Diagonal imbalance is a consequence of other dimensions of natural asymmetry:
- A horse is left-bended or right-bended,
- left- or right-handed,
- has a pushing and a carrying hind leg
- and its shoulders are narrower than its hips.
In movement, this has consequences for the position of the horse's center of mass: it will shift diagonally towards the strongest front leg. This is called the diagonal imbalance.
Diagonal shift of the center of mass
- A symmetrical horse carries equal weight on all four legs. The point of weight is then in the center of the horse (the blue dot).
- A left bended horse - as on the drawing - will carry most on its right front leg. Because of the natural lateral bend, the left- or right-handedness and the pushing and carrying hind legs, the center of mass moves diagonally towards the right front leg.
Leaning in or out on circles
The diagonal shift of the center of mass is most clearly visible on circles.
When the center of mass is not corrected and remains more towards one front leg, the horse will try to follow its center of mass.The consequence is a horse that leans in on the inside shoulder or out over the outside shoulder.
Let's have a look my right-bended horse Maestro. He will fall in on the inside shoulder to the left and he will fall over the outside shoulder to the right.
Let's dive into a little more details:
Right bended horse on a circle to the left
Because of the diagonal shift to the left front leg, the horse will lean in on the circle. Therefore the horse tends to make the circle smaller.
Because so much weight is put on the inside shoulder, it has a braking effect as the horse puts the right front leg down. The hindquarter is moving, thus resulting in a hindquarter that falls out.
Right bended horse on a circle to the right
Because of the diagonal shift to the left front leg, a centrifugal force arises. Therefore the horse tends to make the circle larger and larger.
This is why longeing to the right can be impossible in canter, because the horse pulls loose as a result of the enormous centrifugal force.
- A horse that lean in or out on the circle will tense its back, lift its head and sometimes flex its head to the outside or overbend to the inside to keep balance.
- The pressure on the inside front leg and sacro-iliac joint can be very high and can cause premature damage to the leg and joints.
- A horse with most weight on a particular front let might have the tendency to step shorter with that front leg, and also the hind leg that's on the same side might swing less forward than the other hind leg.
- When the rider's weight is added during riding, this extra weight is also pushed towards this front leg when it's not straightened during riding. So for example if you ride a left bended horse without rebalancing the horse, this leads to overloading of this right front leg. And over a period of time, when you ride a horse every day out of balance, that might lead to navicular disease. Now when a horse is diagnosed navicular disease on the right front leg it's often times a left bended horse. And when it's diagnosed on the left front leg, the horse is often times a right bended horse.
The rider must be able to recognize the symptoms on the circle and acknowledge that the horse is not equal to both sides.
Straightness training is the solution!
What about your horse?
- Does he make the circle bigger on one rein?
- And smaller on the other?
- Or does he lean inwards both to the left and to the right?
- Or outwards?
- Is he overbending the neck on the circles?
- Or is he looking to the outside?
- Or is he already diagnosed "navicular disease"?