Character and organization labor activity have a significant impact on the change in the functional state of the human body. The various forms of labor activity are divided into physical and mental labor.
Physical work It is characterized by a load on the musculoskeletal system and functional systems of the human body (cardiovascular, neuromuscular, respiratory, etc.), which ensure its activity. Physical labor, while developing the muscular system and stimulating metabolic processes, at the same time has a number of negative consequences. First of all, it is the social inefficiency of physical labor associated with its low productivity, the need for high physical exertion and the need for long-term (up to 50% of working time) rest.
Brainwork combines works related to the reception and processing of information that requires a predominant sensory apparatus, attention, memory, as well as the activation of thought processes, the emotional sphere. This type of labor is characterized by hypokinesia, i.e. a significant decrease in human motor activity, leading to a deterioration in the reactivity of the body and an increase in emotional stress. Hypokinesia is one of the conditions for the formation of cardiovascular pathology in mental workers. Prolonged mental stress has a depressing effect on mental activity: the functions of attention (volume, concentration, switching), memory (short-term and long-term), perception deteriorate (a large number of errors appear).
In modern human labor activity, the volume of purely physical labor is insignificant. In accordance with the existing physiological classification of labor activity, there are:
Forms of labor that require significant muscle activity. This type of labor activity takes place in the absence of mechanized means for performing work and is characterized by increased energy costs;
mechanized forms of labor. A feature of mechanized forms of labor is the change in the nature of muscle loads and the complication of the action program. Under the conditions of mechanized production, there is a decrease in the volume of muscle activity, small muscles of the limbs are involved in the work, which should provide greater speed and accuracy of movements necessary to control the mechanisms. The monotony of simple and mostly local actions, the monotony and the small amount of information perceived in the process of labor lead to the monotony of labor and the rapid onset of fatigue;
Forms of labor associated with semi-automatic and automatic production. With such production, a person is excluded from the process of direct processing of the object of labor, which is entirely performed by the mechanism. The task of a person is limited to performing simple operations for servicing the machine: submit material for processing, set the mechanism in motion, remove the machined part. Characteristic features of this type of work: monotony, increased pace and rhythm of work, loss of creativity;
Group forms of labor - assembly line. This form of labor is determined by the division of the labor process into operations, a given rhythm, a strict sequence of operations, automatic supply of parts to each workplace using a conveyor. At the same time, the shorter the time interval spent by the worker on the operation, the more monotonous the work, the more simplified its content, which leads to premature fatigue and rapid nervous exhaustion;
Forms of work associated with remote control. With these forms of labor, a person is included in the management system as a necessary operational link, the load on which decreases with an increase in the degree of automation of the management process. There are forms of production process control that require frequent human actions, and forms of control in which the operator's actions are episodic, and his main task is to control instrument readings and maintain constant readiness to intervene, if necessary, in the process of managing an object;
Forms of intellectual (mental) labor are divided into operator, managerial, creative, labor medical workers, work of teachers, pupils, students. These types differ in the organization of the labor process, the uniformity of the load, the degree of emotional stress.
The work of the operator is characterized by great responsibility and high neuro-emotional stress. For example, the work of an air traffic controller is characterized by the processing of a large amount of information in a short time and increased neuro-emotional tension.
The work of the head of institutions, enterprises (managerial work) is determined by an excessive amount of information, an increase in the shortage of time for its processing, increased personal responsibility for decisions taken, periodic occurrence of conflict situations.
The work of teachers and medical workers is characterized by constant contacts with people, increased responsibility, often lack of time and information to make the right decision, which causes the degree of neuro-emotional stress.
The work of pupils and students is characterized by the tension of the main mental functions, such as memory, attention, perception; the presence of stressful situations (exams, tests).
The most complex form of labor activity, which requires a significant amount of memory, stress, attention, is creative work. The work of scientists, designers, writers, composers, artists, architects leads to a significant increase in neuro-emotional stress. With such tension associated with mental activity, one can observe tachycardia, an increase in blood pressure, an increase in pulmonary ventilation and oxygen consumption, an increase in body temperature and other changes in the autonomic functions of a person.
