The Effects of Standing Working Posture on Operation Force and Upper Limb Muscle Activation When Using Different Pointing Devices

This study investigated how sitting and standing working postures affected operation force, upper limb muscle activation, and task performance using different pointing devices. Fifteen male participants completed cursor aiming and dragging tasks using a conventional mouse, a vertical mouse, and a trackball at sitting and standing workstations. A custom-made force plate was used to measure operation forces applied to the pointing devices. Surface electromyography (EMG) was used to capture the activation of the biceps brachii, triceps brachii, deltoid, and trapezius. Task performance was measured by task success rates, and subjective ratings were obtained for the force required for operation, smoothness of operation, accuracy, and local fatigue in the upper limb. We quantified the following significant outcomes: (1) greater operation forces were found when standing; (2) standing reduced EMG amplitudes of the triceps and trapezius muscles for all tasks; (3) during the aiming task, the vertical mouse had greater operation forces; (4) during the dragging task, both the vertical mouse and trackball had greater operation forces; and (5) task success rates differed for pointing devices only when sitting. This study revealed the distinct biomechanical properties of standing working posture and suggested limited beneficial effects of alternative pointing devices in terms of task performance and subjective ratings.

Physical exertion at work and addictive behaviors: tobacco, cannabis, alcohol, sugar and fat consumption: longitudinal analyses in the CONSTANCES cohort

We examined the prospective association of physical exertion at work with subsequent tobacco, cannabis, alcohol use, and sugar and fat consumption. Volunteers of the French population-based CONSTANCES cohort currently employed were included from 2012 to 2017 for tobacco and cannabis outcomes (n = 100,612), and from 2012 to 2016 for alcohol and sugar and fat outcomes (n = 75,414). High level of physical exertion at work was defined as a score ≥ 12 at the Rating Perceived Exertion Borg scale. Substance use was self-reported and diet rich in sugar and fat was obtained from principal component analysis and analyzed as quartiles. Generalized linear models computed odds of substance use and sugar and fat consumption at follow-up according to baseline physical exertion at work, while adjusting for sociodemographic factors, depressive symptoms and baseline level of consumption. High physical exertion was associated with tobacco use with dose-dependent relationships. It was also associated with increased odds of cannabis use at least once per month compared to no use in the past and with increased odds of diet rich in sugar and fat. Hence, the role of physical exertion at work on tobacco and cannabis use and diet rich in sugar and fat should be tackled for information and prevention strategies.

The Association of Physical Activity and Urinary Incontinence in US Women: Results from a Multi-Year National Survey

OBJECTIVES

To evaluate the relationships between physical activity, both work and recreational, and urinary incontinence among women.

METHODS

We assessed women aged 20 years and older in 2008-2018 NHANES (National Health and Nutrition Examination Survey) cycles who answered self-reported urinary incontinence and physical activity questions. Weighted, multivariate logistic regression model was used to determine the association between incontinence and physical activity levels after adjusting for age, body mass index, diabetes, race, parity, menopause and smoking.

RESULTS

A total of 30,213 women were included in analysis, of whom 23.15% had stress incontinence, 23.16% had urge incontinence, and 8.42% had mixed incontinence (answered "yes" to both stress and urge incontinence). Women who engaged in moderate recreational activity were less likely to report stress and urge incontinence (OR 0.79, 95% CI 0.62-0.99 and OR 0.66, 95% CI 0.48-0.90, respectively). Similarly, women who engaged in moderate activity work were less likely to report stress, urge and mixed incontinence (OR 0.84, 95% CI 0.70-0.99; OR 0.84, 95% CI 0.72-0.99; and OR 0.66 95% CI 0.45-0.97, respectively).

CONCLUSIONS

Moderate physical activity and greater time spent participating in moderate physical activity are associated with a decreased likelihood of stress, urge and mixed incontinence in women. This relationship holds for both recreational and work-related activity. We hypothesize that the mechanism of this relationship is multifactorial, with moderate physical activity improving pelvic floor strength and modifying neurophysiological mediators (such as stress) involved in the pathogenesis of incontinence.

The effect of leisure time physical activity and sedentary behaviour on the health of workers with different occupational physical activity demands: a systematic review

BACKGROUND

Although it is generally accepted that physical activity reduces the risk for chronic non-communicable disease and mortality, accumulating evidence suggests that occupational physical activity (OPA) may not confer the same health benefits as leisure time physical activity (LTPA). It is also unclear if workers in high OPA jobs benefit from LTPA the same way as those in sedentary jobs. Our objective was to determine whether LTPA and leisure time sedentary behaviour (LTSB) confer the same health effects across occupations with different levels of OPA.

METHODS

Searches were run in Medline, Embase, PsycINFO, ProQuest Public Health and Scopus from inception to June 9, 2020. Prospective or experimental studies which examined the effects of LTPA or LTSB on all-cause and cardiovascular mortality and cardiovascular disease, musculoskeletal pain, diabetes, metabolic syndrome, arrhythmias and depression among adult workers grouped by OPA (low OPA/sitters, standers, moderate OPA/intermittent movers, high OPA/heavy labourers) were eligible. Results were synthesized using narrative syntheses and harvest plots, and certainty of evidence assessed with GRADE.

RESULTS

The review includes 38 papers. Across all outcomes, except cardiovascular mortality, metabolic syndrome and atrial fibrillation, greater LTPA was consistently protective among low OPA, but conferred less protection among moderate and high OPA. For cardiovascular mortality and metabolic syndrome, higher levels of LTPA were generally associated with similar risk reductions among all OPA groups. Few studies examined effects in standers and none examined effects of LTSB across OPA groups.

CONCLUSIONS

Evidence suggests that LTPA is beneficial for all workers, but with larger risk reductions among those with low compared to high OPA jobs. This suggests that, in our attempts to improve the health of workers through LTPA, tailored interventions for different occupational groups may be required. More high-quality studies are needed to establish recommended levels of LTPA/LTSB for different OPA groups.

PROTOCOL REGISTRATION

PROSPERO # CRD42020191708 .

Correlation between real-time heart rate and fatigue in chest compression providers during cardiopulmonary resuscitation: A simulation-based interventional study

BACKGROUND

The American Heart Association guidelines recommend switching chest compression providers at least every 2 min depending on their fatigue during cardiopulmonary resuscitation (CPR). Although the provider's heart rate is widely used as an objective indicator for detecting fatigue, the accuracy of this measure is debatable.

OBJECTIVES

This study was designed to determine whether real-time heart rate is a measure of fatigue in compression providers.

STUDY DESIGN

A simulation-based prospective interventional study including 110 participants.

METHODS

Participants performed chest compressions in pairs for four cycles using advanced cardiovascular life support simulation. Each participant's heart rate was measured using wearable healthcare devices, and qualitative variables regarding individual compressions were obtained from computerized devices. The primary outcome was correct depth of chest compressions. The main exposure was the change in heart rate, defined as the difference between the participant's heart rate during individual compressions and that before the simulation was initiated.

RESULTS

With a constant compression duration for one cycle, the overall accuracy of compression depth significantly decreased with increasing heart rate. Female participants displayed significantly decreased accuracy of compression depth with increasing heart rate (odds ratio [OR]: 0.97; 95% confidence interval [CI]: 0.95-0.98; P < .001). Conversely, male participants displayed significantly improved accuracy with increasing heart rate (OR: 1.03; 95% CI: 1.02-1.04; P < .001).

CONCLUSION

Increasing heart rate could reflect fatigue in providers performing chest compressions with a constant duration for one cycle. Thus, provider rotation should be considered according to objectively measured fatigue during CPR.

