What are oxidative muscle fibers? Muscle types and training. High threshold muscle fibers

According to the generally accepted classification, slow muscle fibers belong to type I, and fast muscle fibers belong to type II fibers.

Among fast muscle fibers, there are two subtypes - II-A and II-B. Subtype II-A has a higher oxidative capacity. Their oxidative capacity, however, is lower than that of type I slow fibers. Fibers of this subtype (II-A) are called fast oxidative-glycolytic. Fast oxidative-glycolytic fibers are part of fast fibers adapted to fairly intense aerobic energy production along with very powerful anaerobic system energy supply.

Subtype II-B is characterized by the highest glycolytic activity of all muscle fibers, so fibers of this type are called fast glycolytic.

It is interesting to trace changes in the finger flexor muscles as their training develops, expressed in an increase in the time of holding the grip. Unprepared people can usually hang on the bar for 1.5 - 2.5 minutes, after which their forearm muscles “numb” and their grip weakens.

Static work to maintain a grip requires relatively large muscle efforts, so the finger flexor muscles of untrained athletes work exclusively in anaerobic mode.

As the intensity of the load increases and the activation of glycolysis becomes more pronounced, the factor limiting performance is the ability of the oxidative system to utilize pyruvic acid. The greater this ability, the less lactic acid is formed and accumulated in the muscles. It turns out that in order to increase the duration of grip retention, it is necessary to increase the power of the oxidative energy supply system for statically working muscles. But an increase in the oxidative capacity of, for example, glycolytically working fast muscle fibers practically means the conversion of II-B fibers to II-A, i.e. conversion of glycolytic muscle fibers into oxidative-glycolytic ones.

Conversion of muscle fibers requires a lot of effort on the part of the athlete and takes a lot of time. Often, the time to maintain a secure grip begins to increase significantly only after many months of targeted training. This is especially true for athletes who initially have a short hanging time. The fact is that the aerobic mechanism of energy supply, which largely determines the performance of the finger flexor muscles of qualified athletes, begins to play a noticeable role only after 1 - 1.5 minutes of pull-ups; Before this, the athlete performs pull-ups using the capabilities of anaerobic mechanisms. Thus, by performing approaches consisting of 20-25 pull-ups and spending from one to one and a half minutes on their implementation, the athlete activates only the glycolytic mechanism, developing only its capabilities. So, if at the beginning of the training cycle an athlete did 25 pull-ups in 1.5 minutes, and at the end - 25 times in 1.15 minutes, this means that the power of glycolysis has increased. To develop the power and capacity of the oxidative energy supply mechanism, it is necessary to perform pull-ups in sets for a longer time. The rapid development of the capabilities of the glycolytic energy supply system inhibits the development of aerobic resynthesis of ATP, which is necessary to perform pull-ups within the four minutes allotted for this.

Muscle composition.

IN different muscles body, the ratio between the number of slow and fast muscle fibers is not the same. The strength, speed of contraction and endurance of muscles are largely determined by the percentage of these two types of fibers. Moreover, it is possible to identify a certain pattern - the greater and longer the load a muscle bears under natural (domestic) conditions, the higher its capacity for respiratory resynthesis of ATP (activity of oxidative enzymes and intensity of muscle respiration) and the better conditions to ensure it (a larger number of mitochondria, a higher myoglobin content. For the same muscles, which are characterized by a sharp transition from rest to very intense work, performed for a relatively short time, but with close to maximum power, high ATPase activity, a significant content of creatine phosphate and large possibilities of glycolysis.

Thus, fast but early-tired muscles, for example, the muscles of the forearm, are characterized by the predominant presence of type II fibers, and muscles capable of long-term work of moderate power contain mainly type I fibers. If the muscle contains both fast and slow fibers, it is predisposed to both rapid contractions and prolonged work.

The finger flexor muscles responsible for holding the grip are required to maintain significant forces for a long time. Muscles performing such a load must have both oxidative and glycolytic muscle fibers. Glycolytic fibers alone are not enough here due to the duration of the exercise being excessive for glycolysis, and oxidative fibers alone are not able to maintain the tension of the required value.

Since dynamic strength abilities are easier to train than static ones, athletes who are initially able to perform a long hang, and the longer the better, are more promising for pull-ups at the selection stage. Athletes with a high “natural” hang will spend relatively less time in the future to achieve the planned result; they are not afraid long breaks in the training process, their results are more stable and do not depend so much on warm-up, preparation of palms, air temperature in gym and other “little things” that athletes whose hang is not “natural”, but trained, have to pay attention to.