ENERGY BALANCE- the difference between the amount of energy supplied with food and the energy expended organism.
Work Exchange is the amount of energy required to do external work. The total energy requirement for mental work is 2500 - 3200 kcal (10 475 - 13 410 kJ), for mechanized labor or light non-mechanized work - 3200 - 3500 kcal (13 410 - 14 665 kJ), for partially mechanized labor or moderate non-mechanized work gravity. 3500 - 4500 kcal (14 665 - 18 855 kJ), with heavy non-mechanized physical labor - 4500 - 5000 kcal.
Energy exchange during physical labor
Muscular work significantly increases energy consumption, so the daily energy consumption of a healthy person who spends part of the day in motion and physical work, significantly exceeds the value of the main exchange. This increase in energy expenditure constitutes a working increase, which is greater, the more intense the muscular work.
During muscular work, thermal and mechanical energy is released. The ratio of mechanical energy to all the energy expended on work, expressed as a percentage, is called the efficiency. With physical labor of a person, the efficiency varies from 16 to 25% and averages 20%, but in some cases it can be higher.
The efficiency factor varies depending on a number of conditions. So, in untrained people, it is lower than in trained people, and increases with training.
The more intense the muscular work performed by the body, the greater the energy expenditure. The degree of energy expenditure during various physical activities is determined by the coefficient of physical activity (CFA), which is the ratio of total energy expenditure for all activities per day to the value of the main metabolism. According to this principle, the entire male population is divided into 5 groups (Table 10.5)
Significant differences in energy requirements in groups depend on gender (more for men), age (decrease after 40 years), the degree of recreational activity and the level of public services.
In old age, energy consumption decreases and by the age of 80 is 8373-9211 kJ (2000-2200 kcal).
Energy exchange during mental work
With mental labor, energy consumption is much lower than with physical labor.
Difficult mathematical calculations, work with a book and other forms of mental labor, if they are not accompanied by movement, cause an insignificant (2-3%) increase in energy expenditure compared to complete rest. However, in most cases, various types of mental labor are accompanied by muscular activity, especially when the worker is emotionally aroused (lecturer, artist, writer, speaker, etc.), and therefore energy consumption can be relatively large. Experienced emotional arousal can cause an increase in metabolism by 11-19% over the next few days.
Types of energy costs
For each person, the amount of energy entering his body and the amount of energy that is expended in the process of his activity is of great importance. It is important that the income and expenditure of energy are in a ratio that allows a person to feel vigorous and healthy.
Allocate such energy costs:
- unregulated;
- Adjustable.
Unregulated are the energy costs for BX and the specifically dynamic action of food. The basal metabolic energy is expended in order to ensure the work internal organs, goes to redox reactions and maintaining a constant temperature of the human body.
Remark 1
In other words, BX- This is the minimum level of energy consumption that supports the vital functions of the body.
It can be determined under the condition of complete muscular and nervous rest. Value basal metabolism associated with body weight, height, age, gender, the state of the endocrine system, i.e. with the individual characteristics of each person. As a rule, for women, for example, the basic exchange rate is $5$ -$10$% lower than that of men. In children, it is higher than in adults, relative to body weight, by $10$ -$15$%. In increasing the basal metabolism, the specific dynamic action of food associated with the process of digestion plays its role. The basal metabolic rate will be $30$-$40$% higher with protein digestion, $4$-$14$% with fat digestion, and $4$-$5$% with carbohydrate digestion. If the diet is mixed, then the increase in basal metabolism occurs on average by $10$ -$15$%, subject to the optimal amount of digested products.
To the group regulated energy costs include the energy costs in the process of various human activities. As a rule, the greatest energy costs are associated with physical work, because in the working muscles there is a significant increase in oxidative processes. The intensity of muscle movements increases the level of energy consumption. BX when walking calmly, it increases by $ 80 - $ 100 $ %, and while running - by $ 400 $ %.
