It is generally known that muscle fibers are grouped into 2 general category: slow-twitch and fast-twitch muscle fibers.
Slow muscle fibers fire more slowly than fast twitch fibers and can go for a long time before they fatigue. They are more efficient at using oxygen to generate more energy( ATP) for continuous, extended muscle contractions over a long time. Thus the kind of muscle fibers for endurance athlete.
Fast twitch fibers use anaerobic metabolism to create energy, they are much better at generating short bursts of strength or speed than slow muscles. However, they fatigue quite quickly. They are able to do this because they use anaerobic respiration.
The difference in color of these types of muscle fiber was initially noted by Ranvier wayback 1873. And this has to do with the red-pigmented cytochrome complexes and myglobin content of the muscle fibers. Thus with more mitochondria, the red colored muscle is more physiologically equipped with the demands for continuous aerobic respiration which is the characteristic of slow fibers.
So, are the athelets genetically determined to be a sprinter or a marathoner? Then what is the relevance of training ? Can an endurance athlete be trained to attain more slow fibers than fast fibers?
