Strength abilities proper are characterized by great muscle tension and are manifested in overcoming, inferior and statistical modes of muscle work. They are determined by the physiological diameter of the muscle and the functionality of the neuromuscular apparatus.
Statistical power is characterized by two of its manifestations: 1) with muscle tension due to active volitional efforts of a person (active statistical power); 2) when external forces try or under the influence of a person's own weight to forcefully stretch a tense muscle (passive static force).
The upbringing of strength abilities proper can be aimed at developing maximum strength (weightlifting, kettlebell lifting, power acrobatics, athletics throwing, etc.); general strengthening of the musculoskeletal system, which is necessary in all sports (general strength) and body building (bodybuilding).
Speed-strength abilities characterized by unsatisfactory muscle tension, manifested with the necessary, often maximum power in exercises performed at a significant speed, but, as a rule, does not reach the limiting value. It manifests itself in motor actions, in which, along with significant muscle strength, speed of movements is also required (for example, repulsion in long and high jumps from a standing position and from a run, final effort when throwing sports equipment, etc.). At the same time, the more significant the external burden overcome by the athlete (for example, when lifting the barbell to the chest), the greater the role of the strength component, and with less burden (for example, when throwing a javelin) the importance of the speed component increases.
Speed-power abilities include: 1) fast power; 2) explosive power. Rapid strength is characterized by unsatisfactory muscle tension, manifested in exercises performed at a significant speed that does not reach the limiting value. Explosive strength reflects the ability of a person to achieve maximum strength indicators in the shortest possible time during the course of a motor action (for example, at a low start in running for short distances, in athletics jumping and throwing, etc.). To assess the level of development of explosive strength, the speed-strength index I is used in movements where the efforts being developed are close to the maximum:
where Fmax is the maximum strength shown in a particular exercise; tmax - maximum time to the moment of reaching Fmax.
Explosive force is characterized by two components: starting force and accelerating force. Starting force is a characteristic of the ability of muscles to rapidly develop working effort at the initial moment of their tension. Accelerating force - the ability of muscles to quickly build up the working effort in the conditions of their contraction that has begun.
Specific types of strength abilities include strength endurance and strength agility.
Strength endurance is the ability to resist fatigue caused by relatively prolonged muscle tension of considerable magnitude. Depending on the mode of muscle work, static and dynamic strength endurance is distinguished. Dynamic strength endurance is typical for cyclical and acyclic activities, and static strength endurance is typical for activities associated with maintaining the working tension in a certain position. For example, when the hands rest on the sides on the rings or when the hand is held when firing from a pistol, static endurance is manifested, and with repeated push-ups in the lying position, squatting with a barbell, the weight of which is 20-50% of the maximum strength of a person, dynamic endurance affects.
Strength agility manifests itself where there is a changeable nature of the mode of muscle work, changing and unforeseen situations of activity (rugby, wrestling, ball hockey, etc.). It can be defined as "the ability to accurately differentiate muscular efforts of various magnitudes in the face of unforeseen situations and mixed modes of muscle work."
In physical education and in sports training, to assess the degree of development of the actual strength abilities, they distinguish between absolute and relative strength. Absolute strength is the maximum force exerted by a person in any movement, regardless of his body weight. Relative strength is the force exerted by a person in terms of 1 kg of a person's own body. In motor actions, where you have to move your own body, relative strength is of great importance. In movements where there is little external resistance, absolute strength does not matter, if the resistance is significant - it acquires an essential role and is associated with the maximum explosive effort.
Research results suggest that the level of a person's absolute strength is largely determined by environmental factors (training, independent exercises, etc.). At the same time, the indicators of relative strength are more influenced by the genotype. Speed-strength abilities are approximately equally dependent on both hereditary and environmental factors. Static strength endurance is determined to a greater extent by genetic conditions, and dynamic strength endurance depends on the mutual (approximately equal) influences of genotype and environment.
