Muscle Fiber Theory: Speed & Endurance Explained

[caters]

There is a theory that the type of muscle fiber an animal has most determines its speed and endurance.

According to this theory the cheetah which gets exhausted after 45 seconds of chasing has mostly fast twitch muscle fibers.

Also according to this theory we humans have mostly slow twitch muscle fibers which burn fat and make us incredible endurance runners.

But there are also medium twitch muscle fibers.

These according to this theory would mean less endurance than humans but more than cheetahs and less speed than cheetahs but more speed than humans. So according to this theory all types of dogs including the really fast greyhound(47 MPH is record top speed, that is almost as fast as a gazelle) have mostly medium twitch muscle fibers.

But this takes out a lot of factors for speed and endurance like flexibility of joints, age, injuries both current and past, etc.

So the muscle fiber theory as to why a cheetah is so fast and why humans are such great endurance runners isn't really correct. I mean for 1 our body temperature and a cheetah's body temperature both rise during an all out sprint and that would suggest that our endurance is lower than what the muscle fiber theory tells us it is since more body heat leads to exhaustion. Also people with rubber man's syndrome could run faster than most people because the extreme flexibility allows for really long strides. Theoretically people with rubber man's syndrome could have a 25 ft stride like the cheetah and maybe even run at the same speed.

 

[Dr. Courtney]

The existence of other variables does not make a theory wrong that describes the effect of one variable.

There is no claim that the type of muscle fiber is the only factor affecting speed.