restraining hand on a loose rein. And when he was tired you would run him some more and then offer him the opportunity to slow down.

However this certainly isn't me and try galloping down your local main street!!!!! So what else could be done? Firstly be honest and determine if your riding is contributing to the problem, do you shorten up when you feel the excitement mounting, is your horse's head stuck up in the air and is his mouth wide open? If so this must stop.

Perhaps you could work on the horse being able to bring up his energy and bring it back down again without losing the plot. This can be done on the ground before you ever attempt to ride. Round pen work, with the horse at liberty can be useful, with lots of directional changes, circles on line going up and down gaits and obstacles are all things that will help your horse to start to think rather than react. When you are comfortable with the results on the ground you could try riding him and increase and decrease his exposure, pushing his comfort limits until he can mentally accept what you ask of him. If you find yourself in a stiuation that you can't handle and it is safe to do so, get off and don't have that fight with your horse. Mostly your horse is just trying to look after himself and he is not trying to make you look foolish, incompetent or a bad rider. He doesn't care about those things in his world. Whips do not solve anything, they intimidate and bully. And he may just buck harder.!