Originally Posted by Valentina
Riding correctly since it is using the back that develops the neck muscles. (If the horse just tucks its head the underside of the neck will build up - and dressage wants the crest of the neck - topside - to build up.)
Ride horse forward off leg into longer reins and encourage the horse to bring it's head low but use reins to bend horse outside then inside. NOT constantly just once quickly outside followed immediately by a quick bend inside and slight push forward into the reins by a light leg.
When you do the (SLIGHT) bending do NOT make the other rein loose - do when you bend the horse to the outside so you can see the edge of it's eye the inside rein stays at the same length it was pre-bend.
You should be able to do this at walk trot and canter. If horse is not pulling on reins or throwing head into the air then you should see a slight BULGE in the center of the neck (if he's giving over his back into the reins). If not you're not doing it correctly, if he is and you continue to ride him this way he'll develop the muscles you're talking about.
Couldn't agree more.
Re: side reins. I love them, however they're not a miracle tool to develop a topline. The horse needs to have a solid understanding on how to give to the rein and work over the back to get any benifit from them on the lunge. They're also not a training tool to use lightly as a beginner, you need to have a solid understanding of how to correctly lunge a horse in a bridle and saddle in walk, trot and canter. You can flip a horse over backwards in side reins if you don't know exactly what you're doing!!
Once a horse has a firm concept of working into the bit without leaning, and working over its back, you can introduce side reins. You can get elastised or fixed side reins, I prefer elastised for horse's learning about being worked in side reins, as there is a bit of give in them, however in the more advanced horse I like fixed ones. If you introduce them too early and are not exactly clear on how to use them and what you intend to achieve from their use, you will end up with a horse that either sucks back from the contact and while it may look pretty and have it's head tucked in, that's not correct and will compramise your ability to train the horse to any higher degree of dressage as it will not take up contact on your reins. The other result is that you will get a horse that hangs onto the rein, hollows and goes onto the forehand.
Don't think side reins will automatically build top line. All that will build top line is a good diet, correct and consistant work, and perserverance. Hill work is great for building back muscles, work the horse in trot up the hill in long and low (no not on the forehand with it's nose on the ground) and it will be stretching it's back and developing those muscles absolutely necessary to achieve collection and further dressage work. Without these muscles your horse will also struggle to jump ;)