Athletes with high natural abilities to perform static work on holding a grip (which are quite rare) do not experience such problems with pulling up as do athletes deprived of natural abilities, and even more so, completely deprived of these data.

Now we will talk about the processes occurring in the muscles - the flexors of the fingers of athletes, who are completely unsuited to doing pull-ups on the bar.

Since athletes in this group are poorly adapted to perform the muscular work of maintaining a grip, their forearm muscles should primarily consist of fast glycolytic muscle fibers. Based on observations, for such athletes there are two possible scenarios for the development of events preceding a fall from the crossbar while performing pull-ups.

In the first case, during the process of pull-ups, the athlete, long before the breakdown, feels as if his forearms are filled with lead - “numb”, and only after that the muscles stop obeying and lose the ability to intercept. In the second case, the ability to perform interceptions is suddenly lost, the fingers suddenly unclench and the athlete falls off the crossbar.

The second case is the most unpleasant option in terms of predisposition to tightening. Presumably, the processes of fatigue in this case develop as follows. During the first 20-30 seconds, the athlete performs pull-ups, ensuring ATP resynthesis due to the creatine kinase reaction. When the rate of resynthesis in this way begins to decrease, for some time the energy in a volume sufficient to maintain the grip is supplied through glycolysis, which gradually reaches its maximum capacity (which in this case is relatively small). But very soon the total production of ATP from anaerobic sources begins to decrease, the level of ATP in the muscles drops, which leads to an involuntary weakening of the grip. The athlete simply does not have time to reach the stage of muscle “stiffening” due to the limited capabilities of glycolysis. Attempts to perform interceptions or rest in the hang position longer than usual do not allow you to avoid a breakdown, but only postpone it for a short time. Despite increased respiration, aerobic oxidative processes are not able to use the delivered oxygen due to the fact that the oxidative capacity of the muscles is minimal.

Receiving a warning about the imminent failure of the forearm muscles in the form of a feeling of muscle congestion is a less hopeless scenario than the previous one. It can be assumed that in this case the power of glycolysis is sufficient to ensure a longer grip. But during anaerobic oxidation of glycogen and glucose, lactic acid (lactate) is released, which, as already mentioned, regulates the power of glycolysis itself according to the feedback principle. Thus, the accumulation of lactate has a negative effect on the contractile properties of muscles, causing them to quickly fatigue. The progressive “stiffening” of the forearm muscles, followed by loss of controllability and falling off the crossbar, is complicated by the fact that aerobic processes that can ensure the resynthesis of ATP without the formation of lactate either do not have time to reach their maximum power or their power is clearly insufficient.

Acidification of the forearm muscles during pull-ups is often observed in athletes who are able to do pull-ups for 4 minutes or more. But in this case, the unpleasant sensations in the forearm area are short-term, usually begin with the weakest arm and disappear after some time - sometimes on their own, sometimes after special preventive measures such as transferring body weight to the strongest arm. It is clear that in this case, the possibilities of aerobic resynthesis of ATP are sufficient to ensure a reliable grip when performing pull-ups at the selected pace. The mention of tempo here is not accidental, because... when you try to increase it, the rest pauses in the hanging position in the IP are shortened, and this can lead to re-acidification of the forearm muscles. Despite the fact that fast muscle fibers increase the concentration of lactate in the lifting phase, oxidative and oxidative-glycolytic fibers manage to extract it from the blood and fast muscle fibers and utilize it before the next lifting phase.

Related information.

Everyone knows that each person has an individual muscle composition, that is, only he has an inherent combination of muscle cells (fibers) of different types in all skeletal muscles.
But there are several classifications of these types of fibers, and they do not always coincide. What classifications are currently accepted?
Muscle fibers are divided into:

1. White and red;
2. Fast and slow;
3. Glycolytic, intermediate and oxidative;

Fast and slow. They are classified by the activity of the ATPase enzyme and, accordingly, by the speed of muscle contraction. The activity of this enzyme is inherited and cannot be trained. Each fiber has its own constant activity of this enzyme. The release of energy contained in ATP is carried out thanks to ATPase. The energy of one ATP molecule is sufficient for one rotation (stroke) of myosin bridges. The bridges disengage from the actin filament, return to their original position, engage with a new section of actin, and make a stroke. The speed of a single stroke is the same for all muscles. ATP energy is mainly required for uncoupling. Each stroke requires a new ATP molecule. In fibers with high ATPase activity, ATP breakdown occurs faster, and more bridge strokes occur per unit time, that is, the muscle contracts faster.

