Defining a systems framework for characterizing physical work demands with wearable sensors.

Measuring the physical demands of work is important in understanding the relationship between exposure to these job demands and their impact on the safety, health, and well-being of working people. However, work is changing and our knowledge of job demands should also evolve in anticipation of these changes. New opportunities exist for noninvasive long-term measures of physical demands through wearable motion sensors, including inertial measurement units, heart rate monitors, and muscle activity monitors. Inertial measurement units combine accelerometers, gyroscopes, and magnetometers to provide continuous measurement of a segment's motion and the ability to estimate orientation in 3-dimensional space. There is a need for a system-thinking perspective on how and when to apply these wearable sensors within the context of research and practice surrounding the measurement of physical job demands. In this paper, a framework is presented for measuring the physical work demands that can guide designers, researchers, and users to integrate and implement these advanced sensor technologies in a way that is relevant to the decision-making needs for physical demand assessment. We (i) present a literature review of the way physical demands are currently being measured, (ii) present a framework that extends the International Classification of Functioning to guide how technology can measure the facets of work, (iii) provide a background on wearable motion sensing, and (iv) define 3 categories of decision-making that influence the questions that we can ask and measures that are needed. By forming questions within these categories at each level of the framework, this approach encourages thinking about the systems-level problems inherent in the workplace and how they manifest at different scales. Applying this framework provides a systems approach to guide study designs and methodological approaches to study how work is changing and how it impacts worker safety, health, and well-being.

Determining the effects of AR/VR HMD design parameters (mass and inertia) on cervical spine joint torques.

This study aimed to determine gravitational and dynamic torques and muscle activity of the neck across a series of design parameters of head mounted displays (mass, center of mass, and counterweights) associated with virtual and augmented reality (VR/AR). Twenty young adult participants completed five movement types (Slow and Fast Flexion/Extension and Rotation, and Search) while wearing a custom-designed prototype headset that varied the three design parameters: display mass (0, 200, 500, and 750 g), distance of the display's center of mass in front of the eyes (approximately 1, 3, and 5 cm anteriorly), and counterweights of 0, 166, 332, and 500 g to balance the display mass of 500 g at 7 cm. Inverse dynamics of a link segment model of the head and headset provided estimates of the torques about the joint between the skull and the occiput-first cervical vertebrae (OC1) and joint between the C7 and T1 vertebrae (C7). Surface electromyography (EMG) measured bilateral muscle activity of the splenius and upper trapezius muscles. Adding 750 g of display mass nearly doubled root mean square joint torques across all movement types. Increasing the distance of the display mass in front of the eyes by 4 cm increased torques about OC1 for the Slow and Fast Rotation and Search movements by approximately 20%. Adding a counterweight decreased torques about OC1 during the rotation and search tasks but did not decrease the torques experienced in the lower cervical spine (C7). For the flexion/extension axis, the magnitude of the dynamic torque component was 20% or less of the total torque experienced whereas for the rotation axis the magnitude of the dynamic torque component was greater than 50% of the total torque. Surface EMG root mean square values significantly varied across movement types with the fast rotation having the largest values; however, they did not vary significantly across the headset configurations.

Artificial intelligence and the work-health interface: A research agenda for a technologically transforming world of work.

The labor market is undergoing a rapid artificial intelligence (AI) revolution. There is currently limited empirical scholarship that focuses on how AI adoption affects employment opportunities and work environments in ways that shape worker health, safety, well-being and equity. In this article, we present an agenda to guide research examining the implications of AI on the intersection between work and health. To build the agenda, a full day meeting was organized and attended by 50 participants including researchers from diverse disciplines and applied stakeholders. Facilitated meeting discussions aimed to set research priorities related to workplace AI applications and its impact on the health of workers, including critical research questions, methodological approaches, data needs, and resource requirements. Discussions also aimed to identify groups of workers and working contexts that may benefit from AI adoption as well as those that may be disadvantaged by AI. Discussions were synthesized into four research agenda areas: (1) examining the impact of stronger AI on human workers; (2) advancing responsible and healthy AI; (3) informing AI policy for worker health, safety, well-being, and equitable employment; and (4) understanding and addressing worker and employer knowledge needs regarding AI applications. The agenda provides a roadmap for researchers to build a critical evidence base on the impact of AI on workers and workplaces, and will ensure that worker health, safety, well-being, and equity are at the forefront of workplace AI system design and adoption.

