Why Is An Understanding Of Biomechanics Important?

Biomechanics is the science of movement of a living body, including how muscles, bones, tendons and ligaments work together to produce movement. Biomechanics explains the negative impacts upon a horse’s body caused by incorrect riding and training methods, such as Rollkur.

It is important for riders to understand the physical effect that their aids have directly on the horse’s body as a whole, and realise that incorrect aids (such as backwards use of the hand) can make it impossible for the horse to become supple through the back and able to work correctly and also, that long-term use of such aids can lead to serious lameness and behavioural problems.

The position and length of the horse’s neck, through its many anatomical interconnections with the trunk, has a direct biomechanical effect on the back. If the head is placed unnaturally deep or the neck is unnaturally shortened it will inevitably lead to movement faults and eventual health problems.

The purpose of dressage training is to gymnasticise the horse, to make him stronger and in better balance as well as obedient to the aids of the rider.

It takes time and patience to build up muscles. In training a horse, the rider has a job similar to that of a human personal trainer, they must attempt to show and encourage the horse to use his muscles in the correct way in order to strengthen them, but also not overdo it as this will cause pain, possible injury and increase resistance in the horse. It makes sense, then, that a rider must understand something of the anatomy and physiology of the horses’ muscles in order to achieve their goal.

As Chris Bartle, the British international event and dressage rider and trainer of the German eventing team, said in his book, Training the Sport Horse, the key to performance in the sport horse is the back.

The overall aim of training is to strengthen this bridge between the forehand and the hindquarters and so enable the power from the hindquarters to flow uninterrupted, over a supple longissimus dorsi (long back muscle) to an independently carried forehand.
When this is achieved, we can communicate with finer and finer aids, as half-halts flow through easily from the rider’s body, back over the horse’s back to the hindquarters to increase the bending of the hind legs and to cause a moment of collection. I believe that an understanding of biomechanics and the way the muscles work is crucial to achieving this athleticism in a horse.

The horse was not designed to be ridden. Consider what happens when a rider gets on a young horse for the first time. It may arch its back into a spasm and buck. When it relaxes, it will drop its back and is in effect carrying the rider on its skeleton, without the help of its back muscles.

The lower brace (the mass of tendons running from the breastbone to the pelvic girdle) plays an important role in this, because as the horse starts to tire, he places the forelimbs farther forward and the hindlimbs farther back. The ligaments of the lower bracing arch are passively tensed and placed under increasing strain, without the muscles actively helping. The horse can carry the rider in such a way for long periods of time, but its ability to move naturally is severely restricted. He moves unsteadily, swaying from side to side as he moves and the rider feels to be sitting in a rocking hollow.

When this position becomes uncomfortable, or even painful for the horse, he will try to stiffen his back. By tensing all the muscles of the back, he is able to carry the weight. The gait however, feels stiff and tense with the horse taking small steps and the rider is unable to sit to the trot. The long back muscle, which is large and fleshy with little tendon fibre integration, is unable to function this way for long. It will soon build up with lactic acid and become painful. So the horse releases the back muscles, drops its back and reverts to the original position and the process is repeated.

Some horses cope with carrying the rider this way for their entire lives. Their back does not swing and is never supple, and they will never perform at a very high level. So that this does not happen, the young horse must learn to raise the back from an active hindquarter and allow the neck to lower. This means the nuchal ligament together with the abdominal muscles will relieve the back muscles so that the rider’s weight can be comfortably carried.

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Muscle anatomy and function
The function of the long back muscle is purely for forward movement, and not to carry a rider. This task falls to other groups of muscles that need to be built up during the course of the horse’s training so that they can support the weight of the rider and leave the back muscle free to perform its task, which is locomotion.

The musculature of an equine athlete, similarly to that of a human athlete, must be developed gradually over time. The transforming of a muscular body is associated with intense pain, and anyone training horses must be aware of this and watch for signs of muscle pain and fatigue and respond accordingly. This means having frequent breaks on a free rein and days off training when necessary.

German Training Scale
The German Training Scale is often spoken of, but in my experience in Germany, not always strictly followed.

Rhythm
The horse’s natural rhythm is that in which his legs swing like a pendulum under his relaxed swinging back. This rhythm is A LOT SLOWER than most people think. To observe his natural rhythm, let the horse go at his natural speed and find his balance, either on a lunge or with the rider in a light seat.

