In Sporting dogs, as in humans and horses, a balance will be established between power and speed during effort, and have an affect on the nutritional options. The relationship between power and speed will vary based on a certain number of external factors linked to the type of ground surface, the related effort of traction, the speed, and the wind resistance.
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For dogs that exceed 50 km/h, the variation of speed is correlated to the square root of the power, which corresponds to the metabolic aspects developed earlier. Therefore, if the developed power doubles, the speed is multiplied by 1.4 (approximately the square root of 2). For power that is tripled, the speed increases by a factor of 1.7. Studying the racing animal's speed then allows us, conversely, to appreciate the power developed and therefore the metabolism in question.
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With the current different types of competition (speed, medium distance, long distance) for this discipline taken into consideration, dog sledding is a very representative illustration of these theoretical notions.
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Sled dogs that have been trained in endurance can maintain an "Iditarod" type trot (about 16 km/h) for ten to fourteen hours per day, for several days in a row, and they can only do it with a diet that is predominantly lipids. It is therefore reasonable to assume that in these dogs, the preferred energy source is through the oxidation of fatty acids, and to assign it a 1 as the degree of power (equivalent of approximately 0.25 mmol/kg/second in human muscles, for comparison).
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Glucose can be oxidized, which (given the previous information) generates a power developed two times greater (degree of power: 2), and as a result increases the speed by a factor of 1.4 or approximately 23 km/h. This speed corresponds to a moderate gallop or a fast trot that good dogs can maintain for several hours per day for several days (medium-distance "Alpirod" type races).
The use of glycogen ensures a yield of developed power that is two times greater than that of glucose oxidation. Sled dogs use this in speed races to run at speeds greater than 30 km/h (32 to 34 km/h for the best teams), a rhythm maintained by good teams during speed tests taking place in two or three legs of 25 to 35 kilometers.
Finally, phosphagens can intervene by generating a power that is two to three times greater than anaerobic glycolysis, allowing the sled dog to reach maximal speeds near 45 km/h for periods of thirty seconds and even speeds of 50 to 55 km/h for a few seconds.
The theoretical diagram of three clearly separate metabolic energy paths leads to the superposition of these metabolisms in practice that have to be taken into account in training and rationing. From a strictly aerobic metabolism in pure endurance, we can go to an aero-anaerobic metabolism when the test is shortened (but the aero-anaerobic transition zone corresponding to the emergence of the anaerobic threshold is still poorly defined in dogs), or even to the valuation of lactic anaerobic catabolisms (glycogen) or alactic anaerobic catabolisms (phosphagens) during the speed peaks considered to be sprints.
This being the case, it is possible to feed and train the canine athlete in order to encourage oxidative yields and the necessary balance between the use of fatty acids or glucose as energy fuel. We can also increase the supply of muscular glycogen and anaerobic glycolysis with different methods that are from the same field. But we do not currently know of any way to influence the metabolic behavior and supply of phosphagens.
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