[An ergonomic and work physiology assessment of the risk factors for the musculoskeletal system in jobs performed by women]. / Ergonomichna i trudovo-fiziologichna otsenka na riskovite faktori za muskulno-skeletnata sistema pri niakoi professii, izpulniavani ot zheni.

The purpose of the present work is to study the relation between the characteristics of the work activity and especially the parameters of the working posture and work place as well as the complaints of the musculoskeletal system (MSS) among professions where women are mainly engaged. The object of the study were 3 professional group: 1st group--telephone operators on video display (VD), IInd group--hairdressers and IIIrd group--television (TV) tuners. For the investigation was used inquiry-questionnaire for MSS complaints, which includes localization and type of the complaints, subjective evaluation of the working posture, organization and arranging the working place. A 3-step scale was used for each of the observed indices. The results point out, that the frequency of MSS complaints is very high in the examined professions. The complaints of the telephone operators on VD concern mainly the neck [66% of the examined], the shoulders and back [respectively 58% and 50%]; of the hairdressers--the shoulders and back [85% and 80%] and the legs [75%]; of the TV tuners--the fingers of the hand [60%], neck and shoulders [43% and 40%]. The MSS complaints are in positive correlation to the age and length of service of the workers [from 0.75 to 0.91]. The expert ergonomic evaluation shows that for the three examined professions, the working posture is the determining factor for MSS complaints. For hairdressers and TV tuners are the same degrees, followed by the telephone operators on VD. In the organization of the working place there are numerous ergonomic discrepancies: for the telephone operators the most considerable deviations of the ergonomic requirements are in the dimensions of the working places: for the hairdressers and TV tuners--in the dimensions of the working zones and the arrangement of the working place. A statistically positive correlation dependence was received between MSS complaints and the working posture for the three professional groups (r from 0.85 to 0.89) and between the complaints and the ergonomic discrepancies of the working place (r between 0.75 and 0.85).

[Occupational hygiene in industrial assembly work]. / Khigiena na truda pri promishleno-montazhna deinost.

Data on occupational hygienic characteristics of industrial-assembly work are reported, which have not been subject upto now to such studies. Complex hygienic evaluation of the basic physical and chemical factors of the working environment is performed as well as physiological and ergonomic characteristics of the principle professional groups, analysis of the occupational diseases and diseases with temporary disability and clinic and laboratory examinations on the workers. The following peculiarities of occupational hygienic aspect are established: 1. dynamic and multiform professional itinerary of the industrial-installing workers; 2. large variability in the characteristics of the physical and chemical factors of the working environment, most frequently surpassing the admissible norms and requirements, as well as the duration of exposure to them; 3. considerable working engagement (from 63 to 78% operation time), connected with heavy physical loading (dynamic and static), exceptionally unfavourable, compulsory and fixed working posture, possibilities of prolonged working day, high rate of involvement of the psychomotor sphere, analyzers and attention, great professional responsibility and nervous and emotional stress; 4. occupational and general morbidity of workers, adequate to the already established by the authors occupational noxa--acute poisoning with smoking gases, injury of the hearing, diseases as a result of overpressure of the locomotor apparatus and the nervous system.

M-response latencies changes as a tool for studying neuromuscular conduction during cyclic maximal voluntary contractions.

M-response changes during cyclic maximal isometric voluntary forearm flexions were studied using a new method based on the following: 1) Monopolar stimulation of terminal motor point of the brachial biceps muscle by large surface electrodes; 2) Monopolar leading-off by a surface electrode placed on the middle between motor endplates and muscle fibers end; 3) Arm and forearm immobilization; 4) Averaging of M-response triggered by the stimulus during contraction; and 5) Latencies to the peak of negative (L1) and of final positive phase (L2) and peak-to-peak amplitude (PTPA) were measured, and peak-to-peak time (PTPT), which reflected muscle conduction velocity and leading-off electrode-to-end of fibers distance was calculated. Four cycles of 30-s contraction and 5-min rest were performed. Eight M-responses were evoked with a 1 Hz frequency starting from 5th s of the cycle. No significant changes of PTPA and L1 were found. Nevertheless, L2 significantly decreased in the third cycle by 6.4% and in the fourth-cycle by 7.6% of the first cycle value. PTPT decreased in the fourth cycle reaching 87.6% of the initial value. The advantage of the method and the possible causes of changes were discussed.

[Changes in neuropsychic activities during work in clean rooms]. / Promeni v nervno-psikhichnata deinost pri rabotaq v chisti stai.

In clean rooms of the system of electronics are carried out work-physiological examinations on two basic professional groups--working in photolithography and operators. At the end of the workings day a considerable prolongation of the sensomotor reactions and deterioration of the dynamometric indices, characterizing the functional status of the neuro-muscular system were found. The time for performing the complex sensomotor reactions (choice of reaction) remains unchanged. At the end of the working day as a result of the performance of a considerably complex work activity, carried out in the clean rooms, was established a significant decrease in the functional state of the central nervous system and development of general and nervous fatigue.

[Physiological, psychological and ergonomic research on jobs in the manufacture of chocolate products]. / Trudovo-fiziologichni, prikhologichni i ergonomichni izsledvaniia pri niakoi profesii ot proizvodstvoto na shokoladovi i zdeliia.