The most favorable periods for the development of strength in boys and young men is considered to be from 13-14 to 17-18 years old, and in girls and girls - from 11-12 to 15-16 years old, to which the proportion of muscle cape to the total body weight corresponds to a large extent ( by 10-11 years old it is about 23%, by 14-15 years - 33%, and by 17-18 years - 45%). The most significant rates of increase in relation to the strength of various muscle groups are observed in primary school age, especially in children from 9 to 11 years old. It should be noted that during the indicated periods of time, power abilities in most give in to targeted influences. When developing strength, one should take into account the morphological and functional capabilities of the growing organism.
The tasks of developing strength abilities. The first task is the general harmonious development of all muscle groups of the human musculoskeletal system. It is solved through the use of selective strength exercises. Their volume and content are important here. They must ensure that the different muscle groups develop proportionally. Outwardly, this is expressed in the appropriate body shapes and posture. The intrinsic effect of strength training is to provide high level vital functions of the body and the implementation of physical activity. Skeletal muscles are not only organs of movement, but also a kind of peripheral hearts, actively helping blood circulation, especially venous.
The second task is the versatile development of strength abilities in unity with the development of vital motor actions (abilities and skills). This task involves the development of strength abilities of all basic types.
The third task is to create conditions and opportunities (base) for further improvement of strength abilities in the framework of practicing a specific sport or in terms of professionally applied physical fitness... The solution to this problem allows satisfying a personal interest in the development of strength, taking into account motor endowments, a kind of sport or a chosen profession.
Power is the ability of a person to overcome external resistance or to resist it through muscular efforts (stresses).
Strength abilities - this is a complex of different manifestations of a person in a certain motor activity, which are based on the concept of "strength"
Influence on the manifestation of strength abilities have different factors (the ratio of white and red muscle fibers, physiological diameter and mass of muscles; position of the body in space, features of blood circulation and respiration; hormonal factors; readiness for the manifestation of muscular efforts - motivational and volitional components), age, sex and individual characteristics of a person; environmental conditions in which motor activity is carried out.
Classification of strength abilities (proper strength, speed strength, strength agility, strength endurance).
Distinguish between power abilities proper and their connection with other physical abilities (speed-power, power agility, power endurance)
Power abilities proper manifest themselves: 1) with relatively slow muscle contractions, in exercises performed with near-limit, extreme weights (for example, when squatting with a barbell of a sufficiently large weight); 2) with muscle tension of the isometric (static) type (without changing the length of the muscle). Accordingly, a distinction is made between slow (dynamic) force and static force.
Static force is characterized by two of its manifestations: 1) with muscle tension due to active volitional efforts of a person (active static force); 2) when external forces try or under the influence of a person's own weight to forcefully stretch a tense muscle (passive static force).
The upbringing of strength abilities proper can be aimed at developing maximum strength (weightlifting, kettlebell lifting, power acrobatics, athletics throwing, etc.); general strengthening of the musculoskeletal system of those involved, necessary in all sports (general strength) and body building (bodybuilding).
Speed-strength abilities They are manifested in motor actions, in which, along with significant muscle strength, speed of movements is also required (for example, repulsion in long and high jumps from a place and from a run, final effort when throwing sports equipment, etc.).
Speed-power abilities include: 1) fast power; 2) explosive power. Fast power characterized by unsatisfactory muscle tension, manifested in exercises that are performed at a significant speed that does not reach the limiting value. Explosive power reflects the ability of a person, in the course of performing a motor action, to achieve maximum strength indicators in the shortest possible time (for example, at a low start in running for short distances, in athletics jumping and throwing, etc.).
Explosive force is characterized by two components: starting force and accelerating force. Starting force - This is a characteristic of the ability of muscles to rapidly develop working effort at the initial moment of their tension. Accelerating force- the ability of muscles to quickly build up the working effort in the conditions of their contraction that has begun.
Specific types of strength abilities include strength endurance and strength agility.
