Impact of work schedule characteristics on teacher mental health and burnout symptoms while remote working.

BACKGROUND: During the COVID-19 pandemic, teachers quickly shifted to remote teaching with many teachers experiencing increased work demands with limited resources, affecting both mental health and work. METHODS: Within a cross-sectional study, we evaluated the relationship between one type of work demand, non-standard work schedule characteristics, and depressive and burnout symptoms in kindergarten through 8th grade U.S. teachers working remotely in May 2020. We further assessed the impact of COVID-19 and work resources. Work schedule characteristics were self-assessed across six domains on a 5-point frequency scale from always (1) to never (5). We used multilevel Poisson models to calculate prevalence ratios (PRs) and 95% confidence intervals (CIs). RESULTS: In fully adjusted models, frequently working unexpectedly was associated with a higher prevalence of depressive symptoms (PR = 1.18, 95% CI = 1.07-1.31, p < 0.01), high emotional exhaustion (PR = 1.17, 95% CI = 1.05-1.30, p < 0.01), and high depersonalization (PR = 1.40, 95% CI = 1.02-1.92, p = 0.03). Remote work resources were significantly associated with a lower prevalence of depressive symptoms (PR = 0.88, 95% CI = 0.79-0.98, p = 0.02). There was a linear association between low coworker support and a low sense of personal accomplishment (PR = 0.68, 95% CI = 0.53-0.87, p < 0.01). CONCLUSIONS: Frequently having to work unexpectedly while remote teaching was associated with symptoms of depression and burnout during the COVID-19 pandemic. Workplaces should support predictable working times to lessen the disruption caused by unexpected work to promote worker well-being.

Associations between observed time sitting at work and musculoskeletal symptoms: a repeated-measures study of manufacturing workers.

Time sitting at work is known to affect health overall, but its specific effects on musculoskeletal symptoms are unclear. We evaluated the relationship between observed time sitting at work and self-reported musculoskeletal symptoms among 195 manufacturing workers. Longer time sitting at work was significantly associated with lower prevalence of neck/shoulder (prevalence ratio [PR] = 0.70, 95% confidence interval [CI] [0.68, 0.72]; p < 0.001) and arm/wrist/hand (PR = 0.46, 95% CI [0.31, 0.69]; p < 0.001) musculoskeletal symptoms. Associations remained largely unchanged after adjusting for job type or occupational postures and load. Time sitting at work was associated with musculoskeletal symptoms, and should be taken into consideration as part of interventions to prevent musculoskeletal disorders (MSDs) and promote health of manufacturing workers.

The development and initial validation of a new working time scale for full-time workers with non-standard schedules.

BACKGROUND: Working time characteristics have been used to link work schedule features to health impairment; however, extant working time exposure assessments are narrow in scope. Prominent working time frameworks suggest that a broad range of schedule features should be assessed to best capture non-standard schedules. The purpose of this study was to develop a multi-dimensional scale that assesses working time exposures and test its reliability and validity for full-time workers with non-standard schedules. METHODS: A cross-sectional study was conducted using full-time, blue-collar worker population samples from three industries - transportation (n = 174), corrections (n = 112), and manufacturing (n = 99). Using a multi-phased approach including the review of scientific literature and input from an advisory panel of experts, the WorkTime Scale (WTS) was created and included multiple domains to characterize working time (length, time of day, intensity, control, predictability, and free time). Self-report surveys were distributed to workers at their workplace during company time. Following a comprehensive scale development procedure (Phase 1), exploratory factor analysis (EFA) (Phase 2) and, confirmatory factor analysis (CFA) (Phase 3; bivariate correlations were used to identify the core components of the WTS and assess the reliability and validity (Phase 4) in three samples. RESULTS: Phase 1 resulted in a preliminary set of 21 items that served as the basis for the quantitative analysis of the WTS. Phase 2 used EFA to yield a 14-item WTS measure with two subscales ("Extended and Irregular Work Days (EIWD)" and "Lack of Control (LOC)"). Phase 3 used CFA to confirm the factor structure of the WTS, and its subscales demonstrated good internal consistency: alpha coefficients were 0.88 for the EIWD factor and 0.76-0.81 for the LOC factor. Phase 4 used bivariate correlations to substantiate convergent, discriminant, and criterion (predictive) validities. CONCLUSIONS: The 14-item WTS with good reliability and validity is an effective tool for assessing working time exposures in a variety of full-time jobs with non-standard schedules.

