Mechanics of Movement

Part 2

At the gallop, and in jumping, the rear stride must generate as much power as possible to propel the dog as far and as fast as possible. This is a gait of maximum exertion and stride length. To achieve this, the body folds up, roaching the spine and bringing the pelvis as far under the torso as possible. This allows the hind leg to reach forward well past the center of gravity (Fig 1). If the pelvis is set on too flatly or too steeply, its ability to smoothly fold under will be disrupted. The dog also lowers its centre of gravity - the faster the gallop, the lower it goes. This lowered profile helps to reduce wind resistance and makes quick turns easier, much like a racing car. The hind leg in the support position must contract far more at the gallop than at the trot, in preparation for a huge backward thrust, and lowering the body enables this to occur as well (Fig 2). This is why under angulated dogs who cannot show a roomy trot can still demonstrate an impressive gallop. They achieve the angulation required for thrust by dropping the entire body low to the ground. The overangulated dog, on the other hand, cannot achieve good speed at the gallop. Such dogs are usually too long and low stationed to begin with, and dropping any lower would simply cause their excessive angles to collapse under them. So the thrust they produce at the gallop isn’t much greater than the thrust produced at the trot, and neither is the speed. Needless to say, they are not capable of really high, powerful jumping either.

At both the gallop and in jumping, unlike at the trot, the rear thrust of both hind legs is generated more or less simultaneously; the legs tend to move together. Whereas at the trot the pelvis remains relatively stationary, at the gallop it moves in concert with the hind legs. So too does the spine. As the legs thrust backward, the back straightens out like a strip of steel that has been bent, and then springs open, flattening the pelvis with it (Fig 3). This is why the normal orientation of the spine must be straight. If it is roached, it won’t have the ability to straighten with real power. Much of the power and length of the stride at the gallop is generated in the spine, as one can see in cheetahs and greyhounds, whose backbones show huge degrees of flexion. The spine may even, at the point of follow through, arch in the opposite direction, allowing the hind legs to be thrown back virtually level with the line of the body as it sails through the air.

Because the gallop generates extreme speed, the dog will expend as much energy as possible. It is not intended as a long distance, conservative gait. The dog is going flat out in pursuit of some wanted goal, whether it be a ball, a bad guy or escaping livestock. At the end of the stride, at the point of maximum exertion, the hind legs will describe a straight line from hip to toe, with no stored energy remaining. The follow-through will throw the legs upwards almost in line with the body, with everything the dog has surging in one line of progression. This is when the dog’s quality of muscling and conditioning, far more so than at the trot, becomes apparent. It’s worthwhile if you get the opportunity to run your hands over a racing greyhound, to get a sense of what professional conditioning feels like. The mental component is also necessary however. No matter how physically perfect, if the dog lacks the mental commitment and drive for a goal, what Thoroughbred breeders call heart, its physical abilities will remain untapped.

The back, whether at the trot or the gallop, must transfer the power generated by the hindquarters forward, must add its muscular effort to the generation of stride and power, and must also support without buckling the entire weight of the dog across each period of suspension. It must withstand the stress of twisting and turning, the compression impact of sudden stops, jumping and landing and, in bitches, the added burden of carrying a litter. It should be obvious that faults of back structure should be considered serious. In wild canines there can be wide variations of size, proportion and angulation, but I have never seen a wolf, coyote or cape hunting dog with a roached, swayed or tilted (to the front or back) backline.

Power generated in the rear and transferred along the spine must be supported and maintained by the forehand. However, the dog’s front doesn’t just passively carry the weight of its front half. It must be able to absorb the energy generated from the rear without dissipating or interfering with it. It provides the brakes and the steering, and even generates a degree of propulsive power of its own. The length of stride of the forelegs must match the length of stride of the rear legs (Fig 4). Each front leg must be able to reach as far forward as each rear leg, as well as drive back and follow through to the same degree. To do this, the dog must posses a well angulated shoulder blade and upper arm, as well as a high, well muscled wither to provide leverage and a wide bed of muscle for effective rotation of the scapula blade. Both front and rear paws must strike the ground at the same angle, for the degree of impact to match. They must show the same amount of contraction in the support position and the same degree of follow through. Without an excellent front, the dog won’t enjoy the advantage of an excellent rear.