Correction: Finger Muscle Attachments for an OpenSim Upper-Extremity Model.

[This corrects the article DOI: 10.1371/journal.pone.0121712.].

Evaluating the impact of writing surface and configuration on muscle activation level during a handwriting task: An exploratory study.

BACKGROUND: Tablets are ubiquitous in workplaces and schools. However, there have been limited studies investigating the effect tablets have on the body during digital writing activities. OBJECTIVE: This study investigated the biomechanical impact of writing interface design (paper, whiteboard, and tablet) and orientation (horizontal, 45°, and vertical) on tablet users. METHODS: Fourteen adults (7 male, 7 female) participated in a study during which they performed simple writing tasks. Surface electromyography (sEMG) sensors were used to measure upper extremity muscle activation. RESULTS: Results indicate that the effects of writing surface type were most pronounced in forearm muscle activation. Specifically, in the extensor carpi radialis (ECR), where muscle activity was lower on the tablet PC surface. The effects of writing configuration were prominent in the shoulder and forearm. The activation of the flexor carpi ulnaris (FCU) and trapezius muscles was significantly lower in the 45° configuration. An exception to the efficacy of this configuration was the anterior deltoid muscle, which exhibited the lowest muscle activity in the horizontal orientation. CONCLUSIONS: Tablet surface and the 45° configuration resulted in the lowest muscle activation levels. Future studies should include longer experiment duration to investigate the effects of continuous writing.

Evaluation of vertical and multi-axial suspension seats for reducing vertical-dominant and multi-axial whole body vibration and associated neck and low back joint torque and muscle activity.

The primary aim of this laboratory-based human subject study was to evaluate the biomechanical loading associated with mining vehicles' multi-axial whole body vibration (WBV) by comparing joint torque and muscle activity in the neck and low back during three vibration conditions: mining vehicles' multi-axial, on-road vehicles' vertical-dominant, and no vibration. Moreover, the secondary aim was to determine the efficacy of a vertical passive air suspension and a prototype multi-axial active suspension seat in reducing WBV exposures and associated biomechanical loading measures. The peak joint torque and muscle activity in the neck and low back were higher when exposed to multi-axial vibration compared to the vertical-dominant or no vibration condition. When comparing the two suspension seats, there were limited differences in WBV, joint torque, and muscle activity. These results indicate that there is a need to develop more effective engineering controls to lower exposures to multi-axial WBV and related biomechanical loading. Practitioner Summary: This study found that mining vehicles' multi-axial WBV can increase biomechanical loading in the neck and back more so than on-road vehicles' vertical-dominant WBV. While a newly-developed multi-axial active suspension seat slightly reduced the overall WBV exposures, the results indicate that more effective engineering controls should be developed. Abbreviation: APDF: amplitude probability density function; Aw: weighted average vibration; BMI: body mass index; C7: The 7th cervical vertebra; EMG: electromyography; ES: erector spinae; IRB: institutional review board; ISO: International Organization for Standardization; L5/S1: the fifth lumbar vertebra (L5)/the first sacral vertebra(S1); MSDs: musculoskeletal disorders; MVC: maximum voluntary contraction; PSD: power spectral density; RVC: reference voluntary contraction; SCM: sternocleidomastoid; SD: standard deviation; SPL: splenius capitis; TRAP: trapezius; VDV: vibration dose value; WBV: whole body vibration.

