Diagnosis of human posture

At the modern level of knowledge, the term "constitution" reflects the unity of a person's morphological and functional organization, reflected in the individual features of its structure and functions. Their changes are the response of the body to the constantly changing environmental factors. They are expressed in the features of the development of compensatory-adaptive mechanisms, formed as a result of the individual implementation of the genetic program under the influence of specific environmental factors (including social factors).

In order to objectify the method of measuring the geometry of the human body with regard to the relativity of its spatial coordinates, the somatic system of coordinates of the human body of Laputin (1976) was introduced into the practice of studying movements.

The most convenient location for the center of the somatic coordinate trihedron is the anthropometric lumbar point 1i located at the apex of the spinous process L, vertebrae (a-5). In this case, the numerical coordinate axis z corresponds to the direction of the true vertical, the x and y axes are located at a right angle in the horizontal plane and determine the movement in the sagittal (y) and frontal (x) directions.

Currently, abroad, particularly in North America, is actively developing a new direction - kinantropometry. This is a new scientific specialization that uses measurements to assess the magnitude, shape, proportion, structure, development and general function of a person, studying the problems associated with growth, exercise, performance and nutrition.

Kinantropometry puts a person at the center of study, allows you to determine its structural status and various quantitative characteristics of the geometry of the masses of the body.

For an objective evaluation of many biological processes in the body associated with its mass geometry, it is necessary to know the specific gravity of the substance from which the human body consists.

Densitometry is a method of estimating the total density of a person's body. Density is often used as a means of estimating fat and skimmed masses and is an important parameter. Density (D) is determined by dividing the mass by the volume of the body:

D body = body weight / body volume

To determine body volume, various methods are used, most often a hydrostatic weighing method or a manometer for measuring displaced water is used.

When calculating the volume by means of hydrostatic weighing, it is necessary to make a correction for the density of water, so the equation will have the following form:

D of the _body = P1 / {(P1-P2) / x1- (x2 + G1r}}

Where p, - body weight in normal conditions, p ₂ - weight in water, x1 - density of water, x2 residual volume.

The amount of air that is in the gastrointestinal tract is difficult to measure, but due to the small volume (about 100 ml), it can be neglected. For compatibility with other measurement scales, this value can be adjusted for growth by multiplying by (170.18 / Growth) 3.

The method of densitometry for many years remains the best for determining the composition of the body. New methods are usually compared with it to determine their accuracy. The weak point of this method is the dependence of the body density index on the relative amount of fat in the body.

When using a two-component model of body composition, high accuracy is required for determining the density of fat and net body weight. The standard Siri equation is most often used to convert the body density index to determine the amount of fat in the body:

% body fat = (495 / D) - 450.

This equation assumes a relatively constant density of fat and net body weight in all people. Indeed, the fat density in different parts of the body is almost identical, the conventional figure is 0.9007 g * cm ^-3. At the same time, it is more problematic to determine the net body mass density (D), which, according to the Siri equation, is 1.1. To determine this density, it is assumed that:

• the density of each tissue, including net body weight, is known and remains unchanged;
• in each kind of tissue the proportion of net body weight is constant (for example, it is assumed that bone is 17% of net body weight).

There are also a number of field methods for determining body composition. The bioelectrical impedance method is a simple procedure that takes only 5 min. Four electrodes are installed on the body of the subject - on the ankle, foot, wrist and back of the hand. By detailed electrodes (on the hand and foot) through the tissues passes an unperceived current to the proximal electrodes (wrist and ankle). The electrical conductivity of the tissue between the electrodes depends on the distribution of water and electrolytes in it. Net body weight includes almost all water and electrolytes. As a result, the conductivity of net body weight significantly exceeds the conductivity of fat mass. Fat mass is characterized by a large impedance. Thus, the amount of current passing through the tissue reflects the relative amount of fat contained in the tissue.

With the help of this method, the impedance parameters are converted into indicators of the relative fat content in the body.