Glycolytic, intermediate and oxidative. They are classified by the oxidative potential of the muscles, that is, by the number of mitochondria in the muscle fiber. Let me remind you that mitochondria are cellular organelles in which glucose or fat is broken down into carbon dioxide and water, resynthesizing ATP necessary for the resynthesis of creatine phosphate. Creatine phosphate is used to resynthesize myofibrillar ATP molecules, which are used for muscle contraction. Outside the mitochondria in muscles, glucose can also be broken down into pyruvate with ATP resynthesis, but this produces lactic acid, which acidifies the muscle and causes fatigue.
Based on this feature, muscle fibers are divided into three groups:
1. Oxidative muscle fibers. The mass of mitochondria in them is so great that a significant increase in it during the training process no longer occurs.
2. Intermediate muscle fibers. In them, the mass of mitochondria is significantly reduced, and lactic acid accumulates in the muscle during work, but quite slowly, and they tire much more slowly than glycolytic ones.
3. Glycolytic muscle fibers have very few mitochondria. Therefore, anaerobic glycolysis with the accumulation of lactic acid predominates in them, which is why they got their name. (Anaerobic glycolysis is the breakdown of glucose without oxygen to lactic acid with resynthesis of ATP; aerobic glycolysis, or oxidation, is the breakdown of pyruvate in mitochondria with the participation of oxygen to carbon dioxide, water and resynthesis of ATP.) In people who do not exercise, usually fast fibers are glycolytic and intermediate, and slow ones are oxidative. However, when proper training to increase endurance, fast muscle fibers are converted from glycolytic to intermediate, and then to oxidative, and then they, without losing strength and speed of contraction, will become tireless.

High threshold and low threshold. They are classified according to the level of the excitability threshold of motor units. The muscle contracts under the influence of nerve impulses that are electrical in nature. Each motor unit (MU) includes a motor neuron, an axon, and a set of muscle fibers. The amount of MU in a person remains unchanged throughout life. Motor units have their own excitability threshold. If the nerve impulses sent by the brain have a frequency below this threshold, the MU is passive. If nerve impulses have a threshold value for this MU or exceed it, muscle fibers are activated and begin to contract. Low-threshold motor units have small motor neurons, a thin axon, and hundreds of innervated slow muscle fibers. High-threshold motor units have large motor neurons, thick axons, and thousands of innervated fast muscle fibers.

As you can see, two of the presented classifications remain unchanged throughout a person’s life, regardless of training, and two directly depend on training. In the absence of motor mode, for example, in a coma or during a long stay in a cast, even slow muscle fibers lose their mitochondria and, accordingly, myoglobin and become white and glycolytic.
Therefore, it is currently considered incorrect in sports science to say “training aimed at hypertrophy of fast muscle fibers” or “myofibril hyperplasia in slow muscle fibers,” although ten years ago this was considered acceptable even in specialized scientific publications.
Now, if we are talking about the training effect on muscle fiber (MF), we only use the classification according to the oxidative potential of the muscle. The classifications are the same for those who do not train and for representatives of speed-strength and power sports, where the goal is to raise Weight Limit in a single repetition.
In sports requiring endurance, the classifications will not be the same.
For clarity, a somewhat exaggerated, although theoretically quite possible, example. Please note that all numbers are relative and should not be taken literally.
Let's imagine an athlete who has best result in the bench press 200 kg (without equipment), he can bench press 180 kg 3 times, 150 kg – 10 times. The results show that the oxidative potential of the muscles is very low. Suppose the ratio of fibers is as follows: 90% - fast, 10% - slow. In terms of oxidative potential, 75% are glycolytic, 15% are intermediate and 10% are oxidative. An athlete achieves the best success in increasing muscle mass when he presses for six repetitions. The weight of the barbell is large enough to recruit 75% of glycolytic fibers, and their oxidative potential is so low that six repetitions are enough for the necessary acidification of the muscle. But for some reason, this athlete decided to maximize his endurance and worked for two months, 2-3 times a day daily, to increase mitochondria in glycolytic and intermediate CF.
Plus, the athlete still maintained his strength potential by performing 1-2 repetitions with a near-maximal weight every 7-10 days.
Two months is enough for the muscles to be fully saturated with mitochondria. After two months, the athlete is tested. It shows that he now has 5% glycolytic fibers, 70% intermediate fibers and 25% oxidative fibers. That is, the glycolytic ones became intermediate, except for the highest 5%, and the intermediate ones became oxidative. In terms of ATPase activity, the ratio, naturally, has not changed, also 90% fast and 10% slow. He bench pressed 200 kg at once, myofibrils did not grow from such training, and he did not let the result drop. He squeezed 180 kg 8 times, and 150 kg 25 times. A huge number of new mitochondria “ate” the lactic acid, preventing the muscles from acidifying, which significantly increased their functionality.
Now, working for six repetitions will give practically nothing to our athlete to increase muscle mass. It uses only 5% of the remaining glycolytic fibers in the desired mode. Now he will have to work at least 15 repetitions per set in order to achieve the muscle acidification necessary for muscle growth. And additionally include statodynamic exercises in the training, since only they contribute to the hypertrophy of oxidative muscle fibers, of which he now has 25%, and it is no longer advisable to ignore them.