Labor/leisure decisions in their natural context: The case of the smartphone

In this research, we attempt to understand a common real-life labor/leisure decision, i.e., to perform cognitive work or to interact with one's smartphone. In an ecologically valid experiment, participants (N = 112) could freely switch back and forth between doing a 2-back task and interacting with their own smartphone. We manipulated the value of the 2-back task (by varying the value of monetary rewards; within-subjects) and of the smartphone (by switching on and off airplane mode; within-subjects) while we recorded incoming notifications, such as text messages. Our study produced three main findings: (1) the current value of the smartphone did not increase our statistical model's ability to predict switches from labor to leisure when the current task value was also taken into account; (2) however, participants reacted strongly to naturally incoming notifications, which were the strongest predictor of labor-to-leisure switches; (3) there was no evidence that taking into account individual differences (in the value assigned to labor and leisure) improved the model's ability to predict labor-leisure switches. In sum, using a situated approach to studying labor/leisure decisions, our findings highlight the importance of high task motivation, as well as the temporary distractive potential of smartphone notifications, when people face the challenge of staying focused on their productive tasks.

Interaction between occupational physical burdens and low job control on musculoskeletal pain: Analysis of the 5th Korean Working Environment Survey

OBJECTIVE

This study aimed to investigate the interactive impacts between occupational physical burdens and psychological job demand or control on musculoskeletal pain (MSP) using nationally representative data for Korean workers.

METHODS

Using 5th Korean Working Conditions Survey (KWCS), we explored the interaction between occupational physical burdens and levels of psychological job demand or control on risk of MSP in 49 572 eligible participants. For quantitative evaluation of the interaction, relative excess risk due to interaction (RERI) was calculated.

RESULTS

In a group with low job control and at least one occupational physical burden, odds ratio (OR) for neck and upper extremity pain was 2.44 (95% CI, 2.24-2.66) compared with a group with high job control and no physical burden (a reference group: lowest risk), which was the highest value among the four groups, and the RERI was 0.35 (95% CI, 0.19-0.51). Similarly, OR for lower extremity pain was 2.15 (95% CI, 1.95-2.37) and RERI was 0.26 (95% CI, 0.07-0.45). However, the RERI was not significant in the case of psychological job demand.

CONCLUSION

This study revealed significant interactions between occupational physical burdens and low job control on MSP.

The effectiveness of ergonomics interventions in reducing upper limb work-related musculoskeletal pain and dysfunction in sonographers, surgeons and dentists: a systematic review

The aim of this systematic review was to summarise the effects of ergonomics interventions on work-related upper limb musculoskeletal pain and dysfunction, and on productivity in sonographers, surgeons and dentists. A total of 31 studies were included. All studies reported effects on upper limb pain. Nine studies reported effects on dysfunction and only two studies reported effects on productivity. Moderately strong evidence in reducing upper limb pain was found for instigation of microbreaks into long duration surgical procedures, and the use of wider, lighter handles in dental instruments. Moderate evidence was also found for use of prismatic glasses and favourable positioning in reducing upper limb pain. Weak, inconsistent or no evidence was found for all other ergonomics interventions in reducing upper limb pain and dysfunction and increasing productivity. The lack of high quality research, particularly in sonographers and in the outcome of productivity, should be addressed. Practitioner summary: This systematic review investigates the effectiveness of ergonomics interventions on upper limb pain, dysfunction and productivity in sonographers, dentists and surgeons. Instigation of microbreaks during long duration procedures and the use of wider, lighter instrument handles were most effective in reducing upper limb work-related pain. Abbreviations: ANOVA: analysis of variance; CLS: conventional laparoscopic surgery; DMAIC: define, measure, analyze, improve and control; GRADE: grading of recommendations, assessment, development and evaluations; HD: high definition; PRISMA: preferred reporting items for systematic reviews and meta-analyses; PROSPERO: The International Prospective Register of Systematic Reviews; RCT: randomised control trial; SILS: single incision laparoscopic surgery; VITOM: video telescopic operative microscope; WNSWLHD: Western New South Wales Local Health District; WMSD: work related musculoskeletal disorder.

Exposure to prolonged sedentary behavior on weekdays rather than weekends in white-collar workers in comparison with blue-collar workers

OBJECTIVES

Objectively measured sedentary behavior (SB) on weekdays and weekends has been mainly assessed in white-collar workers, while data in blue-collar workers are sparse. Therefore, this study presented the difference in accelerometer-measured SB levels between weekdays and weekends, stratified by white- and blue-collar occupations.

METHODS

This study was a sub-analysis of accelerometer data from 73 workers (31 blue-collar and 42 white-collar) at a Japanese manufacturing plant. SB was defined as ≤1.5 metabolic equivalents estimated using an accelerometer, and compared between weekdays and weekends by using mixed models adjusted for confounders. The proportion of workers who sat for ≤8 h/day on weekdays and weekends were compared using McNemar's test.

RESULTS

In white-collar workers, SB time on weekdays was significantly longer than that on weekends (598 vs 479 min/day, P < .001). In blue-collar workers, there was no significant difference in SB time between weekdays and weekends (462 vs 485 min/day, P = .43). The proportion of workers who achieved the recommended SB levels (≤8 h) was only 4.8% for white-collar workers on weekdays and 54.8% on weekends (P = .04), while that of blue-collar workers was 45.2% and 58.1% respectively (P > .99).

CONCLUSIONS

White-collar workers were exposed to significantly longer SB time on weekdays than on weekends, which was not the case in blue-collar workers. It may be rather challenging for white-collar workers to limit their SB time to the level recommended by the latest guidelines for better health, especially on weekdays.

Perceived musculoskeletal discomfort and its association with postural shifts during 4-h prolonged sitting in office workers

This study examined the characteristics of perceived discomfort and postural shifts at different magnitudes during a 4-h sitting period and the association between perceived discomfort and number of postural shifts. Forty healthy participants continuously typed a standardized text passage at a computer work station for 4 h. Subjects rated perceived body discomfort using Borg's CR-10 scale in 10 body regions (i.e. neck, shoulder, elbow, wrist/hand, upper back, lower back, buttock, thigh, knee, and ankle/foot). A seat pressure mat device was used to gather seat pressure data during sitting. Postural shifts were determined by analysis of the dispersion index of both ischial tuberosities from seat pressure data. The threshold for a postural shift was set at ±10% and ±20%. Perceived discomfort in all body regions increased continuously during a 4-h sitting period. The body regions with the highest perceived discomfort were the low back, buttocks, upper back, thigh, and neck. The average (±SD) numbers of postural shifts during the 1st, 2nd, 3rd, and 4th hour of sitting were 14.8 ± 9.5, 17.8 ± 9.4, 18.2 ± 11.1, and 18.1 ± 9.8 shifts per hour for the 10% threshold, and were 4.8 ± 4.4, 6.0 ± 5.6, 7.4 ± 6.7, and 7.7 ± 6.6 shifts per hour for the 20% threshold, respectively. Prolonged sitting led to an increase in perceived musculoskeletal discomfort over time. The number of postural shifts at both magnitudes increased in the first 2 h of sitting and, in the second 2-h period of sitting, only the number of larger postural shifts (with 20% threshold) increased. The findings extend our understanding of sitting behaviors.

Impacts of different fabric scissor designs on physical demands and performance in simulated fabric cutting tasks

While there is wide evidence that the occupational use of hand tools increases the risk of musculoskeletal disorder, evidence is limited regarding manual scissors, commonly used by custom tailors for bespoke garment production. We assessed whether scissor design impacts physical demands (muscle activity, perceived discomfort, and wrist posture) and task performance (quality and perceived efficiency). Twenty-four novice volunteers each completed simulated cutting tasks in 24 conditions involving the factorial combinations of four scissor designs (SD), three workstation heights, and two fabric types. SD significantly affected all outcome measures, and differences between SDs were consistent across workstation heights and fabric types. Two wide-handles scissors appeared superior overall, which may be related to the distinct grip type employed with this type of design. These results suggest that careful scissor selection has the potential to both reduce injury risk and enhance performance during fabric cutting tasks, though future testing is needed under more realistic conditions.