Precarious Work Schedules and Sleep: A Study of Unionized Full-Time Workers.

Unlike precarious employment which is temporary and insecure, with inadequate pay, benefits, and legal protections, precarious work schedules can affect workers with permanent full-time jobs in sectors where employment has historically been secure, well-compensated, and even unionized. Precarious work schedules - characterized by long shifts, non-daytime hours, intensity and unsocial work hours - are increasingly prevalent. Relations between precarious work schedules and poor health are not well understood, and less is known about how to attenuate this relation. We examined the indirect effects of precarious work schedules on fatigue and depressive symptoms through sleep quantity. Two moderators - schedule flexibility and sleep quality - were examined as buffers of these associations. Workers from the Departments of Correction and Transportation in a northeast state (N = 222) took surveys and reported on demographics, work schedule characteristics, schedule flexibility, sleep quality and quantity, fatigue, and depressive symptoms. Results revealed that precarious work schedules had indirect effects on fatigue and depressive symptoms through sleep quantity. Schedule flexibility moderated the relation between precarious work schedules and sleep quantity, such that workers with greater schedule flexibility had more hours of sleep. Sleep quality moderated the association between sleep quantity and fatigue and depressive symptoms, such that workers reported greater fatigue and depressive symptoms when they had poorer sleep quality. Findings have direct applicability for developing initiatives that enhance Total Worker Health® through individual and organizational changes. Supplementary Information: The online version contains supplementary material available at 10.1007/s41542-022-00114-y.

Investigating the relationship between working time characteristics on musculoskeletal symptoms: a cross sectional study.

How working hours are organized can have a substantial effect on workers' health. Using a questionnaire and cross-sectional study design, we evaluated the relationship between working time characteristics, job demands, and health behaviors on musculoskeletal symptoms among 316 Department of Transportation (N = 174) and Department of Corrections (N = 142) workers. Low schedule control was associated with neck/shoulder musculoskeletal symptoms (prevalence ratio: 1.20, 95% confidence interval: 1.06-1.34, p < 0.01), and working long (>48 hours per week) hours more frequently was associated with leg/foot musculoskeletal symptoms (prevalence ratio: 1.26 95% confidence interval: 1.06-1.50, p = 0.02). Some working time characteristics were associated with musculoskeletal symptoms, and should be taken into consideration as part of interventions to prevent musculoskeletal disorders and promote health of workers.

Comparison of the Wrist-Worn Fitbit Charge 2 and the Waist-Worn Actigraph GTX3 for Measuring Steps Taken in Occupational Settings.

OBJECTIVES: If consumer-based monitors such as Fitbit can measure activity accurately, it could provide opportunities for improved assessment of physical activity in general and at work for research purposes. The accuracy of the Fitbit has hardly been investigated in an occupational setting. METHODS: We compared measurements of steps taken at work, out-of-work, and in total of a wrist-worn Fitbit to a waist-worn Actigraph. Seventeen participants wore the Fitbit and Actigraph for 1 full workday. RESULTS: Compared with the Actigraph, the Fitbit consistently recorded more steps [mean steps at work Fitbit = 7850 (6974), Actigraph = 4396 (1991); out-of-work Fitbit = 6414 (5691), Actigraph = 4116 (3502); total Fitbit = 13 478 (10 666), Actigraph = 8009 (5167)]. CONCLUSIONS: Compared with the Actigraph, the Fitbit consistently recorded more steps at work, out-of-work, and in total. The Fitbit and Actigraph recordings were more consistent for measuring steps taken out-of-work compared with at work. Steps counts recorded by the Fitbit, especially in occupational settings, may be inaccurate.

Worker perspectives on the impact of non-standard workdays on worker and family well-being: A qualitative study.

