During muscle contraction, a tension is produced that can displace groups of microfilaments.
However, there are different types of muscle contraction with their own characteristics. This article explains what they consist of and the fundamental differences between them, although they share many basic aspects.
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What is muscle contraction?
Muscular contraction is the origin of the motor force of the human being . This motor force allows it to be possible to move objects, move or even perform different vital functions such as breathing or digesting food.
The main idea to keep in mind to understand muscle contraction is that tension occurs. This tension is generated by different physical-chemical mechanisms that are not discussed in depth in this article, but that produce changes in the muscle fibers.
The tension produced by these changes sometimes causes the fibers to shorten or lengthen, although static tension can occur. Later on, the types of muscle contractions that give different results in this regard are explained.
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Types of muscle contractions according to voluntariness
Muscular contractions can be classified according to whether they are voluntary or not . Who controls muscle contractions is the central nervous system, which assumes control of two major types of contractions: voluntary and involuntary.
Muscle contractions are described below with this difference in mind. In each one of them, who controls the contraction is a different nervous structure.
1. Voluntary Contractions
Voluntary contractions are those controlled by the brain . At a conscious level a person can decide to move certain muscles, and if not, these muscles can remain inactive.
An example is climbing a tree to lower a ball. The movements that are made thanks to muscular contractions respond to orders sent from the brain
2. Involuntary contractions
Involuntary contractions are mediated by the spinal cord . These types of contractions occur when there is some stimulus that provokes a reflex response.
For example, withdrawing your hand when touching an object that is very hot. This information is not processed by the brain, the response to withdraw the hand is given by the spinal cord.
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Other types of muscle contractions according to their physiological characteristics
Muscular contractions not only depend on the nervous structure that controls them . These also depend on the way in which the contraction occurs, and that is that not all the muscles of the body work in the same way.
Below are the different types of muscle contractions that can occur in the human body according to their physiological characteristics. As can be seen in the following sections, the tension generated in the muscles has different ways of manifesting itself.
isotonic contractions
Isotonic contractions have nothing to do with generating balanced tension, despite the fact that this is what their name implies. Be that as it may, it is the most common types of contractions in everyday life.
3. Concentric isotonic contractions
In concentric isotonic contractions, a shortening of the muscle occurs . Basically, a tension is developed that allows the mobilization of the tissues. This mobilization is carried out by concentrating the fibers, since the resistance of the resting state is overcome. An example is the contraction of the biceps if a bottle of water is brought to the mouth.
4. Isotonic eccentric contractions
Eccentric isotonic contractions are all about prepositioned movement . The muscle develops a tension that causes it to lengthen instead of concentrating the tissues. An example of this type of muscle contraction is when a bottle of water is left on the table after drinking.
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5. Isometric contractions
These contractions describe muscular efforts in which the muscle neither shortens nor lengthens . The fibers do not contract or suffer elongation, they simply generate tension in a static way. An example of this type of contraction is walking with shopping bags from the store to home.
6. Auxotonic contractions
Auxotonic contractions combine isotonic contractions with isometric contractions . These are contractions that exert tension, initially generating a displacement of fibers, but ending in isometric contraction. An example would be picking up a dog from the ground and then holding onto it with outstretched arms.
7. Isokinetic contractions
Isokinetic contractions are concentration closely related to certain sports . For example, in swimming they produce a type of contractions that require a constant speed. The regulation of these contractions is particular, because it always requires the same tension to produce movement.
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Relaxation
When relaxation occurs, the contraction is over . This means that the nerve impulse is no longer manifesting, otherwise the muscle will continue to contract.
The end of the contraction is associated with changes at the biochemical level that occur in the cell. Calcium and other minerals are highly involved in proper muscle propagation. In the event that there are deficiencies of these trace elements, muscle cramps may occur after intense physical activity.
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Bibliographic references
- Brooks, G.A; Fahey, T.D.; White, T.P. (1996). Exercise Physiology: Human Bioenergetics and Its Applications. (2nd ed.). Mayfield Publishing Co.
- Bullock, J., Boyle, J. y Wang, M.B. (2001). “Muscle contraction” pp. 37–56.. En: National Medical Series for Independent Study (NMS) Physiology. (Cuarta edición). Baltimore, Maryland (EUA): Lippincott Williams and Wilkins.
- Colliander, E.B. y Tesch, P.A. (1990). Effects of eccentric and concentric muscle actions in resistance training. Acta Physiol. Scand., 140 (1), 31–39.
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