Documents strain measurement 19 results

"Objective The aim of this randomized controlled trial (RCT) was to investigate the effectiveness of the Stay@Work participatory ergonomics (PE) program to prevent low-back and neck pain. Methods A total of 37 departments were randomly allocated to either the intervention (PE) or control group (no PE). During a six-hour meeting, working groups followed the PE steps and composed and prioritized ergonomic measures aimed at preventing low-back and neck pain. Subsequently, working groups were requested to implement the ergonomic measures in the departments. The primary outcomes were low-back and neck pain prevalence and secondary outcomes were pain intensity and duration. Data were collected by questionnaires at baseline, and after 3-, 6-, 9-, and 12-months follow-up. Additionally, the course of low-back and neck pain (transitions from no symptoms to symptoms and from symptoms to no symptoms) was modeled. Results The randomization procedure resulted in 19 intervention departments (N=1472 workers) and 18 control departments (N=1575 workers). After 12 months, the intervention was not more effective than the control group in reducing the prevalence of low-back and neck pain or reducing pain intensity and duration. PE did not increase the probability of preventing low-back pain [odds ratio (OR) 1.23, 95% confidence interval (95% CI) 0.97–1.57) or neck pain (OR 1.01, 95% CI 0.74–1.40). However, PE increased the probability of recovering from low-back pain (OR 1.41, 95% CI 1.01–1.96), but not from neck pain (OR 0.95, 95% CI 0.72–1.26).Conclusion PE neither reduced low-back and neck pain prevalence nor pain intensity and duration nor was it effective in the prevention of low-back and neck pain or the recovery from neck pain. However, PE was more effective in the recovery from low-back pain."

"Objectives The number of longitudinal studies reporting evidence for reversed effects of strain on work is growing, but evidence regarding the mechanisms underlying such effects is scarce. In this study, earlier longitudinal findings were reviewed, and the following four mechanisms for reversed effects were proposed that reflect within-person or environmental changes: (i) the rosy perception mechanism, (ii) the gloomy perception mechanism, (iii) the upward selection mechanism, and (iv) the drift mechanism.Methods These mechanisms were tested using structural equation modeling and longitudinal data from a Dutch four-phase study (N=1588 participants).Results The results revealed that work characteristics and mental health influenced each other reciprocally and longitudinally. The reversed effects were examined in more detail, and it was found that these could be accounted for by both within-person and environmental change mechanisms. The rosy perception mechanism was found to explain the positive effects from health on job demands; the upward selection mechanism explained the positive (environmental) effects from health on job control; the gloomy perception mechanism explained the reversed (evaluation) effects from health on supervisory social support. No support was found for the drift mechanism.Conclusions Mechanisms that may explain reversed causation are yet poorly understood. The main contribution of the present study lies in the fact that it proposes (i) a conceptual framework with which to analyze the effects of health on work characteristics and (ii) methods for testing these mechanisms. The study revealed that there is good reason to pursue research on reversed causality."

"Objectives The aim of this study was to examine the association of the discrepancy between externally and self-assessed measures of work environment with long- and short-term sickness absence.Methods The study population included 6997 middle-aged men and women from the Whitehall II cohort, whose work characteristics were examined at baseline (1985–1988) through both an external evaluation and self-report, with a follow-up of up to 13 years of sickness absence reporting from administrative records. The primary exposure of interest was the discrepancy between measures of work stress for fast job pace, conflicting demands, and decision latitude.Results In mutually adjusted models, external measures of job characteristics were more strongly associated with higher rates of sickness absence compared with self-assessed measures, for both lower frequency of fast work pace and lower conflicting demands (ie “passive” levels). Individuals who self-reported higher frequencies of fast work pace and conflicting demands than were reported through external assessment had higher rates of short-term sickness absence [incident rate ratios (IRR) of 1.13 (95% confidence interval [95% CI] 1.11–1.15) and IRR 1.14 (95% CI 1.11–1.16), respectively]. There was no difference in rates of sickness absence found for decision latitude [IRR 1.02 (95% CI 1.00–1.04)].Conclusions Our findings demonstrate that the discrepancy between externally and self-assessed job demand measures have additional predictive power beyond each individual measure of job structure, which may be related to the extent of cognitive and emotional processing of assessment questions as compared to decision latitude measures."

