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

Neck Muscle Stiffness Measured With Shear Wave Elastography in Women With Chronic Nonspecific Neck Pain

OBJECTIVE

Utilizing shear wave elastography, we compared the stiffness of the neck extensor muscles and the stiffness in muscle-specific regions between women with chronic nonspecific neck pain and asymptomatic controls.

DESIGN

Cross-sectional observational study.

METHODS

We measured the average muscle stiffness over multiple neck extensor muscles and in regions corresponding approximately to the trapezius, splenius capitis, semispinalis capitis, semispinalis cervicis, and multifidus muscles using ultrasound shear wave elastography in 20 women with chronic nonspecific neck pain and 18 asymptomatic women during multiple tasks. The measurements were automatically quality controlled and computer processed over the complete visible neck region or a large muscle-specific region.

RESULTS

Pooled over all tasks, neck muscle stiffness was not significantly different between those with neck pain and asymptomatic controls (neck pain median, 11.6 kPa; interquartile range, 8.9 kPa and control median, 13.3 kPa; interquartile range, 8.6 kPa; P = .175). The measure of neck muscle stiffness was not correlated with the intensity of neck pain or perceived disability.

CONCLUSION

Shear wave elastography revealed similar muscle stiffness in people with and without chronic neck pain, despite the sensation of increased neck stiffness in those with chronic neck pain. Therapeutic interventions aiming to reduce neck muscle tone are often based on the assumption that perceived neck stiffness corresponds to objective muscle stiffness. The current results question this assumption. J Orthop Sports Phys Ther 2020;50(4):179-188. Epub 6 Jan 2020. doi:10.2519/jospt.2020.8821.

Work-related musculoskeletal disorder among surgeons in Gujarat

INTRODUCTION

Work-related musculoskeletal symptoms are a major health issue in many occupations all over the world. Past researches on hospital workers have mainly been focused on nurses, and not many studies have examined musculoskeletal symptoms among doctors in various specialties. The work of surgeons can involve high levels of mental concentration and very precise movements that can be categorized as mild-to-moderate physical demands.

OBJECTIVE

To identify the prevalence of musculoskeletal problems and their related physical and psychosocial factors of surgeons who are involved in such work.

METHODOLOGY

Forty-three surgeons were enrolled in this study. To evaluate the musculoskeletal disorders, the participants were assessed through Standardized Nordic Questionnaire, Quick Exposure Check for the work pattern, and Work style Short Form for screening purpose.

RESULTS

Out of 43 participants, 30 were male and 13 were female. Their mean age was 42.07 ± 12.35 years, and the mean working years ± standard deviation of the group was 15.14 years ± 9.017. On an average, they worked a total of about 8.58 h ± 1.96 per day. The prevalence of work-related musculoskeletal symptoms was found in 36 participants (83.70%), while only seven surgeons (16.30%) were symptom free.

CONCLUSION

The present study indicates a high prevalence of musculoskeletal symptoms in surgeons. The results also indicated that surgeons had a high sense of commitment and self-imposed pressure.

Bibliometric analysis of the body posture in relation to visual display terminals (VDTs)

BACKGROUND

In modern society, there is an increase both in the demand and the duration of computer work. Failure to correct body posture while using the computer has become a serious health hazard.

OBJECTIVE

To identify global trends in research related to body posture and visual display terminals (VDTs) using a bibliometric approach.

METHODS

In the search process, the keywords (posture *) AND (computer* OR "visual display terminal") were used in the study title section, in the Wos, Scopus and Medline databases.

RESULTS

149 references published between 1970 and 2016 were analyzed. The studied variables were the years of publication, authorship and collaboration index, publication type, titles of journals, most used languages, impact of the publications, as well as content of the articles.

CONCLUSIONS

In recent years, the studies on body posture in relation to VDT have been increased both in quantity and quality of publications. The analysis and/or design of the workplace, as well as the elements that make up the computer (keyboard and mouse) are the most researched topics in the area.

Workplace Factors Associated With Neck Pain Experienced by Computer Users: A Systematic Review

INTRODUCTION

The purpose of this systematic review was to examine literature on workplace factors associated with neck pain or symptoms in computer users performing clerical functions.

METHODS

A systematic search of the Cochrane, Medline, CINAHL, and EMBASE databases was conducted for observational and experimental studies published since 2000. This review applied the case definition of The Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders.

RESULTS

Seven hundred twenty-nine studies were identified. Seven hundred and two studies were excluded. Twenty-seven studies fulfilled inclusion criteria and were assessed for risk of bias. Cross-sectional studies were commonly at risk from nonresponse bias and lack of adequate case definitions. Experimental studies were mostly at risk of bias due to confounding and participant recruitment methods.

