Whole-body vibration and disorders of the spine

This cross-sectional study is based on interviews and medical examinations of 352 operators of earth-moving machines who had been exposed to whole-body vibrations for at least three years. In addition, available X-rays showing different parts of the spines of 251 machine operators who had been exposed to vibration for at least ten years were used for evaluation. One hundred and forty-nine of the operators were asked about discomfort occurring immediately after an eight-hour work shift. The group of exposed persons was compared with a control group of 215 non-exposed persons. The percentage of subjects reporting spinal discomfort was much higher for the exposed group than for the non-exposed…

Diagnostic significance of cold provocation test at 12°C

In Germany, vibration-induced white finger (VWF) disease is accepted as an occupational disease (BK No. 2104 BKV), for which compensation may be paid provided that the sociolegal requirements are met in accordance with the list of occupational diseases that is valid at the time. A cold provocation test (thermometry, infrared thermography) is helpful in the diagnosis of VWF and we believe that it could contribute to the standardization of vascular assessment methods. In Germany, the approved degree of the decrease in earning power is downgraded as disease symptoms improve with time; therefore, insured individuals suffering from VWF are regularly reassessed every 1–3 years. In the context of …

Acute Effects of Mechanical Vibration

We know that man possesses a highly developed ability to adjust to different environmental conditions. For this function there are physiological regulatory systems, which release reactions in him for protection against such influences. Thus, receptors for light, smell, taste, temperature, sound, touch, position change, pressure, and tension are at hand which, as parts of the cybernetics system, can release physiologically meaningful protective reactions.

Laws, Regulations, Standards, and Guidelines for the Protection of Man Against Mechanical Vibration

Regulations that serve to protect workers from the dangers arising from mechanical vibration have been established by the legislators and agencies responsible for work protection, such as ministries of labor and social affairs and industrial insurance organizations. Furthermore, international agreements have also established such protective measures. The corresponding laws, rules or agreements relate to: 1. Occupational diseases 2. Criteria for the evaluation of risk from mechanical vibration and the establishment of exposure limit values 3. Guidelines for the measurement and evaluation of vibration 4. Medical examinations before employment and regular health examinations 5. Technical and o…

Acute effects of transient vertical whole-body vibration

The question as to whether shock-type whole-body vibration causes increasingly acute strain was investigated. Random vibrations were superimposed with shocks differing in amplitude and in number per unit of time in a systematic manner. The weighted root mean square (rms) acceleration was kept constant in all over the varied experiments. A total of 17 men were exposed to vibration from an electrohydraulic simulator. The following strain criteria were used: biodynamic behavior of the trunk and the head, electrical activity of the muscles of the back and the neck, subjective sensation, skin temperature in the lumbar area and visual and tracking performance. It was found that increasing shock a…

Effects of grip and push forces on the acute response of the hand-arm system under vibrating conditions

The purpose of the occupational medicine component of a joint research project was to study the effects of grip and push forces on the acute reaction of the hand-arm system under vibrating conditions. Several series of experiments were carried out by means of a vibration simulator in a laboratory environment in order to study biodynamic vibration behaviour, muscle response, skin temperature, shifts of the vibration perception threshold and the intensity of subjective vibration perception; in addition, field tests with hammer drills were conducted. On the whole, the findings obtained suggest that the coupling of the hand with the handle involved in using vibrating tools has a considerable im…

Terminology and Definitions

In order to eliminate as much misunderstanding as possible in the evaluation of various forms of vibration stress, it is necessary to define the technical physical concepts used (Table 1). In addition, the special medical terms are explained at the end of the book (p. 158).

Work-Related Stress from Whole-Body Vibration

During the last 10 years, many field experiments have been carried out in various places of work. Vibration has been measured in buildings, in vehicles, and on ships. These data are currently being compiled (Dupuis and Hartung 1982) to be fed into the vibration data bank at the BIA.

Medical and occupational preconditions for vibration-induced spinal disorders: occupational disease no. 2110 in Germany.