As we can see, the same person is forced to use completely different training programs to hypertrophy their fast muscle fibers after changing their oxidative potential!

That is why it is considered incorrect to talk about the training effect on fiber types using classification by ATPase activity.

P.S. Don't be afraid to develop endurance. The change in oxidative potential is a reversible process. Those. if you decide to gain muscle volume in the six-repetition mode, then in a month or a month and a half this mode will again produce its results, and the body will get rid of “extra” mitochondria. But then your stamina will drop.
Which mode to choose is up to you.

Determining a person’s sporting success. At the same time, the main criterion that distinguishes natural athletes from ordinary people is the ratio of fast and slow muscle fibers. It is this ratio that influences whether a particular person will easily burn fat or gain muscle mass.

It is also important that understanding muscle anatomy and knowledge of the basic physiology of muscle function is directly related to the ability to choose the most effective physical training strategy for you. In order to burn fat or build muscle with a minimum amount of effort, you just need to understand exactly how the body works.

What is muscle fiber?

The muscles themselves consist of connective tissue, capillaries, sarcoplasm and, directly, muscle fibers. Muscle fiber is a unique type of physiological structure that has both strength and elasticity. In turn, muscle fibers differ from each other because they are divided into fast and slow.

The basis for the difference lies in the source of energy that different types of muscle fibers use. Slow (red) fibers, responsible for static or monotonous loads, use fat as the main source of energy. Fast (white) fibers necessary for short and high-intensity exercise - reserves and creatine.

Fast and slow muscle fibers

The simplest and most understandable example of the difference in the anatomy of different types of muscle fibers is that of another bird. The breast and wings have a distinctive white color and minimal fat, while the legs and thighs have dark red meat and a higher fat content.

Since the chicken spends most of its time standing, the muscles of its legs experience a constant static load - in fact, the main work is performed by slow muscle fibers (1). In contrast, the wing muscles are used exclusively for short but energetic flapping - the load is placed on the fast muscle fibers.

Slow-twitch (red) muscle fibers

Even though slow-twitch muscle fibers themselves are quite thin and weak, they can support physical activity for an extremely long time. Their red color is largely due to the presence of oxygen molecules necessary for the oxidation of fats (triglycerides), which serve as the main source of energy for slow fibers.

This is why aerobic training and long-term cardio are ideal for losing weight - in fact, such exercise engages slow muscle fibers and literally forces the body to burn fat reserves. However, let us recall that to ensure optimal oxygen supply to muscle fibers, it is important to train in.

Fast (white) muscle fibers

For high-intensity (so-called "explosive") loads, muscles require quickly available energy. However, fat is not suitable for these purposes, since its transportation and oxidation takes at least several minutes. In simple terms, energy must be in an easily accessible form as close as possible to the muscle fibers themselves.

For explosive efforts, the body uses fast-twitch muscle fibers, which work primarily on glycogen (that is, on carbohydrate stores in the muscles), ATP and (2). Let us remember that muscle growth and muscle gain as a result of strength training is largely due to an increase in these same energy reserves.

Set - training strategy and nutrition tips to get pumped up quickly.

How to determine which fibers you have more?

It is also important to note that in reality, the muscles of a particular person always consist of a plexus of muscle fibers of various types. In the stabilizing muscles of the core and spine, and in the muscles of the legs, slow-type fibers usually predominate, while in " normal muscles"and other skeletal muscles - fibers fast type (3) .