For energy cost estimates There are several methods, the most accurate of which is direct calorimetry. Its essence is connected with measuring the amount of thermal energy released during the performance of any work in special chambers with a high degree of thermal insulation. The method does not provide the possibility of measurements in many types of activities and requires long-term observations.
Less accurate, but more accessible and simple, is the method indirect nutritional calorimetry. When using this method, the amount of food consumed is calculated and body weight is monitored.
Energy consumption at physical activity determined heart rate integration method. The bottom line lies in fixing the heart rate with the help of equipment throughout the work.
Forms of activity and energy costs
Human activity is associated with energy costs, which depend on the intensity of muscle work, the working posture of the body, the information saturation of labor, emotional stress, temperature, humidity, air velocity and other factors. Due to the work of the muscles of the body in the sitting position, energy expenditure exceeds the level of basal metabolism by $5$…$10$%, in the standing position by $10$…$15$%, and the forced uncomfortable posture leads to an increase by $40$…$50$%. Different forms of human activity have different hygienic standards for daily energy consumption.
According to energy consumption, the following groups are distinguished:
Employees mental labor. Representatives of this group are business leaders, teachers, scientists, doctors, writers, journalists, students. For men of this group, the daily energy consumption is $2550-$2800 kcal, for women - $2200-$2400 kcal, the average value is $40 kcal/kg of body weight.
Employees light physical labor- workers of automated lines, sewers, veterinarians, agronomists, nurses, sellers of industrial goods, trainers, physical education instructors. Men spend $3000$-$3200$ kcal per day, women of this group spend $2550-$2700 kcal. The average value increases to $43$ kcal/kg of body weight.
Work medium in severity. The workers in this group are surgeons, drivers, workers in the food industry, water transport, food vendors. Energy consumption for men per day is $3200-$3650 kcal and for women $2600-$2800 kcal. For $1$ kg of body weight, energy costs increase to $46$ kcal.
Workers employed hard physical labor- these are builders, metallurgists, machine operators, athletes, agricultural workers. Their daily energy consumption is the highest and for men it is $3700-$4250 kcal, for women it is $3150-$3900 kcal, with an average of $53 kcal/kg of body weight.
The last group includes people particularly hard physical labor. This group includes steelworkers, miners, lumberjacks, loaders, with daily energy consumption for men $3900$-$4300$ kcal. Consumption for women is not standardized. The average energy expenditure per $1$ kg of body weight is $61$ kcal.
Remark 2
The listed energy costs are calculated for men weighing $70$ kg, and for women weighing $60$ kg.
For each group, it is important to observe three age categories:
- From 19 to 28 years old;
- 30 to 39 years old;
- From 40 to 59 years old.
Organization of a rational mode of work and rest
To improve efficiency and prevent fatigue, it is important to be able to properly and rationally organize the regime of work and rest. In the mode, it is necessary to determine the time and duration of breaks for rest during the working day. In the middle of the working day, as a rule, a long lunch break is provided, in addition to which it is important to include short breaks during labor day. So that monotonous work on the assembly line does not lead to fatigue, $5$ -$10$ minute breaks are introduced into the mode after each hour of work, you can turn on calm music that has a beneficial effect on performance. Active recreation is also included in the rational organization of the labor regime.
Remark 3
More THEM. Sechenov, who proved that tired muscles quickly restore their performance when other muscles work, substantiated the expediency of outdoor activities from a physiological point of view.
Under production conditions, the discovery of the scientist was used in the form of a set of physical exercises, specially designed for this. But it was a distant Soviet past, when, indeed, the morning of the whole country began with exercises. Nowadays, morning exercises are done, perhaps, only in kindergartens and in the army, but some companies may be an exception, where employees are forced to spend the whole working day sitting at a computer monitor. True, in the country's schools, too, during the lesson, it is necessary to resort to short physical education sessions.