Comparisons of physical exposure between workers harvesting apples on mobile orchard platforms and ladders, part 1: Back and upper arm postures

This study compared farmworkers' exposure to non-neutral postures using a new mobile platform apple harvesting method and the traditional method using ladders. Twenty-four workers were recruited and assigned into three groups: ladder workers (n = 8) picking apples from full trees using a ladder, mobile platform workers (n = 8) picking apples from upper part of the trees while standing on a moving platform, and ground-based mobile platform workers (n = 8) picking apples from lower part of the trees which the mobile platform workers left out. Upper arm and back inclinations were continuously monitored during harvesting using tri-axial accelerometers over full work shifts (~8 h). Upper arm posture was characterized as the percentage of time that upper arm flexion and abduction exceeded 30°, 60°, and 90°. Back posture was characterized as the percentage of time that torso angles (sagittal flexion or lateral bending) exceeded 10°, 20°, and 30°. The 10th, 50th, and 90th postural percentiles were also calculated. The platform workers had lower exposures to upper arm flexion and abduction than the ground and ladder workers. There were no differences in torso angles between the ladder and mobile platform workers; however, the ground workers were exposed to more and greater percentages of time in torso flexions.

Comparisons of physical exposure between workers harvesting apples on mobile orchard platforms and ladders, part 2: Repetitive upper arm motions

Farmworkers are exposed to physical risk factors including repetitive motions. Existing ergonomic assessment methods are primarily laboratory-based and, thus, inappropriate for use in the field. This study presents an approach to characterize the repetitive motions of the upper arms based on direct measurement using accelerometers. Repetition rates were derived from upper arm inclination data and with video recordings in the field. This method was used to investigate whether harvesting with mobile platforms (teams harvesting apples from the platform and the ground) increased the farmworkers' exposure to upper arm repetitive motions compared to traditional harvesting using ladders. The ladder workers had higher repetitive motions (13.7 cycles per minute) compared to the platform and ground workers (11.7 and 12.2 cycles per minutes). The higher repetitions in the ladder workers were likely due to their ability to work independently and the additional arm movements associated with ladder climbing and walking.

The effect of age, prolonged seated work and sex on posture and perceived effort during a lifting task

The purpose of this investigation was to determine the effect of prolonged seated work, lift task, age and sex on normalized lumbar angles, thoracic angles, perceived effort and duration of lifts. A total of 17 young and 17 mature participants were recruited with an average (standard deviation) age of 23.8 (5.0) years and 63.7 (3.9) years, respectively. Participants completed 3 different floor to knuckle lifts before and following 90 min of seated work. The lifts included; (i) 7 kg symmetrical, (ii) 4.5 kg symmetrical and (iii) 4.5 kg asymmetrical. Prolonged seated work and age interacted to affect normalized peak lumbar angles (p = 0.0469) where older adults adopted 56(15)% flexion after seated work compared to 67(16)% among younger adults. Older adults took significantly longer to complete the lifting tasks compared to younger adults while age did not affect perceived effort across lifting tasks. Older workers may require age specific interventions given age specific responses.

Reducing postural load in order picking through a smart workwear system using real-time vibrotactile feedback

Vibrotactile feedback training may be one possible method for interventions that target at learning better work techniques and improving postures in manual handling. This study aimed to evaluate the short term effect of real-time vibrotactile feedback on postural exposure using a smart workwear system for work postures intervention in simulated industrial order picking. Fifteen workers at an industrial manufacturing plant performed order-picking tasks, in which the vibrotactile feedback was used for postural training at work. The system recorded the trunk and upper arm postures. Questionnaires and semi-structured interviews were conducted about the users' experience of the system. The results showed reduced time in trunk inclination ≥20°, ≥30° and ≥45° and dominant upper arm elevation ≥30° and ≥45° when the workers received feedback, and for trunk inclination ≥20°, ≥30° and ≥45° and dominant upper arm elevation ≥30°, after feedback withdrawal. The workers perceived the system as useable, comfortable, and supportive for learning. The system has the potential of contributing to improved postures in order picking through an automated short-term training program.

Assessing the potential for "undesired" effects of passive back-support exoskeleton use during a simulated manual assembly task: Muscle activity, posture, balance, discomfort, and usability

Back-support exoskeletons (BSEs) are wearable systems designed to reduce physical demands on the back, but which could have undesired effects beyond this design intention. Participants (n = 18) used two commercial BSEs to complete a brief (~15-20 s) simulated manual assembly task in varying conditions, with outcome measures that included: working posture, activity levels in "secondary" muscle groups (shoulders and thighs), perceived balance, discomfort, and usability. Using a BSE led to small and inconsistent changes in working postures (e.g., < ~14° change in lumbar flexion), muscular activity in the secondary muscle groups (<±2% of maximum voluntary isometric contractions), or perceived balance. Limitations in movement were reported for both BSEs, however, along with moderate levels of discomfort. Task-specific responses were evident for all outcome measures, though these depended on the specific BSE used and differed between genders in many cases. Future work should focus on interactions between a given user, BSE design, and task conditions.

A multicomponent ergonomic intervention involving individual and organisational changes for improving musculoskeletal outcomes and exposure risks among dairy workers

A field intervention study was implemented to evaluate the effects of individual (physical exercise programme and worker ergonomics training) and organisational changes (optimising work-rest schedule and revised task procedure) on musculoskeletal outcomes and their exposure risks among milking workers in a dairy plant. A questionnaire survey (including the Cornell Musculoskeletal Discomfort Questionnaire [CMDQ]) and direct observations of working postures by using the Quick Exposure Check (QEC) method were used at baseline and 12-month follow-up. Shoulder, lower back and neck discomfort were found to be the most common problems. The results showed significant improvements in the frequency (neck, shoulder, lower back, forearm and knee symptoms), severity (shoulder, lower back and knee symptoms) and interference with work (particularly due to lower back symptoms) as well as in the exposure risks to musculoskeletal problems (using the QEC method) after the intervention. The findings support the effectiveness of implemented multiple component intervention for improving musculoskeletal health and exposure risks in the studied occupational group.

Effects of working posture and roof slope on activation of lower limb muscles during shingle installation

Awkward and extreme kneeling during roofing generates high muscular tension which can lead to knee musculoskeletal disorders (MSDs) among roofers. However, the combined impact of roof slope and kneeling posture on the activation of the knee postural muscles and their association to potential knee MSD risks among roofers have not been studied. The current study evaluated the effects of kneeling posture and roof slope on the activation of major knee postural muscles during shingle installation via a laboratory assessment. Maximum normalized electromyography (EMG) data were collected from knee flexor and extensor muscles of seven subjects, who mimicked the shingle installation process on a slope-configurable wooden platform. The results revealed a significant increase in knee muscle activation during simulated shingle installation on sloped rooftops. Given the fact that increased muscle activation of knee postural muscles has been associated with knee MSDs, roof slope and awkward kneeling posture can be considered as potential knee MSD risk factors. Practitioner Summary: This study demonstrated significant effects of roof slope and kneeling posture on the peak activation of knee postural muscles. The findings of this study suggested that residential roofers could be exposed to a greater risk of developing knee MSDs with the increase of roof slope during shingle installation due to increased muscle loading. Abbreviations: MSDs: musculoskeletal disorders; EMG: electromyography; ANOVA: analysis of variance; MNMA: maximum normalized muscle activation; RF: rectus femoris; VL: vastus lateralis; VM: vastus medialis; BF: biceps femoris; S: semitendinosus.