However, under the influence of regular physical training, the athlete's body is able to adapt and change this ratio. Scientific research suggests that runners have marathon distances more than 80% of all muscle fibers are slow - in contrast to sprinters, in whom fast fibers predominate, amounting to about 65-70%.

Workouts for muscle growth and weight loss

For training fast muscle fibers (and increasing lean body mass) the best ones are - strength exercises, performed in the range of 6-12 repetitions. The higher the working weight and the lower the number of repetitions (and the shorter the time spent under load), the more actively the fast muscle fibers are involved in the work.

In contrast, burning fat (and recruiting slow-twitch muscle fibers that consume fat reserves) requires both static loads, and monotonous cardio, . Plus, such workouts are especially effective when blood glucose levels are low - this will force the body to focus on fat reserves.

***

Muscle fibers are divided into fast and slow. Strength training primarily recruits fast-twitch fibers, requiring carbohydrates and glycogen. In contrast, long-term low-intensity aerobic exercise performed for at least 30-45 minutes is required to engage slow-twitch fibers and burn fat.

Scientific sources:

1. Muscles – Fast and slow twitch,
2. Skeletal striated muscle,
3. Speed ​​and power training,
4. Fast Twitch, Slow Twitch…. Which One Are You?

Greetings to all our honest brethren! Today we will continue to tedious, because we are waiting for a continuation, the second part, notes called “Types of muscle fibers.” From it you will learn everything about the practical aspects of training of one type or another, identify which fibers predominate in you, and how, in connection with this, you need to build your training process and select exercises.

So, if everything is assembled, then let's begin.

Types of muscle fibers: how to identify dominant ones and train effectively?

Of course, our note would not be complete if we did not consider the practical side of the issue, so let's continue our broadcast in this vein. But before that, read through so that no questions arise. Ready? Now let's start by considering the following question...

Number of repetitions and fibers involved.

The following guide will help you determine the number of repetitions and the type of muscle fibers involved in the work.

No. 1. Development of maximum power.

1-3 . The load is high and amounts to 95-100% from a one-rep max. This training scheme leaves Type IIA and mostly Type IIB fibers to work to complete the last rep. It is most common among the strongest powerlifters. With it, myofibrillar hypertrophy occurs, associated with an increase in protein in the muscles due to satellite cells that help increase the number and size of contractile proteins (actin and myosin). The number of muscle fibers remains the same, but satellite cells fuse with existing cells and donate their nuclei and DNA to help the muscle fibers grow in size.

No. 2. Strength training.

Number of repetitions to failure 2-6 . Intermediate and Type IIB fibers are used to complete repetitions. This training scheme is suitable for those who want to increase their strength and develop anaerobic endurance. Myofibrillar hypertrophy occurs due to satellite cells, an increase in the contractile proteins actin and myosin.

No. 3. Training for the development of hypertrophy.

Number of repetitions to failure 8-20 . This training scheme forces type I, intermediate and type IIB fibers to be activated. Unlike training No. 1 and No. 2, hypertrophy occurs not due to the myofibrillar apparatus, but due to the sarcoplasmic apparatus, increasing the amount of sarcoplasm. The number of repetitions and weights used to perform a given number of repetitions will ensure growth potential for all fiber types.

No. 4. Development of endurance.

Number of repetitions 20 and more. Type I fibers are endurance fibers that recover quickly compared to fast-twitch fibers. The perfect workout endurance training should include approaches 90 seconds using the weight without feeling any failure during that time. In other words, in order not to provoke the activation of stronger muscle fibers - intermediate and fast-twitch, it is necessary to use light weights and not strive for failure in repetitions. In this case, you can only hope to train type I fibers.

Types of muscle fibers. How to train correctly? General tips.

The following tips will help you navigate your training strategy and use of training principles.

