MUSCLE FIBRE CHARACTERISTICS

There are different types of skeletal muscle fibres, and it is type of muscle fibre that predominates in a particular Greyhound, that determines if that Greyhound is a sprinter or stayer, and just how fast it can run.

Muscle fibres have specific measurable properties such as:

Peak Force: Or just how much strength the muscle fibre can produce.
Contraction Velocity: Or just how fast a muscle fibre can contract.
Resistance to Fatigue: Or just how long a muscle fibre can produce contractions before it tires.

Because Greyhounds aren't weight lifters, the Peak Force or the strength the muscle fibre can produce, while important, it is not a major consideration.

However, it is the ability of the muscle fibres to contract at high speed, and still be Fatigue Resistant, that is of more interest to the Greyhound trainer.

_{Research into the structure of skeletal muscle fibre has found three main distinctly different types, and these have been classified as:}

_{Slow Fibre}
This type of muscle fibre displays slow contraction speed, and an extremely high resistance to fatigue.

_{Fast, Fatigue Resistant}
Of the fibres with fast Contraction Velocity, these muscle fibres were found to be able to maintain their Peak Force production even after a large number of contractions.

_{Fast fatigable}
This group of muscle fibres displayed high Contraction Velocity, and extremely large forces, but where unable to maintain contractions for any length of time without resting.

From these research results I would have to conclude that the Greyhound, who is a "dead set" stayer, must therefore have more Slow Fibres in the skeletal muscle tissue, while the Greyhound classified as a "three hundred yard screamer" has mainly Fast Fatigable muscle fibres.

However, what I did find extremely interesting was that the only biochemical difference found between the various types of muscle fibres, is in the way in which they store and use energy, and in the type of energy used.

_{Slow Fibres}
These were found to be high in the specific enzyme that is required by muscle cells to utilise oxygen to release energy from stored fat molecules, while they were extremely low in enzymes that make use of blood sugar as an energy source, and were low in ATP activity.

Which confirms what we have known all along, and that is to be able run on in a race you need oxygen, and the body needs to be able to use it.

The other interesting aspect of that bit of information is that if a stayer makes use of fat molecules for energy, it makes sense to feed a more fatty diet to a stayer than a sprinter.

It would also make sense to use substances such as L-Carnitine prior to a race to assist in delivering those fat molecules to the muscle cells, and to use B15 in the form of DADA 250 to increase the delivery of oxygen to the muscle tissue.

_{Fast Fatigable}
These muscle fibres were found to be extremely low in the enzymes needed to utilise oxygen, but high in the enzymes needed to use blood sugar for energy, and high in ATP activity.

Therefore, for those Greyhounds that can only run over the shorter sprint distances, it would make sense to provide them with more complex carbohydrates in the form of kibbled biscuit in the diet.

It would also make sense to use substances such as injectable ATP in the form of Dynacleine, Enerzyme or AMP 5.

_{Fast Fatigue Resistant}
These muscle fibres, which are the ones we all want our dogs to have, were found to be high in enzymes that utilise oxygen and blood sugar, and high in ATP activity.

So if you are fortunate enough to have a Greyhound with Fast, Fatigue Resistant muscle fibres, you can in fact make use of all the substances mentioned, such as:

A tablespoon of lard in the diet if the meat you use is lean

L-Carnitine to improve the utilisation of fatty acids

DADA 250 to dilate blood vessels and improve oxygen delivery

Enerzyme to increase ATP stores

There is no doubt at all, that the structure of the Greyhounds muscle tissue is an inherited trait.

However, excellent training methods, and the perfect health of the animal, can enhance the function of any type of muscle fibre.

There again, from my point of view, excellent training methods also include obtaining whatever information or knowledge you can, so that you can be more targeted and efficient in those training methods.

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