Introduction to Muscle Fiber Types

Hey guys,

Today I wanted to discuss the topic of muscle fibers. We are being told by our favorite social media fitness influencers and coaches that different muscle fibers are being used when we perform exercises like deadlifts, sprints or squats. What exactly are muscle fibers? I go over this subject in greater detail in my Muscle gain ebook. For now, I will share with you what slow-twitch fibers and fast-twitch fibers are, how they differ from each other and what types of physiques they can develop.

Muscle fiber types

Slow-twitch (type 1) and Fast-twitch (type 2) fibers: (a) definition and (b) differences

a) The body’s muscles contain two distinct muscle fibers: slow twitch (also known as type 1) muscle fibers and fast twitch (type 2) muscle fibers. Each of these muscle fibers serve a distinct function and can be found in both male and female athletes.

Fast-twitch fibers

b) Slow-twitch muscle fibers can sustain longer periods of exercise (ie: walking or biking) whereas fast-twitch muscle fibers are better suited for sustaining short bursts of intense exercise (ie: explosive or heavy lifting) . Type II muscle fibers are quicker than type I muscle fibers. Furthermore, women have larger type I muscle fibers than men do which could help explain womens’ tendency to perform cardio and more endurance-type exercises. Slow twitch fibers also contract slowly and fatigue less quickly than fast twitch fibers.

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Marathon runners utilize more slow-twitch fibers during their training.

Fast-twitch fibers

Fast twitch fibers fatigue quickly as they are utilized during speed/power type actions such as sprinting of lifting weights. These fibers also generate higher energetic force compared to slow twitch muscle fibers. Sprinters therefore develop more fast twitch fibers as a result of hours spent performing sprints.

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Sprinters mostly utilize fast-twitch fibers during their training resulting into more developed physiques (especially in their lower bodies).

As a weight-lifter, you will be utilizing your fast twitch muscle fibers more as a result of the process of lifting weights which is a power movement. It both tires muscles out and requires force.

Furthermore, these are the muscles which we will be responsible for maintaining our already existing muscle mass. They therefore require adequate recovery periods before our next weight-lifting sessions.

I hope that you guys enjoyed this post on muscle fibers, please let me know what you thought of it in the comments below!

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