"The prediction of physiological strain is essential for the safety of personnel in high-risk environments especially when wearing personal protective equipment (PPE). This study aimed to develop a usability-enhanced variant of the Heat Strain Decision Aid (HSDA), named HSDA-FL, by implementing automatic workload estimations, alternative environmental inputs, and a revised initialization delay logic. The second aim was to evaluate whether these modifications preserved the original model's validity. The third aim was to evaluate the performance of HSDA, HSDA-FL, and the PHS-FL models while wearing CBRN PPE. Eleven acclimatized participants completed a 40-minute simulated chemical, biological, radiological, and nuclear (CBRN) reconnaissance scenario involving walking and inspection tasks. The HSDA-FL was tested with both the original and the revised delay logic, demonstrated significantly lower residual errors than the original HSDA (p<0.001), with the revised delay logic variant achieving the highest accuracy (MAE=0.151°C, RMSE=0.191°C, bias=0.011°C). In contrast, the PHS-FL performed significantly worse than all HSDA-based models (p<0.001). These findings confirm that HSDA-FL maintains and slightly exceeds the predictive validity of the original HSDA while improving usability, whereas PHS-FL was not deemed sufficiently reliable for use with CBRN clothing."

"This study examined the effects of psychosocial job strain on the excretion of neuroendocrine stress hormones (adrenaline, noradrenaline, and cortisol) on workdays and days off. ... Psychosocial job strain is associated with greater noradrenaline excretion over time. This finding suggests unwinding sympathetic nervous activity. The low cortisol levels of the high-strain group may indicate circadian rhythm disturbance induced by job strain. Supervisory relationships may have a particular influence for the studied occupation because the participants had more administrative contact with supervisors than support at the worksite; therefore, supervisory support may increase adrenaline excretion."

This study evaluated the effect of an intensive ergonomic approach and education on workstation changes and musculoskeletal disorders among workers who used a video display unit (VDU).Both the intensive ergonomics approach and education in ergonomics help reduce discomfort in VDU work. In attempts to improve the physical ergonomics of VDU workstations, the best result will be achieved with cooperative planning in which both workers and practitioners are actively involved.

"The aim of this study was to explore the prospective relation between job stress and symptoms of depression within a cohort study. METHODS: Altogether 2821 workers were involved in the longitudinal Belstress study (Belgian job stress study); there were two measurements with a mean follow-up time of 6.6 years. Job stress was assessed by the Job Content Questionnaire. Depression symptoms were assessed by the Iowa form of the Center for Epidemiological Studies-Depression Scale. Baseline and repeated exposures to job stress were related to the development of high levels of depression symptoms through logistic regression analysis. RESULTS: Within a population free of high depression scores at baseline, job stress increased the risk of developing high levels of depression symptoms after a mean follow-up time of 6.6 years. Independent associations were found for low decision latitude, high job strain, and isolated strain among women, but not among men. The adjusted association with high job strain among men was borderline significant. Repeated high job strain was associated with a more elevated risk of developing high levels of depression symptoms among both the women and the men. CONCLUSIONS: The results of this study confirm that job stress is a risk factor for developing symptoms of depression. Stronger associations were found for women. The impact of high job strain among both men and women was more harmful when there was repeated exposure."

