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Biomedical subjects

M H Frings-Dresen

Publications and source records attributed to M H Frings-Dresen.

At least 19 recordsLinked to original sources
PubMed2001

Gender differences in upper extremity musculoskeletal complaints in the working population.

OBJECTIVES: This study analysed the association between gender and upper extremity musculoskeletal complaints, among the general working population and in various occupational groups. The hypothesis was tested whether the higher risk for women in the general working population for these complaints could partly be explained by differences in the distribution of men and women in occupations with different risks for the onset of upper extremity musculoskeletal complaints. METHODS: The data for this study came from cross-sectional questionnaire data from 16,874 employees categorised in 21 different occupational classes. Associations between gender and complaints of the upper extremities were analysed for the total study sample and for each occupational class separately. An adjustment was made for the variable 'occupational class' in the final model in order to study the impact of occupational gender segregation on gender differences in upper extremity complaints in the working population. RESULTS: In the total study sample, significantly higher risks of complaints of the neck, shoulder, elbow, and wrist among the women were observed. Within many occupational classes, women reported significantly higher risks than did men, in particular for complaints of the neck and shoulder. Adjustment for occupational class showed increased risks for female workers for complaints of the neck, shoulder, elbow, and wrist, hence, rejecting our hypothesis on occupational gender segregation as an explanation for the higher risks for upper extremity complaints among women in the general working population. CONCLUSIONS: This study confirmed the presence of gender differences in upper extremity musculoskeletal complaints among the working population and in many occupational classes, with female workers having the higher risk. The results, however, do not lend support to a differential occupational exposure theory as an explanation for the higher risks for these complaints among women in the general working population. Careful consideration of gender influence in ergonomic epidemiological studies is recommended.

Adult↗
PubMed2001

The trucker strain monitor: an occupation-specific questionnaire measuring psychological job strain.

OBJECTIVES: To develop and validate a short and user-friendly questionnaire measuring psychological job strain in truck drivers. METHODS: In cooperation with an occupational physician in the Dutch road transport industry we developed items on the basis of face validity and information of existing questionnaires on the subject. These items were pilot-tested, by means of interviews, in 15 truck drivers. Study I examined the factorial structure of the initial 30-item trucker strain monitor (TSM) in a sample of 153 truck drivers. Subsequently, number of items per factor was reduced on the basis of reliability analyses (Cronbach's alpha). Study II examined construct and criterion validity of the TSM in a randomly selected group of 2,000 truck drivers, of whom 1,111 participated (adjusted response = 63%). Additionally, sensitivity and specificity were assessed by examining the ability of the TSM to identify truck drivers with or without self-reported sickness absence in the past 12 months because of psychological complaints. RESULTS: Factor analyses of the initial 30-item TSM revealed a two-factor solution. Item reduction resulted in a six-item work-related fatigue scale and four-item sleeping problems scale with high internal consistency. Results of study II confirmed the internal consistency of the TSM scales and provided support for construct and criterion validity. The composite, work-related fatigue, and sleeping problems scale had a sensitivity of 83%, 80% and 71% respectively, in identifying truck drivers with prior sickness absence because of psychological complaints. Specificity rates were 72%, 73% and 72% respectively. CONCLUSION: Despite methodological limitations, the results suggest that the TSM is a reliable and valid indicator of psychological job strain in truck drivers. In particular, the composite and work-related fatigue scale identified drivers with prior absenteeism because of psychological complaints, quite accurately. Future longitudinal research in specific sub-groups of truck drivers including both self-reported and objective psychological health measures should evidence whether (1) the distinction between two indicators of psychological job strain is useful, and whether (2) the TSM can be used in screening out truck drivers at risk of developing psychological health problems.

Fatigue↗
PubMed2001

The relation between work-induced neuroendocrine reactivity and recovery, subjective need for recovery, and health status.