So remember:

• To develop type I fibers, you need to do more aerobic training per week, in particular in the ratio 4 against 1-2 power;
• Type IIA fibers respond well to growth during long-term anaerobic training using supersets, giant sets, drop sets;
• if your goal is to lose weight, and you have predominantly red (slow) fibers, then you need to focus on running at a moderate pace at long distances. In this case, thanks to the aerobic method of obtaining energy, fats are burned;
• if your goal is to increase strength and the number of white type IIB fibers, then you need to train in the range 3-7 repetitions;
• In order for fast-twitch fibers to come into play and muscle mass to increase, it is necessary to train intensively, because only in this case fibers with large motor neurons (type II) are included in the work;
• number of repetitions in range 8-12 in combination with a high degree of intensity of the entire workout will have the maximum effect on increasing muscle size;
• strength training for the development of fast-twitch fibers involves short approaches (before 7 repetitions) With several ( 2-4 ) minutes of rest;
• continuous loads from 40 minutes in the aerobic heart rate zone are aimed at burning fat and recruiting slow fibers;
• workouts on an empty stomach (with low glycogen levels) aimed at training type I fibers.

Actually, all this time we have been talking about the types of muscle fibers and training schemes, but how can we find out which type of fibers predominates specifically in us? The next subchapter will help with this.

Pregnancy test fast/slow muscle fiber ratio

Bodybuilding, oddly enough, also has its own tests, and some of them do not require any handy equipment. So, in particular, in order to identify the type of muscle fiber that predominates in an athlete, the following test is performed - the limit of repetitions of a muscle compared to its maximum strength. The meaning is this:

1. choose 1 insulating (conditional isolation) exercise for a specific muscle group, for example, biceps - lifting a dumbbell with one hand / EZ-bar with two;
2. select the weight of the projectile so that you can perform “cleanly” independently only 1 repetition ( 1 RM);
3. rest 3-5 minutes;
4. take a weight that is 80% from 1 R.M. (to do this, multiply the maximum by 0,8 ) and perform as many repetitions as possible.
5. 4 before 7 , then you have predominantly fast (glycolytic) muscle fibers that are strong but not durable;
6. if the number of repetitions is 10 , then there is parity of fast and slow fibers;
7. if the number of repetitions falls within the range of 12 before 15 , then you have a predominance of slow (oxidative) muscle fibers.

Let me explain more popularly what we are talking about. For example, you need to determine which fibers predominate in your biceps brachii muscle. you were able to raise 1 times dumbbell for biceps with weight 30 kg means 1 RM= 30 kg, 80% will be 24 kg. Then you rested and completed a set of reps 13 , therefore, your biceps are inhibitory :), because consists predominantly of red muscle fibers.

Using such an algorithm, you need to go through each muscle group and, using your isolation exercises, identify the type of predominant muscle fibers. Having such data, it will be easier for you to build your workout and achieve maximum output from your muscles.

I think a reasonable question has arisen: what isolation exercises can be used for each muscle group. You will find the answer in the following memo.

In the text version, exercises for muscle groups look like this:

• chest - on a horizontal bench;
• biceps - / lifting dumbbells for biceps;
• triceps -;
• back - traction upper block to the chest while sitting;
• shoulders – ;
• front surface of the thigh – leg extensions in the simulator;
• back of the thigh – .

Muscle groups by fiber type

Agree, it would be interesting to know how to train this or that muscle group in the key of knowing the types of fibers corresponding to it. After all, in this case, the training turns out to be more meaningful, and you can try it yourself.

In this regard, I compiled a kind of generalized atlas of muscle groups by type of muscle fiber. That's what he is.

As for some of the features of muscle fiber types (m.f.) of muscle groups, they are as follows:

• hamstrings and gluteus maximus are of the mixed type, with a predominance of slow m.v. Therefore, they must be loaded with a higher number of repetitions to failure;
• soleus consists of 70% , and the gastrocnemius is on 55% from red m.v. (i.e. she is a borderline mixed type with a slight predominance of slow m.v.). Therefore, due to the fact that seated calf raises load the soleus, it is necessary to perform more repetitions to failure when training it. In turn, calf training should be approached with a small number of repetitions (up to 8 ) , but with a lot of weight, so standing calf raises must be performed with maximum weights;
• the anterior surface of the thigh is a fairly individual muscle group, in which the types of muscle fibers vary and are mixed from fast to slow. The rectus femoris muscle predominantly has fast-twitch movements. Therefore, squats (multi-joint movement) Barbell exercises on the chest/shoulders should be done with heavy weights but low reps. However, when performing extensions in knee joint sitting in the gym (single joint movement) the best option would be a combined approach to loading;
• delts are a mixed fiber type with a red bias, so it is best to train them using a combined approach, with an emphasis on higher reps up to muscle failure;
• biceps, triceps, pectoral muscles - white muscles predominate in these muscle groups, so it is better to work them with an emphasis on high load and low number of repetitions;
• The latissimus dorsi muscle has almost perfect balance ( 50/50 ) mixed with fast and slow movements, so the “wings” need to be worked out using a combined approach;
• the press is an intermediate type with a predominance of fast twitch fibers, therefore it is more advisable to use a combined approach when training the abdominal muscles;
• trapezius and back extensors - they are dominated by oxidative fibers, these are hardy muscles that need to be “pounded” with a large number of repetitions.