Work and worker health in the post-pandemic world: a public health perspective.

The COVID-19 pandemic has highlighted the importance of work in shaping population health and wellbeing. This Viewpoint applies a multilevel systems framework to assist in understanding the diverse and complex interactions of forces affecting worker health and wellbeing, and how trending changes in employment and working conditions have been accelerated by the pandemic. Government agencies concerned with population health and wellbeing, and economic activity must expand their capacity to monitor, evaluate, and respond to these trends. In addition, integrated enterprise and workplace-based approaches that consider the interactions among these multidimensional drivers will build organisation and worker resilience to navigate the continual changes in work and worker safety, health, and wellbeing in a post-pandemic world.

The effects of a new seat suspension system on whole body vibration exposure and driver low back pain and disability: Results from a randomized controlled trial in truck drivers.

Through a randomized controlled trial, we evaluated the effects of an electro-magnetic active seat suspension that reduces exposure of a long-haul truck driver to whole body vibration (WBV) on low back pain (LBP) and disability. Among 276 drivers recruited from six trucking terminals of a major US trucking company, 135 eligible drivers were assigned to either having an Active Seat (Intervention: n = 70) - the BoseRide® electro-magnetic active seat - or Passive Seat (reference: n = 65) - a new version of their current seat (passive air suspension seat) - installed in their truck via block (terminal) randomization. Low back pain (LBP) severity, on a 0-10 scale and the Oswestry LBP Disability Index were collected before and 3-, 6-, 12-, 18-, and 24-months post seat installation. LBP severity and LBP disability scores were significantly lower post seat installation in both groups. At 3 months, LBP severity decreased -1.4 [95% CI: -2.1 to -0.7: n = 46] for drivers in the Active Seat arm, and -1.5 [95% CI: -2.3 to -0.8: n = 41] for drivers in the Passive Seat arm. In a subset of drivers, WBV exposures were collected before and after the seat installation. WBV exposures significantly decreased post seat installation for Active Seat (p < 0.01) but not for Passive Seat (p = 0.15). While the new seat-suspension technology reduced WBV exposures, LBP appeared to be improved by multiple factors. These results were limited by the secondary prevention approach and the longer-term loss to follow up due to large rates of driver turnover typical for the industry.

Working Conditions Influencing Drivers' Safety and Well-Being in the Transportation Industry: "On Board" Program.

The conditions of work for professional drivers can contribute to adverse health and well-being outcomes. Fatigue can result from irregular shift scheduling, stress may arise due to the intense job demands, back pain may be due to prolonged sitting and exposure to vibration, and a poor diet can be attributed to limited time for breaks and rest. This study aimed to identify working conditions and health outcomes in a bussing company by conducting focus groups and key informant interviews to inform a Total Worker Health® organizational intervention. Our thematic analysis identified three primary themes: lack of trust between drivers and supervisors, the scheduling of shifts and routes, and difficulty performing positive health behaviors. These findings demonstrate the value of using participatory methods with key stakeholders to determine the unique working conditions and pathways that may be most critical to impacting safety, health, and well-being in an organization.

Muscle co-contractions are greater in older adults during walking at self-selected speeds over uneven compared to even surfaces.

Falls in the aging population are a major public health concern. Outdoor falls in community-dwelling older adults are often triggered by uneven pedestrian walkways. Our understanding of the motor control adaptations to walk over an uneven surface, and the effects of aging on these adaptations is sparse. Here, we study changes in muscle co-contraction, a clinically accepted measure of motor control, due to changes in walking surfaces typically encountered in the outdoor built environment. We address the following research questions: 1) are there walking surface and sex-based differences in muscle co-contractions between young and older adults? and 2) is muscle co-contraction associated with age? We calculated muscle co-contractions from 13 young and 17 older adults during walking at self-selected speeds over even and uneven brick walkways. Muscle co-contraction at the ankle joint was determined from the tibialis anterior and lateral gastrocnemius muscle pair, and at the knee joint from the rectus femoris and semitendinosus muscle pair. Older adults displayed 8-13% greater ankle muscle co-contractions during walking over uneven compared to even surfaces. We found 55-61% (entire gait) and 73-75% (stance phase) greater ankle muscle co-contractions in older females compared to older males during walking over even and uneven surfaces. We found 31-43% greater knee muscle co-contractions in older females compared to older males during the swing phase of walking over even and uneven surfaces. This study underscores the need for determining muscle co-contractions from even and uneven surfaces for quantifying motor control deficits due to aging or neuromuscular disorders.

