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Biomedical subjects

M Hagberg

Publications and source records attributed to M Hagberg.

At least 55 records · Page 3Linked to original sources
PubMed1996

Musculoskeletal Symptoms among Computer-assisted Design (CAD) Operators and Evaluation of a Self-assessment Questionnaire.

A self-administered questionnaire with questions related to the physical workload at video display units (VDUs) was tested for intra- and intermethod reliability among 36 men and 64 women working with research and documentation. The results showed an acceptable test-retest agreement. The answers to three questions were validated by direct measurements: the locations of keyboard and mouse on the table, and the distance between elbow and keyboard heights when working. The self-reported locations of keyboard and mouse showed good agreement with the direct measurements. A revised version of the questionnaire was used at a telecommunication laboratory to study work postures and musculoskeletal symptoms. Among CAD operators with identical work tasks, the women (n = 67) reported a higher prevalence of musculoskeletal symptoms than did the men (n = 475). Calculated prevalence rate ratios (women/men) for musculoskeletal symptoms ranged from 1.4 (low back) to 3.4 (left elbow). The CAD operators with at least 5.6 hours of mouse use/week (median) reported more symptoms in the arms than did the CAD operators with fewer hours' work. Operators with the mouse located outside an "optimal" area on the table reported more symptoms from shoulder joints (upper arms), shoulders (scapular), elbows, and wrists than did operators with the optimal mouse location. Thus, long hours of work with the mouse, as well as working with the mouse non-optimally located on the table, seemed to be risk factors for upper-limb symptoms.

Journal Article↗
PubMed1996

Musculoskeletal Disorders: Work-related Risk Factors and Prevention.

Work-related musculoskeletal disorders cause chronic pain and functional impairment, impose heavy costs on society, and reduce productivity. In this position paper from the Scientific Committee for Musculoskeletal Disorders of the ICOH, the most important risk factors at work are described. Work-related musculoskeletal disorders have high incidences and prevalences among workers who are exposed to manual handling, repetitive and static work, vibrations, and poor psychological and social conditions. The application of ergonomic principles in the workplace is the best method for prevention. International organizations should develop standards, common classifications, and terminologies. Surveillance systems should be further developed nationally and in workplaces, and more effort should be directed to information dissemination, education, and training.

Journal Article↗
PubMed1996

Vibrotactile perception thresholds as determined by two different devices in a working population.

OBJECTIVES: The purpose of this study was to investigate whether two devices for measuring vibrotactile perception thresholds produced similar results on an individual basis and to compare the thresholds in the presence or absence of sensorineural hand symptoms and vibration exposure. METHODS: Vibrotactile perception thresholds were measured with a vibrameter and a tactilometer in 178 men. The tactilometer uses seven discrete frequencies from 8 to 500 Hz, and the vibrameter uses one frequency (100 Hz). Agreement was assessed from the correlations and from a comparison of subjects who had thresholds above the upper quartile of each device as to the presence of sensorineural hand symptoms and occupational vibration exposure. RESULTS: The correlation between the vibrameter and the tactilometer (125 Hz) was 0.59. The agreement between the vibrameter and the tactilometer (63 Hz), when the upper quartile was used as a limit, had a sensitivity of 0.56 and a specificity of 0.85. The sensitivity and specificity for the agreement with symptoms were 0.44 and 0.79, respectively, for the tactilometer and 0.40 and 0.78, respectively, for the vibrameter. The indices combined from the different frequencies of the tactilometer did not improve the agreement. CONCLUSIONS: Some of the discrepancy between the measurement of the vibrameter and tactilometer can be explained by differences in the equipment, the measurement procedures, and the examiner, combined with high inter-and intraindividual variability. Neither of the two devices was superior when the results were compared as to the occurrence of hand symptoms and vibration exposure. As evaluated in this study vibrotactile perception threshold has a restricted value for screening and diagnostic purposes on an individual basis.

Adult↗
PubMed1996

Comparison of different methods for vibration measurements on hand-held vibrating tools.