OBJECTIVES: The purpose of this cross-sectional study with repeated measurements was to find out to what extent neuroendocrine reactivity during work and neuroendocrine recovery from work, and work characteristics, are related to subjective need for recovery and perceived health status. METHODS: Neuroendocrine reactivity and recovery were studied in 59 subjects by measuring urinary adrenaline and cortisol repeatedly during five consecutive days. Measures of work characteristics, subjective need for recovery, and health status were obtained by self-reports. Two hierarchical multiple linear regression analyses were performed. RESULTS: The work characteristics alone explained 39% and 28% of the variation in subjective need for recovery and health status, respectively, while these figures rose to 49% and 53% in the full models. Significant neuroendocrine contributors were found for cortisol in reactivity during work and recovery immediately after work and recovery during the day off-work, and for adrenaline in baseline level and recovery during the day off-work. Job characteristics contributed significantly as well. CONCLUSION: Both neuroendocrine measures and work characteristics were predictors for the amount of perceived need for recovery after work as well as for health status. The results are consistent with the cognitive activation theory of stress.

Adult↗
PubMed2001

Assessment of short-term physical loading of the back: is serum keratin sulfate an appropriate biomarker?

STUDY DESIGN: A prospective experimental study. OBJECTIVES: To investigate the potential of serum keratan sulfate (KS) as an indicator of biochemical changes in intervertebral discs induced by physical loading of the back. BACKGROUND: By providing objective information on exposure and effects at the tissue level, biomarkers may enable us to improve our understanding of the intermediate steps between exposure to physical loading and the occurrence of back disorders. Serum KS has been proposed as a potential biomarker of the molecular changes in intervertebral discs that occur because of physical loading and are a potential cause of back disorders. METHODS AND MEASURES: Thirty-two nonimpaired men volunteers with a mean age of 22.5+/-2.3 years participated in the experimental condition, a manual lifting task, as well as in the control condition, lying on the back. Serum KS levels were measured immediately before and after both conditions, as well as 24 hours and 1 week later. RESULTS: No significant changes in serum KS levels were found after exposure to physical loading (mean SD serum KS before, 287.4+/-83.9 ng/mL; immediately after, 279.5+/-65.5 ng/mL; 24 hours after, 266.6+/-71.9 ng/mL; and 1 week after, 268.9+/-79.3 ng/mL), and no significant changes were found after lying on the back for 8 hours (mean+/-SD serum KS before, 273.0+/-94.3 ng/mL; immediately after, 261.6+/-68.9 ng/mL; 24 hours after, 277.3+/-68.9 ng/mL; and 1 week after, 274.5+/-68.5 ng/mL). CONCLUSIONS: These results indicate that the serum KS level is not suitable as a biomarker of the effects of short-term physical loading of the back induced by a manual lifting task.

Adult↗
PubMed2001

Group-based measurement strategies in exposure assessment explored by bootstrapping.

OBJECTIVES: The precision of mean exposure to pushing was examined in 2 occupational groups using various combinations of the number of workers and measurements per worker. METHODS: The frequency and duration of pushing of the 2 occupational groups was assessed using onsite observation. All data were divided into successive periods of 30 minutes of observation. The precision of the group mean exposure to pushing was expressed by 90% confidence intervals obtained by bootstrapping. The effect on the confidence interval of varying numbers of workers and numbers of periods per worker was examined. RESULTS: For both occupational groups there was little precision to be gained when >10 workers were observed. Within the maximum number of workers used in the bootstrap simulations, it appeared that, beyond 10 workers, the confidence intervals decreased by <5% for every worker that was added, when each worker was observed at least 8 periods of 30 minutes. If workers were observed exactly 4 periods of 30 minutes per worker, an additional 4 workers were required to compensate for the loss of precision. An unbalanced strategy with approximately 8 periods of 30 minutes per worker hardly decreased the precision of the group mean, however. CONCLUSIONS: The precision of the group-based mean exposure to pushing is influenced by the number of workers observed and by the number of repeated measurements per worker. In the planning of measurement strategies, it is advisable to account for possible sources of variance in advance and to assess the exposure variability.