Ergonomics assessment of passive upper-limb exoskeletons in an automotive assembly plant

Over the years, the industry's interest in using external support devices, such as exoskeletons, is increasing. They are introduced as a new technique for improving the conditions of workers and for reducing the risk of musculoskeletal injuries. An investigation of muscle activity, Jonsson's (Jonsson, 1982) ergonomic acceptance ranges, and shoulder range of motion was conducted with a sample of 12 workers using an upper extremity exoskeleton in an automotive assembly line. The operators performed continuous cycles of dynamic overhead work consisting of the assembly of the car body at the underside of the car making use of pneumatic screwdrivers. The EMGs (anterior part of deltoid, trapezius, latissimus dorsi and erector spinae) were measured for the muscle activity analysis on the one hand, and for the ergonomics study on the other hand. The latter consisted of an approach based on Jonsson's work, that establishes acceptance thresholds of cumulative percentage of maximum voluntary contraction of muscle activity (%MVC) in a work cycle. The joint angles motion capture was carried out by measuring the angles of the neck, back, and arms joints. All measurements were performed during experimental sessions with and without an exoskeleton. The key findings show reductions of 34% and 18% of the deltoid and the trapezius muscular activities, respectively, which in turn could lead to a reduction of discomfort and fatigue. The erector spinae and latissimus dorsi muscles were not significantly affected by exoskeleton. The values of muscular activity were also represented over Jonsson's acceptance areas. Referring to the posture, some differences were found in the range of movement of back, neck, and arms owing to the use of the exoskeleton; however, the differences were smaller than 5% in all cases.

Forearm muscular strength and performance fatigability in orthopaedic surgeons when performing bone screw fixations

This study investigated the muscle strength and performance fatigability of the forearms in eight male orthopaedic surgeons when performing bone screw fixations. Each surgeon performed an eight-bone screws operations in a porcine femur model to simulate fractural fixation using plating technique. The pre- and post-fatigue maximum isometric forces and corresponding electromyography responses were measured to assess the forearm muscle strength loss and fatigue due to screwing. Results showed that after eight bone screws were inserted, the maximal grip force, maximal driving torque and maximal push force losses were approximately 29%, 20% and 23%, respectively. While the grip force and/or driving torque acting, both the brachioradialis and extensor carpi ulnaris had a higher percentage change of EMG than the biceps brachii. The driving forces decreased with the number of screw insertions; however, the insertion time increased parabolically with the number of screws and significantly decreased the insertion rate of the screws, indicating that forearm muscle fatigue may occur in surgeons who treat fracture fixation using more than eight bone screws.

Air-assisted devices reduce biomechanical loading in the low back and upper extremities during patient turning tasks

This laboratory study evaluated different assistive devices for reducing biomechanical loading during patient turning tasks. Twenty caregivers (18 females and 2 males) performed standardized patient turning tasks with two simulated patients (body mass: 74 kg and 102 kg). The turning tasks were performed in two turning directions (toward vs. away relative to caregivers) using five device conditions: draw sheet, friction-reducing turning sheet, air-assisted transfer device, air-assisted turning device, and no assistive device. Low back and upper extremity muscle activity, trunk and shoulder postures, low back moment, and self-reported usability ratings were evaluated. While all assistive devices reduced trunk flexion, both air-assisted transfer and turning devices reduced the trunk flexion (p's < 0.001) and muscle activity (p's < 0.001) in the erector spinae and triceps compared to no assistive device condition. These results suggest that the air-assisted devices have potential as an effective intervention to considerably reduce physical risk factors associated with caregivers' musculoskeletal disorders in low back and upper extremities.

Quantifying surgeon maneuevers across experience levels through marker-less hand motion kinematics of simulated surgical tasks

This paper compares clinician hand motion for common suturing tasks across a range of experience levels and tissue types. Medical students (32), residents (41), attending surgeons (10), and retirees (2) were recorded on digital video while suturing on one of: foam, pig feet, or porcine bowel. Depending on time in position, each medical student, resident, and attending participant was classified as junior or senior, yielding six experience categories. This work focuses on trends associated with increasing tenure observed from those medical students (10), residents (15), and attendings (10) who sutured on foam, and draws comparison across tissue types where pertinent. Utilizing custom software, the two-dimensional location of each of the participant's hands were automatically recorded in every video frame, producing a rich spatiotemporal feature set. While suturing on foam, increasing clinician experience was associated with conserved path length per cycle of the non-dominant hand, significantly reducing from junior medical students (mean = 73.63 cm, sd = 33.21 cm) to senior residents (mean = 46.16 cm, sd = 14.03 cm, p = 0.015), and again between senior residents and senior attendings (mean = 30.84 cm, sd = 14.51 cm, p = 0.045). Despite similar maneuver rates, attendings also accelerated less with their non-dominant hand (mean = 16.27 cm/s², sd = 81.12 cm/s², p = 0.002) than senior residents (mean = 24.84 cm/s², sd = 68.29 cm/s², p = 0.002). While tying, medical students moved their dominant hands slower (mean = 4.39 cm/s, sd = 1.73 cm/s, p = 0.033) than senior residents (mean = 6.53 cm/s, sd = 2.52 cm/s). These results suggest that increased psychomotor performance during early training manifest through faster dominant hand function, while later increases are characterized by conserving energy and efficiently distributing work between hands. Incorporating this scalable video-based motion analysis into regular formative assessment routines may enable greater quality and consistency of feedback throughout a surgical career.

What does ergonomics have to do with nanotechnologies? A case study

Despite recent concerns for workers' health, exposure situations to nanoparticles can occur in numerous workplaces. Understanding how exposures occur considering human work in these transformations remains a crucial issue of nanotechnologies. The objective of this article is to understand exposure situations to nanoparticles, their determinants and the resources to act on them. This understanding was achieved by specific measurement of nanoparticles aerosols, combined with an analysis of work activity (actions performed and physical strain) in a rubber industry. The presentation of real time measurements, associated with the video of work situations, during confrontation interviews becomes a means of making exposing work activities visible, to analyze and transform them from the points of view formulated by the company's stakeholders. In this way, characterized "typical exposure situations" serve to trigger discussions and open up new spaces for debate highlighting how innovation affects work and gives rise to enhanced prevention projects.

An ergonomic assessment of using laterally-tilting operating room tables and friction reducing devices for patient lateral transfers

Patient lateral transfers between two adjacent surfaces pose high musculoskeletal disorder risks for nurses and patient handlers. The purpose of this research was to examine the ergonomic benefits of utilizing the laterally-tilting function of operating room (OR) tables during such transfers - along with different friction-reducing devices (FRD). This method allows the patient to slide down to the adjacent surface as one nurse guides the transfer and another controls the OR table angle with a remote control. Sixteen nursing students and sixteen college students were recruited to act as nurses and patients, respectively. Two OR table angles were examined: flat and tilted. Three FRD conditions were considered: a standard blanket sheet, a plastic bag, and a slide board. Electromyography (EMG) activities were measured bilaterally from the posterior deltoids, upper trapezii, latissimus dorsi, and lumbar erector spinae muscles. The Borg-CR10 scale was used for participants to rate their perceived physical exertions. The efficiency of each method was measured using a stopwatch. Results showed that the tilted table technique completely replaced the physical efforts that would have been exerted by the pushing-nurse, in that muscle activation did not increase in the pulling-nurse. On the contrary, EMG activities of the pulling-nurse for most of the muscles significantly decreased (p < 0.05). The subjective Borg-ratings also favored the tilted table with significantly lower ratings. However, the tilted table required on average 7.22 s more than the flat table to complete the transfer (p < 0.05). The slide board and plastic bag were associated with significantly lower Borg-ratings and EMG activities for most muscles than blanket sheet, but they both were not significantly different from each other. However, they each required approximately 5 s more than the blanket sheet method to complete the patient transfer (p < 0.05). By switching from flat + blanket sheet to tilted + slide board, EMG activities in all muscles decreased in the range of 18.4-72.3%, and Borg-ratings decreased from about 4 (somewhat difficult) to 1 (very light). The findings of this study propose simple, readily available ergonomic interventions for performing patient lateral transfers that can have significant implications for nurses' wellbeing and efficiency.

