The 4 types of muscle contraction, with examples

How do muscles work? How many muscles would you say we have in the human body?

In this article, in addition to answering these and other questions, you will see explained what is a muscle contraction, and what are the different types of muscle contraction that exist. Here you will also find examples of each one, through simple exercises or everyday actions of the day to day.

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Muscles and How They Work When Exercising

Before talking about the different types of muscle contraction that exist, it is necessary to know, roughly, what a muscle is and what a muscle contraction consists of.

As we well know, people and animals have muscles throughout our bodies, which cover our skeletons. Specifically, human beings we have about 650 muscles distributed throughout the bodyor, of different sizes. All of them are voluntary muscles, that is, we can move at will (unless we have some pathology or disease that prevents it).

Muscles are a type of organ made up of

a fabric of fibers that contracts and relaxes, depending on the type of movements we make. That is, the muscles allow movement.

For its part, a muscle contraction is a physiological process in which the muscles develop a certain tension, and shorten or stretch (lengthen); they can also stay the same length, depending on the type of contraction.

A) Yes, a muscle contraction is an effect on the muscles that involves their fibers creating tension in themselves; As we have seen, this tension occurs in various ways, for example when the muscle is lengthened, shortened, moves, stays at the same length, etc.

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Types of muscle contraction

Within the field of bodybuilding and training, we find different types of muscle contraction according to the exercises we perform and the muscles we want to train and strengthen.

Here we are going to talk about the great types of muscle contraction that exist: the isotonic contraction (which in turn is divided into concentric and eccentric), isometric contraction, auxotonic and isokinetic.

1. Isotonic contraction

The first of the types of muscle contraction is the isotonic contraction, also called heterometric, which consists of the most frequent contraction when we do most sports.

The term "isotonic" means "of equal tension". In isotonic contractions, muscle fibers contract and change their length. In this type of contraction, the fibers of our muscles shorten and lengthen.

As we have advanced, the isotonic contraction, in turn, is divided into two types of muscular contraction: the concentric and the eccentric.

1.1. Concentric contraction

In concentric contraction, the muscle acts, generating tension, to overcome a certain resistance.

Thus, there is a shortening of the muscle fibers and later a mobilization of some part of the body. For you to understand better, this type of movement would be like "concentrating" the muscle.

An example of a concentric contraction would be an act as simple as taking a fork and putting it in your mouth, in which we observe how our biceps swells (in this case, it is a concentric shortening). Another example, this time in the field of sports, would be doing certain exercises with weights, such as the dumbbell curl.

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1.2. Eccentric contraction

In eccentric contraction, the second type of isotonic muscle contraction, the opposite occurs than in the previous case. In this case, in the face of resistance, we exert tension on the muscle while lengthening it. Simplifying it, it would be like "stretching" the muscle.

To illustrate, an example would be to lower the bar to the chest in a bar exercise called the bench press (in the concentric phase, we would raise the bar).

2. Isometric contraction

The second of the types of muscle contraction is the isometric contraction, which consists of a static contraction.

"Isometric" means "of equal measure or length." In this type of contraction, the muscle is static (that is, it neither lengthens nor shortens, its length does not vary, as it does in other types of muscle contraction). In addition, a tension is generated in him.

A clear example of isometric contraction would be grab a toolbox and move it around; that is, we generate a certain tension in our arms, which remain static (to prevent the box from falling). As we see in this example, the muscle fibers of the arms are not lengthened or shortened, but are in a permanent position.

Another example of an isometric contraction, in this case in sports exercises (gym), would be to hold the bar (bench press) for a few moments.

3. Auxotonic contraction

Another type of muscle contraction is the auxotonic contraction. In this case, the two types of muscle contraction above are combined (isotonic and isometric). That is, for practical purposes: when starting the muscular contraction, the isotonic contraction occurs, to later produce the isometric contraction.

An example of an auxotonic contraction is stretching the elastic bands (extensors) with the feet together (a type of exercise); In this case, we contract the muscles and keep them in the same position for a few seconds, and then we return to the starting position.

That is, we gradually stretch the muscle, and we keep it in a certain position for a few seconds. There are many types of exercises to practice this type of contraction (as in the other cases).

4. Isokinetic contraction

Finally, the last of the types of muscle contraction is the isokinetic contraction. In this case, maximum muscle contraction occurs, at constant speed, throughout the muscle's range of motion.

This type of contraction is typical of sports that do not require acceleration of movement, such as rowing or swimming. As we see, in this type of sports, it is required to maintain a constant and uniform speed to advance in the water.

In order not to get confused, we must be clear about the difference between isokinetic and isotonic contractions (the first mentioned). When we perform isokinetic contractions, we constantly regulate the speed of the movement, and we exert a maximum tension throughout the time. On the other hand, in isotonic contractions, we do not control the speed of the movement, nor do we always exert the same tension during it.

Bibliographic references:

• Correa, J.E. and Ermith, D. (2009). Principles and methods for muscle strength training. Collection Texts of Rehabilitation and Human Development. Editorial Universidad del Rosario.
• Mora, I.S. (2000). Muscular system. Sabinamora.
• Vilanova, N.G., Martínez, A. and Monge, A.T. (2007). Muscle toning. Theory and practice. Editorial Paidotribo.