Adult↗
PubMed2000

Gender differences in exerted forces and physiological load during pushing and pulling of wheeled cages by postal workers.

The aim was to determine gender differences regarding exerted forces and physiological load during push/pull tasks simulating the daily working practice of postal workers. Eight female and four male workers handled four-wheeled cages under eight conditions corresponding to the cage weight (130, 250, 400, 550 kg) and the direction of force exertion (pushing, pulling). For each of the five dependent variables, average force, initial force, ending force, oxygen uptake and heart rate, two analyses of variance with repeated measurements were performed, i.e. with and without correction for the worker's body weight, body height and maximum capacity regarding the dependent variable. Exerted forces and physiological load were high for the cages weighing 400 and 550 kg. Gender differences were significant for all dependent variables (p = 0.030-0.000). When the personal factors were included in the model, male workers exerted significantly higher average forces and ending forces than their females, while differences regarding initial forces and physiological load were not significant. However, none of the personal factors were significantly related to any of the dependent variables. It is concluded that gender differences in exerted forces were not caused by differences in anthropometry and maximum capacity, but due to application of different work methods by women in order to balance work demands and work ability.

Adult↗
PubMed2000

Reactivity and recovery from different types of work measured by catecholamines and cortisol: a systematic literature overview.

OBJECTIVES: To review occupational health, laboratory, and sports literature on neuroendocrine reactivity and recovery from mental, combined mental and physical, or physical tasks. METHODS: A systematic literature search was performed in eight databases. Studies with catecholamines or cortisol as effect variables measured in blood, urine, or saliva were included. RESULTS: After application of inclusion and exclusion criteria, 77 studies from the initial 559 identified were taken into account. In occupational settings it was found that relatively few studies were conclusive about recovery, which formed a contrast with sports research. For reactivity and recovery up to 1 hour after performing the task, half of the studies considered physical tasks and more than two thirds showed incomplete recovery compared with baseline excretion of catecholamines and cortisol. Recovery extending to 3 days after the task was performed was often incomplete for cortisol after combined mentally and physically demanding tasks, and less often after solely mental or physical tasks. This type of recovery was more often incomplete for adrenaline (epinephrine) than for noradrenaline (norepinephrine), which was the case after mental as well as combined mental and physical tasks. CONCLUSIONS: The results from laboratory and sports research may be transferable to some occupations, but more research is needed on the course of recovery relative to health effects in occupational settings.

Biomarkers↗
PubMed2000

A forward-facilitating influence of cortisol on catecholamines assessed during the work of garbage collectors.

OBJECTIVES: In this study, the hypothesis was tested of whether part of the hypothalamic-pituitary-adrenal system can have a facilitating influence on mean adrenomedullary reactivity during a workday. METHODS: Data of a field study on 115 male garbage collectors were used for this purpose. Catecholamines and cortisol were assessed by urinary sampling during a workday and during a day off. The within-subjects baseline levels of the catecholamines, personal factors, physical work load, and work characteristics were controlled for in the analyses. RESULTS: The results showed that there is reason to assume a "forward-facilitating influence" between the aforementioned systems. The morning cortisol excretion rate explained a reasonable amount of the mean catecholamine excretion rates during a workday. The morning cortisol level explained more variance in the adrenaline than in the noradrenaline values, and for both catecholamines the influence of cortisol was more pronounced than the influence of psychosocial stress factors like autonomy and job demands. CONCLUSIONS: The morning level of cortisol proved to be a more powerful predictor of the reactivity of adrenaline than that of noradrenaline during work. The association between the pituitary adrenocortical system and the adrenomedullary system could therefore be a "forward-facilitating influence". It is recommended that future research should focus on cortisol as the predictor of neuroendocrine reactivity and on determining whether this predictive power is expandable to work-induced health complaints.

Adrenal Medulla↗
PubMed2000

Neuroendocrine reactivity and recovery from work with different physical and mental demands.

