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.
Before talking about the different types of muscle contraction that exist, it is necessary to know, broadly speaking, what a muscle is and what a muscle contraction consists of.
As we well know, people and animals have muscles throughout their bodies, which cover our skeleton. Specifically, human beings We have around 650 muscles distributed throughout the body or, of different sizes. All of them are voluntary muscles, that is, they can move at will (unless we have some pathology or disease that prevents it).
Muscles are a type of organs made up of a tissue of fibers that contracts and relaxes, depending on the type of movements we perform. That is, 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 remain the same length, depending on the type of contraction.
So, A muscle contraction is an effect on the muscles that involves their fibers generating tension on themselves; As we have seen, this tension is produced in various ways, for example when the muscle is lengthened, shortened, moves, remains at the same length, etc.
Within the field of bodybuilding and training, we find different types of muscle contraction depending on the exercises we do and the muscles we want to train and strengthen
Here we are going to talk about the major types of muscle contraction that exist: isotonic contraction (which in turn is divided into concentric and eccentric), isometric contraction, auxotonic and isokinetic.
1. Isotonic contraction
The first type of muscle contraction is isotonic contraction, also called heterometric, which It consists of the most frequent contraction when we do most sports
The term “isotonic” means “of equal voltage.” 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 mentioned, isotonic contraction, in turn, is divided into two types of muscle contraction: concentric and eccentric.
1.1. Concentric contraction
In concentric contraction, the muscle acts, generating tension, to overcome a certain resistance
Thus, a shortening of the muscle fibers occurs and subsequently a mobilization of some part of the body. So that you understand it better, this type of movement would be like “concentrating” the muscle.
An example of 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 swell (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 dumbbell curls.
1.2. Eccentric contraction
In eccentric contraction, the second type of isotonic muscle contraction, the opposite occurs as 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 “extending” the muscle.
To illustrate, an example would be lowering the bar to the chest in a barbell exercise called the bench press (in the concentric phase, we would raise the bar).
2. Isometric contraction
The second type of muscle contraction is the isometric contraction, which consists of a static contraction
“Isometric” means “of equal measurement 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, 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 in the arms do not lengthen or shorten, but are in a permanent position.
Another example of isometric contraction, in this case in sports exercises (gym), would be holding the bar (bench press) for a few moments.
3. Auxotonic contraction
Another type of muscle contraction is auxotonic contraction. In this case, the two previous types of muscle contraction (isotonic and isometric) are combined. That is, for practical purposes: When muscle contraction begins, isotonic contraction occurs, followed by isometric contraction
An example of auxotonic contraction is stretching rubber 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 initial position.
That is, we stretch the muscle gradually, and keep it in a certain position for a few seconds. There are many types of exercises to practice this type of contraction (same as in other cases).
4. Isokinetic contraction
Finally, the last of the types of muscle contraction is isokinetic contraction. In this case, a maximum contraction of the muscle occurs, at a constant speed, throughout the entire range of motion of the muscle
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.
To avoid confusion, 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 movement, and we exert 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.
I’m Emily Williams Jones, a psychologist specializing in mental health with a focus on cognitive-behavioral therapy (CBT) and mindfulness. With a Ph.D. in psychology, my career has spanned research, clinical practice and private counseling. I’m dedicated to helping individuals overcome anxiety, depression and trauma by offering a personalized, evidence-based approach that combines the latest research with compassionate care.
