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Types of muscle fibers. Important knowledge about the different types of muscle fibers. MIM training is aimed at

Myths about fast and slow

It is customary to share muscle fibers into two main types:

red = slow and white = fast.

In modern biochemistry, recent times indeed, it is customary to divide fibers into fast and slow - each fiber is innervated by a certain number of nerve impulses. The more nerve impulses, the higher the ATPase activity, the faster the fiber contracts.

As for the color. Myoglobin in the muscle cell performs the same functions that hemoglobin performs in blood plasma - it carries oxygen.

Regardless of the activity of ATPase, the fibers are divided into oxidative and glycolytic. So far, biochemists have not found red (rich in myoglobin) fibers that have high ATPase activity. Therefore, the division into red-slow and white-fast is very conditional.

Almost all biopsy samples showed that slow fibers are much superior in development. The conclusion is quite logical - the growth potential of the fast ones is much greater than that of the slow ones. Empirically, more or less, many have crept up to a fairly effective method of developing fast fibers - explosive force and work at the level of 80-90% of the maximum maximum strength, and you are provided with significant hypertrophy of this type of fiber.

Bodybuilders, step by step, have found the path to hypertrophy of slow fibers - a large number of repetitions when working at lower levels of 20-40% (or 10-50%) of strength leads to acidification and failure - it is this state that corresponds to the optimal concentration of hydrogen ions, in combination with volume training (from 4 to 12 sets per muscle group) - this gave the result of the growth of slow fibers.

Biopsies (samples of muscle tissue) of professional bodybuilders prove that red fibers reach absolutely the same size in diameter as fast ones. Slow ones muscle fibers grow no worse than fast ones. You just need to train them properly.

2 Myth. It is believed that fast fibers develop much more effort than slow ones. In other words, the fast ones are stronger than the slow ones.

fast fibers turn on only when the explosive force or weight exceeds 80% of the maximum force limit. Therefore, the conclusion suggests itself that they are strong - stronger than slow ones. The biopsy almost always "protruded" on the side of the fast fibers - their diameter was, as a rule, larger. And if thicker, then stronger. BUT slow ones can be as thick as fast ones, which means they can develop no less strength!

It's believed that fast fibers develop, because due to the high activity of the ATPase enzyme, there are more bridge connections per unit time. This is true - but only for a unit of time, that is, if given time, they will develop the same effort.

Slow capable develop such the same effort as fast fibers(ceteris paribus - fiber thickness, etc.) !

Slow ones grow just as "easily" as fast ones - you just need to develop them correctly.

Synopsis based on "Heart rate, lactate and endurance training" (Jansen Peter)

A muscle contains various types of muscle fibers. Muscle fibers differ in their functions. Each type of muscle fiber is trained in a specific way.

Muscle fibers are divided into two types

red, or slow fibers, or type I fibers;
white, or fast fibers, or type II fibers.

There is no difference in the ratio of fast twitch to slow twitch fibers in men and women. The response to training muscle fibers in women and men is the same.

red muscle fibers

Red muscle fibers are densely dotted with capillaries. For ATP resynthesis, a predominantly oxygen mechanism is used (see). Therefore, red fibers have a high aerobic and limited anaerobic capacity. The red fibers work relatively slowly, but don't tire as quickly. They are able to keep working for a long time. This is important for endurance.

White muscle fibers

In white muscle fibers, the content of capillaries is moderate. ATP resynthesis occurs predominantly anaerobically due to the phosphate and lactate mechanism (see). Therefore, white fibers have a high anaerobic capacity and a relatively low aerobic capacity. They work fast and get tired quickly. White fibers can produce energetic explosive exercises in a short period of time. This is important in speed-strength sports - sprinting, throwing, jumping, wrestling, weightlifting.

White fibers are divided into types IIa and IIb. Fibers IIb are purely anaerobic. IIa fibers have a high anaerobic and aerobic capacity for ATP resynthesis. IIa fibers support type I fibers during long-term endurance work.