Associations Between Work-Related Factors and Psychological Distress Among Construction Workers.

OBJECTIVE: Identify work-related factors associated with the mental health and well-being of construction workers. METHODS: We completed eight key informant interviews, six worker focus groups, and a survey, informed by the interviews and focus groups, of 259 construction workers on five construction sites. Negative binomial regressions examined associations between psychological distress and work-related factors including safety climate, work-to-family conflict, psychological demands, social support, harassment, and job security. RESULTS: Three themes emerged from the interviews and focus groups, job demands and structure, social support and workplace relations, and job precarity. From the survey higher psychological demands, higher work-to-family conflict, lower supervisor support, higher discrimination, and higher likelihood of losing a job were associated with higher psychological distress. When combined into a single model job demands and work-to-family conflict remained significant. CONCLUSIONS: Work-related factors were associated with high levels of distress.

Development and application of an innovative instrument to assess work environment factors for injury prevention in the food service industry.

BACKGROUND: With the growth the food service industry and associated high injury and illness rates, there is a need to assess workplace factors that contribute to injury prevention. OBJECTIVE: The objective of this report is to describe the development, application, and utility of a new instrument to evaluate ergonomics and safety for food service workers. METHODS: Starting with a similar tool developed for use in healthcare, a new tool was designed through a collaborative, participatory process with the stakeholders from a collaborating food service company. The new instrument enables the identification and assessment of key safety and health factors through a focused walkthrough of the physical work environment, and structured interviews exploring the organizational work environment. The researchers applied the instrument at 10 of the partnering company's worksites. RESULTS: The instrument identified factors related to both the physical work environment and organizational and contextual environment (e.g., vendor-client relationships) impacting worker safety and health. CONCLUSIONS: Modern assessment approaches should address both the physical and organizational aspects of the work environment, and consider the context complexities in which the worksites and the industry operate.

Building Capacity for Integrated Occupational Safety, Health, and Well-Being Initiatives Using Guidelines for Total Worker Health® Approaches.

OBJECTIVES: To describe the process used to build capacity for wider dissemination of a Total Worker Health® (TWH) model using the infrastructure of a health and well-being vendor organization. METHODS: A multiple-case study mixed-methods design was used to learn from a year-long investigation of the experiences by participating organizations. RESULTS: Increased capacity for TWH solutions was observed as evidenced by the participation, plans of action, and experience ratings of the participating organizations. The planning process was feasible and acceptable, although the challenges of dealing with the COVID-19 pandemic only afforded two of the three worksites to deliver a comprehensive written action plan. CONCLUSIONS: A suite of services including guidelines, trainings, and technical assistance is feasible to support planning, acceptable to the companies that participated, and supports employers in applying the TWH knowledge base into practice.

The future of research on work, safety, health and wellbeing: A guiding conceptual framework.