The effectiveness of ergonomic interventions in material handling operations

This study evaluated the effectiveness of ergonomic interventions in material handling operations involving 33 employers and 535 employees from 2012 to 2017. Outcomes included employee-reported low back/upper extremity pain and safety incidents at baseline, every three months, and annually for up to two years. A total of 32.5% of employees completed at least one survey, while 13.6% completed all nine surveys over two years. Among highly exposed employees (who reported handling >= 50 lbs. > 33% of the time), upper extremity pain frequency and severity were lower among those who reported using the intervention routinely versus those that reported using their body strength alone to handle objects >= 50 lbs. After excluding from analyses one employer that used anti-fatigue mats, low back pain frequency was also significantly lower among highly exposed intervention users. In conclusion, there was some evidence that the interventions were effective in reducing employee-reported pain for highly exposed employees.

Risk of hypoglycaemia associated with professional, recreational, and traffic-related activities in patients with type 2 diabetes: a cross-sectional study by questionnaire

AIMS

We aimed to quantify the exposure to physical exercise associated with professional, recreational, or traffic-related activities in patients with type 2 diabetes, which may provoke or aggravate hypoglycaemic episodes, and to assess whether such risks determine the choice of medications minimizing the risk of hypoglycaemia.

METHODS

In total, 203 patients with type 2 diabetes (98 women, 105 men, age 65 [56;72; median, inter-quartile range] years, diabetes duration 10 [5;15] years) were recruited from a German diabetes practice. A questionnaire assessed their engagement in professional, recreational, or traffic-related activities. The prescription insulin or sulphonylureas was quantified in relation to the number of such activities.

RESULTS

63.5% of the patients were treated with insulin, 7.4% with sulphonylureas, and 70.9% with either. Sixty-six patients (22.7%) were professionally active: 36 (54.4%) of those were professionally exposed to risky behaviour (14 [31.8%] patients with exposure to multiple risks and 20 (30.3%) who experienced hypoglycaemic episodes in the past year). In total, 194 (95.6%) patients were exposed to risky behaviour during recreational activities, 129 (63.6%) to multiple ones. All patients were exposed to traffic-related activities, 144 (70.9%) were exposed to more than being pedestrian, and 24 (11.8%) experienced hypoglycaemic episodes while in traffic.

CONCLUSIONS

Patients with type 2 diabetes are exposed to risks associated with professional, recreational, and traffic-related activities. We recommend a careful assessment of such risks before glucose-lowering medications with a potential for provoking hypoglycaemic episodes are prescribed.

Development and evaluation of a dual density insole for people standing for long periods of time at work

BACKGROUND

Appropriate footwear is important for those who stand for prolonged periods of time at work, enabling them to remain comfortable, healthy and safe. Preferences for different footwear cushioning or hardness are often person specific and one shoe or insole will not be the choice for all. The aim of this study was to develop a range of insole options to maintain comfort during long periods of standing at work and test insole material preferences in the workplace.

METHODS

The study consisted of two parts. Part one evaluated 9 insoles of the same geometry that varied in hardness under 2 different plantar regions (n = 34). Insole preference, plantar pressure and selected anthropometric foot measures were taken. Three insole designs based on the most preferred options were identified from this part. In part two, these three insoles were evaluated with 22 workers immediately after trying them on (1 min) and after a working day. Foot anthropometric measures and subjective questions concerning material hardness preferences and self-reported foot characteristics were used to investigate whether either had a relationship with insole preference.

RESULTS

Part one found insole preference predominantly varied according to material hardness under the medial arch rather than the heel/forefoot. Softer material under the heel and forefoot was associated with a reduction in peak pressures in these regions (p < 0.05). The most preferred insole had lower pressures under the hallux and first metatarsal phalangeal joint, and greater pressures and contact area under the medial midfoot (p < 0.05) compared to the least preferred insole. Height and foot anthropometrics were related to insole preference. In part two, under real world conditions, insole preference changed for 65% of participants between the immediate assessment (1 min) and after a whole workday, with dorsum height related to the latter (p < 0.05). Subjective questions for self-assessed arch height and footwear feel identified 66.7% of the insole preferences after 1 day at work, compared to 36% using immediate assessment of insole preference.

CONCLUSION

Preference for material hardness varies underneath the medial arch of the foot and is time dependent. Simple foot measures and questions about comfort can guide selection of preferred insoles.

Temporal leeway: can it help to reduce biomechanical load for older workers performing repetitive light assembly tasks?

Current industrial production systems allow assembly of customised products which include additional elements distinguishing them from a reference model. This customisation can result in significant additional time constraints which compel workers to complete their tasks faster, which may pose problems for older workers. The objective of this laboratory study was to investigate the impact of restrictive or flexible pacing during assembly of customised products among groups of younger and older participants. The data gathered were used to analyse cycle-time, assembly performance, muscular load, and kinematic adaptations. The flexible pacing condition was found to improve production performance, increasing customised assembly cycle-time and reducing biomechanical load, for both young and older participants. However, as the task required fine manual dexterity, older participants were subjected to a higher biomechanical load, even in the flexible pacing scenario. These results should encourage assembly-line designers to allow flexible time constraints as much as possible and to be particularly attentive to the needs of older workers.

Risk factors for development of lower limb osteoarthritis in physically demanding occupations: A systematic review and meta-analysis

This systematic review and meta-analysis identified and critically reviewed the findings of recent studies (last 15 years) examining relationships between specific physically demanding occupations or occupational tasks and development of lower limb osteoarthritis (OA). Twenty-eight studies with 266,227 cases of lower limb OA were included. Occupational tasks contributing to OA included farming, floor laying, and brick laying. Activities significantly contributing to the risk of knee OA were lifting heavy loads (>10 kg/week) (odds ratio [OR] = 1.52, 95% confidence interval [95%CI] 1.29-1.79), squatting/kneeling (OR = 1.69, 95%CI 1.15-2.49), standing (>2 h/daily) (OR = 1.22 95%CI 1.02-1.46) and walking (OR = 1.40 95%CI 1.14-1.73). Lifting contributed significantly to the risk of hip OA (OR = 1.35, 95%CI 1.16-1.57). The effects of occupational exposures appear to be magnified by previous injury and BMI >25 kg/m². Since specific occupational activities increase OA risk, ergonomist should encourage the use of existing tools, or oversee the design of new tools that may decrease exposure to such activities.

A thorough investigation on pushing activities in industry: The impact of the variation in the speed of motion and load conditions on initial and sustained forces

Pushing and pulling wheeled objects represent a significant part of manual material handling activities in industry. Medical investigations and epidemiological studies proved the correlation between such activities and the occurrence of lumbago, low back pain and adverse effects on the shoulders. The ISO 11228-2:2007 provides the recommended limits for pushing and pulling. Such values are the results of psychophysical studies realized under prescribed speed conditions referring to a slow walk. However, observation of real industrial and service sector environments reveals that workers are required to perform pushing activities at higher speed of motion. The aim of this study was to investigate the impact of the variation in the speed of motion and load conditions on push forces. 96 subjects performed a total of 2592 trials consisting of pushing an industrial trolley for warehouse applications, at different speed values and load conditions. Results confirm the presence of correlation between the increasing speed of motion and push forces. The findings have practical value for researchers, occupational physicians and ergonomics practitioners.