Table 1.2 Comparison of red and white muscle fibers

White fibers (fast twitch)	Red fibers (slow twitch)
Explosive/sprint abilities	Endurance
Moderate capillary network	dense capillary network
High anaerobic capacity	High aerobic capacity
Low aerobic capacity	Low anaerobic capacity
Energy supply: lactate/phosphate systems	Energy supply: oxygen system
The number of white fibers does not increase with training	The number of red fibers increases with exercise
Short run time	Long working time
High lactate production	lactate is not produced
With age, the number of white fibers decreases	With age, the number of red fibers does not decrease
Get tired quickly	get tired slowly
Contraction speed is high	Contraction rate is low
Contraction force is great	contraction force is small

The ratio of red and white muscle fibers

The more fast-twitch fibers in the athlete's muscles, the higher his sprint capabilities. The ratio of slow twitch to fast twitch fibers can vary greatly between individuals, but the ratio of muscle fibers in an individual is the same. Initially, we are born as either sprinters or stayers.

Important!!! A sprinter has a 50/50 slow to fast fiber ratio, while a marathon runner can have a 90/10 slow to fast fiber ratio (Figure 5).

Graph 5. The ratio of muscle fibers in different types of athletes

Under the influence of training, white fibers can turn red. A sprinter can turn into a good stayer, although with an increase in endurance, his sprinting qualities will decrease. An endurance athlete will not be able to change the composition of his muscles by performing loads of a speed-strength nature.

With age, an athlete's sprint ability decreases faster than the ability to perform long-term work. Ability to perform long-term work can be maintained until old age.

Muscle fiber types and load intensity

During light exercise (walking, cycling, jogging), energy is supplied by the aerobic system - fat oxidation in type I muscle fibers. Fat reserves are inexhaustible.

Under moderate intensity exercise (running, cycling) in type I muscle fibers, in addition to fat oxidation, the proportion of carbohydrate oxidation increases, although energy supply is still aerobic. Well-trained athletes can maintain a maximum aerobic capacity of 1-2 hours. During this time, there is a complete depletion of the supply of carbohydrates.

With an increase in the intensity of work (competitive 10 km run), muscle fibers of type IIa are switched on and carbohydrate oxidation becomes maximum. Energy supply is due to the oxygen mechanism, but the lactate system also contributes. The body processes lactic acid as fast as it produces it. If the level of intensity and the share of participation of the lactate system in energy supply continue to increase, lactic acid accumulates and carbohydrate stores are quickly depleted. Such a load can be maintained for a limited period of time, depending on the fitness of the athlete.

During maximum power sprinting or high intensity intervals, type IIb muscle fibers are turned on. Energy supply is completely anaerobic. The source of energy is exclusively carbohydrates. The levels of lactic acid are greatly increased. The duration of the load cannot be large.

Hi all! Today we are waiting for Nudnyakov's note, and it will be devoted to such an issue as the types of muscle fibers. Despite your tediousness, you will learn a lot of useful things, in particular, what types of fibers exist, where they are located, and what training strategies should be applied to them.

So, sit down comfortably, we begin to annoy.

Muscle fiber types: what are they?

As you know, sometimes specialized notes on the physiology of training and aspects of their proper construction slip through the project. I won’t say that such information is easily perceived (especially by beginners), but it is extremely necessary and allows you to better understand the essence of the processes occurring in the body and the existing mechanisms. Therefore, ignorance of them on our part affects the final bodily result. In other words, we do not fully reveal the potential of our own muscles and often mark time in one place. So, in order to avoid such trampling, you need to study the physiologically applied side of training, or rather, know what we are pumping and how to do it as efficiently as possible. That's about it, specifically about the types of muscle fibers, we'll talk today.

Note:
For better assimilation of the material, all further narration will be divided into subchapters.

As you know, in training, athletes pump muscles - complex structures consisting of different types fibers.

In total, in the human body it is customary to isolate 3 their type:

type I - slow-twitch, oxidative. It is characterized by low strength, power, speed, but a high degree of endurance.
type IIB - fast-twitch, glycolytic. It is characterized by increased strength, power, speed, but a low degree of endurance;
type IIA - fast-twitch, oxidative. Occupies an intermediate position.

Different names suggest different functional characteristics. The latter are the result of the composition of MHC heavy chain myosin fibers with MHC isoforms (I, IIa and IIx) of the corresponding type I, IIA, IIB muscle fibers. Working in the gym according to different programs (with different number of repetitions / intensity), the athlete pumps any (or several) of the presented types of fibers.