Now let's talk about...

Muscle Fiber Types and Recovery

An important aspect of training is understanding the issues of recovery of muscle groups depending on the types of predominant fibers. So, when talking about fiber restoration, we will always keep the following reminder in mind.

Here are some clarifying points:

• IIB fibers are recruited only during the last 2-20 seconds of contraction, near muscle failure (depletion of muscle resource);
• the recovery time of IIB fibers is about 4-10 days, for this reason there is no point in going to Gym for training fast fibers;
• if strength training was resumed before type IIB fibers were restored (for example, after 3 rest days), then you will feel that muscle exhaustion will occur much earlier than in the previous session. A certain part of the fibers will be, as it were, “canned” and will not be available for “hire”. Recovery, repair and growth of muscles occurs only after sufficient rest;
• Unlike Type IIB, Type I hardy fibers become available for recruitment after 90 seconds of rest.

Conclusion: in connection with the above calculations, the optimal training strategy is to use moderately heavy weights. This allows for rapid progression across all types of motor units (fiber types), recruiting them into action - not so fast that only the white fibers receive the bulk of the stimulation, and not so slow that the red and intermediate motor units can recover. Thus, it turns out that for the fullest impact (total coverage) for the entire spectrum of muscle fibers, the weight of the weight should not be light, but not too heavy.

These were general calculations, now let's go specifically through each type of fiber and identify the optimal number of repetitions and time of work under load.

Types of muscle fibers: optimal time time under load and number of repetitions per set

To make it clearer and clearer, let’s summarize all digital and text data into a consolidated table. As a result, we get the following (clickable).

Remember which fibers predominate in you, and what characteristics this or that type has, this will help you determine the quantitative parameters of your training.

So, in this regard, it will be useful to know how to train in the light of the inherited bodily inheritance. This is what we will look into. Let's start with body type...

No. 1. Ectomorph.

A lean type with long limbs and a predominant red type of muscle fiber. That is why these representatives slowly gain muscle mass, because... their fibers inhibit and there are many of them. With strength training, you can expect an increase in strength and, to a lesser extent, muscle mass. In general, the ectomorph needs to focus his efforts on stimulating the RMV (fast m.v.), and although the ratio between the RMV and the RMV does not change much (within 10% ) As a result of training, the ratio of the masses of these fibers can be controlled quite well. Those. if the ectomorph has a conditional ratio of BMW and MMV before the start of training = 20:80% , then during exercise the “specific gravity” of fast fibers will increase. In other words, proper training will promote hypertrophy of white fibers and atrophy of red fibers. And, as a result, such an athlete potentiates his muscle growth.

Conclusion: the ideal number of repetitions per set is 4-8 .

No. 2. Mesomorph.

Lean and generally athletic body type, with a high percentage of fast-twitch muscle fibers type 2A and 2B. When doing strength training, you can expect an increase in both strength and volume indicators.

No. 3. Endomorph.

Round, stocky athletes with a high percentage of fast-twitch 2B fibers. With strength training, you can count on an even greater increase in strength, with an adjustment towards increasing muscle mass.

Mesomorphs and endomorphs initially have more muscle mass, so to increase muscle mass they just need to push themselves a little.

Conclusion: perfect (in terms of increasing muscle mass) the number of repetitions for a mesomorph is 8-12 , endomorph 12-15 for the approach.

The general rule for increasing muscle mass is high intensity training, because it is this that allows you to turn on (last reps) fast-twitch muscle fibers responsible for hypertrophy. And in light of the fact that white fibers have a much larger surface area than red ones, muscle volume will grow better. Thus, it turns out that training to increase muscle mass involves high intensity in the failure range of reps for 8-12 once.

Well, in conclusion (or are you already asleep? :)) Let's consider a training scheme for maximum development of fast muscle fibers.

How to use white muscle fibers to the maximum? Training scheme.