The method of interaction of infrared radiation is a procedure based on the principles of absorption and reflection of light using infrared spectroscopy. On the skin above the measuring point, a sensor is installed, sending electromagnetic radiation through a central bundle of optical fibers. Optical fibers on the periphery of the same sensor absorb the energy reflected by the tissues, which is then measured with a spectrophotometer. The amount of reflected energy shows the composition of the tissue immediately below the sensor. The method is characterized by a sufficiently high degree of accuracy when performing measurements in several areas.

Many measurements of the spatial arrangement of body biopsies were carried out by researchers on corpses. To study the parameters of human body segments over the past 100 years, about 50 corpses were dissected. In these studies, the corpses were frozen, dissected along the axes of rotation in the joints, after which the segments were weighed, the positions of the centers of mass (CM) of the links and their moments of inertia were determined, mainly using the known method of a physical pendulum. In addition, the volumes and average tissue densities of the segments were determined. Studies in this direction were also conducted on living people. At present, for the lifetime determination of the geometry of the masses of a person's body, a number of methods are used: water immersion; photogrammetry; sudden release; weighing the human body in various changing poses; mechanical vibrations; radioisotope; physical modeling; method of mathematical modeling.

The method of water immersion allows us to determine the volume of segments and the center of their volume. By multiplying by the average tissue density of the segments, the experts then calculate the mass and localization of the center of mass of the body. Such a calculation is made taking into account the assumption that the human body has the same tissue density in all parts of each segment. Similar conditions are usually applied when using the photogrammetry method.

In the methods of sudden release and mechanical vibrations, this or that segment of the human body moves under the action of external forces, and the passive forces of ligaments and antagonistic muscles are assumed to be zero.

The method of weighing the human body in various changing poses has been criticized, since the errors introduced by the data taken from the results of the studies on corpses (the relative position of the center of mass on the longitudinal axis of the segment), due to interference caused by respiratory movements, and inaccuracies in reproduction poses with repeated measurements and determination of the centers of rotation in the joints, reach large values. In repeated measurements, the coefficient of variation in such measurements usually exceeds 18%.

At the heart of the radioisotope method (gamma-scan method) lies the familiarity in physics of the attenuation of the intensity of a narrow monoenergetic beam of gamma radiation as it passes through a certain layer of a material.

In the variant of the radioisotope method , two ideas were put forward:

• Increase the thickness of the crystal detector to increase the sensitivity of the device;
• rejection of a narrow beam of gamma radiation. In the course of the experiment, the test subjects determined the massaging characteristics of 10 segments.

As the scan was recorded, the coordinates of the anthropometric points, which are the index of the boundaries of segments, the places of passage of planes separating one segment from the other.

The method of physical modeling was used by making casts of the extremities of the subjects. Then, on their gypsum models, not only the moments of inertia, but also the localization of the centers of mass were determined.

Mathematical modeling is used to approximate the parameters of segments or the whole body as a whole. In this approach, the human body is represented as a set of geometric components, such as spheres, cylinders, cones, and the like.

Harless (1860) was the first to suggest the use of geometric figures as analogues of human body segments.

Hanavan (1964) proposed a model that divides the human body into 15 simple geometric figures of uniform density. The advantage of this model is that it requires a small number of simple anthropometric measurements necessary to determine the position of the common center of mass (CMC) and the moments of inertia at any position of the links. However, three assumptions, as a rule, in the modeling of body segments limit the accuracy of estimates: the segments are assumed to be rigid, the boundaries between the segments are made clear, and segments are assumed to have a uniform density. Based on the same approach, Hatze (1976) developed a more detailed model of the human body. The 17-link model proposed by him to take into account the individualization of the structure of the body of each person requires 242 anthropometric measurements. The model subdivides segments into elements of small mass with different geometric structure, allowing to model in detail the shape and variations of the density of segments. Moreover, the model makes no assumptions about bilateral symmetry, and takes into account the structural features of the male and female body by regulating the density of certain segments (in accordance with the content of the subcutaneous base). The model takes into account changes in the morphology of the body, for example, caused by obesity or pregnancy, and also allows imitating the features of the structure of the children's body.