Remark 4
In general, a set of special exercises, selected for people of different specialties, performs very important work- first of all, it helps to improve the activity of the cerebral cortex, activates the functional processes of the whole organism, increases emotional tone and, as a rule, performance.
Energy costs for morning exercises per minute is $ 0.0648 kcal / kg of body weight. The highest level of efficiency, in accordance with the daily cycle, is observed in the morning and afternoon hours. Accordingly, from $8$-$12$ hours and from $14$-$17$ hours.
By the evening performance goes down and at night reaches its minimum.
different performance and in a week. On Monday, there is an induction into the labor process after a day off, and the highest level falls on the $2$-th, $3$-th, $4$-th day of the working week. By the end of the week performance declining.
There are 3 principles for establishing a rational regime of work and rest:
- Production needs (they must be satisfied);
- The highest working capacity of the employee (it must be ensured);
- Public and private interests (they must be combined).
Remark 5
Thus, a comprehensive socio-economic approach is needed when choosing the optimal mode of work and rest. This approach has a specific goal - to give a complete and comprehensive assessment of its optimization from the point of view of both personal and public interests, the interests of production and the physiological capabilities of a person.
The level of human energy consumption in various forms of activity serves as a criterion for the severity and intensity of the work performed, is of great importance for optimizing working conditions and its rational organization. Energy consumption level determined by the method of complete gas analysis, while taking into account the volume of oxygen consumption and carbon dioxide released. With an increase in the severity of labor, oxygen consumption and the amount of energy consumed increase significantly.
The severity and intensity of work characterized by the degree of functional stress of the body. It can be energetic, depending on the power of work (during physical labor), and emotional (during mental labor), when information overload occurs.
Physical work It is characterized by a high load on the body, requiring predominantly muscle effort and appropriate energy supply, and also affects the functional systems (cardiovascular, neuromuscular, respiratory, etc.), stimulates metabolic processes. Its main indicator is heaviness. Energy consumption during physical labor, depending on the severity of the work, is 4000-6000 kcal per day, and with a mechanized form of labor, energy costs are 3000-4000 kcal.
Brainwork combines work related to the reception and transmission of information, requiring activation of the processes of thinking, attention, memory. This type of labor is characterized by a significant decrease in motor activity. Main indicator mental labor is tension, reflecting the load on the central nervous system. Energy consumption during mental work is 2500–3000 kcal per day. But energy costs vary depending on the working posture. So, in a working posture sitting, energy costs exceed the level of basal metabolism by 5-10%; standing - by 10-25%, with a forced uncomfortable posture - by 40-50%. With intensive intellectual work, the brain's need for energy is 15-20% of the total metabolism in the body.
The increase in total energy costs during mental work is determined by the degree of neuro-emotional tension. Daily energy expenditure during mental work increases by 48% when reading aloud while sitting, by 90% - when lecturing, by 90-100% - among computer operators. In addition, the brain is prone to inertia, because after the cessation of work, the thought process continues, which leads to greater fatigue and exhaustion of the central nervous system than during physical labor.
The severity and intensity of work. Static and dynamic loads. The monotony of work.
The severity of labor is a quantitative characteristic of physical labor.
Labor intensity is a quantitative characteristic of mental labor. It is determined by the amount of information load.
In production (in accordance with the hygienic classification of labor R.2.2.013-94), there are four levels of exposure to factors of working conditions on a person:
1. comfortable working conditions ensure the optimal dynamics of human performance and the preservation of his health;
2. relatively uncomfortable working conditions, when exposed for a certain period of time, provide a given performance and health preservation, but cause subjective sensations and functional changes that do not go beyond the norm;
3. extreme working conditions lead to a decrease in human performance, do not cause functional changes that go beyond the norm, but do not lead to pathological changes;
4. super-extreme working conditions lead to pathological changes in the human body and loss of ability to work.
Medical and physiological classification of the severity and intensity of labor is carried out on the basis of a comprehensive quantitative assessment of the factors of working conditions, called the integral value of the severity and intensity of labor.