OBJECTIVES: The purpose of this study was to examine the extent to which the type or nature (physical, mental or mixed mental and physical) of work and work characteristics is related to the course of neuroendocrine reactivity and recovery from work. METHODS: Neuroendocrine reactivity and recovery were studied by measuring the urinary excretion of adrenaline, noradrenaline, and cortisol during and after 3 workdays, 1 consecutive day off, and a baseline day. The assessment was made in 3 groups of Dutch male workers (N=60) who differed in the nature (mental, physical, and combined mental and physical demands) of their work. Multilevel analyses were performed to fit linear mixed-effects models for each hormone. RESULTS: Main or interaction effects with time of day were found between the workers in combined mental and physical work and the 2 other groups of workers for cortisol, adrenaline, and noradrenaline excretion. In addition, the baseline levels of the 3 hormones were higher in the workers with combined mental and physical work when compared with the other 2 groups. The excretion rates during the workdays were higher than those on the day off, but a trend towards mobilizing less activity was found from the 1st to the 3rd workday. Job demands were negatively related to cortisol excretion. Job control and social demands at work did not affect the excretion rates of the hormones. CONCLUSIONS: Unfavorable effects on cortisol and adrenaline reactivity or recovery was found for workers with combined mental and physical demands when compared with workers doing mainly mental or mainly physical work. The results of the present study are in accordance with the cognitive activation theory and the allostatic load model.

Adult↗
PubMed1999

The influence of work characteristics on the need for recovery and experienced health: a study on coach drivers.

Work characteristics, occupationally-induced fatigue, and health complaints were investigated on the basis of questionnaire data from 363 randomized coach drivers. The hypothesis was tested that, apart from high job demands and low job control, need for recovery is an indicator of occupationally-induced health complaints. Multiple linear regression analyses showed that need for recovery was a major predictor of psychosomatic complaints, sleep complaints, and complaints of emotional exhaustion in coach drivers. The influence of job demands and job control on health problems was moderately confirmed. The results of this study draw attention to the role of the need for recovery, as a sign of occupationally-induced fatigue and predictor of health complaints, in future research on occupational stress.

Adult↗
PubMed1998

Keratan sulfate as a potential biomarker of loading of the intervertebral disc.

STUDY DESIGN: A review of the literature. OBJECTIVE: To investigate the potential of serum levels of keratan sulfate as a biomarker of the effects of loading of the spine. SUMMARY OF BACKGROUND DATA: Exposure to mechanical loading of the spine causes changes in metabolism of intervertebral discs, eventually leading to accelerated disc degeneration. This process is characterized by the degradation of proteoglycans, which is reflected by an increase in the blood level of proteoglycan components. The serum level of keratan sulfate, an epitope present on these proteoglycan components, has been suggested as a marker of changes in metabolism of cartilaginous tissues. METHODS: A review of the literature on serum keratan sulfate levels in relation to degenerative changes in cartilaginous tissue. RESULTS: In a number of studies keratan sulfate in serum was reported to be related to degeneration of articular cartilage in patients with osteoarthritis. In addition, massive and rapid degradation of intervertebral discs was determined to result in a large rise in serum keratan sulfate levels. Whether degenerative changes of intervertebral discs induced by mechanical stress also cause a detectable increase in serum keratan sulfate should be subjected to further investigation. CONCLUSION: Quantification of keratan sulfate in serum offers a promising measure for the early effects of mechanical loading of the spine, but research is needed for validation.

Biomarkers↗
PubMed1998

Pushing and pulling in relation to musculoskeletal disorders: a review of risk factors.