To determine the partial (partial, from the Latin word pars - part) of the human body dimensions, Guba (2000) recommends on his biofarches to draw reference reference points (reference points) that differentiate between functionally different muscle groups. These lines are drawn between the bone points, determined by the author in the measurements performed during the preparation and dioptrography of cadaveric material, and also checked by observing the performance of typical movements by the athletes.

On the lower extremity, the author recommends the following reference lines. On the hip - three reference lines separating the groups of muscles, extending and bending the knee joint, flexing and leading the hip in the hip joint.

The outer vertical (HB) corresponds to the projection of the anterior margin of the biceps femoris muscle. It is carried along the posterior edge of the large trochanter along the external surface of the thigh to the middle of the outer nadma-femoral cleft.

The front vertical (PV) corresponds to the anterior edge of the long adductor muscle in the upper and middle third of the thigh and the sartorius muscle in the lower third of the thigh. It is carried out from the pubic tubercle to the inner epicondyle of the femur along the anterior inner thigh surface.

The posterior vertical (3B) corresponds to the projection of the anterior margin of the semitendinous muscle. It is carried from the middle of the ischial tuber to the internal epicondyle of the femur along the posterior internal surface of the thigh.

On the lower leg are three reference lines.

The outer calf shank (HBG) corresponds to the anterior edge of the long fibular muscle in its lower third. It is carried from the apex of the fibular head to the anterior edge of the external ankle along the outer surface of the shin.

The anterior vertical of the tibia (PGI) corresponds to the crest of the tibia.

The posterior calf shank (TSH) corresponds to the inner edge of the tibia.

On the shoulder and forearm, two reference lines are drawn. They separate the flexors of the shoulder (forearm) from the extensors.

The outer shoulder vertical (CWP) corresponds to the outer groove between the biceps and triceps muscles of the shoulder. It is carried out with the arm lowered from the middle of the acromial process to the external epicondyle of the humerus.

The internal vertical of the shoulder (GDP) corresponds to the medial humeral groove.

The outer vertical of the forearm (NVPP) is drawn from the outer supracondylosis of the humerus to the subulate process of the radial bone along its outer surface.

The inner vertical of the forearm (VVPP) is drawn from the inner epicondyle of the humerus to the styloid process of the ulna along its inner surface.

The distances measured between the reference lines allow one to judge the severity of individual muscle groups. So, the distances between PV and HB, measured in the upper third of the thigh, allow to judge the severity of the hip flexors. Distances between the same lines in the lower third allow us to judge the severity of extensors of the knee joint. The distances between the lines on the tibia characterize the severity of flexors and extensors of the foot. Using these arc dimensions and the length of the bio-link, it is possible to determine the volumetric characteristics of muscle masses.

The position of the body center of the human body was studied by many researchers. As you know, its location depends on the location of the masses of individual parts of the body. Any changes in the body, connected with the movement of its masses and the violation of their former relationship, change the position of the center of mass.

For the first time, the position of the common center of gravity was determined by Giovanni Alfonso Borelli (1680), who in his book On Locomotion of Animals noted that the center of mass of the human body, which is in a straightened position, is located between the buttocks and the pubis. Using the method of balancing (a lever of the first kind), he determined the location of the OCM on the corpses, placing them on the board and balancing it on a sharp wedge.

Harless (1860) determined the position of the common center of mass on certain parts of the corpse using the Borelli method. Further, knowing the position of the centers of mass of the individual parts of the body, he geometrically summed the gravity forces of these parts and determined the position of the center of mass of the whole body from the given position in accordance with the figure. The same method used to determine the frontal plane of the body's OCM was Bernstein (1926), who used profile photography for the same purpose. To determine the position of the center of the human body, a lever of the second kind was used.

To study the position of the center of mass, much has been done by Braune and Fischer (1889), who conducted their studies on corpses. Based on these studies, they determined that the center of mass of a person's body is located in the pelvic area, on average 2.5 cm below the cape of the sacrum and 4-5 cm above the transverse axis of the hip joint. If the body is pushed forward when standing, the vertical axis of the body's OMC passes ahead of the transverse axes of rotation of the hip, knee and ankle joints.