BACKGROUND: Non-standard work schedules (NSWSs), occurring outside of regular and predictable daytime hours, may negatively affect worker and family health. This qualitative study sought to understand worker perspectives on the health and well-being impacts of NSWSs among full-time, transportation maintainers, correctional, and manufacturing workers. METHODS: Forty-nine workers participated in 8 focus groups. Data were transcribed and analyzed with ATLAS.ti, using the constant comparative method to identify themes and sub-themes. RESULTS: Workers reported that long work hours and irregular and unpredictable schedules posed the biggest obstacles to their well-being. Workers reported that NSWSs were associated with behavior impacts (poor family and social connections, poor eating, poor sleep, lack of exercise recovery), physical health impacts (exhaustion, weight gain) and extended work exposures (increased stress, increased accidents). CONCLUSIONS: This highlights the importance of developing and implementing effective workplace interventions to address these barriers to health and health behaviors.

Evaluation of the HearWell Pilot Program: A Participatory Total Worker Health® Approach to Hearing Conservation.

Our objective was to pilot test HearWell, an intervention created to preserve hearing among highway maintainers, by using a participatory Total Worker Health® (TWH) approach to designing, implementing and evaluating interventions. Regional maintenance garages were randomized to control (n = 6); HearWell (n = 4) or HearWell Design Team (n = 2) arms. Maintainer representatives from the HearWell Design Team garages identified barriers to hearing health and collaborated to design interventions including a safety leadership training for managers, a noise hazard management scheme to identify noise levels and indicate the hearing protection device (HPD) needed, and a comprehensive HearWell training video and protocol. These worker-designed interventions, after manager input, were delivered to the HearWell Design Team and the HearWell garages. Control garages received standard industry hearing conservation training. Periodic surveys of workers in all 12 garages collected information on the frequency of HPD use and a new hearing climate measure to evaluate changes in behaviors and attitudes over the study period and following interventions. An intention-to-treat approach was utilized; differences and trends in group HPD use and hearing climate were analyzed using a mixed-effects model to account for repeated measures from individual participants. The HearWell Design Team maintainers reported the highest frequency of HPD use. Hearing climate improved in each group 6 months following intervention implementation, with the largest increase and highest value for the HearWell Design Team workers. The HearWell pilot intervention showed promising results in improving HPD use through a participatory TWH approach to hearing conservation. Furthermore, results suggest that employee participation in hearing conservation programs may be necessary for maximal effectiveness.

Working Time Characteristics and Mental Health among Corrections and Transportation Workers.

OBJECTIVES: Mental health disorders are a leading cause of work disability and while the psychosocial workplace environment plays a critical role, working time characteristics are also implicated. We sought to examine the association between working time characteristics and mental health in a cohort of two unionized, full-time worker populations, correctional supervisors, and transportation maintainers. METHODS: Using a cross-sectional study design, we surveyed workers on working time characteristics across seven domains including length of the shift, the intensity or proximity of sequential shifts, the time of day, and social aspects of work hours including predictability, variability, control, and free time. Burnout symptoms (Oldenburg Burnout Inventory) and depressive symptoms (eight-item Centers for Epidemiologic Studies Depression Scale) were assessed along with the psychosocial work environment and health behaviors. We used log-binomial regression models to estimate prevalence ratios and 95% confidence intervals after adjusting for age, gender, and company. RESULTS: A total of 318 workers were surveyed. The majority (72%) of workers reported a fixed shift. The prevalence of burnout symptoms was higher among workers reporting more frequent shift intensity (working 6 or more days in a row) (PR: 1.15, 95% CI: 1.01, 1.31; P = 0.04). Low psychological demands and high worker social support were associated with fewer burnout symptoms, independent of working time characteristics. The prevalence of depressive symptoms was higher in workers reporting more frequent unpredictable work (PR: 1.17, 95% CI: 1.01, 1.35; P = 0.04) and was lower among workers reporting increased schedule control (PR: 0.86, 95% CI: 0.77, 0.96; P = 0.01). Higher worker social support as well as sufficient sleep and adequate exercise were associated with fewer depressive symptoms, independent of working time characteristics. CONCLUSIONS: Different working time characteristics were associated with work-related mental health (i.e. burnout) as well as general mental health (i.e. depressive symptoms). Work intensity was associated with the prevalence of burnout symptoms and the results suggest that the mechanism may be through the need for recovery from the psychosocial exposures of work. Both schedule control and predictability were associated with depressive symptoms and the results suggest that work-life imbalance and lack of recovery may be implicated. Comprehensive prevention policies that consider work organization along with the psychosocial work environment and work-life balance may help to improve workers' mental health.

