Compare greyhounds with foxhounds. Greyhounds are fast, but after one lap of the track, they are spent. Foxhounds, on the other hand, can run after a fox for a very long time without getting tired. What is the difference?
This is a very basic anatomy lesson, but it is enough to help you understand more about your dog’s body.
There are basically two types of muscle fibers in dogs. There are fast twitch fibers, and slow twitch fibers. Just to add to the confusion, there are actually two types of fast twitch fibers, known as “a” and “x”.
Fast twitch “a” fibers are fast, powerful and use energy from intracellular stores and glucose metabolism. They work quickly, they fatigue easily, and are the fiber type most likely to be found in sprinting breeds such as greyhounds and whippets.
Slow twitch fibers are most likely to be seen in endurance dogs, as they are more efficient at burning fat for energy. These fibers also tend not to tire as quickly. Yep, you guessed it, these are the fibers you’re more likely to find in hunting dogs.
Your dog’s running performance depends on what proportion of his muscle fibers are fast twitch, or slow twitch.
It’s also fair to say that within each breed, certain “lines” have the potential to be better athletes than others.
Can you change your dog’s muscle composition? You can’t change your dog’s anatomy, but you can train the muscle fibres to some extent with the right training program.