Vibration measurements have been done on hand-held tools in a group of 48 platers by evaluating the individual vibration acceleration and absorption of vibration energy. The measurement of acceleration has been done frequency-weighted and frequency-unweighted in accordance with ISO 5349 and NIOSH (USA) recommendations for hand-arm vibration standards, respectively. The acceleration and the energy absorption have been measured simultaneously in the three orthogonal directions, the latter by using a specially designed adapter. The exposure time has been determined by both subjective rating and objective measurements. Individual energy-equivalent accelerations and vibration dosages have been calculated from these data. The outcome shows that the type of tool was critical to vibration load when the different measures for determining vibration levels were used. Of the methods used, the evaluation specified by ISO 5349 makes most consideration of low frequencies of vibration (< 50 Hz), absorption of vibration energy middle frequencies (50-200 Hz) and NIOSH of high frequencies (> 200 Hz). The results show a poor correlation between the three methods used. Close agreement between mean subjective rating and objective measurement of the average exposure time was found. Further studies of the relation between results presented here and generated disturbance will be conducted, which may clarify any exposure-response relationship.

Acceleration↗
PubMed1995

Occupational and individual factors related to musculoskeletal symptoms in five body regions among Swedish nursing personnel.

The relationship between individual factors, physical and psychosocial exposure at work, and musculoskeletal symptoms in the neck, shoulders, low back, hands, and knees was studied among female nursing personnel working at a Swedish hospital. The personnel had participated in a course in work technique (patient transfer and handling principles). Prior to the course, the subjects had filled in a questionnaire (n = 688). The aim of this cross-sectional study was to elucidate whether different individual and work factors are related to musculoskeletal symptoms in a specific body region. Due to the cross-sectional design, however, causality cannot be discussed. Univariate analyses and multiple logistic regression analyses were performed and yielded similar results. The latter analyses showed that in the present hospital setting, individual factors together with physical and psychosocial work factors were related to symptoms in the neck, low back, and hands; individual factors and psychosocial work factors were related to symptoms in the shoulders; while only individual factors were related to symptoms in the knees. The results of the present study showed that various individual factors and physical and psychosocial work factors were related to musculoskeletal symptoms in the different body regions. Thus, the identification of risk factors might have far-reaching implications for the way in which effective health programs for prevention should be designed in the hospital setting.

Adult↗
PubMed1995

Interview protocols and ergonomics checklist for analysing overexertion back accidents among nursing personnel.

No documented strategy, including preventive strategies, for systematic investigation of overexertion back accidents among nursing personnel has yet been published. One aim of the present study was to develop standardized instruments for the systematic investigation of back accidents among nursing personnel in order to develop preventive strategies. Another aim was to produce a screening tool that could easily be used for identifying potential overexertion back accident hazards. Two structured interview protocols were developed, one for the injured person and one for the supervisor. An ergonomics checklist was designed for the most important spaces according to accident statistics: patient's room, corridor, toilet, and also one for 'other space', eg X-ray and treatment rooms. The instruments were developed by frequent discussions and adjustments in a task force of researchers and occupational health personnel. The protocols were tested in two steps before a final version was established. The construct validity and interobserver reliability of the checklist were tested by ten ergonomists, who checked a patient's room, a toilet and a corridor with some known hazards. The constructed validity agreement was 90% in 19 of 26 items in the checklist. The interobserver reliability had the same figures as the validity for all items in the checklist. The interview protocols and checklist appear to be suitable for systematic investigation of overexertion back accidents.

Journal Article↗
PubMed1995

Reports of work related musculoskeletal injury among home care service workers compared with nursery school workers and the general population of employed women in Sweden.