We also use muscles/fibers in our daily life, but lifting weights recruits more slow/fast twitch motor units. The degree of fiber involvement is different for all athletes, and it depends on the level of training and the width of the brain-muscle channel. In other words, conditionally, if an experienced athlete approaches the projectile, then he will use 100 motor units, if a beginner approaches, then the number of fibers involved will be an order of magnitude smaller, 20-30 units.

Fast twitch muscle fibers are divided into two subtypes: A and B. They have higher levels of absolute strength and tire much faster (compared to type I). The main difference between subtypes A and B is the time to reach peak power, for IIA fibers the process takes longer - on average 50 milliseconds vs. 25 ms. Due to the higher compression rate, the total peak power of IIB fibers can be up to 5 times higher than IIA.

From all this we can draw the following conclusion. Fast twitch fibers (type II) contract faster, have more peak power, and have the advantage of developing strength under high speed conditions. In other words, if you are bench pressing in an explosive power style - a small amount (up to 5-7 ) reps with maximum weight, then all the work is done by white fibers. They use oxygen-free metabolism (glycolysis) to produce energy for contraction, and athletes with a predominance of these fiber types perform well in disciplines such as weightlifting, powerlifting, bodybuilding, and sprinting (sprinting). For their speed, white fibers pay with increased fatigue - glycolysis leads to the formation of lactic acid and acidification of the muscles, as a result of which this stops their work.

Slow fibers - use the aerobic (oxygen) way of obtaining energy, and therefore they have a well-developed capillary network. Such fibers do not get tired for a relatively long time and are able to withstand long-term stress. Transitional type - fibers from the series “neither fish nor meat” :), i.e. they occupy an intermediate position and can use both aerobic and anaerobic pathways as an energy source of contraction.

This is what all three types of fibers look like.

And here are the characteristics of each of them.

Note:
Often also type I and type II are called red and white fibers, and this is determined by the presence of the red muscle pigment myoglobin in them: in red there is a lot of it, in white - very little.

Brain and muscles. How important is communication?

As we have already found out, several types of fibers are intertwined in the muscles, and when the glands are pulled, they are recruited, i.e. are included in the work. The ability of the central nervous system to recruit a large number of motor units in a short period of time is what determines progression in working weights and the ability of an athlete to pull heavy weights. In other words, until your brain is trained enough to send strong “lifting” signals to your muscles, you will not see an increase in muscle mass. Therefore, remember - the nervous system determines the degree of participation of motor units, and it also needs to be trained by consistently attending gym and adjusting.

As for the number of muscles involved in the work, the average visitor to the simulator has access to about 50-55% from all motor units, for experienced athletes this figure is 65-70% , for professionals - order 80% . Those. the degree of muscle involvement varies from athlete to athlete, and of the order 20% we don't have it available.

The fibers are different black, white, red - what do I care?

And really, what about what kind of fibers you have? In fact, this is very important in terms of achieving the goals and ongoing work. Have you ever wondered why someone has enough 1-2 go to the gym for a year, and he radically changes his physique, and someone can walk for years, but have very modest results. It's all about the ratio of muscle fibers and knowledge of the work that needs to be done on the body in connection with the inheritance.

In particular, remember some features of different types of fibers, they are:

IIB fibers play a primary role in gaining muscle mass and muscle hypertrophy, therefore, if they prevail in you, then with muscle mass you will have everything in order;
if you were engaged in sprinting, boxing and came into bodybuilding, then remember that fast muscle fibers predominate in you;
if you were engaged in a marathon, skiing, long-distance walking, then remember: you are dominated by slow muscle fibers;
in theory, it is believed that the number of muscle fibers does not increase with training with iron, only their thickness increases (the process of hypertrophy);
endurance training is aimed at increasing the number of capillaries surrounding muscle fibers and delivering more oxygen to them;
strength training, among other things, aims to increase the cross section of the fibers;
slow fibers (as opposed to fast ones) have a smaller cross-sectional area;
in the process of working with iron, the fibers are involved from small to large, i.e. no matter how much weight is on the bar, the slow ones contract first.

In general, the muscles of the average person have the following ratio of fast and slow fibers: 50% on the 50% , i.e. there is parity. This is the average value over the entire skeletal muscle of the human body. According to the theory, it is considered that the ratio of the number of fibers is genetically determined, i.e. invariably. However, practice shows that special training can affect the ratio of fast and slow fibers, tilting the scales in one direction or another. 10-15% . In particular, strength training can increase the number of type II fibers, and aerobic training will increase the presence of I fibers.

