Trailing hind single stance (Figs 10.2–10.4)
Fig. 10.2 shows the left hind in contact with the ground (because the horse is in right canter so the left hind is called the trailing limb). This part of the stride is known as the trailing hind single stance because the left hind is the only limb in contact with the ground. Note the position of the horse’s head and neck as it rocks forwards in preparation for the left fore and right hind to hit the ground.
Hind tripedal stance (Figs 10.5–10.7)
In Fig. 10.5 the left fore and right hind have landed and the left hind has not yet been lifted, so the horse has three limbs in contact with the ground. This is known as the hind tripedal stance. As the horse is on the right lead, the right hind is called the hind leading limb. The neck and head are raised so that the centre of gravity has moved back and the horse carries more weight on the hind limbs (Fig. 10.2).
Balance and the centre of gravity
The horse is balanced when its weight is over its centre of gravity. Try balancing a ruler on the end of your finger. When you have manoeuvred the ruler so that it stays horizontal, you have found its centre of gravity. The centre of gravity in a standing horse is located around the 12th to 13th ribs, close to a line connecting the point of the shoulder with the point of buttock, more or less beneath the position of the rider’s seat bones. When the horse is standing square its centre of gravity can be judged by drawing a chalk line from the point of the shoulder to the point of the buttocks, then counting forwards from the last (18th) rib. When you get to the space between the 12th and 13th ribs, follow the groove to the chalk line. The position of the centre of gravity varies with the individual horse and depends on its conformation and bodyweight. Because the centre of gravity lies nearer to the shoulder than to the hips the horse carries about two-thirds of its weight on its front legs. This is why many horses tend to fall onto their forehand.
As the position of the head and neck has a significant effect on the horse’s balance and weight distribution the horse is able to alter the position of its centre of gravity by moving them. When the head and neck are lowered, more weight is carried on the front limbs and the horse’s centre of gravity moves forward (Fig. 10.2). However, when the head and neck are raised, more weight is carried on the hind limbs and the centre of gravity moves back (Fig. 10.5).
Right diagonal double stance (Figs 10.8–10.10)
In Fig. 10.8 the left hind has left the ground but the right fore has not yet impacted. This leaves the horse with the right hind and left fore on the ground. This is known as the right diagonal double stance. The right (leading) fore then hits the ground so that the horse now has three legs on the ground: the right hind, left fore and right fore. This is known as the fore tripedal stance.