Join Date: Sep 2011
Location: Germany- but not German =D
Never too old to learn! I brought my 19yo dressage horse back in to fitness last year, and as for under neck muscle, trying to get rid of it off my new mare!
Firstly, you have to think time scale. This is a minimum 4-6 month training programme as he's older and needs some re-education!
I have no idea what a Tom Thumb bit is, but for dressage you are better off in a snaffle. This also depends on how strong he is, however you can alter the thickness of the bit till it suits you. Remember a horses mouth gets narrower as they age, so a big chunky bit will only get in the way.
Under neck muscles are the worst to get rid of! I suggest to help with fitness and to get rid of these lots of lunge work. Make your first two weeks pure lunging, using a roller with elasticated bungee attached between the front legs so he has to come long, and low.
Then start riding, long warm up, lots of bendings, and a fair few breaks! Just till his fitness is up. Try not to ride in an outline constantly, the neck muscles will go and a top line will build up when he is working correctly from the hind end, relaxed in his back and comes long and low. Lots of leg yielding and shoulder in will help keep him flexible and you may want to look in to a joint supplement to help stave off any fitness because of approaching winter.
But lunge work is the best option for building fitness, and working on those neck muscles!