The objective was to review the literature on risk factors for musculoskeletal disorders related to pushing and pulling. The risk factors have been described and evaluated from four perspectives: epidemiology, psychophysics, physiology, and biomechanics. Epidemiological studies have shown, based on cross-sectional data, that pushing and pulling is associated with low back pain. Evidence with respect to complaints of other parts of the musculoskeletal system is lacking. Risk factors have been found to influence the maximum (acceptable) push or pull forces as well as the physiological and mechanical strain on the human body. The risk factors have been divided into: (a) work situation, such as distance, frequency, handle height, and cart weight, (b) actual working method and posture/movement/exerted forces, such as foot distance and velocity, and (c) worker's characteristics, such as body weight. Longitudinal epidemiological studies are needed to relate pushing and pulling to musculoskeletal disorders.

Arm Injuries↗
PubMed1998

Assessment of mechanical exposure in ergonomic epidemiology.

In recent years several different methods have been developed to assess mechanical exposures, which are related to musculoskeletal disorders in ergonomic epidemiology. Each of these methods is capable of measuring one or more aspects of risk factors, but has drawbacks as well. Improper application of methods might result in biased exposure estimates, which has serious consequences for risk estimates arising from epidemiological studies. The aim of this paper was to systematically evaluate the usefulness of different measurement methods in terms of accuracy and applicability. Assessment of external exposure measures by subjective judgements (from experts or self reports from workers), observational methods (on site or afterwards from video recordings), and direct measurements methods (at work or during laboratory simulations) are discussed for each of the dimensions of exposure level, duration, and frequency. It is concluded that expert judgements and self reports give only limited insight into the occurrence of tasks and activities. Further information can be obtained from observations, which can best be combined with direct measurements of exposure to posture, movement, and exerted forces to achieve exposure profiles by occupational task. Internal exposures estimated by biomechanical modelling mostly consider the low back and require information on postures of the different body segments and exerted forces, completed with movement data in the case of dynamic models. Moreover, electromyography (EMG) and measurements of intra-abdominal pressure might be used for this purpose. Both biomechanical models and EMG are useful methods to assess internal exposure, but biomechanical models should not be restricted to the level of compressive forces on the lower back. Finally, current problems and future directions in measurement strategies and methods are discussed.

Biomechanical Phenomena↗
PubMed1998

Work stress and recovery measured by urinary catecholamines and cortisol excretion in long distance coach drivers.

OBJECTIVES: To evaluate coach drivers' work stress during work and in the course of recovery from work by measurement of urinary catecholamines and cortisol. METHODS: The urinary excretion rate of adrenaline, noradrenaline, and cortisol of 10 coach drivers was studied during a long distance trip of three days and two consecutive days off. Each driver was asked to provide seven urine samples on the working days and six urine samples on the days off. The second day off was considered as the baseline. RESULTS: An occupationally induced disturbance of the circadian rhythmicity was found for adrenaline and noradrenaline but not for cortisol. The mean excretion rates of adrenaline on the first working day and most samples on all working days were higher than the baseline. For both adrenaline and noradrenaline the mean excretion rates on the first day off were lower than the baseline. For cortisol, the mean excretion rate on all working days was higher than the baseline. A trend towards accumulation of cortisol excretion from the first working day to the third working day was found. A backward shift in peak concentrations was found for adrenaline and noradrenaline on the second working day, as was a forward shift in peak concentration of cortisol on both days off. CONCLUSIONS: Long distance coach drivers showed occupationally induced reactivity in rates of urinary excretion of adrenaline, noradrenaline, and cortisol. After the outward journey the rates of excretion of catecholamines did not return to baseline values. The course of recovery in adrenaline excretion after the journey showed a new phenomenon, which has been called "fatigue debt". It is recommended that longer resting times in shuttle bus trips and fixed days off after these kind of trips should be planned. Extensive future research should be focused on the additional relations between fatigue debt and health complaints.

Adult↗
PubMed1997

Musculoskeletal complaints in The Netherlands in relation to age, gender and physically demanding work.

