muscle fiber types

Muscle Fiber Types: Are You A Sprinter Or A Long Distance Runner?

Sprinters or long-distance runners – it’s all a question of the muscle fiber types with which every person is individually equipped. Find out more about the different muscle fiber types and what you can achieve through targeted training.

The human body consists of more than 650 muscles: the smooth muscles ensure that our organs are used for us every day. It works in the background, so we cannot control it.

The situation is different with the striated muscles, also called skeletal muscles. We can consciously tense and relax you for every movement – regardless of whether you are picking up cutlery, changing your sleeping position or exercising.

The heart muscle also belongs to the striated muscles, but is controlled separately and outside of our sphere of influence.

The skeletal muscles consist of individual muscle strands that are enclosed by fascia tissue. These strands, in turn, are made up of a bundle of muscle fibers.

The building blocks of muscle fibers are proteins that form so-called filaments. These are structures of different volumes that move during muscle activity. For example, if you tense your biceps, the filaments slide into one another in such a way that the muscle fibers become shorter. These muscle contractions allow you to move your body, lift weights, or run a marathon.

Once again you have it in black and white: proteins are the building materials of your muscle fibers. It is not without reason that you should rely on a high-protein diet, especially as a strength athlete. You get support, for example, with our whey protein in many delicious flavors – for strong muscle fibers and consequently more power during training.

What types of muscle fibers are there?

There are basically two or three types of muscle fibers:

  • Muscle fiber type 1 (slow twitch or ST fibers, slowly twitching)
  • Muscle fiber type 2 (Fast Twicht or FT fibers, fast twitching), which in turn can be subdivided into Type 2a and Type 2b

How do the muscle fiber types differ?

Let’s take a closer look at the muscle fiber types. They differ in their color, the speed at which they contract, their volume, and the number of their mitochondria. These are the “power plants” of the muscle cells in which fat and glucose are converted into energy, more precisely into ATP.

The muscle fibers fulfill different functions according to their type. You can imagine that when you sprint you have different demands on your muscles than in a marathon.

Muscle Fiber Type 1 Muscle Fiber Type 2a Muscle Fiber Type 2b
Very slow
Speed of contraction
Energy supply
Aerobic (with oxygen)
Aerobic (with oxygen)
Anaerobic (without oxygen)
Main energy storage
Carbs, Creatine
ATP, creatine
> 30 minutes
< 30 minutes
< 1 minute
Types of Sports
Endurance sports over long distances (e.g. marathon)
Endurance sports over medium distances, strength endurance training (e.g. climbing and swimming)
Sprinting, strength training, weight lifting

As soon as you activate a muscle, the body tries to work as efficiently as possible. First of all, it controls the type 1 fibers, which are slower and consequently use the least energy. The type 2 muscle fibers are only switched on when the effort really requires it.

For example, if you go from A to B, your type 1 muscle fibers are sufficient. For a squat, on the other hand, you need significantly more strength. Your body activates the type 2a muscle fibers and finally the muscle fiber types 2b to handle the load.

Which muscle fiber type are you?

Just like you, your muscles are also unique. Every muscle in your body has proportions of all three muscle fiber types. The distribution or number, however, is completely individual and depends on two factors: the function of the muscle and genetics.


Your back muscles, for example, have the main function of straightening and stabilizing the body. It doesn’t have to work explosively and quickly, but withstand loads over a long period of time. The back muscles are naturally equipped with more type 1 muscle fibers.

In addition, the distribution of the muscle fiber types is genetic. So whether you have more endurance or, above all, powerful muscles and whether you prefer endurance runs rather than sprints is a predisposition.

Exercise muscle fiber types

The distribution of muscle fiber types – fast and powerful vs. slow and persistent – was born in your cradle. You’re more of an endurance or strength type by nature. Is it then even possible to turn a born bodybuilder into a marathon runner and vice versa?

A muscle fiber type 1 will always remain type 1. You can’t screw that up, no matter how much time you spend in the gym. With appropriate training you can make your muscle fiber types more efficient, so that the proportions within the muscle strands change. The more area muscle fiber type 1 or 2 occupies, the greater your endurance or your maximum and speed strength.

So basically everything is a question of training and your own motivation. If you want to run a marathon and do your best to do it, you will manage it – no matter how your muscle fibers are composed. Whether you enjoy doing it and how successful you are is of course another matter.

Summary: Muscle Fiber Types

  • Muscles are made up of different types of muscle fibers: muscle fiber type 1 is persistent and slow-twitching, muscle fiber type 2 is powerful and fast-twitching.
  • In endurance sports with exercise times of more than 30 minutes, for example in a marathon, muscle fiber types 1 are active.
  • In strength training or sprints, when fast, explosive and powerful movements are required, type 2 muscle fibers come into play.
  • The distribution of the muscle fiber types is individual and depends on the respective function of the muscle and on the genetic requirements.
  • The number of muscle fiber types is innate, but they can be made more efficient through appropriate training.
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