The current state of scientific knowledge of the biodynamic behaviour of the vertebral column under the influence of whole-body vibration whilst sitting and results from epidemiological studies caused the medical board of experts on occupational health of the Federal Ministry of Labour in Germany to add a new occupational disease to the official list of occupational diseases. The occupational disease “diseases of the lumbar spine from disc degeneration caused by long-term (mainly vertical) whole-body vibration exposure” has been introduced. The medical preconditions with the symptoms and the diagnostic methods are presented. With regard to the occupational preconditions for the acknowledgem…

Effects of combined hand-arm vibration and cold on skin temperature

Under laboratory conditions 14 healthy male subjects were exposed to hand-arm vibration (ahzw = 6.3 m/s2) at different air temperatures (5 degrees, 12 degrees, 18 degrees and 25 degrees C). Static load (grip force 15 N, push force 40 N) was kept constant. Finger tip temperature as an indirect criterion of the peripheral blood circulation was measured. As expected, low air temperatures (5 degrees, 12 degrees and 18 degrees C) cause a strong decrease of skin temperature. Under additional stress of vibration connected with static load, a further decrease of the mean skin temperature was noted. At this, static load proved to have a predominant influence on the acute diminution of skin temperatu…

Hand-arm vibration and the central nervous system

Biodynamic behavior of the trunk and the abdomen during whole-body vibration

Vibration strain may be defined as the sum of all reactions of the human being to vibration exposure. This also includes the biomechanical behavior of particular parts of the body. Knowledge about these reactions is necessary in the field of occupational health and ergonomics. Biomechanical models, experimental methods, and results are presented. It can be shown that under vibration exposure with different conditions (body posture, vibration direction), the body parts are in resonance at varying frequencies, mainly in a low frequency range.

Stress-Strain Concept in Whole-Body Vibration

The strain-stress concept defines stress. First of all, stress refers to vibration exposure (kind, intensity, and duration of vibration) and the additional stress factors that act upon man when exposed. Strain, on the other hand, means the effects of such stress, that is, the reaction (biodynamic, psychological, physiological, damaging) of the human being, taking into consideration the individual endogenous conditions (see Table 2).

Acute effects of shock-type vibration transmitted to the hand-arm system.

The aim of the project was to find out whether shock-type vibration of hand-tools compared to non-impulsive vibration has stronger acute effects on the hand-arm system and therefore needs a stricter evaluation from the occupational health point of view in comparison with the requirements of the Draft International Standard ISO-DIS 5349. Under laboratory conditions, subjects were exposed to simulated vibration of hand-tools (grinder, chain saw, hammer-drill, pneumatic hammer, rivet hammer and nailer). The following evaluation criteria were used: biomechanical transmissibility of the hand-arm system (wrist, elbow joint, shoulder joint); muscle-activity (m. flexor carpi ulnaris, m. biceps, m. …

Chronic Effects of Whole-Body Vibration

The reactions of the body to stress from mechanical vibration, presented in the section “Acute Effects of Mechanical Vibration” (see p. 12), deal with individual organs and functions. It is now time for the following question to be asked: Are these physiological or pathophysiological changes in reality the external symptoms of a vibration-induced illness of the whole organism? Above all, some Soviet scientists are of this opinion. Andreeva-Galanina (1967) has especially called this concept “vibration illness” and has used it in the sense that the totality of vibration-induced changes in the human organism can be characterized (Rublack 1978). In this systemic “vibration illness,” Andreeva-Ga…

The Influence of Particular Modes of Vibration

When vibration stress occurs at the place of work, 1, 2, or 3 directions of the coordinate system related to man, or vectors of these axes, can be involved (Fig. 1). In such multiaxial vibration, the stress may predominate in one direction or may have similar magnitudes in all directions. In addition, rotational vibration about these axes may also take place (see section “Rotational Vibration,” p. 125).

Different acute effects of single-axis and multi-axis hand-arm vibration.

Under laboratory conditions the effects of single-axis and multi-axis hand-arm vibration exposure on several strain parameters were tested in up to 20 male subjects. As parameters of these acute effects, the biodynamic vibration behavior of the hand-arm system, the electrical activity of the most affected muscle groups, the skin temperature, the vibration sensitivity of the fingertips, and the subjective vibration sensation were measured. When comparing simulated three-axis vibration exposure with single-axis vibration exposure, synergistic effects in the form of an increasing reaction could be found. It could be proven that the vector sum of the frequency-weighted acceleration in the three…