Effect of whole-body vibration exposures on physiological stresses: Mining heavy equipment applications

The aim of this study was to employ validated biological markers to quantify the physiologic consequences of exposure to whole-body vibration (WBV) and evaluate the relative impact of mining vehicle operator vibration exposure on physiological responses as compared to vertical-axial dominant WBV. In a laboratory-based study with a repeated-measures design, we played actual field-measured floor vibration profiles into a 6-degree-of-freedom motion platform to create different realistic WBV exposures: 1) vertical-dominant vibration collected from long-haul trucks, 2) multi-axial vibration collected from mining heavy equipment vehicles, and 3) no vibration (control condition). Circulating biomarkers of interest were cortisol and catecholamines (epinephrine and norepinephrine) to assess physiological stress, interleukin-6 (IL-6) and tumor necrosis factor-α (TNFα) to test for inflammation, thiobarbituric acid reactive substances (TBARS) to measure oxidative stress, and myoglobin and plasma creatine kinase to assess muscle damage. We collected blood samples at pre-exposure (0 h), during-exposure (2 and 4 h), and 2 h into recovery after the WBV exposure (6 h) in all four exposure conditions. The results showed that a single, 4-h acute exposure to WBV may not be sufficient to induce skeletal muscle damage, inflammation or physiologic stress measurable in the blood. No significant differences were observed between conditions for any of the biomarkers that could be attributed to the exposure contrast between vertical-dominant and multi-axial WBV exposures. These findings further indicate known complications of WBV exposure likely arise secondary to chronic, repeated exposures that give rise to subclinical stresses that were not captured here.

Does sEMG normalization change results on sex differences in the activation of the shoulder girdle muscles during a simulated work task?

The aim was to investigate if the method of normalizing surface electromyography (sEMG) can change results on sex differences in the muscular activation of the shoulder girdle muscles during a simulated work task. sEMG was recorded in 36 asymptomatic participants (17 females, 19 males) from four parts of trapezius and from serratus anterior muscles during a simulated work task. Four normalization methods, one involving maximal voluntary contractions (MVCs) and three involving submaximal voluntary contractions were applied. Sex differences in absolute and normalized amplitude of sEMG were analyzed. The normalization method had a significant influence on the observed sex differences. Females only showed higher sEMG amplitude than males when the sEMGs were normalized to MVC and to a submaximal contraction based on 20% of MVC for the upper trapezius (acromial fibers). Researchers and practitioners should be aware of the impact of the sEMG normalization method in sex differences investigation.

Shoulder pain among male industrial workers: Validation of a conceptual model in two independent French working populations

This study aims to validate a conceptual model for shoulder pain risk factors in two independent samples of male industrial workers: the Cosali cohort (n = 334) and one pharmaceutical company (n = 487). Direct and indirect relationships between work organization factors (automatic speed of a machine or movement of a product and work pace dependent on customers' demand), psychosocial factors (Job strain model), biomechanical factors (working with abducted arms, working with arms at or above shoulder level, and perceived physical exertion), perceived stress, and shoulder pain were explored using structural equation models. Shoulder pain was positively associated with biomechanical exposure in both samples, and with perceived stress only in the pharmaceutical preparation manufacturer, while factors related to work organization and psychosocial factors had indirect impacts on the risk of chronic shoulder pain in both samples. The results provide a deeper understanding of the complex relationships between workplace risk factors and shoulder pain.

Extending work tolerance time in the heat in protective ensembles with pre- and per-cooling methods

OBJECTIVES

Investigate whether a range of cooling methods can extend tolerance time and/or reduce physiological strain in those working in the heat dressed in a Class 2 chemical, biological, radiological, nuclear (CBRN) protective ensemble.

METHODS

Eight males wore a Class 2 CBRN ensemble and walked for a maximum of 120 min at 35 °C, 50% relative humidity. In a randomised order, participants completed the trial with no cooling and four cooling protocols: 1) ice-based cooling vest (IV), 2) a non-ice-based cooling vest (PCM), 3) ice slushy consumed before work, combined with IV (SLIV) and 4) a portable battery-operated water-perfused suit (WPS). Mean with 95% confidence intervals are presented.

RESULTS

Tolerance time was extended in PCM (46 [36, 56] min, P = 0.018), SLIV (56 [46, 67] min, P < 0.001) and WPS (62 [53, 70] min, P < 0.001), compared with control (39 [30, 48] min). Tolerance time was longer in SLIV and WPS compared with both IV (48 [39, 58 min]) and PCM (P ≤ 0.011). After 20 min of work, HR was lower in SLIV (121 [105, 136] beats·min^-1), WPS (117 [101, 133] beats·min^-1) and IV (130 [116, 143] beats·min^-1) compared with control (137 [120, 155] beats·min^-1) (all P < 0.001). PCM (133 [116, 151] beats·min^-1) did not differ from control.

CONCLUSION

All cooling methods, except PCM, utilised in the present study reduced cardiovascular strain, while SLIV and WPS are most likely to extend tolerance time for those working in the heat dressed in a Class 2 CBRN ensemble.

Consistent individual motor variability traits demonstrated by females performing a long-cycle assembly task under conditions differing in temporal organisation

Research suggests an association between motor variability (MV) during repetitive work and work-related musculoskeletal disorders (MSDs). However, whether MV is a consistent individual trait, even across working conditions or tasks, remains unknown. This study assessed whether individual MV traits were consistent during complex work performed under different temporal conditions. Fifteen women performed cyclic assembly under four conditions differing in pace and organisation (line-type, batch-type). MV of trapezius muscle activity and upper arm elevation was quantified and partitioned into variance components. For all MV metrics, a non-zero between-subjects variance was found, indicating consistent individual MV traits across conditions. Variance between subjects was higher for electromyography (EMG) MV metrics compared with kinematic metrics. Our results showed individuals exhibited consistent MV traits across working conditions differing in pace and production process. Further research is needed to understand whether MV is an individual predictive factor for MSD onset or progression.

Collaborating with radiographers to address their work-related musculoskeletal discomfort

The prevalence of musculoskeletal (MSK) symptoms in radiographers is high, similar to other healthcare occupations that involve high levels of physical exertion (e.g. patient handling; grasping and moving equipment). Reports of interventions to reduce MSK discomfort in radiographers are limited. A participatory approach was used to investigate daily challenges, needs, and opportunities for developing interventions to address exposures to many of the risk factors that contribute to MSK symptoms in radiographers. In this paper, we present the expressed needs of experienced radiographers (including assistance with patient handling, security, supportive design of equipment and work spaces), along with their evaluations of several intervention concepts intended to address some of those needs. We also report results from tests of three prototype interventions stemming from this participatory process that demonstrate the potential for new engineering control concepts to reduce the physical effort associated with some of the most common tasks radiographers perform.

The Role of Work Environment in Training Sustainment: A Meta-Analysis

OBJECTIVE

The purpose of this meta-analytic review is to examine the role of three work environment support variables (i.e., peer, supervisor, and organizational support) in training transfer and sustainment or long-term use of learned knowledge, skills, and attitudes (KSAs).

BACKGROUND

Estimates demonstrate that little training is transferred to the job, wasting billions in organizational spending each year and resulting in significant loss to safety and individual and team performance. Prior research shows the importance of a supportive work environment to facilitating transfer; however, we know little of the relative importance of specific support variables. This study seeks to examine the unique roles of distinct support variables in training transfer.

METHOD

A meta-analysis was conducted with multiple regressions to answer three primary research questions.