How are muscle fibers involved?

So, let's figure out how fibers are recruited into work. This process takes place as follows. With proper moderate exercise (the one that allows you to achieve fatigue), the type I fibers are depleted first, which are fired first. Then, when they have exhausted their potential, the intermediate fibers (IIA) take over, when they are exhausted and you can barely lift the projectile, type IIB come into play. The first type is the weakest fiber type, however it can shrink over long periods of time if the load is low enough. Type IIB muscle fibers are the strongest fibers, but they are easily “burned out”, although they have the greatest potential for growth. So, successively replacing each other, different types of muscle fibers are involved in the work.

A-uuu, are you still here or am I shaking the air idly? :) I want to report that we have just crossed the equator, and there is still approximately the same amount of nonsense ahead of us). Therefore, I propose to end the broadcast and meet next time - already with a fresh mind. I don't hear any objections, so let's do it.

Afterword

Today we did a great job - we began to understand the topic "Types of muscle fibers". Now you know what they are and what their features are, the only thing left is to understand how to manage them, i.e. train competently. That's what we'll talk about in the second part of the note, but for now - bye!

Thank you for investing this time in yourself, see you soon!

PS. Friends, I remind you that 15.03 once again it will be possible to create a personal training program and nutrition plan for you, so 15 March is our meeting place. In addition, on Sunday you will find another pleasantness, come in, you will find out everything.

With respect and gratitude, Dmitry Protasov.

Each muscle is made up of cells called muscle fibers (myofibrils). They are called “fibers” because these cells are strongly elongated: with a length of several centimeters, they are only 0.05-0.11 mm in cross section. Let's say there are more than 1,000,000 of these fiber cells in the biceps! 10-50 myofibrils are collected in a muscle bundle with a common sheath, to which a common nerve (motor neuron) approaches. At his command, the bundle of fibers shortens or lengthens - these are the muscle movements that we perform during training. Yes, and in everyday life, of course, too. Each bundle consists of fibers of the same type.

slow muscle fibers

They are red or oxidizing, in sports terminology they are called "type I". They are quite thin and well supplied with enzymes that allow them to receive energy with the help of oxygen (hence the name "oxidative"). Please note that in this way - oxidizing, that is, burning, both fats and carbohydrates are converted into energy. These fibers are called “slow” because they are reduced by no more than 20% of the maximum, but they can work long and hard.

And they are “red” because they contain a lot of myoglobin protein, which is similar in name, function and color to blood hemoglobin.

Long-term uniform movement, endurance, weight loss, cardio and fat burning workouts, slim, wiry figure.

fast muscle fibers

Either white or glycolytic, they are called "type II". They are noticeably larger than the previous ones in diameter, they have little myoglobin (and therefore “white”), but a large supply of carbohydrates and an abundance of so-called glycolytic enzymes - substances with which the muscle extracts energy from carbohydrates without oxygen. Such a process, glycolysis, (hence the name "glycolytic") produces a rapid and large release of energy.

These fibers can provide a powerful push, jerk, sharp blow. Alas, the release of energy is not enough for a long time, so fast fibers do not work for long, they need to rest often. The strength training designed for them is therefore divided into several approaches: if you move continuously, the work is transferred to slow fibers.

What is connected with these muscle fibers. Strength training, sprints, accelerations, muscular, inflated figure, figure modeling, voluminous muscles.

Two types of fast muscle fibers

Yes, it's not that simple! Fast muscle fibers are also divided into two "divisions".

Fast oxidative-glycolytic or intermediate fibers (subtype IIa) - fast (white) fibers, in which, nevertheless, there are the same enzymes as in slow ones. In other words, they can receive energy both with and without oxygen. They are reduced by 25-40% of the maximum, and they are “included” in work both in strength training and in loads for weight loss.

Fast non-oxidative fibers (subtype IIb) designed exclusively for short-term and very powerful efforts. They are thicker than all the others and, during strength training, increase in cross section more noticeably than others, and shrink by 40-100%. It is at their expense that bodybuilders increase muscle volumes, weightlifters and sprinters set records. But for fat-burning workouts, they are useless. It is important that about 10% of muscle fibers (those very fast intermediate ones - subtype IIa) can change their type.

