Fast Twitch vs. Slow Twitch Muscle Fibers

[mousey]

how do you know which one's you got?

Is it just based on your natural physique? ie) fat guys have fast twitch, skinny guys have slow?

Can you have both?

 

[TommyTrainR]

how do you know which one's you got?

Is it just based on your natural physique? ie) fat guys have fast twitch, skinny guys have slow?

Can you have both?

Everyone has both. It's dependent on genetics as well as your training. Here's a basic breakdown

Type I - "red" muscle aka slow oxidative (SO). known as "red" muscle to due to large abundance of capillaries which helps transport oxygen and support aerobic activity.

Type II - Fast twich muscle (3 kinds)
....Type IIa - "red" muscle like SO muscle, rich in capillaries
....Type IIb - fastest muscle, quickest contraction, but only sustain SHORT anaerobic bursts
....Type IIx - "white" muscle which is anaerobic