OBJECTIVES: This cross-sectional study was performed in order to elucidate the relationship of musculoskeletal complaints with age, gender and physically demanding work in the Netherlands. METHODS: Questionnaire data of male (n = 36756) and female (n = 7730) employees, gathered as part of periodical occupational health surveys among active workers in the Netherlands, were stratified for age, gender, and type of work demands. For each stratified group prevalence rates (PR) were calculated for complaints of the back, neck, upper and lower extremities. Moreover, prevalence rate differences (PRD) were estimated as an absolute effect measure of exposure to various types of physical work demands, with active employees in mentally demanding work acting as a reference population. RESULTS: Musculoskeletal complaints among workers in physically demanding occupations were found to increase with age for both sexes. For several complaints, substantially higher rates were reported for women than for men, with a relatively high number of complaints observed among the older female workers (around 40% for complaints of back, upper and lower extremities). Significant PRDs were present in particular for employees in heavy physically demanding occupations and in jobs with mixed mental and physical work demands. CONCLUSIONS: With the ageing of the workforce in mind, these findings stress the need for implementation of preventive measures. Special attention towards the susceptible group of female employees, the elderly age groups in particular, seems justified. In order to clarify the combined effects of age and physical work demands on musculoskeletal complaints, additional studies are required.

Adolescent↗
PubMed1997

Repeated survey on changes in musculoskeletal complaints relative to age and work demands.

OBJECTIVES: To examine changes in musculoskeletal complaints over four years in groups of employees relative to age and work demands. METHODS: Repeated questionnaire data of male employees in heavy physical work (exposed group, n = 7324) and mental work (control group, n = 4686), stratified for age (20-9, 30-9, 40-9, 50-9), were analysed. For each employee, data on the occurrence of musculoskeletal complaints from two surveys with a mean interval of around four years were available. Changes in prevalences over the follow up interval were analysed. Proportions of new, recovered, and chronic cases as well as those free of complaints at both surveys were studied. RESULTS: For most complaints, there were significantly greater increases in prevalences in the exposed group compared with the control group over the follow up interval particularly within the group aged 40-9 for back, neck, and several sites of the upper and lower limbs. The 20-9 year age group also had significantly greater changes for several musculoskeletal complaints. Within the oldest age group (50-9) exposure to heavy physical work demands only affected changes in prevalences of neck and upper arm complaints. After four years in the cohort free of complaints at the start of the follow up the group aged 40-9 had the highest prevalence of complaints of the back, neck, and the upper and lower limbs. CONCLUSIONS: Middle aged and younger employees develop musculoskeletal complaints as a result of exposure to heavy physical work. In the oldest age group health related selection seems to mask the occupational health risks under study. To prevent the expected increase in musculoskeletal disorders and related work disability in our aging workforce, preventive measures should be taken at all stages of a working life.

Adult↗
PubMed1997

Selection related to musculoskeletal complaints among employees.

OBJECTIVES: To (a) describe differences in the outcome of cross sectional and longitudinal analysis on musculoskeletal complaints relative to age and work demands, and (b) to assess the entrance and drop out selection on musculoskeletal complaints among groups of employees relative to age and work demands. METHODS: A study population was selected on the basis of questionnaire data from periodical occupational health surveys of almost 45,000 employees collected between 1982 and 1993. From all companies within this data base that participated twice in company wide surveys four years apart, male employees were selected, and stratified for age and work demands. There were several populations: follow up (participation in both surveys); drop out (participation only in the first survey); entrance (participation only at the second survey); and two cross sectional populations (all participants at each survey). Prevalences of back complaints and turnover rates were analysed. RESULTS: Reported back complaints in the cross sectional analysis declined over the oldest age groups in heavy physical work versus a small increase in the longitudinal analysis. The age group 50-9 and back complaints were identified as predictors at the first survey for not participating at the second survey. Neither age nor work demands at the first survey indicated drop out among those employees with back complaints at the first survey. The effects of entrance selection on estimated prevalences were small. CONCLUSIONS: The results indicate that musculoskeletal disorders lead to selection out of work, affecting the validity of both cross sectional and longitudinal epidemiological studies. In future studies analyses of turnover figures on musculoskeletal complaints relative to work demands and age are recommended.

Adult↗