Work plays a central role in health. A conceptual model can help frame research priorities and questions to explore determinants of workers' safety, health, and wellbeing. A previous conceptual model focused on the workplace setting to emphasize the role of conditions of work in shaping workers' safety, health and wellbeing. These conditions of work include physical, organizational, and psychosocial factors. This manuscript presents and discusses an updated and expanded conceptual model, placing the workplace and the conditions of work within the broader context of socio-political-economic environments and consequent trends in employment and labor force patterns. Social, political and economic trends, such as growing reliance on technology, climate change, and globalization, have significant implications for workers' day-to-day experiences. These structural forces in turn shape employment and labor patterns, with implications for the availability and quality of jobs; the nature of relationships between employers and workers; and the benefits and protections available to workers. Understanding these patterns will be critical for anticipating the consequences of future changes in the conditions of work, and ultimately help inform decision-making around policies and practices intended to protect and promote worker safety, health, and wellbeing. This model provides a structure for anticipating research needs in response to the changing nature of work, including the formation of research priorities, the need for expanded research methods and measures, and attention to diverse populations of enterprises and workers. This approach anticipates changes in the way work is structured, managed, and experienced by workers and can effectively inform policies and practices needed to protect and promote worker safety, health and wellbeing.

Designing a Participatory Total Worker Health® Organizational Intervention for Commercial Construction Subcontractors to Improve Worker Safety, Health, and Well-Being: The "ARM for Subs" Trial.

Background: Evidence supports organizational interventions as being effective for improving worker safety, health and well-being; however, there is a paucity of evidence-based interventions for subcontracting companies in commercial construction. Methods: A theory-driven approach supplemented by formative research through key stakeholder interviews and focus groups and an iterative vetting process with stakeholders, resulted in the development of an intervention for subcontractors in the commercial construction industry. We piloted the intervention in one subcontracting commercial construction company. We used these findings to adapt and finalize the intervention design to be tested in a future large-scale trial. Results: There were several key findings from the formative research, including challenges faced by companies and assets that should be considered in the intervention design. This resulted in a communication infrastructure company-based, continual improvement, participatory intervention design, consisting of a needs assessment and report, committee-led prioritization, action planning and implementation, and worker communication/feedback cycle. The pilot contributed to the final intervention design with modifications made with respect to timing, implementation support, capacity building, adaptability and sustainability. Conclusions: The use of a theory-driven participatory approach to developing an integrated organizational intervention for commercial construction subcontracting companies was important and necessary. It allowed us to consider the empirical evidence and relevant theories and tailor these to meet the needs of our target population. This study gives pragmatic insight into the early development of a complex intervention, with practical experience of how we adapted our intervention at each stage. This intervention will be tested in a future randomized trial.

A database of human gait performance on irregular and uneven surfaces collected by wearable sensors.

Gait analysis has traditionally relied on laborious and lab-based methods. Data from wearable sensors, such as Inertial Measurement Units (IMU), can be analyzed with machine learning to perform gait analysis in real-world environments. This database provides data from thirty participants (fifteen males and fifteen females, 23.5 ± 4.2 years, 169.3 ± 21.5 cm, 70.9 ± 13.9 kg) who wore six IMUs while walking on nine outdoor surfaces with self-selected speed (16.4 ± 4.2 seconds per trial). This is the first publicly available database focused on capturing gait patterns of typical real-world environments, such as grade (up-, down-, and cross-slopes), regularity (paved, uneven stone, grass), and stair negotiation (up and down). As such, the database contains data with only subtle differences between conditions, allowing for the development of robust analysis techniques capable of detecting small, but significant changes in gait mechanics. With analysis code provided, we anticipate that this database will provide a foundation for research that explores machine learning applications for mobile sensing and real-time recognition of subtle gait adaptations.

Associations between a safety prequalification survey and worker safety experiences on commercial construction sites.

BACKGROUND: While assessment of subcontractors' safety performance during project bidding processes are common in commercial construction, the validation of organizational surveys used in these processes is largely absent. METHODS: As part of a larger research project called Assessment of Contractor Safety (ACES), we designed and tested through a cross-sectional study, a 63-item organizational survey assessing subcontractors' leading indicators of safety performance. We administered the ACES Survey to 43 subcontractors on 24 construction sites. Concurrently, we captured the safety climate of 1426 workers on these sites through worker surveys, as well as injury rates, for the duration of the project. RESULTS: At the worksite level, higher average ACES scores were associated with higher worker safety climate scores (P < .01) and lower rates of injury involving days away (P < .001). Within subcontracting companies, no associations were observed between ACES and worker safety climate scores and injuries. CONCLUSIONS: These results suggest the overall and collective importance of the construction project and its worksite in mediating worker experiences, perhaps somewhat independent of the individual subcontractor level.