OBJECTIVES: To describe the nationwide occurrence of work related musculoskeletal injuries among all home care service workers in Sweden, and to identify relative risks and risk factors of the injuries. METHODS: The study was based on work related injuries reported to the Swedish occupational injury information system in 1990-1. The work related musculoskeletal injuries were divided into overexertion accidents and musculoskeletal diseases. The incidence of the injuries in female home care service workers was compared with those in nursery school workers and all other employed women in Sweden. RESULTS: In home care service workers, the annual incidence of injury from overexertion accidents and musculoskeletal diseases were 19.2 and 15.1 per 1000 workers, respectively, which was higher than those in nursery school workers and all employed women in Sweden. For five injury locations including the back, all the age standardised relative risks (SRR) of overexertion accidents exceeded 4.0, and most of those for musculoskeletal diseases were 1.5 or more in home care service workers compared with all other employed women in Sweden. Total duration of sick leave due to overexertion accidents was 7.7 times, and musculoskeletal diseases 3.5 times, longer than in nursery school workers. National loss due to sick leave resulting from only musculoskeletal injuries in home care service workers was about 8.2% of the total work related sick leave in all employed women in Sweden, although the number of home care service workers represented only some 5% of this population. Lifting other people was most frequently reported as the main risk cause of overexertion accidents in both kinds of workers. CONCLUSIONS: The results support the hypothesis that home care service workers have higher annual injury incidence of musculoskeletal injuries than nursery school workers due to physically stressful tasks that are far less common in nursery school workers.

Accidents, Occupational↗
PubMed1995

Vibrotactile perception sensitivity and its relation to hand-arm vibration exposure.

Vibrotactile perception thresholds (VPT) at seven test frequencies (8-500 Hz) have been measured and evaluated among 170 male employees at a heavy engineering production workshop, 125 of them were at present, or in the past, exposed to hand-arm vibration. All participants were examined by a physician and none had symptoms of diseases or were exposed to other factors known to cause sensory neuropathies. VPTs [for the three lowest (8-32 Hz; non-Pacinian), for the four highest (63-500 Hz; Pacinian) and for all test frequencies together] and a sensitivity index (SI) has been individually graded in four (normal, slightly deteriorated, deteriorated and seriously deteriorated) and two (normal, abnormal) stages, respectively, and put in relation to individual exposure of vibration. The results do not show any clear relationship on an individual basis between vibration exposure and degraded vibrotactile perception. On a group basis, however, there is a clear tendency towards detoriorated VPTs when the study group is divided in exposure categories. The detorioration is most pronounced in the frequency range mediated by Pacinian corpuscles. In this range an approximately four-fold increase of relative risk for elevated VPT for those in the highest exposure category was observed compared to the non-exposed group. Corresponding relative risk estimate for SI is about 6. Therefore, the results suggest an existence of an exposure-response relationship.

Adult↗
PubMed1995

Assessment of heat pain perception in relation to vibration exposure.

The effect of vibration on thin unmyelinated sensory fibers was studied by perception threshold measurement of heat pain. The investigation was a cross-sectional study of 98 vibration-exposed and 53 non-vibration-exposed workers. Pain perception was determined by using the "Marstock" method. The perception threshold of contact heat induced pain was assessed by the method of limits. Quantified personal energy-equivalent vibration exposure was assessed for all subjects on a group basis. The cumulated lifetime equivalent frequency-weighted vibration exposure was estimated based on measurements according to ISO 5349. The mean heat perception threshold was 46.2 degrees C (SD 2.6 degrees C) for the right hand and 46.0 degrees C (SD 2.7 degrees C) for the left. The results showed no mean difference (left = 0.1 degree C, right = 0.6 degree C) in heat pain perception between vibration-exposed and non-exposed subjects. There was a high correlation between the right and left hand measurements (r = 0.81). The risk (rate ratio) for impairment was 1.02 (95% CI 0.81-1.30) for the right hand and 1.00 (95% CI 0.79-1.26) for the left. The results of the study did not indicate any impairment as assessed by an increased perception threshold for heat pain. The lack of an increased heat pain threshold among the vibration-exposed workers in our study cannot exclude a possible lesional somatosensory influence from the exposure, as the lesional effect may also be a lowering of the threshold. The multiple and unrelated percepts of thermal sensations imply that it is not legitimate to draw conclusions about the total status of the small calibre afferents when testing only the heat pain perception.

Adult↗
PubMed1994

Variation in upper limb posture and movement during word processing with and without mouse use.

