A year-long case study of multicomponent interventions to promote physical activity in office workers: A randomized control trial.

The purpose of this study was to identify if workplace interventions, (i.e., mindfulness classes and monetary incentives for gym attendance), influenced workers' physical activity. Office-based participants were randomized into one of four intervention assignments: 1) CONTROL (no interventions) (n = 40), 2) MINDFULNESS (n = 33), 3) GYM INCENTIVE (n = 41), or 4) BOTH mindfulness and gym incentive (n = 31). Activity-tracker and self-reported metabolic expenditure and step counts were gathered between January 2020 and December 2020 whereas the eight-week long interventions were provided between January and March 2020, when the impact of COVID-19 pandemic started. While physical activity decreased during the follow-up months, percent changes of physical activity at 1-, 2-, and 9-month follow-ups compared to baseline show no significant differences between or across the four intervention assignments (p > 0.05). These results suggest that the intervention assignments had no effect on physical activity from baseline. The lack of effectiveness of these interventions on participant physical activity could be attributed to the influence of the COVID-19 pandemic, and any effects of the interventions could not outweigh the effects of the pandemic.

Work from home: Facilitators for an effective ergonomic work system.

Previous studies on Human Factors and Ergonomics (HFE) have primarily examined the impact of Work-From-Home (WFH) on worker health and well-being, yet little research has examined the optimal implementation process of WFH programs. Work systems perspective suggests that organizational policies, leadership, and psychological factors collectively influence the success of organizational change efforts. Our study explored the roles of managerial/supervisory, psychological, and organizational policy factors in facilitating the relationship between employees' HFE awareness and their acceptance and satisfaction with the WFH arrangement. Using data from 3195 knowledge workers in the US who use computers as their primary work tool and have worked from home at least one day in the past 30 days, we employed structural equation modeling to test our hypotheses. Transformational HFE leadership and employees' general self-efficacy are pivotal in implementing ergonomic WFH arrangements. The combination of employees' HFE awareness, transformational HFE leadership, and adequate levels of self-efficacy may foster positive process outcomes (e.g., readiness for WFH arrangement, workspace design satisfaction) in WFH arrangements. Efforts that are coordinated across organizational levels determine the effectiveness of organizational change.

Physiological responses, trunk posture, and work pace in commercial building cleaning in Washington State: An observational field study.

INTRODUCTION: This study aimed to investigate whether work pace is a critical indicator for predicting a janitor's risk of work-related musculoskeletal disorders (WMSDs). METHOD: Field measurements were obtained from commercial building janitors as well as the determination of work pace. Physiological responses collected were heart rate, energy expenditure (calories), activity level (METs), steps, trunk posture. Data were obtained using direct measurements, along with a time study, which was performed by shadowing 13 janitors in Washington State. The measured values were summarized descriptively, and five of the most common janitorial tasks were compared. The relationships between work pace and the physiological response variables were determined by calculating the Pearson product-moment correlation coefficients. RESULTS: The highest average percent heart rate reserve (47.4%) was reported during restroom cleaning, while the highest activity and energy expenditure levels (3.6 METs and 217.1 calories/h) were reported for mopping. The top 90% of trunk flexion angles and the highest percentage of time in trunk flexion from 20° to 60° were recorded during restroom cleaning. Restroom cleaning showed the highest correlation between all the physiological response variables and work pace. In most of the tasks, a high work pace may have increased the degree and duration of severe trunk flexion. CONCLUSION: Overall, when several tasks were considered, the extent of physiological responses, trunk joint angles, and exposure time to awkward postures tended to increase with an increase in work pace. PRACTICAL APPLICATIONS: This study showed the feasibility of using the work pace measured from time studies as a predictive indicator of WMSDs risks. Using this information, managers may compose a schedule that can minimize WMSDs risks while considering actual work pace deviations that may impact a janitor's ability to complete assigned tasks properly within a shift.

Comparison of the observer, single-frame video and computer vision hand activity levels.

Observer, manual single-frame video, and automated computer vision measures of the Hand Activity Level (HAL) were compared. HAL can be measured three ways: (1) observer rating (HALO), (2) calculated from single-frame multimedia video task analysis for measuring frequency (F) and duty cycle (D) (HALF), or (3) from automated computer vision (HALC). This study analysed videos collected from three prospective cohort studies to ascertain HALO, HALF, and HALC for 419 industrial videos. Although the differences for the three methods were relatively small on average (<1), they were statistically significant (p < .001). A difference between the HALC and HALF ratings within ±1 point on the HAL scale was the most consistent, where more than two thirds (68%) of all the cases were within that range and had a linear regression through the mean coefficient of 1.03 (R2 = 0.89). The results suggest that the computer vision methodology yields comparable results as single-frame video analysis.Practitioner summary: The ACGIH Hand Activity Level (HAL) was obtained for 419 industrial tasks using three methods: observation, calculated using single-frame video analysis and computer vision. The computer vision methodology produced results that were comparable to single-frame video analysis.

