Observations show that square, well-angled dogs do not run at as demanding a trot as those of more extended build. The opening and closing of the joints proceed according to the laws of the minimum application of force. For that reason the dog that is too long cannot, in continuous trotting, bring his legs sufficiently under the trunk in relation to the length of his body. The intersection G goes deeper under the ground. The result is that the dog presses down more than it bounces, and expends a great deal of force.
Endurance is limited.
The centrifugal forces caused by movement will be saved according to the exercise of running energy. The best result follows when the intersection G, as represented in Fig. 5, lies close before the surface. This can only function, however, when the whole system is firmly enclosed within itself with good, strong musculation and precisely working joints. A machine with broken bearings and connecting rods will not run any more. It is clear why sound hips must be demanded.