More muscle?

My horse is the right weight for his height/body type, but he lacks muscle tone. Are there any exercises I can do (on the ground or riding) that can help him build muscle?

Lots of trotting I trail ride 3 to 4 hours six days a week trot most of that time.Heres a pic of my boy late summer

He's a pretty boy spirit!

Mfed58 Thank you he's also well bred I wont buy ugly horses or unregistered.

Do light hill work in walk/trot, cavaletti, long and low work to get him working over his back to build a top line, and just generally riding regularly making him work, do lots of bending/circles/serpentines! Good luck with him :)

harsh! Lol I guess to each their own. A good horse is a good horse to me regardless of registration :)

Jumper12 I like to know age and breeding that's the reason for registered. Sorry that I like good looking horses. I happen to know a good horse is a good horse whether it papered or not. Iv owned unpapered horses and they were great horses sorry if I like to go to breed reconized shows that require the horse to registered in that breed. Sorry that you think that's harsh.

I didnt mean to come of as rude I was just saying! I understand all the reasons people like registered horses it just seemed as though you were lumping ugly and unregistered like those horses couldnt be good, and like I said to each their own.

Jumper12 I didnt mean it to sound like unregistered horses are ugly there are plenty out there that are really nice looking. I go to reconized breed shows so there for need my horses registered in that breed.I own a unregistered mare who is a great horse well in her younger years..... Iam not against unpapered horses and sure don't want it to come off that way. There are plenty great upapered horses out there and yes they can be good horses.