"Older experienced firefighters may show signs of heat adaptation, and thus reduced physiological strain, due to repeated occupational heat stress exposure. The aim was to examine physiological and perceptual strain, and hydration, responses to intermittent exercise in the heat in 12 older Non-Firefighter (Non-FF) and experienced Firefighter (FF) males, pair matched for age (Group mean ± SE: Non-FF = 51.7 ± 1.5, FF = 49.8 ± 1.1 years), VO(2peak) (Non-FF = 39.4 ± 2.2, FF = 40.7 ± 1.8 mL·kg(-1)·min(-1)), body surface area (Non-FF = 1.94 ± 0.04, FF = 2.03 ± 0.03 m(2)), and percent body fat (Non-FF = 24.4 ± 2.3, FF = 19.3 ± 1.8%). Rectal (Tre) and mean skin (MT(sk)) temperatures, heart rate (HR), local sweat rate (LSR), hydration indices, and ratings of thermal sensation and perceived exertion were measured during 4 ×15-min (rest 15-min) moderate-to-heavy cycling bouts (400 W heat production) in Dry and Humid heat (35°C, ?20 and ?60% relative humidity, respectively). No differences were observed between the Non-FF and FF for T(re), T(re) change, MT(sk), HR,% max HR, LSR, physiological strain index (PhSI), or % plasma volume change. Plasma protein concentration was reduced at baseline for the Non-FF (7.6 ± 0.1 g·100 mL(-1)) than FF (8.0 ± 0.1 g·100 mL(-1)). The Perceptual Strain Index overestimated PhSI for Non-FF and FF in both thermal conditions. At the end of exercise, the Non-FF showed a greater Tre difference between thermal conditions (0.27 ± 0.05°C) compared to the FF (0.10 ± 0.09°C). Although the Non-Firefighters and Firefighters demonstrate similar cardiovascular and hydration responses during moderate-to-heavy intensity exercise within each of the thermal conditions, the attenuated thermal effects between the two heat stress conditions in the Firefighters suggests a protective adaptation."

"Negli ultimi anni le segnalazioni di disturbi muscoloscheletrici lavoro-correlati, (Work Related Musculo- Skeletal Disorders = WMSDs), sono aumentate in modo significativo, anche per un più diffuso meccanismo di riconoscimento delle patologie e dei rischi. Per questi ultimi però i pur numerosi modelli di valutazione non trovano un unanime riconoscimento. In questo studio viene presentata l'applicazione a 12 postazioni di lavoro a diverso livello di sovraccarico biomeccanico, di quattro metodi (Check list OCRA, OREGE, Strain Index, ACGIH). Il confronto, ha permesso di evidenziare una discordanza tra i metodi nelle situazioni a rischio intermedio, mentre per quelle a rischio assente o elevato i metodi forniscono dati sostanzialmente sovrapponibili. Nelle situazioni in cui la valutazione del rischio era concordante i metodi non erano in grado di evidenziare in modo univoco e ripetibile le singole componenti del rischio. Risulta pertanto utile una successiva valutazione analitica dei singoli fattori di rischio che concorrono a determinare il valore degli indici sintetici. Questi ultimi non dovrebbero essere pertanto considerati in grado di definire in modo inequivocabile componenti "accettabili" o "non accettabili" nel complesso dei fattori di rischio biomeccanico."

"Empirical studies on job strain and cardiovascular disease (CVD), their internal validity, and the likely direction of biases were examined. The 17 longitudinal studies had the highest validity ratings. In all but two, biases towards the null dominated. Eight, including several of the largest, showed significant positive results; three had positive, nonsignificant findings. Six of nine case-control studies had significant positive findings; recall bias leading to overestimation appears to be fairly minimal. Four of eight cross-sectional studies had significant positive results. Men showed strong, consistent evidence of an association between exposure to job strain and CVD. The data of the women were more sparse and less consistent, but, as for the men, most of the studies probably underestimated existing effects. Other elements of causal inference, particularly biological plausibility, corroborated that job strain is a major CVD risk factor. Additional intervention studies are needed to examine the impact of ameliorating job strain upon CVD-related outcomes."