While much is usually made of the necessity for a good shoulder, excellent withers are often overlooked. High withers provide the attachment for a good shoulder, and enable the blade to move sufficiently far forward and backward for the foreleg to show good reach and follow through (Fig 5). As well,the broad shoulder attachment provided by a high wither means a wide harness of muscle about the dog’s forequarters, literally a sling in which the full weight of the dog’s front half is carried. In jumping, this sling must catch the dog’s total weight, and absorb and distribute it evenly. When the dog stops suddenly, it jams its forelegs into the ground to brake itself. If turning abruptly, it does the same and then vaults its weight in the desired direction (Fig 6). In both cases, the shock is directed through the shoulder blades, into the withers and along the back. Other species which specialize in jumping and maneuverability, such as impala and pronghorn, show long, high, powerful withers. The broad muscling provided by high withers is also carried well up into the crest of the neck, and provides the foundation for the power a dog needs when driving into the grip (Fig 7). The hyena, probably possessed of one of the most powerful grips in nature, isn’t so much an animal with a disproportionately small hindquarter, as one with massive jaws, skull, neck, withers and shoulders, all supporting the incredible bite pressure it is able to generate.

Good reach and support is also aided by a good prosternum, that point of bone (actually cartilage) in the center of the dog’s forechest. To this process is anchored a fan of muscles that spread up either side of the neck and pull the head down, and across both points of shoulder and the upper arms (Fig 8). These muscles draw the shoulder joint and humerus forward, and the foreleg inward, and are part of the sling that supports the weight of the chest. Better leverage is achieved when the point of sternum is positioned slightly ahead of the point of shoulder, as seen from the side (Fig 9). That way, the prosternum can better act as a guide when drawing the shoulder forward, especially at the trot. At the gallop, the dog throws it’s entire fore assembly forward well past the sternum, with reach that is much higher than we want at the trot. It uses a great deal of of energy, but it achieves a huge stride (Fig 10). Too much prosternum makes the dog’s chest appear to protrude, and interferes with its ability to maneuver sideways. This sort of structure seems to go hand in hand with chests which are far too deep and narrow, more like the keel of a boat, and a hindrance to agility.

When viewed from the front and rear, the stride should give the appearance of single tracking, with the paws converging towards the centre line of the body while the legs remain relatively straight. This requirement shouldn’t be taken too literally however. First, the leg which is in contact with the ground, supporting and driving the dog’s weight, should be as straight as possible from the shoulder or hip to the ground. Any tendency for the joints to buckle or twist both waste energy and greatly increase the leg’s vulnerability to injury. The other leg, the one moving ahead, need not be totally straight. This leg is bearing no weight or stress. In fact, the contraction of the leg whether front or rear, while being lifted bunches the muscles and will tend to bring the leg away from the center line. The more heavily muscled the dog, the more this tendency is apparent (Fig 11). Too much emphasis on a precise, single tracking gait will produce animals with flat, thin muscling and narrow bodies, as has already happened in some show lines.

Single tracking is really just an impression given by the convergence of footsteps towards the center line of the body. The animal doesn’t really walk with its footsteps falling along a single line, like a tight-rope walker. In fact, the GSD when moving correctly at the trot actually triple tracks (Fig 12).

True single tracking would require the stride to be so short that the footstep of the rear fell short of the footprint of the front, a gait typical of many terriers (Fig 13). Double tracking appears when the dog either moves wide in both front and rear (Fig 14), or shows a crabbing action, with front and rear single tracking on separate paths (Fig 15). Triple tracking, while it may sound bizarre, actually allows a long overreach of the rear past the front, without necessitating a crabbing action, as the three lines of progression are very close together and to the centre line of the body. For instance, the right front foot may travel its own path, the left front and right rear feet will track the same center line, and the left rear foot will follow the third path. In this case, the dog’s rear end will be slightly shifted to the left (Fig 16). The pattern may be reversed and the dog’s rear shifted to the right. Interestingly, the Belgian sheepdog standard recognizes this when it states that the dog, at the trot, shows a slight tendency to move in a wide arc to the left or right, rather than in a perfectly straight line. The lines of progression are barely a paw’s width apart, only enough to allow the feet to pass each other without interference, and one must look very, very closely to see that the body itself is a degree or two off the straight. Without the ability to triple track, the dog cannot achieve the length of stride required for the flowing, effortless trot that is so unique to this breed.