An Integrative Total Worker Health Framework for Keeping Workers Safe and Healthy During the COVID-19 Pandemic.

OBJECTIVE: The aim was to recommend an integrated Total Worker Health (TWH) approach which embraces core human factors and ergonomic principles, supporting worker safety, health, and well-being during the COVID-19 pandemic. BACKGROUND: COVID-19 has resulted in unprecedented challenges to workplace safety and health for workers and managers in essential businesses, including healthcare workers, grocery stores, delivery services, warehouses, and distribution centers. Essential workers need protection, accurate information, and a supportive work environment with an unwavering focus on effective infection control. METHOD: The investigators reviewed emerging workplace recommendations for reducing workers' exposures to the novel coronavirus and the challenges to workers in protecting their health. Using a theoretical framework and guidelines for integrating safety and health management systems into an organization for TWH, the investigators adapted the framework's key characteristics to meet the specific worker safety and health issues for effective infection control, providing supports for increasing psychological demands while ensuring a safe work environment. RESULTS: The recommended approach includes six key characteristics: focusing on working conditions for infection control and supportive environments for increased psychological demands; utilizing participatory approaches involving workers in identifying daily challenges and unique solutions; employing comprehensive and collaborative efforts to increase system efficiencies; committing as leaders to supporting workers through action and communications; adhering to ethical and legal standards; and using data to guide actions and evaluate progress. CONCLUSION: Applying an integrative TWH approach for worker safety, health, and well-being provides a framework to help managers systematically organize and protect themselves, essential workers, and the public during the COVID-19 pandemic. APPLICATION: By using the systems approach provided by the six implementation characteristics, employers of essential workers can organize their own efforts to improve system performance and worker well-being during these unprecedented times.

Mental Health Stigma and Wellbeing Among Commercial Construction Workers: A Mixed Methods Study.

OBJECTIVE: The aim of this study was to understand the relationship between mental health stigma and wellbeing in a sample of commercial construction workers. METHODS: A sequential quantitative to qualitative mixed methods study was conducted. First, 264 workers were surveyed and logistic regression examined the associations between mental health stigma and psychological distress, substance abuse, and sleep; then, data from eight key informant interviews and six focus groups with workers were analyzed thematically. RESULTS: Stigma was significantly associated with psychological distress and impaired sleep, but not with substance abuse. Key informants and workers discussed the prominence of stigma on worksites and how the masculine culture of the industry and job insecurity contributed to stigma. CONCLUSION: Stigma poses a barrier to addressing mental health among workers; peer support and improved human resources may be promising.

Associations Between the Breakroom Built Environment, Worker Health Habits, and Worker Health Outcomes: A Pilot Study Among Public Transit Rail Operators.

OBJECTIVE: To investigate the association between the breakroom built environment and worker health outcomes. METHODS: We conducted this study in a mass transit organization (rail). We collected a user-reported breakroom quality score (worker survey), a worksite health promotion score (validated audit tool), and self-reported worker health outcomes (survey). RESULTS: Among the 12 breakrooms audited and 127 rail operators surveyed, the average worksite health promotion score was 9.1 (out of 15) and the average user-reported breakroom quality was 3.1 (out of 7). After multivariable regression, breakrooms with higher worksite health promotion scores and user-reported breakroom quality were associated with lower odds of depression and fewer medical disability days. CONCLUSIONS: This cross-sectional study demonstrates an association between the quality of the breakroom built environment and worker health, specifically depression and medical disability days.