How to fit… Asymmetry

General notes on musculature

Horses do not have a collar bone “Clavicle” and therefore their fore limbs are held to the rest of their bodies by muscle. The muscles attach the fore limbs by a connection between the scapula and the rib cage of the horse.
We all know that muscle develops at different rates dependent on exercise and loading. Horse and rider are affected by any difference in the development of the muscles that hold the scapula in relation to the rib cage and the rest of the horse’s body.

It should be noted that a horse that works asymmetrically or carries an asymmetric rider does not build compensatory muscle that will carry the load more even or equal over time. The horse will develop more and more asymmetry as time goes on. In more severe cases this will lead to the horse being un-level or even lame.

What follows assumes that either the rider sits to the right and/or the horse is “right hind drive”. In other words the horse is better at trot on the right rein and better at canter on the left rein. Note that it is almost impossible for a horse to be better at both trot and canter on the same rein this is due to the muscle groups used to propel the horse at these gaits.

With the horse above the rider will look like this…

In the example above the horse has a smaller and stronger left shoulder, this will encourage the saddle to slide to the right.

There will be a hollow behind the right shoulder blade (Scapula) that the saddle will be encouraged to fall into.

The left should blade will push the left side of the saddle up and back.

The rib cage will roll to the right and feel lower than the left.

If your horse is the reverse of this image then the saddle will move left.

The scapula is not attached to the rest of the body by bone, only muscle. As a muscle develops it shortens this will in turn pull the scapula down closer to the rib cage. This in effect makes the left leg longer and a severe case will show unlevel left rein trot and good right rein trot.