CONCLUSIONS

Neck pain was not significantly associated with high job demands, low skill discretion, low decision authority, or low peer support. However, when these variables were combined with increased duration of computing tasks, or ergonomic demands, they reached significance. Supervisor support was found to be the only significant buffer capable of preventing these variables reaching significance in female office workers.

Associations of Family Demands and Work⁻Life Conflict with Musculoskeletal Disorders among Korean Workers

Although family-related demands play a role in the effect of psychosocial work characteristics on health, research on work-related health has neglected the family domain. The aim of the present study was to identify the effects of family demands and work⁻life conflict (WLC) on musculoskeletal disorders (MSDs) among Korean workers. We analyzed data from the nationally representative Korean Working Conditions Survey conducted with 50,007 workers in 2014. Logistic regression analyses stratified by gender were performed to identify gender differences, and interaction terms including WLCs and key covariates were also incorporated. Childcare demands (odds ratio (OR), 1.16) were related to MSD only in male workers, whereas homemaking (OR, 1.09) and eldercare (OR, 1.26) demands were related to MSDs only in female workers. WLC was also associated with MSDs among both male (OR, 1.50) and female (OR, 1.55) workers. We found no gender difference in the effect of WLC on MSDs (p = 0.91). Moreover, childcare demands may exacerbate the effect of WLC on MSDs. Our data suggest that family demands and WLC could be important targets of workplace interventions to prevent MSDs, and future research should evaluate the role of family demands and WLC as stressors in the workplace.

Effect of neck posture on cervicothoracic loads in overhead crane operators

Awkward neck postures are commonly documented to be associated with an increased risk of neck disorders. This study intended to continuously monitor and evaluate neck postures and to estimate the cervicothoracic loads among overhead crane operators during work time. Neck postures were measured among 40 randomly selected operators by an inclinometer during 2 h of work time. To determine the tasks and adapt the posture recordings to each of their corresponding tasks, direct observation was conducted concurrently. The median neck flexion and lateral bend angles were 28.23° and 11.30°, respectively. The mean compression and shear loads on the neck ranged from 75.22 to 113.14 N and from 9.50 to 41.11 N, respectively. The results indicated substantial levels of exposure to awkward and extreme neck postures among the operators. The nature of the operators' work and the visual requirements of some tasks will increase the mechanical loads on the neck.

Work-Life Imbalance and Musculoskeletal Disorders among South Korean Workers

Employed workers often have family responsibilities such as childcare or homemaking. This dual burden may increase work-related health problems, particularly if there are conflicts between work and family responsibilities. This study assessed whether difficulty in work–life balance is associated with musculoskeletal disorders (MSD) among Korean employees. Data from the population-based Korean Working Conditions Survey of 2011, including 28,640 male and 21,392 female workers, were used. Men and women were analyzed separately to investigate gender differences. MSD were defined as pain in the back, neck, shoulder, or extremities during the past year. Self-assessed difficulty in work–life balance was defined as a work–life conflict (WLC). Adjustments for physical factors, as well as other occupational and socio-demographic variables, were made using multiple logistic regression analysis. Interaction terms including WLCs and key covariates were also incorporated. WLC was significantly associated with increased frequency of MSD in both men (OR: 1.49) and women (OR: 1.50). There were significant interaction effects between WLC and some key covariates (job stress for men and job stress, work hours, physical demand, and frequent overtime work for women). We suggest that having the flexibility to coordinate work and family life is important to prevent MSD among employees.

The effect of psychosocial stress on muscle activity during computer work: Comparative study between desktop computer and mobile computing products

BACKGROUND

The popularity of mobile computing products is well known. Thus, it is crucial to evaluate their contribution to musculoskeletal disorders during computer usage under both comfortable and stressful environments.

OBJECTIVE

This study explores the effect of different computer products' usages with different tasks used to induce psychosocial stress on muscle activity.

METHODS

Fourteen male subjects performed computer tasks: sixteen combinations of four different computer products with four different tasks used to induce stress. Electromyography for four muscles on the forearm, shoulder and neck regions and task performances were recorded.

RESULTS

The increment of trapezius muscle activity was dependent on the task used to induce the stress where a higher level of stress made a greater increment. However, this relationship was not found in the other three muscles. Besides that, compared to desktop and laptop use, the lowest activity for all muscles was obtained during the use of a tablet or smart phone. The best net performance was obtained in a comfortable environment. However, during stressful conditions, the best performance can be obtained using the device that a user is most comfortable with or has the most experience with.

CONCLUSIONS

Different computer products and different levels of stress play a big role in muscle activity during computer work. Both of these factors must be taken into account in order to reduce the occurrence of musculoskeletal disorders or problems.