Work postures and movements of the upper limb were analysed for 12 'mouse' operators and 12 'non-mouse' computer operators employed in word-processing work. Measurements were carried out during correction of a given text. 'Mouse' operators spent 64% of the working time with the operative wrist deviating more than 15 degrees towards the ulnar side, while 'non-mouse' operators spent 96% of the time with the corresponding wrist in neutral position towards radial deviation. The rotation in the shoulder was at all times in neutral position towards inward rotation for 'non-mouse' operators, while 'mouse' operators worked 81% of the time with the shoulder rotated outward more than 30 degrees. 'Mouse' operators corrected a longer text during the given time. Our observations showed long periods of strenuous working postures for 'mouse' operators compared to 'non-mouse' operators. We believe that further investigations need to be carried out on the effects of word-processing techniques and to develop ergonomic work station designs for the 'mouse' and other non-keyboard input devices.

Arm↗
PubMed1994

Musculoskeletal symptoms and psychosocial factors among patients with craniomandibular disorders.

General musculoskeletal symptoms and emotional stress situations in terms of psychosocial stressors at work and sleeping disturbances were compared between patients with craniomandibular disorders (CMD) (56 women, 24 men) and a random population sample (88 men, 86 women in the Stockholm Music 1 study). A multiple-choice questionnaire was used. In comparison with the CMD men the CMD women had an increased rate of tooth clenching and muscular pain in the face. When compared with the women in the population sample, the CMD women showed increased risks for musculoskeletal pain in various parts of the body, such as neck, shoulders, thoracic back, wrist/hands, and the knees. A comparison between the CMD men and the men in the population did not show any clear differences in prevalence of general musculoskeletal symptoms. However, the CMD men differed in reporting higher scores for psychologic demands at work and also in having more sleeping disturbances.

Adult↗
PubMed1994

Impaired nerve conduction in the carpal tunnel of platers and truck assemblers exposed to hand-arm vibration.

OBJECTIVES: The goal of this study was to assess the relative risks of sustaining impaired nerve conduction in the hands among vibration-exposed persons as opposed to nonvibration-exposed referents. METHODS: In a cross-sectional study design platers and truck assembly workers were contrasted to office workers. The 4-h frequency-weighted vibration was 4.6 m.s-2 and 1.0 m.s-2 for the platers and assemblers, respectively. The ergonomic factors were measured as forced grip time. The conduction velocity, distal latency time, and amplitude of the median nerve were measured for both hands. RESULTS: The sensory nerve conduction velocity was slower in the right hand than in the left. An increased risk of prolonged latency time was found for the platers and assemblers when contrasted to the office workers. The relative risks (rate ratios) of impaired nerve conduction for the carpal tunnel segment varied between 1.4 and 2.0 for the distal latency and between 0.9 and 1.7 for the nerve conduction velocity. The rate ratios were generally higher for the left-hand side than for the right-hand side. The risks were not proportional to either the weighted or unweighted vibration exposure. CONCLUSIONS: The contributions from vibration and ergonomic factors to impaired nerve conduction velocity were inseparable in this study. Ergonomic factors such as forceful gripping and extreme positions, apart from vibration exposure, may be strong determinants of impaired nerve conduction in the carpal tunnel area.

Adult↗
PubMed1993

The effectiveness of respirators measured during styrene exposure in a plastic boat factory.

In a plastic boat company we studied workers' attitudes toward wearing respiratory protective equipment and differences in styrene exposure received with and without respirators. The workers studied used either half-facepiece air-purifying or full-face air-supplied respirators as much as possible during the first day of the study. On the second day respirators were used only for short periods or not at all. Individual styrene exposures were measured by personal air sampling in the breathing zone. When using respirators the exposure was measured both inside and outside the respirators. The styrene metabolites mandelic and phenylglyoxylic acids were determined in urine samples collected during the workday. The eleven workers studied used the respirators 52% of the time on the first day and 7% of the time on the second. The reasons for not wearing respirators were that they delayed work, were too tight and uncomfortable, made it difficult to breath, and/or became too warm. The use of respirators during work operations such as spraying, laminating, and painting reduced the styrene exposure by 56%-92%. The excretion rate of mandelic and phenylglyoxylic acids in urine collected at the end of the working day was 30%-99% lower when respirators were worn than when they were not.

