Monday, 21 January 2019

Types of muscle fibers and muscular performance


The physical performance we have when practicing any exercise depends on many things, one of them are the types of muscle fibers . For this reason it is important to know how the muscle works, and in this way use this knowledge in order to work muscle growth.
The first thing that should be mentioned is that a muscle is made up of many muscle fibers, which are muscle cells . These fibers come together and form a muscle. The muscles that we train are made up of striated muscle fibers , which are those that are under our voluntary control. That is, when we want to lift a weight we are making use of these skeletal muscles. The muscles that we do not control voluntarily are those that are composed of smooth muscle fibers, and are those found in some organs such as the stomach and intestines, or around blood vessels.

The motor unit

The motor unit is nothing more than a set of fibers that are connected to a single nerve. There are slow and fast motor units, and this depends on how many fibers are innervated by a single nerve. In the case of fast ones, the neuron innervates many more fibers than slow ones.

Types of muscle fibers

There are three types of muscle fibers: fast, intermediate and slow.

Fast fibers

Fast fibers or also called IIB make up most of the skeletal muscle fibers . They are called in this way because they take approximately 0.01 seconds to contract from the moment of nerve stimulation. This type of muscle fibers is capable of producing a strong muscle contraction. The most important aspect to consider with respect to fast fibers is the time in which they fatigue, and because they consume a large amount of energy in a short time, they tend to run out more quickly . In the event that the activity of these muscle fibers is prolonged, an anaerobic mechanism is used to produce energy, that is, without using oxygen.
The sports in which the IIB muscle fibers are protagonists are those of maximum power in a short time, such as speed races.

Intermediate fibers

Intermediate fibers or IIA are a combination of fast and slow fibers. This type of fibers supports more before fatigue than fast ones. As these fibers are a combination of fast and slow, physical conditioning can favor a specific type of fiber predominates. That is to say, if a muscle is trained so that it has greater resistance, these fibers will be able to adapt and be more resistant to exhaustion.

Slow fibers

Slow fibers or I are much thinner than fast fibers, and are much more resistant to fatigue . This happens because these fibers have a greater oxygen supply , that is, they get more blood, so they must resort less to anaerobic metabolism and resist more contractions followed than the IIB.

The sports that are more related to the slow muscular fibers are those in which the resistance predominates, like for example the sportsmen that participate in marathons.
What all this indicates, is that athletes who have a predominance of fast fibers can have greater advantage in quickness exercises that are brief, for example, while in those that predominate the slow ones can have greater facility for performance sports where It is necessary more time practicing the sport.
When making a comparison between the twin muscles (located in the back of the leg) of a marathon runner and a sprinter , we can find that in the case of the marathoner between 93 and 99% of the fibers are slow, so They can withstand the full race time. On the other hand, the sprinter has only 25% slow fibers in his twins, so fast fibers predominate to achieve fast and strong contractions for a short time.

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