Suppleness and relaxation
The horse must be relaxed or you will make no progress. Without the correct rhythm, you will not achieve true suppleness. A lot of horses under a rider will rush and go too fast, because they are tense and find it easier to balance at a faster pace. If a horse is too fresh and not concentrating, there is no use continuing with training until he is relaxed and listening. He must be calm, moving at his slow, natural rhythm and starting to reach his neck forward and down.

At this stage the reins are long; we have not reached contact yet. The reins are very long, they are not completely loose, there is a soft connection to the horse’s mouth but the head and neck are free to ‘breathe’. If a firm contact is taken up too early, this means we are working from the front to the back and the movements of the hindlegs will be disturbed. If the rider stays in a light seat and lets the horse travel at his very slow natural rhythm, he will start to relax and drop his head. The front lever is then working to raise the back.

As the back starts to raise, the hindlegs start to be freed up and are able to move farther forward under the centre of gravity. The horse will feel very comfortable to ride, his tail swings back and forth, the steps will be very regular and now it is time to shorten the reins, but very slowly. You should then start to feel a connection from the horse’s hindlegs to the bit.

As one hindlimb goes forward, there is a movement towards the bit on this side. The rider must not block with the reins, as this would restrict the forward movement of the hindlimbs. The hands must remain still in relation to the horse’s mouth and the rider remains independently in balance in the horse’s centre of gravity. Depending on how strong the horse’s back and hindquarters are at this stage, the rider will need to keep the weight fairly far forward and light off the horse’s back to free up the back until it becomes stronger.

The horse’s back is often likened to a suspension bridge with levers at both ends. The front lever is made up of the neck (the nuchal ligament and upper neck muscles) and these do the job of pulling the backwards-facing spinous processes forward and thus raising the back. At the other end, muscles of the hindlimbs and the abdominal muscles working via the sacro-iliac joint, raise the back from behind by pulling the spinous processes of the vertebrae farther back, which are oriented facing forwards.
Early on in the horse’s training, the upper neck muscles do the majority of the work in raising the back, aided by the passive nuchal ligament (which runs along the top of the neck from the back of the skull to the withers). The lower the head is positioned, the more work the nuchal ligament does (this function requires no energy from the horse and it is used to support the back during grazing), the higher it is, the more the upper neck muscles must work.

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LOSGELASSENHEITOne of those terms that is hard to define because it’s about the feel between horse and rider. Here’s what it says in the German National Federation hand book.

Losgelassenheit can be interpreted as suppleness combined with looseness and with a complete absence of any tension ie. the horse is unconstrained.

A correct rhythm can be achieved only if the horse’s back is swinging. The muscles of the neck and back must not only be relaxed, but must work and swing with the movement of the horse’s legs.

All joints should bend and stretch equally well, and horse’s whole body must convey the impression of looseness and suppleness in all joints, as well as a willingness to co-operate and to move actively forward. Without the willingness of the horse, there cannot be true losgelassenheit.

It is a prerequisite for any work in a contact, or on straightness, impulsion or collection. Without losgelassenheit, attempting work on these things creates tension and resistance.
The upper neck muscles have a lot of tendinous fibres within them, so are classed as postural muscles and can work in the same position for a very long time. Nevertheless, they must be trained gradually over time until they are strong enough. This training requires a lot of alternate stretching and raised work.

When the neck is raised in this fashion the hindlegs start to take over some of the work of raising the back from behind. The horse must not lean on the bit, but should work in balance with only a very light contact. If the horse wants to drop the head lower and fall on its forehand, the head must be raised by getting the hindlimbs to work harder, not by pulling on the reins!
In riding, we are constantly trying to create a more supple athlete who is in better balance, both longitudinally and laterally. For this to be achievable, the rider must be able to sit in balance. If the longitudinal balance is disrupted by the rider pulling backwards on the rein or by use of gadgets such as draw reins, the horse will fall on the forehand, and either lean on the bit for balance or suck behind the bit, tensing the underneck muscles. This tension will be transmitted to the back and the natural movement will be destroyed.

Straightness follows

Straightness

As most people are right or left handed, most horses are right or left footed. Their spine has a right or left handed bend to it and they move crookedly; putting more weight on one shoulder and escaping to the side with one hindleg.

In Germany this fact is taught to all children learning to ride, but many experienced vets are unaware of this fact, which can make a horse appear uneven when trotting in a straight line. If bent to the right (as most are), the right hind spends less time on the ground as it has less ground to cover so these horses can appear right hind lame.

