by Victor Roffel

Created on: October 31, 2009

Ever heard of people commenting on how an athlete has God-given talent? Although reluctant, I have to admit that in a way, they are technically correct. Genetics has determined for us our potential for height, intelligence, body frame, etc. Having so much influence in our lives, genetics play a role in muscle as well.

There are 2 kinds of muscle fibers in a muscle: Slow-twitch (Type I) and fast-twitch (Type II). As the name suggests, slow-twitch muscles are slow in nature but have great endurance. Fast-twitch, on the other hand, performs in short bursts of speed. In an average person, there is a equal distribution of fast-twitch and slow-twitch muscle fibers. Some unlucky ones have distribution of muscle fibers which works against them. (Picture a sprinter with marathon runners attributes)

According to a study, these muscle fibers can be manipulated to change their characteristics into their counterparts. Which means, although genetics play a role in pre-determining our muscle fiber-makeup, we can change the characteristics of our muscle fibers to suit our needs. Before discussing in detail about how to use this to our advantage and build muscle quicker, you have to understand more about the different muscle fiber types.

Slow-twitch muscle fibers

Marathon runners and joggers have a large amount of slow-twitch muscle fibers as compared to fast-twitch ones. This is because of the fact that these endurance athletes perform a low power output activity lasting for a long period of time.

Slow-twitch muscle fibers use oxygen to fuel the activity done. The muscle contractions of slow-twitch fibers are slow but have a huge capacity for endurance. Excessive walking, jogging or any activity which lasts a long period of time has an effect to change the characteristics of fast-twitch muscle fibers to slow-twitch ones.

Fast-twitch muscle fibers

Sprinters have a large amount of fast-twitch muscle fibers and little slow-twitch ones. Fast-twitch fibers are anaerobic in nature and uses glycogen directly as fuel. The contractions of type II muscle fibers are faster than type I by as much as 10x. Fast-twitch muscle fibers can be sub-categorized into type IIA and type IIB. High intensity movements like sprinting and plyometrics can change the characteristics of slow-twitch fibers to fast-twitch fibers.

Type IIA muscle fibers have properties of type I and type IIB muscle fibers. It has the ability to use both aerobic and anaerobic metabolism equally. It is called intermediate fast-twitch

• 1
• 2
• 3
• Next Page >>