Strength endurance is the ability to resist fatigue caused by relatively prolonged muscle tension of considerable magnitude. Depending on the mode of muscle work, static and dynamic strength endurance is distinguished. Dynamic strength endurance is characteristic of cyclic and acyclic activity, and static strength endurance is typical for activities associated with maintaining the working tension in a certain position (when the hands are resting on the sides on the rings - static endurance, and with repeated push-ups in the lying position - dynamic endurance).
Strength agility manifests itself where there is a changeable nature of the mode of muscle work, changing and unforeseen situations of activity (rugby, wrestling, ball hockey, etc.). It can be defined as "the ability to accurately differentiate muscular efforts of various magnitudes in the face of unforeseen situations and mixed modes of muscle work."
In physical education and in sports training to assess the degree of developmentproper power abilities distinguish between absolute and relative strength. Absolute strength is the maximum force shown by a person in any movement, regardless of his body weight. Relative strength - the force exerted by a person in terms of 1 kg of his own weight. It is expressed by the ratio of maximum strength to human body weight. In motor actions, where you have to move your own body, relative strength is of great importance. In movements where there is little external resistance, the absolute force does not matter, if the resistance is significant - it acquires an essential role and is associated with the maximum explosive effort.
The level of a person's absolute strength is largely determined by environmental factors (training, independent exercises, etc.), the indicators of relative strength are more influenced by the genotype.
The most favorable periods for the development of strength in boys and young men is considered to be from 13-14 to 17-18 years old, and in girls and girls - from 11-12 to 15-16 years old. The most significant rates of increase in the relative strength of various muscle groups are observed in primary school age, especially in children from 9 to 11 years old.
Metrology of strength. Quantitative power capabilities are assessed in two ways: 1) using measuring devices - dynamometers, dynamographs; 2) with the help of special control exercises, strength tests.
Measuring devices measure force muscle groups in standard tasks (flexion and extension of body segments), as well as in static and dynamic efforts (measuring the strength of an athlete's action in motion). To assess the level of development of strength qualities, special control exercises (tests) are used. To determine the maximum strength - bench press, squat with a bar, etc.
To determine the level of development speed-strength abilities and strength endurance control exercises: jumping rope, pull-ups, push-ups, lifting the torso, hanging on bent and half-bent arms, long jump from the spot, raising and lowering straight legs to the limiter, throwing a medicine ball (1 - 3 kg), etc. According to control tests, standards were drawn up and levels (high, medium, low) were developed, characterizing different power capabilities.
Power -it is the ability to overcome external resistance through muscular effort.
The strength of a muscle depends on its diameter. Its increase is accompanied by an increase in the strength of this muscle. The increase in muscle size as a result of physical exercise is called working muscle hypertrophy. Muscle fibers are highly specialized differentiated cells, apparently incapable of cell division with the formation of new fibers. The division of muscle cells takes place only in special cases and in very small numbers.
Working muscle hypertrophy occurs almost or exclusively due to the thickening of existing muscle fibers.
With a significant thickening of muscle fibers, their longitudinal mechanical splitting is possible with the formation of daughter fibers with a common tendon. During strength training, the number of longitudinally split fibers increases.
Two extreme types of working hypertrophy of muscle fibers can be distinguished - sarcoplasmic and myofibrillar. Sarcoplasmic working hypertrophy is a thickening of muscle fibers due to a predominant increase in the volume of sarcoplasm, that is, not their contractile part. Hypertrophy of this type occurs due to an increase in the content of non-contractile (in particular, mitochondrial) proteins and metabolic reserves of muscle fibers: glycogen, without nitrogenous substances creatine phosphate, myoglobin, etc. A significant increase in the number of capillaries as a result of training can also cause some muscle thickening.
The most susceptible to sarcoplasmic hypertrophy are apparently slow and fast oxidative fibers.
Working hypertrophy of this type has little effect on the growth of muscle strength, but at the same time significantly increases the ability to work for a long time, that is, increases their endurance.