Many scientific studies come to the conclusion that the following training scheme - split - can achieve maximum BMW recruitment:

• workout #1: 1-5 repetitions, 3-5 minutes of rest, multi-joint exercises;
• workout #2: 8-12 repetitions, 60-90 seconds of rest, only multi-joint movements;
• workout #3: 12+ repetitions, 30-60 seconds rest, supersets, multi-joint and isolation movements.

In other words, one workout per week should be strength training (lifting) and consist of exercises - deadlift, squats, bench press, pull-ups, dips, shoulder presses and barbell rows. The other is classical bodybuilding with a number of repetitions 8-12 and the third - intense pump with exercises in the style of a train (supersets).

Phew, actually, that’s all I have, now let’s sum up all this chatter and say goodbye.

Afterword

Well, we have completed the boring technical note about the types of muscle fibers. Well done for reading to the end, now you know what types of fibers there are, how to identify them and stimulate them to grow. All this will help you maximize your muscle potential and achieve the physique you always wanted. That's all, I was glad to fall asleep writing for you, see you later!

PS. Do you divide your training by fiber type?

P.P.S. Attention! 22.03 The ability to send questionnaires for and food will become available. I will be glad to see you working together!

With respect and gratitude, Dmitry Protasov.

Humans have oxidative ( slow), and glycolytic ( fast) muscle fibers. The former have a red color, which is due to the high content of oxygen molecules in them. The latter are white, since they use anaerobic glycolysis, with the participation of creatine phosphate, as the main energy resource. What does this information mean for a fitness enthusiast? She can help you overcome plateaus in power types sports, and achieve greater muscle hypertrophy if the goal is body aesthetics.

Fast muscle fibers and their role

Glycolytic muscle fibers are designed to perform work with high power but short duration. For example, when doing the clean and jerk or the 50m sprint, we train them primarily. They use “carbohydrate” fuel, that is, they feed through the process of glycolysis. The predominance of white muscle fibers means that a person is naturally prone to power load with low reps and heavy weights. He can do more work per unit of time if the “more” is a significant amount of weight on the bar and not the number of repetitions.

Fast-twitch muscle fibers are often not prone to hypertrophy (high volume), but are quite stiff. People with their predominance may not be endowed with great muscle mass initially. But they are precisely those who bench press their own weight in their first workout, and everyone around them wonders why this is happening, since they do not see impressive muscle hypertrophy.

Slow muscle fibers and their role

Now imagine that we are performing the same barbell push, but for a large number of repetitions, as CrossFit athletes do. Fast twitch muscle fibers exhausted their glycogen and creatine phosphate resources in about 30 seconds and became fatigued. And we need to keep moving. Then the so-called slow muscle fibers are recruited. They run on "aerobic" fuel and can perform many contractions. People with their predominance will have a predisposition to crossfit, bodybuilding pump training and ... all sports that require endurance, but not explosive strength.

It is often said that slow-twitch muscle fibers are useless in terms of building beautiful figure, but that's not true. You can achieve their hypertrophy with the help of competent and regular training.

Which fibers are there more, and does it matter during training?

Predisposition to engage in certain sports depends on anthropometry (bone structure, limb length, ratio of angles in basic exercises), body composition (susceptibility to gaining fat mass), hormonal levels, and the predominance of certain muscle fibers. But a significant role is played by how a person’s central nervous system processes loads, and what exactly he himself wants to do.

If we are talking about amateur fitness, when the goal of the activity is beauty and health, and not medals and cups of serious competitions, knowledge about the predominant type of muscle fiber can build training program so that you can achieve results faster.

For people with a predisposition to high-repetition work, “bodybuilding” workouts have been created for 8-12 repetitions in basic exercises, and 15-20 repetitions in isolation exercises. Such fitness specialists tolerate cardio exercise well, which means they can successfully fight excess fat deposits.

If you have a predisposition to strength training in a low-rep mode, it would be ideal to master the basics, and, for a beginner, work in the range of 5-6 repetitions, and for those who continue - in fewer repetitions too. It is still necessary to add relatively high-repetition modes of work to achieve more balanced development, but the foundation can be built on training borrowed from the powerlifting arsenal.

In both cases, there is no point in focusing on any one training style; it is better to use a yearly cycle, in which the load will periodically change its volume and intensity.

Most people have approximately the same number of muscle fibers, so combined training, or cycling, is suitable for them. Try to build your training harmoniously, combine different elements in it, and you will definitely achieve your goal, whatever it may be.