Development and application of a noise-hazard scheme for road maintainers.

BACKGROUND: Transportation road maintenance and repair workers, or "maintainers," are exposed to hazardous and variable noise levels and often rely on hearing protection devices (HPD) to reduce noise-exposure levels. We aimed to improve upon HPD use as part of the HearWell program that used a Total Worker Health, participatory approach to hearing conservation. METHODS: Full-shift, personal noise sampling was performed during the routine task of brush cutting. Work activities and equipment were recorded and combined with 1-min noise measures to summarize personal noise-exposure levels by equipment. Using noise-monitoring results, HPD noise reduction ratings, and input from worker-based design teams, a noise-hazard scheme was developed and applied to the task and equipment used during brush cutting. RESULTS: Average (standard deviation) and maximum Leq 1-minute, personal noise-exposure levels recorded during brush cutting included chainsaws at 92.1 (7.6) and max of 111 dBA, leaf blowers at 91.2 (7.5) and max 107 dBA, and wood chipper at 90.3 (7.3) and max of 104 dBA. The worker-designed noise-hazard scheme breaks down noise exposures into one of three color bands and exposure ranges: red (over 105 dBA), orange (90-105 dBA), or yellow (85-90 dBA). The scheme simplifies the identification of noise levels, assessment of noise-hazard, and choice of appropriate hearing protection for workers. CONCLUSION: Combining noise-exposure assessment with intervention development using participatory methods, we characterized noise exposure and developed an intervention to educate and assist in protecting workers as they perform noisy tasks.

Safety climate, hearing climate and hearing protection device use among transportation road maintainers.

BACKGROUND: It is important to understand workplace factors including safety climate that influence hearing protection device (HPD) use. We sought to investigate the association between HPD use, safety climate, and hearing climate, a new measure specific to hearing. METHODS: A survey was developed and distributed among transportation "maintainers" who perform road maintenance and repair. A new hearing climate measure was designed by adapting a safety climate measure. HPD use was assessed by asking workers how often they wear HPD while in noise. The differences in safety climate and hearing climate were compared by the frequency of HPD use using analysis of variance. RESULTS: Among 166 maintainers, 54% reported always or almost always wearing HPD while noise exposed. High-frequency HPD users reported a statistically significant higher safety climate (P = 0.004) and hearing climate (P = 0.003). CONCLUSIONS: Hearing climate predicts the frequency of HPD use and may be a useful measure when assessing and improving hearing conservation programs.

Predicting Forearm Physical Exposures During Computer Work Using Self-Reports, Software-Recorded Computer Usage Patterns, and Anthropometric and Workstation Measurements.

Objectives: Alternative techniques to assess physical exposures, such as prediction models, could facilitate more efficient epidemiological assessments in future large cohort studies examining physical exposures in relation to work-related musculoskeletal symptoms. The aim of this study was to evaluate two types of models that predict arm-wrist-hand physical exposures (i.e. muscle activity, wrist postures and kinematics, and keyboard and mouse forces) during computer use, which only differed with respect to the candidate predicting variables; (i) a full set of predicting variables, including self-reported factors, software-recorded computer usage patterns, and worksite measurements of anthropometrics and workstation set-up (full models); and (ii) a practical set of predicting variables, only including the self-reported factors and software-recorded computer usage patterns, that are relatively easy to assess (practical models). Methods: Prediction models were build using data from a field study among 117 office workers who were symptom-free at the time of measurement. Arm-wrist-hand physical exposures were measured for approximately two hours while workers performed their own computer work. Each worker's anthropometry and workstation set-up were measured by an experimenter, computer usage patterns were recorded using software and self-reported factors (including individual factors, job characteristics, computer work behaviours, psychosocial factors, workstation set-up characteristics, and leisure-time activities) were collected by an online questionnaire. We determined the predictive quality of the models in terms of R2 and root mean squared (RMS) values and exposure classification agreement to low-, medium-, and high-exposure categories (in the practical model only). Results: The full models had R2 values that ranged from 0.16 to 0.80, whereas for the practical models values ranged from 0.05 to 0.43. Interquartile ranges were not that different for the two models, indicating that only for some physical exposures the full models performed better. Relative RMS errors ranged between 5% and 19% for the full models, and between 10% and 19% for the practical model. When the predicted physical exposures were classified into low, medium, and high, classification agreement ranged from 26% to 71%. Conclusion: The full prediction models, based on self-reported factors, software-recorded computer usage patterns, and additional measurements of anthropometrics and workstation set-up, show a better predictive quality as compared to the practical models based on self-reported factors and recorded computer usage patterns only. However, predictive quality varied largely across different arm-wrist-hand exposure parameters. Future exploration of the relation between predicted physical exposure and symptoms is therefore only recommended for physical exposures that can be reasonably well predicted.

