Judging by what can often be seen in schooling rings and in competition arenas, not many, it seems.

Dressage rider Karin Blignault's latest book - following on from Successful Schooling: Train Your Horse with Empathy and Stretch Exercises for Your Horse, will be a valuable addition to the equine reference library for riders (and judges) looking to understand more fully the "operation" of the horse.

Equine Biomechanics starts out with the 'nuts and bolts' of the horse - biomechanical concepts and anatomy: how the horse is put together and what this means for movement. The book is illustrated throughout with colour photographs showing examples, as well as detailed drawings. Examples are given where needed, and there are also experiments that you can perform either yourself or with your horse, to demonstrate the points in the text.

Added to the major points throughout the book are riding and teaching applications, and where appropriate, judging significance. For example, when looking at co-contraction of the head and neck, the third point is that "When the rider allows the horse to hold his neck rigid, the flying changes will be crooked and the quarters will swing. When the horse yields instantly and perfectly to light pressure on the reins his flying changes will be straight."

In the same section, a point of significance to judging is "Swinging hindquarters during the flying changes usually means that the horse's neck muscles are in co-contraction or he is not yielding to inside rein pressure. This should be penalised under the 'correct use of aids' section of the test as well as in the 'suppleness of the back' section."

There's a section covering biomechanical misconceptions, which include the horse's musculature - for example "the top line neck muscles hold the horse on the bit"; the mouth and bit (example: "the horse resists the bit by opening his mouth"); responses to leg aids and engagement (example: "the horse pivots around the rider's inside leg"); and bending and balance (example: "the horse is on the forehand when long and low").

No book on the horse would be complete without mention of the trends and gadgets which riders and trainer apply to the (often unfortunate) animals. The biomechanical effect of bits, whips, spurs, and other lunging equipment (including running reins), as well as the effect of the riders' hands, is also looked at. This is where the detrimental effects of rollkur - or hyperflexion - is discussed.

The last word on this topic belongs to the author, who recommends riders try this exercise: "Take 10 minutes of your time to get into a kneeling position and crawl around with your chin stuck to your chest. After doing this, it is very doubtful that you will ever ride in the 'deep and round' position."

The book's later chapters cover the effects of the rider's movement on the horse, and nature versus training in terms of the horses's gait and movement.

This is an excellent volume for all riders, and one that could be regarded as a 'bible' for understanding the form and function of the horse. It will also be valuable for judges, and serve as a reference for the correct way of going in the horse.