Myofibrillar working hypertrophy is associated with an increase in the number and volume of myofibrils, that is, the actual contractile apparatus of muscle fibers. This increases the packing density of myofibrils in the muscle fiber. This working hypertrophy of muscle fibers leads to a significant increase in muscle MS. The absolute strength of the muscle also increases significantly, and with working hypertrophy of the first type, it either does not change at all, or even slightly decreases. Apparently, fast muscle fibers are most prone to myofibrillar hypertrophy.
In a real situation, muscle fiber hypertrophy is a combination of the two named types with a predominance of one of them. Long-term dynamic exercises that develop endurance with a relatively small force load on the muscles cause mainly work hypertrophy of the first type. Exercises with high muscle tension (more than 70% of the MPS of the trained muscle groups), on the contrary, contributes to the development of working hypertrophy, mainly of the second type.
At the heart of working hypertrophy is intense synthesis and reduced breakdown of muscle proteins. Accordingly, the concentration of DNA and RNA in the hypertrophied muscle is higher than in the normal one. The creatine content of which is increased in the contracting muscle can stimulate increased synthesis of actin and myosin and thus contribute to the development of working hypertrophy of muscle fibers.
The following types of power abilities can be distinguished:
1. Own power (in static modes and slow movements).
2. Speed-power (dynamic force in fast movements).
Muscle strength measured under dynamic muscle conditions is referred to as dynamic strength. An increase in dynamic strength resulting from dynamic training may not cause an increase in static strength. Isometric exercises either do not increase dynamic strength, or increase significantly less than statistical strength. All this points to the extreme specificity of training effects: the use of a certain type of exercise (statistical or dynamic) causes the most significant increase in the result in this particular type of exercise. The greatest increase in muscle strength is found at the same speed of movement at which training occurs.
An important variety is " explosive power"- the ability to exercise large amounts of force in the least amount of time.
One of the varieties of muscle strength is the so-called explosive strength, which characterizes the ability to quickly manifest muscle strength. Explosive strength is understood as the ability to overcome resistance with high speed muscle contraction, as well as - in the course of movement to achieve large indicators of the displayed strength in the shortest possible time.
It largely determines, for example, the height of an upward jump with straight legs or a long jump from a place, the maximum possible speed running on short stretches. As indicators of explosive strength, force gradients are used, i.e., the rate of its growth, which is defined as the ratio of the maximum exerted force to the time of its achievement, or as the time to reach a certain selected level of muscle strength (absolute gradient), or half of the maximum force, or some other part of it (relative force gradient). The power gradient is higher in speed-strength sports than in non-athletes or endurance athletes. Differences in absolute force gradients are especially significant.
Explosive force indices depend little on the maximum arbitrary isometric force. So, isometric exercises, increasing static strength, insignificantly change explosive strength, determined by the indicators of the force gradient or by indicators, for example, jumping ability. Therefore, the physiological mechanisms responsible for explosive strength are different from those responsible for static strength. Among the coordination factors, an important role in the manifestation of explosive strength is played by the nature of the impulse of motor neurons of active muscles - the frequency of their impulse at the beginning of the discharge and the synchronization of impulse of different motor neurons. The higher the initial frequency of impulses of motor neurons, the faster the muscle strength grows.
Explosive power depends on overall ability the neuromuscular system to the manifestation of significant stresses in a short period of time, from the absolute strength of the muscles, manifested at their maximum tension without time limitation: from the specific ability of muscles to a rapid increase in effort at the beginning of movement.
When a fast force is manifested in a single movement, its magnitude (with the same weights) is less than when an explosive force is manifested in the same movements. Rapid strength can be manifested both with the overcoming and inferior nature of the work of the muscles separately, and with an emphasis on their combination. The features of the mechanism of muscle contraction can apparently be attributed to the following: the manifestation of the rapid strength of each individual muscle is associated not so much with synchronization, but with the asynchronization of active motor units with a high (but not reaching the limit values) degree of tension at the optimal frequency of nerve impulses, coming through the motor nerve.