Differences in the prevalence of musculoskeletal symptoms among female and male custodians.

BACKGROUND: The prevalence of musculoskeletal symptoms among custodians is high. We sought to compare musculoskeletal symptoms between female and male custodians and to explore how task might affect this relationship. METHODS: A cross-sectional study was performed among 712 custodians who completed a survey assessing upper extremity, back, and lower extremity musculoskeletal symptoms and exposure to cleaning tasks. Chi-square tests and logistic regression analyses were used to test for associations between gender, cleaning tasks, and musculoskeletal symptoms. RESULTS: Gender was significantly (P < 0.05) associated with musculoskeletal symptoms in χ(2) tests and multivariate analyses. The prevalence ratio of symptoms among women was roughly 50% higher than men, regardless of the tasks that workers performed. CONCLUSIONS: The prevalence of musculoskeletal symptoms differed for female and male custodians and appeared to be consistent across a range of job tasks. Am. J. Ind. Med. 59:841-852, 2016. © 2016 Wiley Periodicals, Inc.

Time Course of Heart Rate Variability Response to PM2.5 Exposure from Secondhand Smoke.

PURPOSE: Exposure to secondhand smoke (SHS) has been associated with decreased heart rate variability (HRV). However, the time course of this association is unclear. Therefore, the objective of this study was to investigate the association between 15-240 minute SHS-related fine particulate matter (PM2.5) moving averages and indices of HRV. METHODS: With a panel study design, we used personal monitors to continuously measure PM2.5 and HRV of 35 participants who were exposed to SHS for approximately 6 hours. RESULTS: We observed negative, significant associations between 5-minute HRV indices and 15 minute PM2.5 moving averages and 240 minute PM2.5 moving averages: there was a significant (p<0.01) 7.5% decrease in the 5-minute square root of the mean squared differences of successive normal heart beats associated with (RMSSD), and a significant (p<0.01) 14.7% decrease in the 5-minute high frequency (HF) power associated with the 15 minute PM2.5 moving averages; there was also a significant (p<0.01) 46.9% decrease in the 5-minute RMSSD, and a significant (p<0.01) 77.7% decrease in the 5-minute high frequency (HF) power associated with the 240 minute PM2.5 moving averages. CONCLUSIONS: Our findings that exposure to SHS related PM2.5 was associated with HRV support the hypothesis that SHS can affect the cardiovascular system. The negative associations reported between short and longer term PM2.5 and HRV indicate adverse effects of SHS on the cardiovascular system.

Demographic, health-related, and work-related factors associated with body mass index and body fat percentage among workers at six Connecticut manufacturing companies across different age groups: a cohort study.

BACKGROUND: Effective workplace interventions that consider the multifactorial nature of obesity are needed to reduce and prevent obesity among adults. Furthermore, the factors associated with obesity may differ for workers across age groups. Therefore, the objective of this study was to identify demographic, health-related, and work-related factors associated with baseline and changes in body mass index (BMI) and body fat percentage (BFP) and among Connecticut manufacturing workers acrossage groups. METHODS: BMI and BFPof 758 workers from six Connecticut manufacturing companies were objectively measuredat two time points approximately 36 months apart. Demographic, health-related, and work-related factors wereassessed via questionnaire. All variables were included in linear regression models to identify factors associated with baseline and changes in BMI and BFP for workers in 3 age groups: <45 years (35 %), 45-55 years (37 %), >55 years (28 %). RESULTS: There were differences in baseline and changes in BMI and BFP among manufacturing workers across age groups. Being interested in changing weight was significantly (p < 0.01) associated with higher baseline BMI and BFP across all age categories. Other factors associated with higher baseline BMI and BFP differed by age group and included: male gender (BMI p = 0.04), female gender (BFP p < 0.01), not having a college education (BMI p = 0.01, BFP p = 0.04), having childcare responsibilities (BMI p = 0.04), and working less overtime (p = 0.02) among workers in the <45 year age category, male gender (BMI p = 0.02), female gender (BFP p < 0.01) and reporting higher stress in general (BMI p = 0.04) among workers in the 45-55 year age category, and female gender (BFP p < 0.01) and job tenure (BFP p = 0.03) among workers in the >55 year age category. Few factors were associated with change in BMI or BFP across any age category. CONCLUSIONS: Among manufacturing workers, we identified associations between individual, health-related, and work-related factors and baseline BMIand BFP that differed by age. Such results support the use of strategies tailored to the challenges faced by workers in specific age groups rather than adopting a one size fits all approach. Effective interventions should consider a full range of individual, health-related, and work-related factors. More work must be done to identify factors or strategies associated with changes in obesity over time.