Air Pollutants, Occupational↗
PubMed1993

d-limonene exposure to humans by inhalation: uptake, distribution, elimination, and effects on the pulmonary function.

The toxicokinetics of d-limonene were studied in human volunteers exposed by inhalation (2 h, work load 50 W) in an exposure chamber on three different occasions. The exposure concentrations were approximately 10, 225, and 450 mg/m3 d-limonene. The relative pulmonary uptake was high, approximately 70% of the amount supplied. The blood clearance of d-limonene observed in this study, 1.1 l kg-1 h-1, indicates that d-limonene is metabolized readily. About 1% of the total uptake was eliminated unchanged in the expired air after the end of exposure, while approximately 0.003% was eliminated in the urine. A long half-time in blood was observed in the slow elimination phase, which indicates accumulation in adipose tissues. A decrease in vital capacity was observed after exposure to d-limonene at a high exposure level. The subjects did not experience any irritative symptoms or symptoms related to the central nervous system (CNS).

Administration, Inhalation↗
PubMed1993

A conceptual model for work-related neck and upper-limb musculoskeletal disorders.

This paper presents a conceptual model for the pathogenesis of work-related musculoskeletal disorders. The model contains sets of cascading exposure, dose, capacity, and response variables, such that response at one level can act as dose at the next. Response to one or more doses can diminish or increase the capacity for responding to successive doses. The model is used as a framework for discussing the development of work-related muscle, tendon, and nerve disorders. It is intended as a beginning, to be modified to explain new findings as they become available. In research, it can help to identify areas needing additional data for the development and expression of work-related musculoskeletal disorders. Researchers can use it to design laboratory and field studies. In practice, it demonstrates the relationship between common exposure factors and different responses. This information can be used to evaluate and design jobs for the prevention of work-related musculoskeletal disorders.

Arm Injuries↗
PubMed1993

Shoulder tendinitis and its relation to heavy manual work and exposure to vibration.

Three categories of construction industry workers (54 bricklayers, 55 rockblasters, and 98 foremen) were compared in a cross-sectional study. In a structured interview they reported exposure to loads lifted, vibration, and years of manual work. They were also subjected to a clinical investigation including medical history and a detailed shoulder examination. Among the rockblasters 33% had signs of tendinitis in the left and 40% in the right shoulder. Among the bricklayers and foremen 8-17% had signs of shoulder tendinitis. In a multiple logistic regression being a rockblaster compared with being a foreman showed an odds ratio (OR) of 3.33 for left-sided and 1.71 for right-sided shoulder tendinitis. Vibration exposure yielded an OR of 1.84 and 1.66 for the left and right sides, respectively. Vibration exposure or work as a rockblaster seemed to be risk indicators for tendinitis of the shoulders.

Adult↗
PubMed1992

Exposure variables in ergonomic epidemiology.

The ergonomic field is rather new to epidemiology and ergonomists are usually without knowledge in epidemiology. This review presents exposure variables used in ergonomic epidemiology, especially those that concern mechanical trauma to the musculoskeletal system at the workplace and suggests how to approach exposure definition, exposure assessment, and exposure evaluation. The exposure variables that define the exposure can be divided into five main categories: posture, motion/repetition, material handling, work organization, and external factors. There is no consensus on how different exposure variables should be pooled and interpreted as single estimates of cumulative exposure. For future ergonomic epidemiology, it is suggested that exposure be described by different exposure variables giving an exposure profile and not by a single estimate of the exposure. The possibly short time-response relationship for many work-related musculoskeletal disorders provides a challenge in evaluating different cumulative exposure measures. These measures could easily turn into effective hazard surveillance tools. Large etiological fractions found for some musculoskeletal diseases indicate a great potential for ergonomic interventions.

Biomechanical Phenomena↗