In the manifestation of explosive strength, the high-speed contractile properties of muscles play a very large role, which largely depend on the composition, that is, the ratio of fast and slow fibers. Fast fibers make up the bulk of muscle fibers in highly qualified representatives of speed-strength sports. During training, these fibers undergo more significant hypertrophy than slow fibers. Therefore, in athletes of speed-strength sports, fast fibers make up the bulk of the muscles (otherwise they occupy a much larger area on the cross section) in comparison with representatives of other sports, especially those that require predominantly endurance.
In the theory and methodology of sports, explosive strength and speed-strength abilities are identical concepts. Explosive strength reflects a person's ability to rapidly build up working muscle tension to the maximum possible.
Explosive strength is manifested in the overcoming nature of the work of muscles in many motor actions, where it is necessary to show the maximum possible strength under these conditions in a minimum time. This is typical for sprint running, various kinds of jumping exercises, throwing and other actions, in games, martial arts.
Under the action of explosive force, speed and strength do not reach absolute greatness, however, the developed force always exceeds the value of the burden. Depending on the amount of weight applied, different values \u200b\u200bof the maximum dynamic force can be achieved. When overcoming the limiting weights, allowing to develop acceleration, the maximum force reaches the absolute values \u200b\u200bfor the dynamic force.
The features of the mechanism of muscle contraction during explosive force include the following: when overcoming small weights, when the time of effort is limited, not all are synchronized, but the maximum possible number of motor units with the highest degree tension of individual muscle fibers. At the same time, it is of particular importance to maintain the optimal frequency of incoming nerve impulses.
As the value of the overcome resistance increases, the number of synchronized motor units increases. When overcoming the maximum values \u200b\u200b(allowing to maintain acceleration during movement), the largest number of active motor units is included in the work.
With explosive force, there may be no tension in the antagonist muscles. This feature is associated with the high rate of mobilization of chemical energy located in the muscles and its transformation into mechanical energy, and the value depends not only on the content of ATP and its analogs in the muscles, but also on the rate of its splitting at the moment of the motor impulse entering the muscle and its subsequent resynthesis. For the manifestation of explosive strength, when it is required to overcome weights at maximum speed, maximum speed will also be of particular importance. cleavage of ATP per unit of time. The number and rate of cleavable ATP molecules depend on the enzymatic activity of myosin. The peculiarities of the chemistry of the manifestation of rapid strength in single acyclic exercises basically boils down to the fact that the decay of ATP per unit time will be somewhat less than with explosive force, in other words, the decay rate of ATP is somewhat less. As for the chemistry of the manifestation of rapid strength in repeated cyclic exercises, it is fundamentally different. As you know, the reserves of creatine phosphate are not large enough to provide energy for all the work. The creatinophoskinase reaction reaches its maximum at 2-3 seconds of work, after which it decreases rapidly. The main source of energy for ATP resynthesis then becomes the respiratory mechanism associated with the aerobic performance of the body. In this case, glycogen stores are used, which are not only in the muscles, but also deposited in the liver. The body develops a significant oxygen debt.
Explosive strength reflects a person's ability to quickly build up working muscle tension to the maximum possible (jumping, throwing and hitting, undermining the barbell in a snatch, and others). Explosive power can be divided into two components; starting force and accelerating force.
Starting force is a characteristic of the muscle's ability to rapidly develop working effort at the initial moment of their tension.
Accelerating force - the ability of muscles to quickly build up the working effort in the conditions of the beginning of their contraction.
The level of explosive strength is determined by two components acting in an organic unity - speed and power. The magnitudes of the explosive force are determined by the possibility of the total tension of all muscle groups participating in the movement, which is possible only with perfect intermuscular coordination. However, intermuscular coordination is improved only if the exercises are performed with a competitive speed or faster. Of course, this is only possible when using relatively small weights. Such work helps to improve the speed component of the explosive force, but does not affect the development of the force component. An increase in weights above the competition has the opposite effect; the power component is being improved in the absence of a positive effect on the development of the speed component. This pattern is typical for dynamic operation. The use of the isokinetic regime when performing movements at high speed allows one to overcome this contradiction and, in parallel, improve both components of the explosive force. The improvement of the speed and power components of the explosive force should be carried out in parallel.