Category III includes work in which, due to not quite favorable working conditions, people develop reactions characteristic of the borderline state of the body (deterioration of some indicators of the psychophysiological state by the end of work).
Category V includes work in which, as a result of exposure to very unfavorable working conditions, people at the end of the working period develop reactions characteristic of the pathological functional state of the body.
Dynamic load - a load characterized by a rapid change in time of its value, direction or point of application and causing significant inertial forces in structural elements. Dynamic loads are experienced by parts of impact machines, such as presses, hammers, etc. Parts of crank mechanisms also experience significant dynamic loads during operation from changes in the magnitude and direction of speeds, that is, the presence of accelerations. Impact loads are also referred to as dynamic loads. When designing parts of a structure that are under the action of shock or vibration load from mills, engines, hammers, etc., a calculation is made for the effect of dynamic load. To eliminate dynamic loads, they are reduced or limited, for example, using an electric drive, braking devices and other mechanisms.
Static load - load, the magnitude, direction and point of application of which change slightly over time. In strength calculations, the influence of inertial forces caused by such a load can be neglected. A static load, for example, is the weight of a structure.
Monotony is the same repetition of work operations. The danger of monotony lies in the reduction of attention to the production process, rapid fatigue and a decrease in interest in the labor process, which affects labor safety in general. One of the forms predisposing to the formation of monotony is automatism - an activity carried out without the direct participation of consciousness. It is formed as a result of several factors: many years of experience, routine work, lack of involvement in the labor process, imagination and creativity, physical overload. Special meaning this is in complex industries or industries with harmful working conditions, where accuracy and attention are crucial. Monotony is accompanied by boredom, apathy to work. But it cannot be precisely determined that the performance of these particular actions is a monotonous and boring task. Each person determines for himself the type of his activity and gives it his own objective assessment. For example, one employee working on an assembly line considers his work monotonous and boring, while another, on the contrary, considers it very interesting. Many people involved in dynamic, active work, which cannot be called monotonous, they consider it boring, uninteresting.
In such cases, much depends on motivation.
Therefore, strict observance of labor safety regulations, control over the labor process and the alternation of periods of work and rest (physical minutes and others) are of decisive importance.
microclimate well-being people energetic
Labor activity requires from a person high mobility of nervous processes, fast and precise movements, increased activity of perception, attention, memory, thinking, emotional stability. The study of a person in the labor process is carried out by physiology and psychology of labor, as well as other sciences, such as engineering psychology, ergonomics, technical aesthetics, etc.
Occupational physiology is a section of occupational hygiene devoted to the study of changes in the functional state of the human body under the influence of production activities and the development of recommendations for the organization of the labor process.
Diverse forms of labor activity are conventionally divided into physical and mental labor. Physical labor requires great muscular activity and takes place in the absence of mechanized means for work (the labor of a steelworker, loader, vegetable grower, etc.). It develops the muscular system, stimulates metabolic processes in the body, but at the same time it is socially inefficient, has low productivity, and requires a long rest.
The mechanized form of labor requires social knowledge and long-term skills; small muscles of the arms and legs are included in the work, which ensure the speed and accuracy of movement, but the monotony of simple actions, the small amount of perceived information leads to the monotony of labor.
The work associated with automatic and semi-automatic production has the following disadvantages: monotony, increased pace and rhythm of work, lack of creativity, since the mechanism is engaged in the processing of objects, and the person performs simple machine maintenance operations.
Conveyor work is distinguished by the fragmentation of the process into operations, a given pace and rhythm, and a strict sequence of operations. Its disadvantage is monotony, leading to premature fatigue and rapid nervous exhaustion.