Characterization of Urinary Phthalate Metabolites Among Custodians.

Phthalates, a ubiquitous class of chemicals found in consumer, personal care, and cleaning products, have been linked to adverse health effects. Our goal was to characterize urinary phthalate metabolite concentrations and to identify work and nonwork sources among custodians using traditional cleaning chemicals and 'green' or environmentally preferable products (EPP). Sixty-eight custodians provided four urine samples on a workday (first void, before shift, end of shift, and before bedtime) and trained observers recorded cleaning tasks and types of products used (traditional, EPP, or disinfectant) hourly over the work shifts. Questionnaires were used to assess personal care product use. Four different phthalate metabolites [monoethyl phthalate (MEP), monomethyl phthalate (MMP), mono (2-ethylhexyl) phthalate (MEHP), and monobenzyl phthalate (MBzP)] were quantified using liquid chromatography mass spectrometry. Geometric means (GM) and 95% confidence intervals (95% CI) were calculated for creatinine-adjusted urinary phthalate concentrations. Mixed effects univariate and multivariate modeling, using a random intercept for each individual, was performed to identify predictors of phthalate metabolites including demographics, workplace factors, and personal care product use. Creatinine-adjusted urinary concentrations [GM (95% CI)] of MEP, MMP, MEHP, and MBzP were 107 (91.0-126), 2.69 (2.18-3.30), 6.93 (6.00-7.99), 8.79 (7.84-9.86) µg g(-1), respectively. An increasing trend in phthalate concentrations from before to after shift was not observed. Creatinine-adjusted urinary MEP was significantly associated with frequency of traditional cleaning chemical intensity in the multivariate model after adjusting for potential confounding by demographics, workplace factors, and personal care product use. While numerous demographics, workplace factors, and personal care products were statistically significant univariate predictors of MMP, MEHP, and MBzP, few associations persisted in multivariate models. In summary, among this population of custodians, we identified both occupational and nonoccupational predictors of phthalate exposures. Identification of phthalates as ingredients in cleaning chemicals and consumer products would allow workers and consumers to avoid phthalate exposure.

Traditional and environmentally preferable cleaning product exposure and health symptoms in custodians.

BACKGROUND: We investigated the associations between traditional and environmentally preferable cleaning product exposure and dermal, respiratory, and musculoskeletal symptoms in a population of custodians. METHODS: We analyzed associations between symptoms and exposure to traditional and environmentally preferable cleaning product exposure among 329 custodians. RESULTS: We observed increased odds of dermal (P < 0.01), upper (P = 0.01) and lower respiratory (P = 0.01), and upper extremity (P < 0.01), back (P < 0.01), and lower extremity (P = 0.01) musculoskeletal symptoms associated with increased typical traditional cleaning product exposure. We observed significant trends for increased odds of dermal (P = 0.03) and back (P = 0.04) and lower (P = 0.02) extremity musculoskeletal symptoms associated with increased typical environmentally preferable cleaning product exposure. CONCLUSIONS: Fewer positive associations and reduced odds of health symptoms associated with environmentally preferable cleaning product exposure suggest that these products may represent a safer alternative to traditional cleaning products.

Office workers with high effort-reward imbalance and overcommitment have greater decreases in heart rate variability over a 2-h working period.

