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The Equine Athlete

Equine Locomotion

Locomotion involves cyclical movement of the limb. Muscles act to accelerate and decelerate the limb through the gait cycle. There is a very defined difference behind the function of the fore and the hind limb in the horse. They both have different functions and evolution has caused musculo-skeletal adaptations to each of them.

The forelimbs carry 60% of the horses weight. Their function is mainly weight bearing and decelerating the horses body when at speed. The forelimb is only attached to the trunk by muscular tissue. This means that the horse has no clavicula or bony structure to limit the range of movement in the shoulder. The scapula glides and rotates over the thorax during locomotion. This increases the range of movement of the forelimb and contributes to the horses stride length (hence the importance of a good fitting saddle).

The tendons of the horse are very long and they act like springs, they absorb energy when they are stretched during stance phase, and release it when the leg goes of the ground. They also contribute to the stride length of your horse (hence the importance of well balanced feet, as you can change the tension in the tendons and create major problems).

The hind limbs articulate with the body via the hip joint, and provide much of the forward propulsive effort for locomotion. It is easier to push than pull, although some horses do `pull` because of imbalance in the front feet, and you get the typical `heavy forehand` and `weak quarters` conformation. Effective propulsion is aided by the large muscle mass of the quarters.

The spine of the horse is rigid. The arrangement of the vertebral bodies and the direction of the joints limit movement. The vertebral bodies are strongly linked by very stiff intervertebral disc material and a number of strong ligaments. Noticeable spinal movement is only achieved by the accumulation of tiny movements between each vertebra along the spine. In the thoracic area the ribs and sternum are attached to the vertebral bodies and also limit movement in this area.

It is often claimed that vertebrae or pelvis are `out` (i.e. displaced or out of alignment) and that they can be `put back in` with manipulations. This has been shown to be impossible. Significant displacement between vertebrae implies the presence of fractures. Likewise, sacroiliac subluxation involves severe damage to the joint and ligaments and cannot be manually reduced.

In other words...

The vertebral column of the horse only allows small amount of movements. We have all been taught to bend the horse around our inside leg when riding a circle. Actually, the horse can’t do that.

Lateral bending occurs when the horse’s vertebral column bends to the left or right. This is the `bend` that riders try to achieve in lateral dressage movements.

The amount of movement achievable depends on the amount of movement in each intervertebral joint. Most of the lateral bending in the horse comes from the neck. The rest of the vertebral column has little or no movement. The part which is mostly important for lateral work is the scapula and the way it glides over the thorax. This is directly situated near the saddle which will automatically inhibit any movement if it is too narrow. The vertebral column is rigid because it acts as a strut against which the hind limbs exert their power to propel the horse forwards. It is for this reason that ill fitting saddles can have such an effect on the movement of the horse. If there was more movement in the lumbar area the horse would wobble from side to side. The real only movement in this area is flexion and extension of the lumbo-sacral joint.

As explained in the text on locomotion the horse has no collar bone and the scapula is attached to the trunk by a series of muscles. Together with the pectoral muscles, this system allows the chest to `swing` just as if it were in a cradle (see fig.). When the horse is `bending` around the inside leg he is swinging his body in the pectoral cradle, which gives the rider the impression of bending.

Any lateral bending behind the saddle is non-existent because it is an anatomical impossibility. The optical illusion is created because the horse is narrower across the shoulders than the hips. On the circle the horse is ridden with lateral bending of the neck. The outside fore leg of the horse abducts and the inside leg adducts, causing the observer to perceive a bending of the whole body (see fig.).

The way to maximize this perceived bend is to direct your attention towards increasing the range of movement of the shoulder blades. This can be done through suppling exercises and passive stretches.

When we are working in an outline we are flexing the vertebral column. Greatest range of flexion and extension are at the poll and the base of the neck. There is a considerable amount of flexion and extension in the lumbo-sacral joint. This has a significant effect on athletic ability and it is important to ensure that this joint is well maintained and developed. The abdominal muscles play a very important part in collecting the horse. The weaker they are, the weaker the support to the vertebral column. This will affect performance and the outline of your horse.

References

• Back and Clayton, (2001) Equine Locomotion, W.B. Saunders.
• Cauvin, E. (1997) Assessment of back-pain, Equine Practice Nov.Dec 97
• Jeffcott, L.B. (1985) Conditions causing thoracolumbar pain and disfunction in horses. Proceedings of the 31st Annual Convention of The American Association of Equine Practitioners, Toronto pp285-296.
• Pailloux&Denoix, `Physical therapy and massage for the horse`, Manson Publishing.
• Williams, G. `No foot, no horse`, Kenilworth press
• Wilson, A. (2000) Optimization of the muscle-tendon unit for economical locomotion in cursorial animals. The Royal Veterinary College, North Mymms, Hatfield