Physical activity changes among office workers during the COVID-19 pandemic lockdown and the agreement between objective and subjective physical activity metrics.

After the onset of the COVID-19 pandemic, many office workers transitioned to working-from-home (WFH) which altered routine physical activity (PA). To understand how these workers' PA were affected throughout the pandemic, PA data collected in January, April, June, and December 2020 with an activity tracker and a validated survey were analyzed. Between January and December, it was found that step counts during the weekday decreased (p < 0.01), weekday heart rate was higher than weekends (p < 0.01), activity-tracker and self-reported PA decreased (p < 0.01), and sitting time increased (p < 0.01). To understand the agreement between the objective and subjective METs, Bland-Altman analyses were completed and demonstrated an acceptable level of agreement. Findings show decreased level of PA amongst WFH office workers and that the activity tracker and survey are reliable methods of recording WFH PA.

Cleaning in the 21st Century: The musculoskeletal disorders associated with the centuries-old occupation - A literature review.

Workers performing cleaning duties experience higher injury rates, especially in the form of musculoskeletal disorders (MSDs), than other industries. It is essential to understand the inherent risks associated with the nature of this occupation. Based on the Balance Theory (Smith & Carayon-Sainfort, 1989), this review surveys the current literature, especially those published since the previous review paper (Kumar & Kumar, 2008), and identifies which elements contributing to MSD risks were examined: task, technology, organization, environment, individual, and their interactions. Thirty-nine research papers published between 2005 and 2021 are identified and summarized. Among these papers, task and individual elements received the most attention, at 42 and 34 occurrences, respectively. The interaction elements of technology-organization, technology-environment, and organization-environment received less than three mentions. The goal of this literature review is to update the knowledge base and identify current trends for the cleaning occupation. Possible interventions for risk reduction and future research directions are suggested.

The job demand-control-support model and work-related musculoskeletal complaints in daytime and nighttime janitors: The mediating effect of burnout.

Janitors' jobs require repetitive work with low control (skill discretion, decision authority) and social support. Previous studies have found this constellation of work conditions leads to high stress levels. This study investigated the relationships among job demand-control-support, burnout, and musculoskeletal symptoms for commercial janitors in Washington State. Structural equation modeling was performed using data from 208 participants with analyses comparing models of daytime and nighttime janitors. Burnout fully mediated the relationship between job demands and musculoskeletal complaints among daytime janitors. Among nighttime janitors, burnout mediated between job demands, job control, and social support, and musculoskeletal complaints. The nighttime janitors' model was more fully supported compared to the daytime model. This study is one of a small number that examine and bring attention to the importance of janitors' burnout. Recommendations to improve the psychosocial work environment toward mitigating burnout and reducing musculoskeletal complaints are provided.

Simple benchmarking method for determining the accuracy of depth cameras in body landmark location estimation: Static upright posture as a measurement example.

To evaluate the postures in ergonomics applications, studies have proposed the use of low-cost, marker-less, and portable depth camera-based motion tracking systems (DCMTSs) as a potential alternative to conventional marker-based motion tracking systems (MMTSs). However, a simple but systematic method for examining the estimation errors of various DCMTSs is lacking. This paper proposes a benchmarking method for assessing the estimation accuracy of depth cameras for full-body landmark location estimation. A novel alignment board was fabricated to align the coordinate systems of the DCMTSs and MMTSs. The data from an MMTS were used as a reference to quantify the error of using a DCMTS to identify target locations in a 3-D space. To demonstrate the proposed method, the full-body landmark location tracking errors were evaluated for a static upright posture using two different DCMTSs. For each landmark, we compared each DCMTS (Kinect system and RealSense system) with an MMTS by calculating the Euclidean distances between symmetrical landmarks. The evaluation trials were performed twice. The agreement between the tracking errors of the two evaluation trials was assessed using intraclass correlation coefficient (ICC). The results indicate that the proposed method can effectively assess the tracking performance of DCMTSs. The average errors (standard deviation) for the Kinect system and RealSense system were 2.80 (1.03) cm and 5.14 (1.49) cm, respectively. The highest average error values were observed in the depth orientation for both DCMTSs. The proposed method achieved high reliability with ICCs of 0.97 and 0.92 for the Kinect system and RealSense system, respectively.