The investigations include job description and analysis of the activity, functional examinations of basic dynamometric indices (muscle strength and endurance of static effort), the pulse rate and the time of carrying out of one operation and for manufacturing of unit product. Psychological tests for subjective evaluation of the stress and monotony, the type and rate of vertigo, of the psychic status in the presence of monotony, are applied. The ergonomic analysis comprises evaluation of the work place work posture and equipment. The results of the investigations point out that the activity of the basic professions in this production is expressed monotonous, with significant static load of the muscle system and total hypokinesia and hypodynamia. Changes in the working capacity and fatigue are registered in the middle of the working day as well as disturbances in the neuro-vegetative and adaptation mechanisms of the organism and appearance of unfavourable psychic conditions (decreased vigilance, boredom, satiating). Ergonomic incongruities were found in the dimensions and the order of the working place and equipment.

[Problems of working under local muscle loading]. / Niakoi problemi pri rabota s lokalno muskulno natovarvane.

The present labour motor activity is characterized by local loading with constant increase of the static muscular tension. The static work is the cause of reduction of capacity for work, of early advancing fatigue and various occupational diseases of the locomotory system in case of long-lasting activity. With the purpose if studying the connection between the occupational diseases of the locomotory apparatus (LMA) and the characteristics of the labour motor activity--a study on the diseases of the LMA was carried out at the Neurological Department of the Clinic of Occupational Diseases, looking for the correlation between them and the labour physiological data about the severity and tension of the motor activity and some parameters of working movements. The following main characteristics of the motor activity are indicated as risk factors of the occupational diseases--number of movements per a working shift, their velocity and duration, movements needing strength and movements with a big volume, pronounced motor monotony. The correlation between the occupational diseases of LMA, age, sex, length of service, etc. are stressed on. The problem of the optimization pf motor labour activity is discussed as a basic element of prophylaxis of overstrain and occupational diseases of the locomotory system.

Muscular synergies during different conditions of postural activity.

With the view to studying the muscular synergies in maintaining of upright posture EMG activity of soleus (SOL), tibialis anterior (TA), peroneus longus (PL), biceps femoris (BF), vastus lateralis (VL) and gluteus medius (GM) muscles during easy standing, voluntary leaning and induced body oscillations in frontal and sagital plane were recorded. The data showed that during easy standing and during small external disturbances the vertical posture was maintained mainly by the activity of SOL (triceps surae muscle) which was modulated by the modification of the external force field. TA remained silent. PL muscle was slightly active as a synergist of SOL. The pattern of muscular synergies during fast voluntary leaning and induced body oscillations differed as compared to the muscular synergies at easy standing. The activity of all muscles studied increased and became continuous with exception of that of the TA. The latter was silent but was involved earlier when gravity center passed behind its projection. VL being a synergist of TA during slow sway became continuously active as a synergist of SOL during the fast sway. Typical changes in muscular synergies appeared when induced body oscillations were imposed during horizontal and rotational movements of the platform. The various patterns of muscular synergies during pronation and supination of the foot depended on the knee joint angle. The amplitude of body leaning forward and backward and its variability as well as the plane of the lateral sway depended on the biomechanical variables and related motor programs for postural control.

Changes in the H-reflex amplitude with different characteristics of the preceding conditioned stimulus.

The post-stimulus inhibition of the H-reflex was studied in human subjects with the following experimental sets: Presentation of a pair of stimuli, with intensity of the conditioned stimulus, S1, of 30% Hmax, and with varying intensities of the test stimulus, S2, from threshold to maximal values. Varying intensity of S1 from threshold values, 30% Hmax, 50% Hmax, and varying intensity of S2 from threshold to maximal values, for the H2-reflex-curve to be obtained. Varying intensity of S1 from 0.9 to 1.15-1.20 threshold and constant intensity of S2 of 30-40% Hmax. In the first two experiments the curve "intensity of S1/H2-reflex amplitude" at different intensities of S1 and different delays of S2 has been investigated. In the third experiment the H2-reflex recovery with diminishing the S1 to subthreshold values has been investigated. The results have shown: H2-reflex was strongly suppressed even with threshold values of S1. H2-reflex-curve after a conditioned stimulus was significantly lower to the H-reflex-curve after a single stimulus. The recovery of the H-reflex amplitude after S1 was observed with subthreshold values of S1. The possible role of the presynaptic inhibition for the suppression of the H1-reflex with the presentation of a pair of stimuli has been considered.

Influence of the visual feedback for some parameters of the body oscillations on their stability.

In accordance with the hypothesis that in addition to the generalized information from the visual feedback about the body oscillations, the information from the different parameters of the oscillations may also play a stabilizing role for the vertical posture of the body and its balance, studies were carried out on the influence of the parameters of body position, velocity of the body oscillations and accelerations on body stability. The results have shown that the visual feedback about the position of the body and about the velocity of the oscillations leads to stabilization of its balance. Visual feedback about the accelerations of the body oscillations also has a stabilizing action on the vertical posture and equilibrium. Its influence did not prove greater than the visual feedback about the velocity of body oscillations. Repeated recordings of the body oscillations under the experimental conditions manifested a slight initial training effect, expressed in a decrease of the total way of the body oscillations.