Horses have varying degrees of crookedness and often the most difficult horses to get working over the back are more crooked than average. No work should be attempted on straightening the horse until he is losgelassen and swinging through the back into an even contact on both reins. In a horse bent to the right this will probably require some shoulder-fore work using right leg driving aids and gentle flexions with the right rein to get the right hind limb in line under the body.

Lateral balance (ie straightness) is developed as the contact improves and is even in both reins. Then we start to work more on bent lines and circles, as well as on lateral work. However, it is important to make sure that the contact is even (and stays even) on both reins and the horse pushes forward evenly with both hindlegs (ie becomes straight). As straightness develops, the thrust or impulsion from the hindlimbs is improved, and the horse carries himself more uphill and relieves the forehand.

As the hindlimbs develop in strength and the horse can carry himself in a more raised posture for longer, the rider can start to ask for collection, that is, bending of the haunches. The rein then acts on the hindlimb as it is in the stance phase and prolongs the stance phase. This causes the horse to flex the joints of the hindlimb more, and when the half-halt is released, elastic power contained in the flexed hindlimb is let out forward producing a springy, expressive gait. If the hand is used in the moment the hindlimb is being drawn forward, it will restrict the forward movement of that hindlimb and cause a gait irregularity.

It must be kept in mind that this is like asking a human walking along, to do squats at the same time. It must be worked on gradually as the muscles need to be strengthened slowly over time.

Contact Issues

Contact can only be achieved with a relaxed horse that is moving regularly and freely forward into the rein and accepting the bit. Only a light and steady contact leads to throughness and later carriage of the horse.
A horse that refuses to take the contact does this to avoid bending his haunches. He can do this either by leaning on the bit, pushing off with almost straight hindlegs or he can escape backwards by not letting the bit rest against the bars of his mouth. He goes above the bit or behind the bit and shows a restricted gait, taking short, hurried or long, dragging steps. Often the bit can be heard rattling, the teeth grinding, or tense chewing is seen. All of these are signs of tension. Every correction that starts with an attempt to act on the mouth is doomed to failure, because the cause of the problem has been confused.

What to do: Let the horse relax and move at his slow natural rhythm with head long and low and with no contact. After he relaxes and his back starts to swing, he can be asked for more activity from behind, which will raise the forehand, maybe only for a few strides at a time but gradually he will build up a stronger connection over the back into a soft contact.

Realise this as you train your young horse. Draw reins will do nothing in the long run except put your horse on the forehand and prevent the building up of correct muscles.

It is beneficial to take young horses for rides outside the arena as they have increased motivation to push from behind and it is easier to develop their strength this way.

For a horse to learn to balance and hold himself in a raised carriage, he cannot be held in or up by the rider. Self-carriage means he carries himself. Anything else is a horse on the forehand and is not increasing strength in the upper neck postural carrying muscles, but instead causing wear on the forelimbs. At first the horse will only be able to carry himself for a short period of time, then he must be allowed to ‘chew the reins out of the rider’s hands’ and stretch forwards and down. If a horse isn’t willing to do this, he is not working correctly over the back and is a ‘leg mover’ – this demonstrates a severe lack of basic training.
The popular training methods often seen in competition warm-up arenas, often referred to as ‘Rollkur’ or ‘LDR – low, deep and round’ are anatomically incorrect and physically damaging to the horse. The back is overstretched and tense, therefore the hindlimbs cannot step under properly and instead trail out behind. As the hindlimbs cannot step under and be used properly, the muscles do not increase in strength so cannot start to take the weight and lighten the forehand.

The horse works for long periods on the forehand, and instead of increasing the power in the upper neck muscles he must use his under-neck muscles to hold the neck in this unnaturally flexed position. The discomfort these horses experience is plain for for all to see in the violently swishing tails, rolling eyes, grinding teeth, excessive foaming at the mouth, it can also be often be seen in the four-beat canter, croup-high piaffe with uneven steps, and dramatic toe flicking in extended trot. It looks like a real physical effort to ride these horses. A loose, supple, correctly trained horse should look effortless. I am thinking here of a test I saw last year of Carl Hester with Uthopia where Carl looked round at the crowd and waved as he went down the centre line to the final halt.

That is dressage.