Distinguish absolute and relative strength.
Absolute strength is determined by the maximum indicators of muscle tension without taking into account the body weight of a person. The absolute strength can be characterized, for example, by the indicators of the dynamometer, the limit weight of the lifted bar.
Relative strength determinedthe ratio of the magnitude of the absolute force to its own body mass. In people with approximately the same level of fitness, an increase in body weight leads to an increase in absolute strength, but the value of relative strength decreases.
The drop in relative strength is explained by the fact that the weight of a person's own body is proportional to the volume of the body, that is, to the cube of its linear dimensions; the force is proportional to the physiological diameter, that is, to the square of the linear dimensions. Consequently, with an increase in body size, its weight will increase faster than muscle strength grows.
For success in some sports (for example, for absolute achievement in weightlifting), absolute strength is important above all.
In those sports that involve multiple movements of athletes of their bodies or where weight gain is limited to weight categories, relative strength becomes decisive. So, for example, in gymnastics, hand support to the sides on the rings ("cross") can be performed only by athletes whose relative strength in this movement is close to 1 kg. Per kilogram of weight. (sixteen)
In the process of motor skills formation, the main motor abilities are developed: speed, endurance, motor-coordination, flexibility and strength.
Human muscles can exhibit force:
without changing its length - isometric mode;
with decreasing fiber length - overcoming mode;
with increasing fiber length - inferior mode.
In this regard, strength abilities can be classified into the following physical qualities (Figure 5.1.):
Figure 5.1. Classification of strength abilities
2. Factors determining the development of strength abilities
Factorsensuring the development of strength abilities:
Personally - mental (emotional).
Physiological.
Composition (composition) of muscle fibers, the ratio of weak and more excitable slow muscle fibers (oxidative, less fatigued) and more powerful high-threshold fast muscle fibers (glycolytic, fatigued).
Activating manymotor units (DE) - with an increase in the number of MUs involved in the motor act, the muscle contraction force increases.
Intermuscular coordination - muscle strength depends on the activity of other muscle groups: muscle strength grows while its antagonist relaxes, it decreases while other muscles contract and increases when the trunk or individual joints are fixed by antagonist muscles. For example, when lifting the barbell, the phenomenon of straining occurs (exhalation with a closed glottis), which leads to fixation by the muscles of the athlete's torso and creates a solid foundation for overcoming the weight being lifted.
Hormone.Male sex hormones (androgens) play an important role in the development of strength, which ensure the growth of the synthesis of contractile proteins in skeletal muscles. Men have 10 times more of them than women.
Biomechanical.The location of the body and its links in space affects the magnitude of the force of action due to unequal stretching of muscle fibers in different initial postures of a person: the more the muscle is stretched, the greater the magnitude of the force shown.
Temperature.With an increase in body temperature, the rate of metabolic processes increases, along with this, muscle contractility increases.
Pharmacological.The discovery of the "androgen effect" led to attempts by a number of coaches and athletes to use the analogs of sex hormones - anabolic steroids - to develop strength. However, the harmful effects of their intake were soon discovered. Particularly severe consequences from the use of anabolic steroids are observed in adolescents. As a result, such drugs were classified as prohibited doping.
3. Sensitive periods of development of strength abilities
Age-related development of muscle mass goes along with the increase in the production of androgenic hormones. With the onset of puberty (at the age of 11-15), an intensive increase in muscle mass in boys begins, which continues after puberty. In girls, the development of muscle mass generally ends with puberty. The growth of muscle strength at school age has a corresponding character. According to Professor P.V. Zimkina, in the period from 8 to 18 years old, muscle strength increases 2.5 times.
Even after correcting strength indicators with body size, strength indicators in adult women are lower than in men. At the same time, if in women as a result of certain diseases the secretion of androgens by the adrenal glands increases, then muscle mass increases intensively, a well-developed muscle relief appears, and muscle strength increases.