Skeletal muscles of a dog Fats or carbohydrates, overheating or acidification?
Before I go on to list translations and excerpts of some studies, I will first explain the terms you will find here. This will prevent misinformation and misunderstanding of the article as a whole.
Svalová vlákna:
Základní stavební jednotka svalu. Jejich poměr a typ se během života
nemění a je ovlivněn dědičně po rodičích a prarodičích, a to až z 95 %. Existuje domněnka, že některá svalová vlákna mají tendenci se během života přizpůsobovat nejčastěji vykonávané činnosti.
VO2max:
Maximum oxygen utilization. It is given in milliliters per kilogram for one
minutes. The average healthy man has a VO2max of 30-40 ml / kg / min, a top athlete can reach more than 70 ml / kg / min. The average German hound can have a VO2max between 350-450 ml / kg / min.
Known types of muscle fibers:
•Type I - SO (slow oxidative): Slow oxidizing "red" fibers with a high content myoglobin, high oxidizing capacity and slow fatigue are applied especially at endurance loads of lower intensity. Thanks to the high oxidation capacity they can use fats very efficiently as a primary energy source.
• Type II A - FOG (fast oxidative glycolytic): Fast oxidative glycolytic fibers with
medium oxidation capacity, high glycolytic capacity, rapid contraction and
moderately fast fatigue are applied at medium to submaximal loads
intensities that accompany both aerobic and anaerobic methods of energy recovery.
• Type II B - FG (fast glycolytic): Fast glycolytic fibers with low oxidation capacity, the highest glycolytic capacity, rapidly contracting, but also fast tiring are involved in power and speed performance of maximum intensity with a predominance of anaerobic energy metabolism.
•Type III undifferentiated: Their exact determination is not known. Several studies it is assumed that these muscle fibers have the ability to adapt during life the type of work and load that prevails.
Muscle
Skeletal muscles make up 30% - 50% of a dog's body weight. There is little connective tissue in canine muscles, muscle tissue predominates, while slow red type I (SO) fibers predominate in the deep limb muscles, which provide constant tension without getting tired. In the superficial muscles, there are red fibers together with fast white type II A fibers (FOG), which allow fast force movement and are also very resistant to fatigue. The muscles correspond to the adaptation of the dog as a persistent runner. Fast red fibers, which allow maximum force movement type II B (FG), which gets tired quickly, are in the dog only in a very negligible amount.
Interesting: The muscles of the greyhound and all its relatives have much larger reserves of glycogen. Further they can wash away lactic acid more efficiently and are more easily oxygenated than hybrids and other breeds.
Composition of fibers in a dog
The dog's muscles are very well adapted to fast and long-lasting performance. Due to their construction, where type I fibers predominate, in some places supplemented with type II A fibers, it is therefore a prerequisite for high resistance to acidity and subsequent fatigue due to movement. The main energy source of these two types of fibers is fat and partly the energy stored in muscles in the form of glycogen. Due to the absence of type II B muscle fibers, there is no need supplying skeletal muscle with fast energy from simple sugars.
Depending on the composition of the dog's muscles and its high VO2max, excessive work will lead to complete overheating of the body than excessive accumulation of lactic acid in the muscles.
Maximum oxygen utilization and type of muscle fibers play a major role Recall that in his lecture, which took place at the European Championships in Nové Město na Moravě, Rob Downey mentioned a study that confirmed that the dog's VO2max is up to six times higher than that of top endurance runners. Based on this information, it is clear that the so-called over-acidification of the dog will have to occur in completely different loads than in humans. However, this finding also supports the claim that the dog manages to playfully use fat as a resource energy even in crisis force phases of the load, when a person only reaches for carbohydrates, which can be burned even in the absence of oxygen.
So it helps not only its huge VO2max, but also the composition of muscle fibers. With enough oxygen, muscle fibers type I SO and II A FOG do not have to reach for carbohydrates, but they can oxidize fats, ie a more efficient source of energy.
Reality of internet discussions:
In online discussions, we often read various conflicting opinions, such as the following:
• The dog mainly needs carbohydrates for its performance.
• The dog only needs fats for his performance.
• Due to excessive stress, a dog can become acidic just like a human, and therefore in performance significantly allow.
What is and what is not true, no one will probably crack. Feed manufacturers, competitors, scientific studies and other groups will always have their own opinion. However, I enclose a few facts here,
which can help you to illustrate your opinion.
As RNDr. Milan Šťourač in an article on meat feeding: "There are a number of studies by which various companies confirm the positive impact of industrial diet on dog health and life. Natural diet studies could be counted on the fingers of one hand. No meat plant has commissioned such a study, no meat plant motivates veterinarians to promote its products."
• The dog does not need mainly carbohydrates for its performance. Definitely not simple carbohydrates obtained before exercise from the diet. When it uses carbohydrates, it is the energy stores stored in the form of glycogen in the muscles. However, each muscle uses only its own glycogen supply. Consumed glycogen is automatically replenished after the procedure and it is not a condition to artificially replenish carbohydrates, although it is a faster solution. The oligosaccharide maltodextrin is often used for supplementation. Unfortunately, recent studies have shown that it has a high glycemic index and therefore has a large effect on insulin levels in the blood. Side effects such as allergic skin reactions, breathing problems and unwanted weight gain have also been reported.
• The dog does not use only pure fats for its performance. It always uses a mixture of fats, glycogen and other substances in every load. The ratio of this mixture depends on the level of load and the body's ability to effectively use fats even at higher loads. Therefore, if the dog is fed carbohydrates, its ability to break down fats at a higher load is very low and the body relies on fast sugars, which it consumes very quickly - in the order of several minutes depending on the level of load.
• The value of the dog's maximum oxygen utilization and its inability to cool off with sweat answers the question of whether the dog overheats or becomes sour first. According to Rob Downey, the dog's body temperature rises much faster during exercise than in the warmest desert in the world. In a trained dog in good physical condition, on the other hand, lactic acid does not have much chance of accumulating, because the usability of oxygen, ie muscle oxygenation, is at a very high level. However, this does not mean that acidification is impossible. In extreme cases, when the dog reaches a very high speed and at the same time has to perform force work, the risk of acidification is real.
In conclusion
Please note that this article is for information purposes only and how you handle the information is entirely up to you. This is an excerpt from various studies, lectures and script information for veterinarians. In this article I discuss the metabolism and muscle fibers of trained dogs in a regular training process.
Sources:
https://link.springer.com
http://onlinelibrary.wiley.com
https://www.ncbi.nlm.nih.gov articles by RNDr. Milan Šťourač (leading specialist in dog nutrition and B.A.R.F)
Rob Downey's lecture