Activation patterns of shoulder internal and external rotators during pure axial moment generation across a postural range.

Musculoskeletal risk is mediated by body posture, especially for static tasks. Workstations that require non-neutral postures can lead to increased load, muscular fatigue and injury risk. However, demands during simple axial rotation tasks are not well-defined. The purpose of this study is to quantify the muscular activity of during static axial rotation in a range of postures. Eighteen participants performed 76 axial rotation exertions in varying combinations of humeral elevation angles (30°-60°-90°-120°-150°), plane of elevation (30°-60°-90°-120°) and exertion intensity (20-40%). Six unilateral (right) muscles (pectoralis major (clavicular and sternal), posterior deltoid, teres major, infraspinatus, latissiumus dorsi) were monitored using surface electromyography (EMG). EMG was normalized and integrated over 2 s. The influences of elevation, plane, and intensity on activity levels were then tested with a 3-way ANOVAs (p < .05). During internal rotation, activity was highest at low elevation/high plane combinations for the internal rotators, but at high elevation/low plane combinations for the external rotators. During the 40% intensity exertions, activity levels were highest at lower elevations for internal rotator but at high elevations for the external rotators. During external rotation, as the degree of elevation increased, the activity of the external rotator muscles also increased while internal rotators were unaffected. Humeral muscles responsible for axial rotation are influenced by arm posture during axial rotation exertions. High elevation and plane combinations resulted in high demands for external rotator muscles and this should be considered for job design and injury risk.

Factors Affecting Material-Cart Handling in the Roofing Industry: Evidence for Administrative Controls.

Material-cart handling can be strenuous and lead to overexertion injuries. The aim of this study is to produce a thorough understanding of how the cart condition, tire type, physical environment-related factors, and load interact to influence the ergonomics and productivity of cart handling. Eighteen roofing carts with different conditions, tires, and loads were tested by one subject on three laboratory tracks: one L-shaped, one with ramps within constrained spaces, and one with obstacles within constrained spaces. A multiple linear regression analysis was performed to quantify the main and interaction effects of the factors of interest on the cart operations. The research findings confirm that using aged carts increases the injury risk by as much as 30.5% and decreases productivity by 35.4%. Our study also highlights the necessity of keeping an open space for cart operation; the travel distance from a cart to a ramp/obstacle should be greater than 61 cm. Finally, the results suggest the at-risk thresholds for different ramp slopes and obstacle heights, and the safe load capacities for the various working circumstances that are common on construction sites. The evidence created in this study can be translated into administrative controls for cart handling to reduce overexertion injuries and enhance performance.

Are Work-Related Musculoskeletal Disorders Claims Related to Risk Factors in Workplaces of the Manufacturing Industry?

OBJECTIVES: Varied work-related musculoskeletal disorders (WMSDs) claim rates were found between companies even when they were in the same sectors with similar sizes. This study aimed to (i) identify common risk factors for back, shoulder, hand/wrist, and knee WMSDs among manufacturing jobs, and (ii) characterize the biomechanical exposures in jobs and work organizational practices between high and low WMSD claim rate companies so that more focused, industry-specific intervention strategies may be developed. METHODS: Using historical workers' compensation data, manufacturing companies were divided into two paired groups (low and high in the lower 25%ile and higher 75%ile, respectively). On-site job evaluations were conducted in 16 companies to determine job biomechanical risk levels. Management and workers' representatives in 32 paired companies were interviewed to identify possible differences between management strategies and management/worker relationships. A total of 39 injured workers were also interviewed to gather information of self-reported injury causes and suggested preventive measures. RESULTS: Analyses of 432 job evaluations showed that more jobs had higher risk levels of prolonged standing and heavy lifting in the high back WMSD claim rate companies than the low claim rate ones. No high biomechanical risk factors were found to be associated with jobs in high shoulder claim rate companies. High repetition, pinch force, and Strain Index were associated with high hand/wrist WMSD claim rate companies. High work pace and job stress were common among high knee WMSD claim rate companies. There were no statistically significant differences for the organizational factors between high and low WMSD claim rate companies. Heavy lifting, fast work pace, high hand/wrist repetition, high hand force, and awkward shoulder postures were identified as major contributing factors by the injured workers. CONCLUSIONS: High WMSD claim rate companies appeared to have more high biomechanical exposure jobs than low WMSD claim rate companies. Available job evaluation methods for the low back and hand/wrists are satisfactory in quantifying job risk levels in the manufacturing industry. Research into more sensitive job evaluation methods for the shoulder and knee are needed.

The effect of sit-stand schedules on office work productivity: A pilot study.

