-15% off your first order*.
Enter your email address to receive your promo code.
*except for the SAFEFIT airbag
Wednesday, January 4, 2017
What is motion symmetry, why is it so important and what factors can influence it?
Symmetry of movement corresponds to the equivalent use of the two front limbs and the two hind limbs. This means that the synchronisation of the limb pose, the duration of the posture, the duration of the swing and the angle of gyration of the right foreleg are identical to those of the left foreleg. The same applies to the hind limbs. "Symmetry of movement is the sine qua non condition for the training of the horse. It is also a central element in the assessment of a performance by the dressage judge who must give a mark to the gaits by evaluating their frankness and regularity".
A healthy horse moving in a straight line and on a flat surface should have symmetrical movements. To measure this, Seaver compares the upward and downward movement and left to right movement of the horse's chest during the placement of each limb on the ground (Figure 1). For a healthy horse, these movements should be symmetrical for each limb. "In the event of asymmetry during a veterinary visit to an international competition, the horse has a high chance of being refused participation in the event. If he takes the start, the horse will be penalised, particularly in the lengthening of the legs, where his weakness is likely to be all the more obvious. Movements revealing asymmetry will not be given a satisfactory mark.
However, this rule obviously only applies to symmetrical gaits such as walk, trot and amble. Petit galop and galop being asymmetrical gaits, the pose of the left foreleg will be different from that of the right foreleg (1). "A horse with asymmetrical movement is likely to be limited in many aspects of its training, and will inevitably be less competitive. Every exercise is likely to suffer from this anomaly. While movements at walk and trot will be the most affected, it may also manifest itself at canter. For example, the change of foot from left to right is likely to be different from the change of foot from right to left in terms of amplitude and/or straightness if the horse is otherwise asymmetrical.
If a horse moves symmetrically, it will bear the same weight on the left forelimb as the right forelimb and the same applies to the hind limbs. Most lameness causes pain during footing so when a horse is lame it will carry less weight on the affected limb to reduce pain (2). "As a rider or trainer, it is essential to be cautious of any asymmetry and to consult a specialist quickly. Anticipation is essential in order to ensure that no health problem can jeopardize the horse's well-being. It is necessary to be able to detect the slightest abnormality, to detect the cause quickly and to take the appropriate measures. In our jargon, we will say that the horse falls to the left. The pain is on the right. Before questioning his riding and observing the problem from a purely technical point of view, the rider must check that his horse is clinically healthy".
A threshold of around 25% asymmetry of movement is suggested to detect a problem, so a horse putting 25% less weight on one limb compared to the opposite limb could have a problem and it seems necessary to consult a vet. Seaver measures weight distribution by limb, helping you to detect a problem early. "The later a veterinary problem is considered, the more likely it is to lead to complications. Asymmetry can be missed, overlooked or misinterpreted. Being able to rely on an accurate symmetry analysis reduces uncertainty and gives you the best chance of keeping your horse in shape.
Figure 2 shows an example of a horse putting more weight on the right foreleg, indicating lameness in the left foreleg.
In addition to lameness, other factors can influence movement symmetry. Symmetry measurements change significantly when comparing a straight-line movement with a circle. When working in a circle, horses naturally lean towards the inside of the circle at an angle of up to 20° compared to a straight position. Obviously, this means that the horse's weight will shift to the inner limbs. The angle of inclination of the horse's body also depends on the diameter of the circle and speed. Seaver can measure all these parameters, enabling data to be compared over the course of different exercises and directions. On the other hand, the angle of inclination of the horse's body can also be used as an indicator of orthopedic problems when speed and diameter are constant. If a horse experiences pain in one of its inner limbs, it will tend to lean less inward, to reduce the loading force on that limb.
Another factor that can influence the symmetry of the horse's movement is the rider's balance. If the rider does not sit upright on his horse, the latter will lose his balance and the movement will be asymmetrical.
Finally the surface is very important. In order to be able to analyse the symmetry of the horse's movement in a correct way, the surface must be flat and regular.
Valérie De Clerck
Doctor of Veterinary Medicine
*A big thank you also to Camille, dressage rider, for her participation in the writing of this article 🙂