To determine the position of the body's OCM at various positions of the body, a special model was constructed, based on the principle of using the method of principal points. The essence of this method lies in the fact that the axes of the conjugated links are taken for the axes of the oblique coordinate system, and the connecting links of these joints are taken by their center as the origin. Bernshtein (1973) proposed a method for calculating the BMC of a body using the relative weight of its individual parts and the position of the mass centers of individual links in the body.

Ivanitsky (1956) generalized the methods for determining the human body's OMCM, proposed by Abalakov (1956) and based on the use of a special model.

Stukalov (1956) proposed another method for determining the BMC of a human body. According to this method, the human model was manufactured without taking into account the relative mass of parts of the human body, but indicating the position of the center of gravity of the individual links of the model.

Kozyrev (1963) developed an instrument for determining the center of a human body, the basis of which was the principle of the action of a closed system of levers of the first kind.

To calculate the relative position Zatsiorsky GCM (1981) proposed the regression equation in which the arguments are the ratio of body weight to body weight (x,) and the anteroposterior diameter ratio srednegrudinnogo to pelvic ridge-2 ). The equation has the form:

Y = 52.11 + 10.308x. + 0,949h ₂

Reitzina (1976) proposed the multiple regression equation (R = 0.937, G = 1.5) for determining the altitude of the position of the GCM in female athletes, including the data on the length of the leg (cm), the length of the body in the supine position (x ₂ cm) and the width of the pelvis (x, cm):

Y = -4.667 _Xl + 0.289x ₂ + 0.301x ₃. (3.6)

Calculation of the relative values of the weight of body segments is used in biomechanics, beginning with the XIX century.

As is known, the moment of inertia of the system of material points relative to the axis of rotation is equal to the sum of the products of the masses of these points per squares of their distances to the axis of rotation:

The center of body volume and the center of the body surface are also referred to the parameters characterizing the geometry of the body masses. The center of body volume is the point of application of the resultant force of hydrostatic pressure.

The center of the surface of the body is the point of application of the resultant forces of action of the medium. The center of the surface of the body depends on the posture and direction of the action of the medium.

The human body is a complex dynamic system, therefore the proportions, the ratio of the sizes and masses of its body throughout life constantly changes in accordance with the patterns of manifestation of the genetic mechanisms of its development, as well as under the influence of the external environment, techno-biosocial conditions of life, etc.

The unevenness of growth and development of children is noted by many authors (Arshavsky, 1975, Balsevich, Zaporozhanov, 1987-2002, Grimm, 1967, Kuts, 1993, Krutsevich, 1999-2002), which usually relate this to the biological rhythms of the development of the organism. According to their data, in the period

The greatest increase in anthropometric indices of physical development in children is an increase in fatigue, a relative decrease in working capacity, motor activity and a weakening of the overall immunological reactivity of the organism. Obviously, in the process of development of a young organism, a genetically fixed sequence of structural-functional interaction is preserved in it at certain time intervals. It is believed that this should be due to the need for increased attention of doctors, teachers, parents to children in such age periods.

The process of biological maturation of a person covers a long period - from birth to 20-22 years, when the growth of the body is completed, the skeleton and internal organs are finally formed. Biological maturation of a person is not a planned process, but proceeds heterochronously, which is most clearly manifested even when analyzing the body's shape. For example, comparing the growth rates of the head and legs of a newborn and an adult shows that the length of the head is doubled, and the length of the legs is five times.

The generalization of the results of studies carried out by various authors makes it possible to provide some more or less specific data on the age-related changes in body length. So, according to the literature, the longitudinal dimensions of the human embryo are estimated to be about 10 mm by the end of the first month of the intrauterine period, to 90 mm at the end of the third month, and to 470 mm by the end of the ninth. In 8-9 months the fetus fills the uterine cavity and its growth slows down. The average body length of newborn boys is 51.6 cm (fluctuations in different groups from 50.0 to 53.3 cm), girls - 50.9 cm (49.7-52.2 cm). As a rule, individual differences in the length of the body of newborns, with a normal pregnancy, lie within the range of 49-54 cm.