BACKGROUND: Sit-stand workstations have been introduced in the workplaces to address the adverse sedentary effect inherent to typical office jobs. Existing field or laboratory studies showed that standing interventions are not a detriment to work productivity or performance. The effect of gradient standing proportion on these measures is still unknown. OBJECTIVE: The current naturalistic pilot study aimed to examine the controlled sit-stand ratio effect on office performances. METHODS: Eleven musculoskeletal symptom free office employees from a large government agency volunteered in this study. They were all equipped with electronic sit-stand desks. Computer usage (N=11) and productivity (N=3) were collected using software and organizational metrics, respectively, for four typical workdays of four different sit-stand ratios (7 : 1, 3 : 1, 2 : 1, and 1 : 1). RESULTS: There were no statistically significant schedule effects on any computer usage measures. While not significant, time using computer, keystrokes, word count, and keyboard errors were all less as standing time increased. Sit-stand ratio and job productivity did not observe a clear cause and effect relationship. CONCLUSIONS: The amount of time spent standing in typical office jobs might not affect computer usage and productivity. Further study with a larger sample is needed for a stronger evidence.

Predicting Sagittal Plane Lifting Postures From Image Bounding Box Dimensions.

OBJECTIVE: A method for automatically classifying lifting postures from simple features in video recordings was developed and tested. We explored if an "elastic" rectangular bounding box, drawn tightly around the subject, can be used for classifying standing, stooping, and squatting at the lift origin and destination. BACKGROUND: Current marker-less video tracking methods depend on a priori skeletal human models, which are prone to error from poor illumination, obstructions, and difficulty placing cameras in the field. Robust computer vision algorithms based on spatiotemporal features were previously applied for evaluating repetitive motion tasks, exertion frequency, and duty cycle. METHODS: Mannequin poses were systematically generated using the Michigan 3DSSPP software for a wide range of hand locations and lifting postures. The stature-normalized height and width of a bounding box were measured in the sagittal plane and when rotated horizontally by 30°. After randomly ordering the data, a classification and regression tree algorithm was trained to classify the lifting postures. RESULTS: The resulting tree had four levels and four splits, misclassifying 0.36% training-set cases. The algorithm was tested using 30 video clips of industrial lifting tasks, misclassifying 3.33% test-set cases. The sensitivity and specificity, respectively, were 100.0% and 100.0% for squatting, 90.0% and 100.0% for stooping, and 100.0% and 95.0% for standing. CONCLUSIONS: The tree classification algorithm is capable of classifying lifting postures based only on dimensions of bounding boxes. APPLICATIONS: It is anticipated that this practical algorithm can be implemented on handheld devices such as a smartphone, making it readily accessible to practitioners.

Occupational cranking operations: The scapula perspective.

Cranking the landing gear is a common task performed by truck drivers to raise or lower trailers. This task poses a risk to the shoulder joint due to the required forceful exertion and the posture constrained to the hand-handle interface. As a potential occupational risk, there has been no definitive guideline for best practices among truck drivers. An operator can crank perpendicular (frontal) or parallel (sagittal) to the crank rotation. In this laboratory study, the effects of cranking method and resistance on scapular range of motion and shoulder muscle activity were observed in 12 participants. Scapular posture was measured using an optical motion tracking system. EMG was monitored on 16 muscles contributing to shoulder movement. The results show that during frontal cranking, the scapular range of protraction was 28 ±â€¯11.6°, which was more than the sagittal cranking (23 ±â€¯10.4°), indicating a decreased subacromial space and elevated shoulder impingement risk. Seven muscles (all three deltoid muscles, middle trapezius, supraspinatus, infraspinatus, and teres minor) demonstrated that when the crank resistance was low, the front cranking method resulted in lower activity than the side cranking. When the crank resistance was 20 Nm, the muscle activity on these seven muscles was greater when cranking from the front than from the side. Based on these observations, we suggest that when the resistance is low (lowering the trailer) the driver should stand facing the trailer. On the contrary, it is advantageous to stand parallel to the trailer and crank while raising the trailer to apply the full body strength to reduce the shoulder load.

An investigation into four different sit-stand workstation use schedules.