THE NATURAL CROOKEDNESS OF HORSES AND ITS ASSOCIATION WITH BRIDLE LAMENESS

What do we mean by the natural crookedness of horses?
Just as people are right or left handed, horses are also born right or left ‘footed’. Their spine is bent either more to the right or left . Most horses are crooked to the right, which means their spine has a right sided curve to it. The right side of the body is concave or ‘hollow’ and the left side is convex and referred to as the ‘stiff’ side. However, it is actually on the right, concave side that the muscles are shortened and more contracted.

It is thought that natural crookedness is due to the left hemisphere of the brain, which controls the sensory-motor control of the right side of the body being dominant (as it is in 80 % of animals. This results in right handedness and right eye dominance.
A horse that is crooked to the right tends to, while grazing, hold his left foreleg in front, right forelimb back under the body. Accordingly, he places his left hindlimb back, and right hindlimb forward.

When standing still, he stands with his right fore and hindlimb closer together as he is bent to the right. Lateral flexion is easier to the right.
In walk, trot and canter there is a displacement of the shoulders to the left and the hindquarters to the right.

What effects does natural crookedness have on riding?
Every horse has a good and a bad side. He is better able to bend one way. This natural crookedness prevents the horse from evenly loading each hindleg and stepping into the tracks of the forefeet. Normally the left hindleg steps between the tracks of the forefeet, while the right hind evades to the right. This causes excessive weight to be transferred to the left shoulder causing uneven wear on the joints and in right footed horses, the left fore is often the first limb he goes lame in for this reason. Each horse must therefore become more or less straightened through gymnastic exercises. The diagonal aids are used to gymnasticise the horse in his longitudinal axis and establish true suppleness. True losgelassenheit has not been achieved until the horse’s back is raised and the hindlimbs are swinging forward under the centre of gravity. The long back muscle becomes relaxed through even sidewards stretching, so that the hollow side can relax and stretch as much and as easily as the ‘stiff’ side. Only then can the back become fully losgelassen or supple and the thrust from the hindlimbs can come through truly uninterrupted to the poll. This takes a long time with a lot of horses.

The natural crookedness of horses means that the right hind is stronger than the left. This makes it easier for them to turn instantly to the left in flight, and means that they bend more easily to the right. Most horses, since they are ‘right footed’ tend to turn to the left when they spook at something. Horses that refuse to move forward try to evade to the left and tend to rear when forced to turn right.

A crooked horse always has the possibility of ignoring the aids, as the rider has not got control of the hindlegs (the horse is not ‘inside the rails’ and on the aids.)

A large part of riding problems are related to the natural crookedness of horses. Especially riders who practice hand dominated riding will encounter major problems due to natural crookedness.

The consequences of natural crookedness can range from unspecific riding problems to very obvious movement faults (lamenesses).

How does natural crookedness lead to bridle lameness?
A rider feels the above mentioned crookedness of their horse, and, in an effort to correct it, pulls on the inside rein. The horse will react to this backwards acting constraint with tension and resistance. This causes many riders to pull back still more, or even hold themselves steady with the rein, because they cannot sit independently from the reins.

This unyielding hold and backwards acting riding is the cause of many riding problems. Many horses presented to vets with lameness problems are never diagnosed satisfactorily. Up to moderately “lame” horses can show no response to nerve blocks. Flexion tests, especially of the hindlimbs worsen the lameness frequently, but except for some incidental findings, it is uncommon that a positive nerve block can be achieved. In the case of most ‘bridle lame’ horses, no injury-related cause can be found.

Horses learn to become ‘bridle lame’ when work on collection is attempted without ensuring the horse is straight (pushing off evenly with both hind limbs into an even rein contact) or also if collecting exercises are performed before the horse’s hindlimbs are strong enough. Energetic horses will tend to make a shorter step and push off more strongly with one hindlimb (usually the left) and the rider feels to have a heavy weight in the left hand and nothing in the right. Lazy horses will appear lame in the right hind as the left hind takes a normal step and the right hind, a weak and short one to avoid reaching out to the bit on the right side.

It is therefore important to be aware of the natural crookedness of horses and its implications and management both from a riding point of view and from a veterinary perspective. It is clear to see that correct dressage training is beneficial for the horse’s longterm soundness as it teaches him to carry weight evenly over all four limbs (and also to reduce concussion on the limbs when he learns to use his back elastically for forward movement). Incorrect training on the other hand, can cause apparent lameness and contribute to uneven weight bearing, as well as preventing correct use of the back.

Below: Diagram showing horse crooked to the right with overburdened left shoulder and escaping right hind.