If you often give your body a long-term load of medium intensity (one that includes a maximum of slow fibers), then the intermediate ones will also adjust to a slow mode in a few months. If you focus on strength, sprint training, then both intermediate and even red fibers will approach fast in their parameters.

Muscle fibers: how to determine your type

Typically, a person has approximately 40% slow and 60% fast fibers. Their exact number is set genetically. Analyze your physique and load perception. As a rule, people who are naturally "wiry", short in stature, with thin bones, who can easily walk, run, ride a bicycle, etc. continuous loads, have a slightly higher percentage of slow and intermediate fibers.

And those who have a wide bone, muscles easily grow even from small loads, but the fat layer is added literally from one glance at cakes or pasta, they are often “carriers” of some excess of fast fibers. If you know a person who, without really training, suddenly amazes everyone with his strength, this is the owner a large number fast non-oxidative fibers. On the network you can find tests that offer to determine your predominant type of muscle fibers. For example, doing an exercise with a weight of 80% of the maximum. Mastered less than 8 repetitions - fast fibers predominate in you. More are slow.

In fact, this test is very conditional and speaks more about fitness in this particular exercise.

Muscle fibers: choice of exercises

The names "fast" and "slow", as you already understood, are not associated with the absolute speed of your movements in training, but with a combination of speed and power. At the same time, of course, muscle fibers are not included in the work in isolation: the main load falls on one or another type, while the other acts “on the hook”.

Remember: if you work with weights, then the higher they are, the more actively fast fibers are trained. If the weights are small, the movements for training fast fibers should be sharper and more frequent. For example, jumping out instead of squats, sprinting 100 meters instead of slow cross-country, etc. But to train slow fibers, you need long, calm workouts such as uniform skating, walking, swimming, calm dancing. Any acceleration and jerk will additionally connect fast fibers.

Muscle fibers: planning a training

* If you need to add volume to one or another part of the body (say, swing your arms, shoulders or hips), train mainly fast fibers in these zones, exercising with weights and doing jumps, push-ups, pull-ups.

* Want to get rid of excess fat- “load” slow fibers throughout the body. Walking with sticks, running, swimming or dancing are best suited for this.

* For additional study of problem areas, add exercises on slow fibers: abduction-adduction of the leg, flexion, etc.

* For overall muscle tone, train both fiber types equally. Say, in the mode of a half-hour strength lesson and a half-hour cardio load after it 3-4 times a week.

By understanding what fast and slow muscle fibers are, you can tailor your workouts more efficiently.

slow muscle fibers

And they are “red” because they contain a lot of myoglobin protein, which is similar in name, function and color to blood hemoglobin.

Long-term uniform movement, endurance, weight loss, cardio and fat burning workouts, slim, wiry figure.

fast muscle fibers

What is connected with these muscle fibers. Strength training, sprints, accelerations, muscular, inflated figure, figure modeling, voluminous muscles.

Two types of fast muscle fibers

Yes, it's not that simple! Fast muscle fibers are also divided into two "divisions".

Muscle fibers: how to determine your type

Typically, a person has approximately 40% slow and 60% fast fibers. Their exact number is set genetically. Analyze your physique and load perception. As a rule, people who are naturally "wiry", short in stature, with thin bones, who can easily walk, run, ride a bike and other long-term loads, have a slightly higher percentage of slow and intermediate fibers.

And those who have a wide bone, muscles easily grow even from small loads, but the fat layer is added literally from one glance at cakes or pasta, they are often “carriers” of some excess of fast fibers. If you know a person who, without really training, suddenly amazes everyone with his strength, then you have a large number of fast non-oxidative fibers in front of you. On the network you can find tests that offer to determine your predominant type of muscle fibers. For example, doing an exercise with a weight of 80% of the maximum. Mastered less than 8 repetitions - fast fibers predominate in you. More are slow.

In fact, this test is very conditional and speaks more about fitness in this particular exercise.

Muscle fibers: choice of exercises

Muscle fibers: planning a training

* If you want to get rid of excess fat, “load” slow fibers throughout your body. Walking with sticks, running, swimming or dancing are best suited for this.

* For additional study of problem areas, add exercises on slow fibers: abduction-adduction of the leg, flexion, etc.

* For overall muscle tone, train both fiber types equally. Say, in the mode of a half-hour strength lesson and a half-hour cardio load after it 3-4 times a week.

By understanding what fast and slow muscle fibers are, you can tailor your workouts more efficiently.