RESULTS

All work environment support variables demonstrate moderate and positive correlations with transfer of training. Furthermore, multiple regressions demonstrate that each factor of the work environment explains unique variance as a predictor, with the model accounting for 32% of transfer and peer support accounting for most of R². Motivation to transfer mediates the relationship between all three work environment support variables and transfer. Furthermore, three support variables are positively related to sustainment, with peer and supervisor support showing the strongest relationships.

CONCLUSION

Findings illuminate the relative contribution of peer, supervisor, and organizational support to transfer and sustainment of training. As transfer continues to be an important yet understudied measure of the effectiveness of workplace training, these findings hold implications for both research and practice.

Occupational variation in the relationship between child health and family size

Empirical evidence for quantity-quality trade-off is hardly ubiquitous, especially when quality is measured by child health outcomes. The paper offers a new explanation to this puzzle. It shows that the quantity-quality relationships are subject to occupational variation when quality is given by nutritional status, and occupations differ in their physical labor intensity. It embeds, in a simple household optimization model, a minimum consumption requirement that rises with physical work intensity of occupation. The occupational differences in subsistence consumption requirement generate variation in child nutritional status, and hence, in the shadow price of children. The nature of the quantity-quality relationship, therefore, varies with work intensity of occupations. The model yields an equilibrium relationship between the number and nutritional status of children that is positive for households in strenuous occupations and ambiguous for other households. These results help reconcile some inconsistent findings on quantity-quality trade-off, which may partly be explained by the omission of occupational variation in nutritional status.

Examining the fatigue-quality relationship in manufacturing

A recent systematic review identified 73 empirical studies that linked human factors (HF) with manufacturing quality. Human fatigue was noted as a frequent (n = 26) issue in the HF-quality relationship - a finding that warrants closer examination. We extend this review by investigating the relationship between fatigue and manufacturing quality by identifying how fatigue has been conceptualized and measured, and we attempted to quantify their relationship. From the original database, 12 of 26 relevant studies (46%) indicated that physical fatigue was the primary contributor to observed quality deficits. There was a positive relationship between fatigue and quality deficits, with fatigue accounting up to 42% of the variance. More studies are needed to improve the resolution, specificity, and power of these analyses. This study sheds light on the role of HF and human fatigue effects on manufacturing quality with macroergonomic implications for embedding HF aspects into design and quality assurance processes.

The effect of wearing insoles with a toe-grip bar on occupational leg swelling and lower limb muscle activity: A randomized cross-over study

OBJECTIVE

Sitting or standing for hours decreases the blood flow in the legs and results in increased pressure on the veins, leading to the development of chronic venous disease. This study aimed to investigate the effects of insoles with a toe-grip bar on occupational leg swelling and lower limb muscle activity.

METHODS

This randomized cross-over study enrolled 12 healthy men who work in a sitting or standing position. They were randomly divided into groups A (wore shoes with insoles with a toe-grip bar for 8 hours each) and B (wore shoes with regular insoles for 8 hours each). After 1 week, groups A and B wore shoes with regular insoles and shoes with insoles with a toe-grip bar, respectively, for 8 hours each. Lower leg volume was measured before and after each intervention, and lower limb muscle activity was measured at the start of each intervention.

RESULTS

Occupational leg swelling was significantly smaller in men wearing insoles with a toe-grip bar (P < .05). Moreover, the integrated electromyogram value of the tibialis anterior muscle and medial and lateral gastrocnemius muscles during the stance phase of walking, and tibialis anterior muscle during the swing phase of walking was significantly greater in men wearing insoles with a toe-grip bar (all P < .05).

CONCLUSION

Insoles with a toe-grip bar contribute to increased lower limb muscle activity, attenuating occupational leg swelling.

Maternal BMI mediates the impact of crop-related agricultural work during pregnancy on infant length in rural Pakistan: a mediation analysis of cross-sectional data

BACKGROUND

Stunted growth in early infancy is a public health problem in low-and-middle income countries. Evidence suggests heavy agricultural work during pregnancy is inversely associated with maternal body mass index (BMI) and infant birth weight in low- and middle-income countries; but pathways linking agricultural work to length-for-age Z-scores (LAZ) in early infancy have not been examined. This study aimed to investigate the relationship between agricultural work during pregnancy, post-natal maternal BMI and LAZ among young infants in rural Pakistan; and explored whether maternal BMI mediated the relationship between agricultural work and infant LAZ.

METHODS

A cross-sectional survey was conducted from December 2015 to January 2016 in rural Sindh, Pakistan. Mother-infant dyads were recruited via systematic random cluster sampling at 2-12 weeks' post-partum (n = 1161). Anthropometric measurements (maternal and infant height/length and weight) and questionnaire data were collected. Multivariable linear regression and structural-equation based mediation analyses were used to examine associations of agricultural work during pregnancy with maternal BMI and infant LAZ.

RESULTS

During pregnancy, women reported engaging in livestock-related work (57.0%), crop-related work (42.7%), and cotton harvesting (28.4%). All three forms of agricultural work were negatively associated with maternal BMI (β = - 0.67 [- 1.06; - 0.28], β = - 0.97 [- 1.51; - 0.48]; and β = - 0.87 [- 1.33; - 0.45], respectively). Maternal engagement in cotton harvesting alone was negatively associated with infant LAZ after controlling for confounding factors. The total negative effect of cotton harvesting on infant LAZ was - 0.35 [- 0.53; - 0.16]. The indirect effect of maternal BMI on infant LAZ was - 0.06 [- 0.08; - 0.03], revealing that 16% (- 0.06/- 0.35) of the relationship between cotton harvesting and infant LAZ, after adjustment, was mediated via maternal BMI.

CONCLUSION

These results underscore a need to reduce labour-intensive agricultural workload demands during pregnancy, especially in cotton harvesting, to reduce risks of negative maternal energy balance and poor growth outcomes in early infancy.

Janitor ergonomics and injuries in the safe workload ergonomic exposure project (SWEEP) study

INTRODUCTION

A Minnesota union identified to researchers at the University of Minnesota a concern relevant to a possible relation between their daily workload and outcome of occupational injuries among a population of janitors.

OBJECTIVE

To assess if the ergonomic workload is related to injuries among janitors.

METHODS

Following an initial group discussion among janitors, which identified common and hazardous tasks potentially leading to occupational injuries, a questionnaire was developed, pre-tested, and distributed to the janitors. Questions addressed various exposures, including workload, and comprehensive information regarding injury occurrence over two six-month sequential periods (May 2016-October 2016, November 2016-April 2017). Quantitative ergonomic analyses were performed on a sub-group of janitors (n = 30); these included data collection to identify Borg Perceived Exertion (Borg) and Rapid Entire Body Assessment (REBA) scores. Descriptive, multivariable with bias adjustment analyses were conducted on the resulting data.

RESULTS

Eight tasks were found to be common for janitors. All average REBA scores for the tasks were identified in the high-risk category. The task of repeatedly emptying small trash cans (<25lb) was significantly related to injuries. Average Borg scores fell between the very light perceived exertion and somewhat difficult perceived exertion categories. Multivariable regression analyses indicated that age-sex-standardized ergonomic workload, measured by task frequencies and REBA or Borg scores, was positively related to injury occurrence.

CONCLUSIONS

Standardized ergonomic workload was positively related to injury occurrence. This information serves as a basis for further research and potential intervention efforts.

