Engagement of the hindquarters is defined as: downward flexion at the lumbo/sacral junction; coiling of the loins.

The following are excerpts quoted from several sources:

US Cavalry Manual -- 1942 (and earlier editions): "The mechanism of impulsion lies in the play of the hip joint (coxo-femoral articulation). The closing of this joint leads to the engagement of the hocks under the mass and allows the horse to cover more or less ground according to the energy of extension of the propellers. Such engagement of the hocks under the mass leads to a lowering of the hindquarters ... the horse must lower his croup and draw his hocks under the mass."

Effective Horsemanship -- Noel Jackson (of the French School of Dressage, learned in Portugal) -- The ramener ("ramener" being on the bit) is the term used to describe the different stages of closing of the angle between the horse's head and neck when he bends longitudinally at the poll. It is complete when the horse's forehead reaches the perpendicular as he momentarily relaxes his jaw. It.... stretches the cervical ligament and the muscles of the dorsal part of the neck and the back, which eventually enables the horse easily to engage his hind quarters and to raise his whole forehand. .. As the horse adopts the attitude of the 'ramener' and tensions his cervical ligament, he gives the rider the distinct impression of raising his whole forehand as he engages his hind quarters, and immediately feels half a hand higher."

Another Horsemanship, Jean-Claude Racinet: "...Engagement of the hindquarters, which the (downward) tipping of the pelvic bone is, and the engagement (or stride under) of the rear feet appear as two distinct phenomena."

The question: Are the hindquarters of the Icelandic Horse engaged in tolt?

It is my opinion that the hindquarters of the Icelandic Horse in tolt are not engaged. Below you will see a couple of pictures of hindquarters that are engaged. There is flexion at the LS joint. Flexion (stretching) of the loins at the lumbo-sacral joint enables the horse to engage his hindquarters, to bring them under his body. His croup and hocks come beneath his mass, and flexion of the LS joint adds bascule to the back.

In the above pictures, the horse's legs and hocks are under the horse, the horse is working off his hindquarters which are well under him. This is very different from the hindquarters of the Icelandic Horse in tolt.

View the following pictures of Icelandic Horse hindquarters in tolt. The hocks are behind the horses rather than under the horse. The flipped up hind hoof is a clue that the hindquarters aren't engaged.

In looking at pictures, the hindquarters of the Icelandic Horse are quite high -- level with, if not higher, than the withers in some cases.

Hindquarter engagement starts with coiling of the loins a lowering of the hindquarters, and increased flexion in the joints of the hind leg. In the tolt, the horse contracts his back, therefore cannot flex at the LS joint. There is no sustained lowering of the hindquarters from the lumbo sacral junction, no increased flexion of all the joints of the hind leg, and no bascule of the back -- without that, there is no engagement.

Are the feet (both feet) under the body... or is one behind?
If both feet are working under the body, it helps to discern pelvic tilt.
If one is trailing behind, it's certain that the pelvis is not tilted for engagement.

This article is about equine biomechanics and gaited horses. It is not meant to be negative to the Icelandic Horse breed, but an educational article to increase the knowledge on the part of owners of Icelandic Horses.

A quick test to see if a horse is working off his hindquarters in tolt, is to ask for a "stop on a dime" or a roll-back and see what happens.

Happy tolting!

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Resources:

Eadweard Muybridge. Animals in Motion. 1757.

Deb Bennett, PhD. Principles of Conformation Analysis. 1989.

Dr Hilary Clayton. Mysteries of the Back. 1999.

Lee Ziegler. Defining Gaits. 2001.

Elisabeth Graves. Ventroflexion. 2002.

Susan E. Harris. Horse Gaits, Balance, and Movement. 1993

Sara Wyche. Understanding the Horse's Back. 1998.

Henry Wynmalen. Dressage, Finer Points of Riding. 1953.