A literature review of the effects of computer input device design on biomechanical loading and musculoskeletal outcomes during computer work

BACKGROUND

Extended use of conventional computer input devices is associated with negative musculoskeletal outcomes. While many alternative designs have been proposed, it is unclear whether these devices reduce biomechanical loading and musculoskeletal outcomes.

OBJECTIVE

To review studies describing and evaluating the biomechanical loading and musculoskeletal outcomes associated with conventional and alternative input devices.

METHODS

Included studies evaluated biomechanical loading and/or musculoskeletal outcomes of users' distal or proximal upper extremity regions associated with the operation of alternative input devices (pointing devices, mice, other devices) that could be used in a desktop personal computing environment during typical office work.

RESULTS

Some alternative pointing device designs (e.g. rollerbar) were consistently associated with decreased biomechanical loading while other designs had inconsistent results across studies. Most alternative keyboards evaluated in the literature reduce biomechanical loading and musculoskeletal outcomes. Studies of other input devices (e.g. touchscreen and gestural controls) were rare, however, those reported to date indicate that these devices are currently unsuitable as replacements for traditional devices.

CONCLUSIONS

Alternative input devices that reduce biomechanical loading may make better choices for preventing or alleviating musculoskeletal outcomes during computer use, however, it is unclear whether many existing designs are effective.

Mobility and Upright Posture Are Associated with Different Aspects of Cognition in Older Adults

Objectives: Aging is associated with cognitive decline, including visuomotor and memory concerns, and with motor system changes, including gait slowing and stooped posture. We investigated the associations of visuomotor performance and episodic memory with motor system characteristics in healthy older adults. Methods: Neurologically healthy older adults (N = 160, aged 50-89) completed a battery of cognitive and motor tasks. Cognitive variables were grouped by principal components analysis (PCA) into two components: visuomotor performance and verbal episodic memory. Our primary predictor variables were two aspects of motor function: timed-up-and-go (TUG) speed and neck angle. Additional predictor variables included demographic factors (age, sex and education) and indicators of physical fitness (body mass index/BMI and grip strength). All seven predictor variables were entered stepwise into a multiple regression model for each cognitive component. Results: Poor visuomotor performance was best predicted by a combination of advanced age, high BMI and slow TUG, whereas poor verbal memory performance was best predicted by a combination of advanced age, male sex, low education and acute neck angle. Conclusions: Upright posture and mobility were associated with different cognitive processes, suggesting different underlying neural mechanisms. These results provide the first evidence for a link between postural alignment and cognitive functioning in healthy older adults. Possible causal relationships are discussed.

A Comparison of Two Strategies for Building an Exposure Prediction Model

Cost-efficient assessments of job exposures in large populations may be obtained from models in which 'true' exposures assessed by expensive measurement methods are estimated from easily accessible and cheap predictors. Typically, the models are built on the basis of a validation study comprising 'true' exposure data as well as an extensive collection of candidate predictors from questionnaires or company data, which cannot all be included in the models due to restrictions in the degrees of freedom available for modeling. In these situations, predictors need to be selected using procedures that can identify the best possible subset of predictors among the candidates. The present study compares two strategies for selecting a set of predictor variables. One strategy relies on stepwise hypothesis testing of associations between predictors and exposure, while the other uses cluster analysis to reduce the number of predictors without relying on empirical information about the measured exposure. Both strategies were applied to the same dataset on biomechanical exposure and candidate predictors among computer users, and they were compared in terms of identified predictors of exposure as well as the resulting model fit using bootstrapped resamples of the original data. The identified predictors were, to a large part, different between the two strategies, and the initial model fit was better for the stepwise testing strategy than for the clustering approach. Internal validation of the models using bootstrap resampling with fixed predictors revealed an equally reduced model fit in resampled datasets for both strategies. However, when predictor selection was incorporated in the validation procedure for the stepwise testing strategy, the model fit was reduced to the extent that both strategies showed similar model fit. Thus, the two strategies would both be expected to perform poorly with respect to predicting biomechanical exposure in other samples of computer users.

Office workers' computer use patterns are associated with workplace stressors

This field study examined associations between workplace stressors and office workers' computer use patterns. We collected keyboard and mouse activities of 93 office workers (68F, 25M) for approximately two work weeks. Linear regression analyses examined the associations between self-reported effort, reward, overcommitment, and perceived stress and software-recorded computer use duration, number of short and long computer breaks, and pace of input device usage. Daily duration of computer use was, on average, 30 min longer for workers with high compared to low levels of overcommitment and perceived stress. The number of short computer breaks (30 s-5 min long) was approximately 20% lower for those with high compared to low effort and for those with low compared to high reward. These outcomes support the hypothesis that office workers' computer use patterns vary across individuals with different levels of workplace stressors.

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.