Trapezius muscle activity variation during computer work performed by individuals with and without neck-shoulder pain

This study aimed at determining the extent to which individuals with neck-shoulder pain and non-symptomatic individuals differ in muscle activation patterns, when performing computer work, as quantified by exposure variation analysis (EVA). As a secondary aim, we also aimed to quantify the day-to-day reliability of EVA variables describing trapezius muscle activation in a non-symptomatic control group. Thirteen touch-typing computer users (pain: n = 5, non-symptomatic: n = 8) completed three pre-selected computer tasks in the laboratory. Upper trapezius muscle activity was recorded using electromyography and analyzed using EVA with five amplitude and five duration categories. Individuals with neck-shoulder pain spent less time at low amplitudes and exhibited longer uninterrupted periods of muscle activation compared to their non-symptomatic counterparts. Thus, non-symptomatic workers tended to switch between exposure levels more often than individuals with pain. For a majority of EVA variables, ICCs ranged from 0.6 to 0.9, and between-days coefficients of variation were between 0.4 and 2.2.

Assessing work-related risk factors for musculoskeletal knee disorders in construction roofing tasks

Roofers often suffer from musculoskeletal disorders (MSDs) to their knees due to spending a large amount of time kneeling while performing work-related roofing activities on sloped rooftops. Several ergonomic studies have identified kneeling as a potential risk factor for knee injuries and disorders. Existing biomechanical models and sensor technologies used to assess work-related risk factors for different construction trades are not applicable in roof work settings especially on slanted rooftop surfaces. This work assesses the impacts of work-related factors, namely working posture and roof slope, on the potential risk of developing knee MSDs due to residential roofing tasks in a laboratory setting. Nine human subjects participated in the experiment and mimicked shingle installation on a slope-configurable wooden platform. Maximum angles of right and left knee flexion, abduction, adduction, and axial rotation (internal and external) were measured as risk indicators using a motion capture system under different roof slope settings. The results demonstrated that roof slope, working posture and their interaction may have significant impacts on developing knee MSDs during roofing activities. Knees are likely to be exposed to increased risk of MSDs due to working in a dynamic kneeling posture during shingle installation. In our study, flexion in both knees and adduction in the right knee were found lower in high-pitched rooftops; however, abduction in the left knee and internal rotation in the right knee were found higher during shingle installation. Hence proper attention is needed for these situations. This study provides useful information about the impact of roof work settings on knee MSDs development, which may facilitate effective interventions such as education, training, and tools to prevent knee injuries in construction roofing tasks.

Differences in spinal moments, kinematics and pace during single-task and combined manual material handling jobs

This study compared the spinal moments (i.e., peak and cumulative moments acting on the L5/S1 joint), kinematics (i.e., peak trunk and knee angles) and work pace of workers, when either removing a box from a shelf or depositing a box on a shelf, under two conditions: as a single task or as part of a combined task. An experiment was conducted, in which the subjects performed the tasks and were recorded using a motion capture system. An automated program was developed to process the motion capture data. The results showed that, when the removing and depositing tasks were performed as part of a combined task (rather than as single tasks), subjects experienced smaller peak and cumulative spinal moments and they performed the tasks faster. The results suggest that investigations into the separate tasks that comprise a combination have a limited ability to predict kinematics and kinetics during the combined job.

Influence of Human Parameters on Labor Productivity in the Construction Industry

OBJECTIVE

The objective of this article is to investigate the influence of human parameters on qualitative assessment of labor productivity (LP) in the construction industry.

BACKGROUND

The theories involving workers have identified various parameters on physical efficiency, such as heart rate, relative heart rate, and calorie count, so as to improve the safety and social conditions of construction labor, thereby increasing LP. However, there is no direct emphasis on assessment of LP using human parameters related to physical strength.

METHOD

An exploratory study was conducted on 17 construction workers by observing their task-level LP in real time at a construction site. Human parameters, such as age, body mass index (BMI), handgrip strength, and upper body muscle strength of the laborers, were measured at the construction site. Performance levels of these workers were placed in three categories, and each worker was assigned a typical weightage to each category when correlated to physical strength.

RESULTS

Labor categories among the human parameters that included middle age, normal-range BMI, and strong muscular strength were shown as having higher LP than others. A quantitative parameter called the Human Parameter Index (HPI) was developed based on the performance categories developed for an individual worker. Human parameters revealed a significant relationship with respect to task-level LP.

CONCLUSION AND APPLICATION

The study determines the influence of human parameters on LP in construction. Introduction of human parameters in the construction industry will help in assessment of LP for various labor-intensive activities.

Indices of physiological strain for firefighters of the Australian Defence Forces

High levels of exertion and physiological strain are the leading cause of fireground injuries. The Physiological Strain Index (PSI) provides a rating of strain based on body core temperature and heart rate; however, it may underestimate the strain of workers in protective clothing as skin temperature may be elevated. This study aimed to examine the relationship between the PSI and an Adaptive Physiological Strain Index (aPSI) that incorporates skin temperature, among firefighters wearing protective clothing. Nine male firefighters of the Australian Defence Force volunteered to participate. Participants conducted scenario-based activities while wearing turnout gear and breathing apparatus. Working in teams of four, participants would respond to a situation around and within a small building with several rooms that could be filled with smoke, however, no live fire was present. Heart rate, gastrointestinal temperature, and skin temperature were monitored throughout work and rehabilitation. Physiological strain was estimated via the PSI and aPSI. Absolute peak PSI and aPSI ratings were significantly different during work (PSI: 7.3 ± 1.6; aPSI 8.2 ± 2.0; p < 0.001). The aPSI produced higher ratings of physiological strain, >0.5 above PSI, progressively from a moderate level of strain (>6). The aPSI may provide a more accurate indication of a level of "maximal strain" for encapsulated workers than the original PSI, coincident with the occupational limits for body core temperature of 38.0 °C for general occupational groups, or 38.5 °C for selected and acclimatised personnel.

Effects of cycling while typing on upper limb and performance characteristics

Active computer workstations may help reduce workplace sedentarism. However, their impact on the upper limb musculoskeletal system is unknown. Subjects participated in two 60-min computer laptop-based Bike-and-Type sessions at different cycling intensities (LOW, HIGH). Upper trapezius and wrist extensor muscle blood flow, sensitivity and pain thresholds, and typing performance were measured intermittently. Neck/shoulder discomfort increased over time (p < 0.001), and was higher in the HIGH intensity (p = 0.036). Blood flow to the trapezius (p = 0.041) and wrist (p = 0.021) muscles were higher during HIGH, and wrist blood flow increased over time (p = 0.01). Trapezius sensitivity threshold significantly decreased over time (p = 0.003). There were no effects on pressure pain thresholds (interaction p = 0.091). Average typing speed was greater during HIGH (p = 0.046) and increased over time (p < 0.001). Time spent biking while typing effectively improved performance, which may facilitate muscle regeneration, although effects depend on biking intensity.

RGB-D ergonomic assessment system of adopted working postures

Ensuring a healthier working environment is of utmost importance for companies and global health organizations. In manufacturing plants, the ergonomic assessment of adopted working postures is indispensable to avoid risk factors of work-related musculoskeletal disorders. This process receives high research interest and requires extracting plausible postural information as a preliminary step. This paper presents a semi-automated end-to-end ergonomic assessment system of adopted working postures. The proposed system analyzes the human posture holistically, does not rely on any attached markers, uses low cost depth technologies and leverages the state-of-the-art deep learning techniques. In particular, we train a deep convolutional neural network to analyze the articulated posture and predict body joint angles from a single depth image. The proposed method relies on learning from synthetic training images to allow simulating several physical tasks, different body shapes and rendering parameters and obtaining a highly generalizable model. The corresponding ground truth joint angles have been generated using a novel inverse kinematics modeling stage. We validated the proposed system in real environments and achieved a joint angle mean absolute error (MAE) of 3.19±1.57^∘ and a rapid upper limb assessment (RULA) grand score prediction accuracy of 89% with Kappa index of 0.71 which means substantial agreement with reference scores. This work facilities evaluating several ergonomic assessment metrics as it provides direct access to necessary postural information overcoming the need for computationally expensive post-processing operations.