PURPOSE: High levels of workplace psychosocial factors have been associated with adverse cardiovascular outcomes, possibly through the pathway of increasing autonomic arousal. The purpose of this study was to investigate whether the workplace psychosocial factors of effort-reward imbalance (ERI) and overcommitment were associated with greater decreases in heart rate variability (HRV) across a 2-h working period in a cohort of office workers performing their own work at their own workplaces. METHODS: Measurements of HRV in 5-min time epochs across a 2-h morning or afternoon working period, as well as self-reports of ERI and overcommitment, were collected for 91 office workers. RESULTS: There was a negative and significant (p < 0.01) ERI*time interaction for the standard deviation of the interval between normal heart beats (SDNN), the square root of the mean squared differences of successive normal heart beats (RMSSD), and the power in the high-frequency range of the heart rate signal (HF power), and a positive and significant ERI*time interaction for the ratio of power in the low-frequency range of the heart rate signal divided by the HF power (LF/HF ratio). There was a positive and significant overcommitment*time interaction for the LF/HF ratio (p < 0.01) in the morning, and a negative and significant overcommitment*time interaction for SDNN, RMSSD, and HF power (p < 0.01) in the afternoon. CONCLUSIONS: The results indicate that participants exposed to high levels of ERI and overcommitment exhibited a more adverse cardiovascular response (a greater decrease in HRV throughout the 2-h measurement period) compared to their colleagues with lower levels of these factors.

Prediction of trapezius muscle activity and shoulder, head, neck, and torso postures during computer use: results of a field study.

BACKGROUND: Due to difficulties in performing direct measurements as an exposure assessment technique, evidence supporting an association between physical exposures such as neck and shoulder muscle activities and postures and musculoskeletal disorders during computer use is limited. Alternative exposure assessment techniques are needed. METHODS: We predicted the median and range of amplitude (90th-10th percentiles) of trapezius muscle activity and the median and range of motion (90th-10th percentiles) of shoulder, head, neck, and torso postures based on two sets of parameters: the distribution of keyboard/mouse/idle activities only ("task-based" predictions), and a comprehensive set of task, questionnaire, workstation, and anthropometric parameters ("expanded model" predictions). We compared the task-based and expanded model predictions based on R2 values, root mean squared (RMS) errors, and relative RMS errors calculated compared to direct measurements. RESULTS: The expanded model predictions of the median and range of amplitude of trapezius muscle activity had consistently better R2 values (range 0.40-0.55 compared to 0.00-0.06), RMS errors (range 2-3%MVC compared to 3-4%MVC), and relative RMS errors (range 10-14%MVC compared to 16-19%MVC) than the task-based predictions. The expanded model predictions of the median and range of amplitude of postures also had consistently better R2 values (range 0.22-0.58 compared to 0.00-0.35), RMS errors (range 2-14 degrees compared to 3-22 degrees), and relative RMS errors (range 9-21 degrees compared to 13-42 degrees) than the task-based predictions. CONCLUSIONS: The variation in physical exposures across users performing the same task is large, especially in comparison to the variation across tasks. Thus, expanded model predictions of physical exposures during computer use should be used rather than task-based predictions to improve exposure assessment for future epidemiological studies. Clinically, this finding also indicates that computer users will have differences in their physical exposures even when performing the same tasks.

The effect of over-commitment and reward on trapezius muscle activity and shoulder, head, neck, and torso postures during computer use in the field.

BACKGROUND: Because of reported associations of psychosocial factors and computer related musculoskeletal symptoms, we investigated the effects of a workplace psychosocial factor, reward, in the presence of over-commitment, on trapezius muscle activity and shoulder, head, neck, and torso postures during computer use. METHODS: We measured 120 office workers across four groups (lowest/highest reward/over-commitment), performing their own computer work at their own workstations over a 2-hr period. RESULTS: Median trapezius muscle activity (P = 0.04) and median neck flexion (P = 0.03) were largest for participants reporting simultaneously low reward and high over-commitment. No differences were observed for other muscle activities or postures. CONCLUSIONS: These data suggest that the interaction of reward and over-commitment can affect upper extremity muscle activity and postures during computer use in the real work environment. This finding aligns with the hypothesized biomechanical pathway connecting workplace psychosocial factors and musculoskeletal symptoms of the neck and shoulder.