Twelve office workers participated in a study investigating effects of four sit/stand schedules (90-min sit/30-min stand, 80/40, 105/15, and 60/60) via several objective and subjective measures (muscle fatigue, foot swelling, spinal shrinkage, and self-reported discomfort). Results showed that there were no significant differences in shoulder and low back static muscle activities between sitting and standing. Muscle fatigue was developed during workday under all schedules. The longest standing schedule seemed to have a tendency of reducing muscle fatigue. None of the schedules helped or worsened foot swelling and spinal shrinkage. More active break-time activities seemed reducing muscle fatigue and foot swelling. While the self-reported bodily discomfort levels were generally low, the preferred schedules among the participants were varied, although the least standing schedule was the least preferred. We may conclude that effects of using sit-stand workstation to improve musculoskeletal health may be limited but promoting more active break-time activities can help. Practitioner Summary: Sit-stand workstations are used to reduce work-related musculoskeletal disorders. This study shows that office workers prefer sit/stand durations in the range between 1:1 and 3:1. Longer standing may have the potential to reduce muscle fatigue. However, active break-time activities may be more effective in reducing muscle fatigue and foot swelling.

Using the Microsoft Kinect™ to assess 3-D shoulder kinematics during computer use.

Shoulder joint kinematics has been used as a representative indicator to investigate musculoskeletal symptoms among computer users for office ergonomics studies. The traditional measurement of shoulder kinematics normally requires a laboratory-based motion tracking system which limits the field studies. In the current study, a portable, low cost, and marker-less Microsoft Kinect™ sensor was examined for its feasibility on shoulder kinematics measurement during computer tasks. Eleven healthy participants performed a standardized computer task, and their shoulder kinematics data were measured by a Kinect sensor and a motion tracking system concurrently. The results indicated that placing the Kinect sensor in front of the participants would yielded a more accurate shoulder kinematics measurements then placing the Kinect sensor 15° or 30° to one side. The results also showed that the Kinect sensor had a better estimate on shoulder flexion/extension, compared with shoulder adduction/abduction and shoulder axial rotation. The RMSE of front-placed Kinect sensor on shoulder flexion/extension was less than 10° for both the right and the left shoulder. The measurement error of the front-placed Kinect sensor on the shoulder adduction/abduction was approximately 10° to 15°, and the magnitude of error is proportional to the magnitude of that joint angle. After the calibration, the RMSE on shoulder adduction/abduction were less than 10° based on an independent dataset of 5 additional participants. For shoulder axial rotation, the RMSE of front-placed Kinect sensor ranged between approximately 15° to 30°. The results of the study suggest that the Kinect sensor can provide some insight on shoulder kinematics for improving office ergonomics.

An entropy-assisted musculoskeletal shoulder model.

Optimization combined with a musculoskeletal shoulder model has been used to estimate mechanical loading of musculoskeletal elements around the shoulder. Traditionally, the objective function is to minimize the summation of the total activities of the muscles with forces, moments, and stability constraints. Such an objective function, however, tends to neglect the antagonist muscle co-contraction. In this study, an objective function including an entropy term is proposed to address muscle co-contractions. A musculoskeletal shoulder model is developed to apply the proposed objective function. To find the optimal weight for the entropy term, an experiment was conducted. In the experiment, participants generated various 3-D shoulder moments in six shoulder postures. The surface EMG of 8 shoulder muscles was measured and compared with the predicted muscle activities based on the proposed objective function using Bhattacharyya distance and concordance ratio under different weight of the entropy term. The results show that a small weight of the entropy term can improve the predictability of the model in terms of muscle activities. Such a result suggests that the concept of entropy could be helpful for further understanding the mechanism of muscle co-contractions as well as developing a shoulder biomechanical model with greater validity.

Evaluation of regression-based 3-D shoulder rhythms.

The movements of the humerus, the clavicle, and the scapula are not completely independent. The coupled pattern of movement of these bones is called the shoulder rhythm. To date, multiple studies have focused on providing regression-based 3-D shoulder rhythms, in which the orientations of the clavicle and the scapula are estimated by the orientation of the humerus. In this study, six existing regression-based shoulder rhythms were evaluated by an independent dataset in terms of their predictability. The datasets include the measured orientations of the humerus, the clavicle, and the scapula of 14 participants over 118 different upper arm postures. The predicted orientations of the clavicle and the scapula were derived from applying those regression-based shoulder rhythms to the humerus orientation. The results indicated that none of those regression-based shoulder rhythms provides consistently more accurate results than the others. For all the joint angles and all the shoulder rhythms, the RMSE are all greater than 5°. Among those shoulder rhythms, the scapula lateral/medial rotation has the strongest correlation between the predicted and the measured angles, while the other thoracoclavicular and thoracoscapular bone orientation angles only showed a weak to moderate correlation. Since the regression-based shoulder rhythm has been adopted for shoulder biomechanical models to estimate shoulder muscle activities and structure loads, there needs to be further investigation on how the predicted error from the shoulder rhythm affects the output of the biomechanical model.