The greatest increase in body length of children is observed in the first year of life. In different groups, it ranges from 21 to 25 cm (average 23.5 cm). By the year of life, the body length reaches an average of 74-75 cm.

In the period from 1 to 7 years, both in boys and girls, annual increments of body length gradually decrease from 10.5 to 5.5 cm per year. From 7 to 10 years, the body length increases by an average of 5 cm per year. Since the age of 9, sexual differences in the growth rate begin to appear. In girls, a particularly noticeable growth acceleration occurs between the ages of 10 and 11, then the longitudinal growth slows down, and after 15 years is sharply inhibited. In boys, the most intensive growth of the body occurs from 13 to 15 years, and then there is also a slowdown in the growth processes.

The maximum growth rate is observed in the pubertal period in girls between 11 and 12 years, and in boys - 2 years later. Due to the simultaneous occurrence of puberty growth acceleration in individual children, the average maximum speed is somewhat lower (6-7 cm per year). Individual observations show that the maximum growth rate reaches the majority of boys - 8-10 cm, and in girls - 7-9 cm per year. Since the pubertal acceleration of girls' growth begins earlier, the so-called "first crossroads" of the growth curves occur - the girls become taller than boys. Later, when the boys enter the pubertal growth acceleration phase, they again overtake the girls along the length of the body ("second cross"). On average, for children living in cities, the crosses of growth curves fall by 10 years 4 months and 13 years 10 months. Comparing the growth curves characterizing the length of the body of boys and girls, Kuts (1993) indicated that they have a double crossing. The first cross is observed from 10 to 13 years, the second - at 13-14. In general, the laws of the growth process are uniform in different groups and children reach a certain level of the definitive value of the body at about the same time.

Unlike length, body weight is a very labile indicator that comparatively quickly reacts and changes under the influence of exogenous and endogenous factors.

A significant increase in body weight is noted in boys and girls during puberty. In this period (from 10-11 to 14-15 years) the body weight of girls is more than the body weight of boys, and the body weight gain in boys becomes significant. The maximum increase in body weight of both sexes coincides with the greatest increase in body length. According to the data of Chtetsov (1983), from 4 to 20 years, the body weight of boys is increased by 41.1 kg, while the body weight of girls is increased by 37.6 kg. Up to 11 years, the body weight of boys is more than the weight of girls, and from 11 to 15 - girls are heavier than boys. The curves of changes in the body weight of boys and girls cross twice. The first cross is 10-11 years and the second at 14-15.

In boys, there is an intensive increase in body weight in the period of 12-15 years (10-15%), in girls - between 10 and 11 years. In girls, the intensity of body weight gain is more vigorous in all age groups.

The research conducted by Guba (2000) allowed the author to reveal a number of features of the increase in the body's bio-links in the period from 3 to 18 years:

• The dimensions of the body, located in different planes, increase synchronously. This is particularly clearly seen in the analysis of the intensity of growth processes or in the index of the increase in length for the year attributed to the total increase over the growth period from 3 to 18 years;
• Within one limb, the intensity of the increase in the proximal and distal ends of the bioequines is alternating. As we approach mature age, the difference in the intensity of the increase in the proximal and distal ends of the bioplants decreases steadily. This same pattern was revealed by the author in the growth processes of the human hand;
• revealed two growth spikes characteristic of the proximal and distal ends of the biopsy, they coincide in magnitude of the increment, but do not coincide in time. Comparison of the growth of the proximal ends of the upper and lower extremity bioplasm revealed that the upper extremity grows more intensively from 3 to 7 years, and the lower extremity grows from 11 to 15 years. The heterochronicity of limb growth is revealed, that is, in postnatal ontogenesis there is a craniocaudal growth effect, which was clearly revealed in the embryonic period.

[1], [2], [3], [4], [5]