Mental work is associated with the perception and processing of a large amount of information and is divided into:
- 1) operator - implies control over the operation of machines; is distinguished by high responsibility and neuro-emotional stress;
- 2) managerial - characterized by a large increase in the volume of information with a lack of time for its processing, great personal responsibility for decisions made, stressful and conflict situations;
- 3) creative work - requires a large amount of memory, tension, attention; it leads to increased neuro-emotional stress, tachycardia. increased blood pressure, ECG changes and other changes in autonomic functions;
- 4) the work of teachers and medical workers is constant contact with people, increased responsibility, frequent lack of time and information to make the right decision, which leads to high neuro-emotional stress;
- 5) the work of pupils and students - implies the concentration of memory, attention; there are stressful situations (at exams, tests).
The level of human energy consumption in various forms of activity serves as a criterion for the severity and intensity of the work performed, is of great importance for optimizing working conditions and its rational organization. The level of energy consumption is determined by the method of complete gas analysis, while taking into account the volume of oxygen consumption and carbon dioxide released. With an increase in the severity of labor, oxygen consumption and the amount of energy consumed increase significantly.
The severity and intensity of labor are characterized by the degree of functional stress of the body. It can be energetic, depending on the power of work (during physical labor), and emotional (during mental labor), when information overload occurs.
Physical labor is characterized by a heavy load on the body, requiring mainly muscle effort and appropriate energy supply, and also affects functional systems (cardiovascular, neuromuscular, respiratory, etc.), stimulates metabolic processes. Its main indicator is severity. Energy consumption during physical labor, depending on the severity of the work, is 4000 - 6000 kcal per day, and with a mechanized form of labor, energy costs are 3000 - 4000 kcal.
With very hard work, oxygen consumption continuously increases, and oxygen debt can occur when non-oxidized metabolic products accumulate in the body. The growth of metabolism and energy consumption leads to an increase in heat generation, body temperature by 1-1.5 ° C. Thus, energy costs are a criterion for the physical severity of labor.
Mental labor combines work related to the reception and transmission of information, requiring activation of the processes of thinking, attention, memory. This type of labor is characterized by a significant decrease in motor activity. The main indicator of mental labor is tension, which reflects the load on the central nervous system. Energy consumption during mental work is 2500 - 3000 kcal per day. But energy costs vary depending on the working posture. So, in a working posture sitting, energy costs exceed the level of basal metabolism by 5 - 10%; standing - by 10-25%, with a forced uncomfortable posture - by 40-50%. With intensive intellectual work, the brain's need for energy is 15-20% of the total metabolism in the body. The increase in total energy costs during mental work is determined by the degree of neuro-emotional tension. Daily energy consumption during mental work increases by 48% when reading aloud while sitting, by 90% - when lecturing, by 90-100% - for computer operators. In addition, the brain is prone to inertia, because after the cessation of work, the thought process continues, which leads to greater fatigue and exhaustion of the central nervous system than during physical labor.
Mental work is associated with nervous tension, which depends on the significance, danger and responsibility of the work. With nervous tension, tachycardia, an increase in blood pressure, an ECG change, and an increase in oxygen consumption occur. For the correct organization of mental activity, it is necessary: gradually “enter” the work, observe the rhythm, systematicity.
Muscular work affects the cardiovascular system, increasing blood flow from 3-5 l / min to 20-40 l / min to ensure gas exchange. At the same time, the number of heart contractions increases to 140-180 per minute. and blood pressure up to 180-200 mm Hg. Art.
An increase in the intensity of work is accompanied by an increase in air exchange (from 5-8 l / min to 100 l / min), respiratory rate (from 10-20 to 30-40 per min) and the proportion of oxygen use (from 3-4% to 4-8% ). The latter is due to the effort of diffusion into the lungs.
Under the influence of muscular work, the morphological composition of the blood, its physicochemical properties change: the number of erythrocytes and hemoglobin content increase, the process of erythrocyte regeneration intensifies, and the number of leukocytes increases. These changes indicate an increase in the function of the hematopoietic organs. Certain changes during physical work occur in endocrine functions (increase in blood levels of adrenaline, etc.), which contributes to the mobilization of energy resources of the body.
