Classification of Work by Degree of Gravity and Intensity

The gravity ofwork is connected with physical gravity of work and characterized by:

· amount of work (in kilogram-meters)

· capacity of work (amount of work per time unit)

By physical gravity work is divided into:

· mild

· of medium gravity

· hard

· very hard

The intensity of work (mental, of an operator) is characterized by:

· demands for attention;

· emotional exertion;

· strain of audition and vision;

· monotony.

By intensity work is divided into:

· not intensive

· slightly intensive

· moderately intensive

· very intensive.

Concepts of "Exhaustion" and “Tiredness”

Tiredness is subjective feeling, as a rule, accompanied by the development of exhaustion. It depends on psychophysiologic condition of a working person, degree of interest in work.

Exhaustion is a complex of objective changes in organism due to work manifested in decrease of capacity for work.

If exhaustion does not disappear before the beginning of the following cycle of work, it gradually accumulates and turns to overexhaustion, i.e. decrease of capacity for work, pathology of CNS, cardiovascular system, immunosuppressive state, growth of traumatism.

Concept of “Capacity for Work”

Capacity for work is ability of man to long work without decrease of qualitative and quantitative characteristics (with high efficiency of work).

Capacity for workdepends on such reasons as health state, hygienic conditions of work, organization of work process, psychophysiologic factors.

Early decrease of capacity for work is an indicator of effect of these factors, therefore studying its dynamics is of great importance for estimation of health and working conditions of working people.

Dynamics of Capacity for Work during a Working Process

During work three stages of capacity for work are distinguished:

· In-work period - a gradual increase of capacity for work;

· Working excitation – a maximal level of capacity for work;

· Incipient exhaustion - a gradual decrease of capacity for work.

Dynamics of Capacity for Work after Termination of Work

· After-work excitation – some increase of work capacity occurs.

· After-work inhibition - a sharp decrease of work capacity occurs.

· Restoration of work capacity. At a long duration of this stage the level of work capacity returns to the initial one and there is no overstrain.

Methods of Studying the Capacity for Work

There are a lot of methods of studyingthe capacity for work or exhaustion, they are represented as psychophysiologic or only physiological tests. The most important of them are the following:

v Methods of studying the capacity for brain work (mental work):

Ø A correcting test– crossing out definite letters or figures in special tables per minute. Estimation of results of the test is made according to Hartridge formula, i.e. according to amount of the processed information in bit/sec.

Ø Verbal-associative experiment - estimation of speed and degree of association between with given words.

Ø Estimation of attention stability (for schoolboys).

Ø Estimation of time of hearing-motor and visual-motor reactions (a latent period of reflex) with the help of chronoreflexometer (for operator‘s work).

v Methods of studying the capacity for any kind of work – chronometric researches:

Ø A selective timing of work elements;

Ø Fixing the distraction of attention (at school);

Ø Phototiming.

v Methods of studying the capacity for physical work:

Ø Estimation of physical tolerance with the help of a dynamometer;

Ø Studying tremor (trembling) of hands (with the help of tremometer)

Exhaustion. Theories of Mechanism of Its Development

Among a great variety of theories of exhaustion development (more than 20) there is no universal one up to now.

At present the most recognized is the central-nervous theory by Sechenov, Uchtomsky, Vvedensky. The basic role in exhaustion is played by decrease of capacity for work of cortex cells, thus the processes of excitation and inhibition in the CNS are disturbed. Thus in the CNS the stable foci of excitation or inhibition occur –this is the theory of disbalance. This theory has been recently supplemented with the theory of reticular formation elucidating the disorder of communications between the upper and lower parts of the CNS.

Earlier the humoral-local theories of exhaustion development at physical work were acknowledged, such as:

· The theory of exhaustion - exhaustion of energy supply in muscles (ATF, glycogen, etc.);

· The theory of poisoning - accumulation in muscles of non-oxidized products (lactic, pyruvic acids).

The inaccuracy of these theories is proved experimentally, besides they do not explain the development of exhaustion at brain work. However, these processes play some role in the development of exhaustion.

The Main Reasons of Development of Premature Exhaustion at Work

They may be subdivided into the following way:

v Endogenous:

Ø diseases and prepathological states;

Ø defects of development of organs and systems;

Ø poor or non-optimal nutrition (food);

Ø the negative attitude to work.

v Exogenous:

Ø violation of hygienic working conditions:

§ non-optimal microclimate;

§ non-optimal illumination;

§ a forced position of body;

§ a high level of occupational harmful factors (chemical, physical, biological) exceeding MPC, MPL.

Ø non-optimal organization of a working process:

§ very long working hours;

§ very hard and intensive work;

§ monotonous work;

§ non-observance of a work and rest regimen.

Ø non-optimal psychoemotional working conditions:

§ a bad moral climate in a collective (conflicts)

§ a negative attitude to work.

 

 

The basic directions of exhaustion prevention are the following:

· Scientific substantiation and keeping hygienic requirements to working conditions (requirement to microclimate, illumination, areas of workplace, avoidance of exceeding MPC of harmful occupational factors);

· Scientific (rational) organization of a working process (following regimen of work and rest, restrictions on working hours, labour-intensiveness, transforming static physical work to dynamic, etc.);

· Technical measures to improve the working conditions of workplace (application of ergonomics – a science concerned with human factors in the design and operation of machines and the physical environment).

· Psychologic measures (psychology of work - industrial psychohygiene, psychologic help in choosing particular occupation, optimization of psychologic climate in a collective).