Occupational Ergonomics

The aim of the study was to investigate musculoskeletal symptoms among tea pluckers in India using standardized Nordic questionnaire. They were interviewed individually for symptoms in the neck, shoulders, elbows, wrists/hands, upper back, lower back, hips/thighs/buttocks, knees and ankles/feet. Among 500 tea pluckers recruited for the study, 463 were females and 37 were males. Symptoms were most commonly reported at the shoulders (71.8%) followed by the neck (66.4%), upper back (65.6%), wrists/hands (50.4%), lower back (47.2%), elbows (39.4%), knees (10.0%), hips/thighs/buttocks (5.4%) and ankles/feet (2.6%). Because of musculoskeletal symptoms on any one or more body regions, at least once in their working life, 36.2% of the subjects sought professional treatment, but none of the tea pluckers were hospitalized. Due to musculoskeletal symptom in the neck, the maximum number of subjects (7.6%) was prevented from doing their normal work. Females were more likely to display musculoskeletal symptoms than males. Subjects with body mass index (BMI) < 18.5 kg/m² were more likely to develop musculoskeletal symptoms than subjects with BMI > 18.5 kg/mm². Musculoskeletal symptoms may be reduced by implementing ergonomic interventions like, reduction of load carriage, improved work organization with job rotations and sufficient rest during work to the tea pluckers.

The purpose of this study was to determine if office workers were capable of using an online version of the Rapid Office Strain Assessment (ROSA) tool to accurately assess musculoskeletal disorder risk factors in their own offices, and see if online training can reduce worker-reported discomfort. Fifty-five participants completed a four week program where they assessed their own office simultaneously with a trained observer, and either received or did not receive feedback on their performance. Significant differences were found between worker- and observer-reported ROSA final scores, and for the mouse and keyboard section, with workers underestimating these risk factors on average, compared to the trained observer. Worker and observer assessments of the chair, monitor and telephone were not significantly different but were significantly correlated (R values of 0.60 and 0.48). There were a greater number of significant correlations between worker-reported ROSA final scores and total body discomfort (3 instances) compared to observer-reported relationships (1 instance). Feedback appeared to have a detrimental effect on worker-assessment accuracy, and the relationship between discomfort and ROSA scores. Mean discomfort decreased across the four weeks of the study (up to a 51.6% decrease), as did ROSA final scores (3.9 to 3.5). Additional work is required to improve the validity of worker-reported scores in all sections of ROSA, but self-assessments of office workstations using the current ROSA online application do show promise in terms of assisting workers to decrease risk factors related to musculoskeletal disorders, and decrease discomfort levels.

The purpose of this study was to examine the biomechanical demands associated with MMH performed in moving environments. Twelve healthy male subjects performed four different lifting tasks (referred to as 10U, 15U, Close25 and Far25) while exposed to a simulated ship motion profile. Dependent measures included electromyographic (EMG) signals from several trunk muscles and thoracolumbar motions collected via a Lumbar Motion Monitor (LMM). A repeated measures ANOVA was employed to examine the differences between thoracolumbar velocities and trunk EMG activities between successful lifts and lifts during which a motion induced interruption (MII) was identified. The maximum EMG signals increased as MII events occurred for the left and right erector spinae and external obliques. The 10U lifting task significantly differed from both the Close25 and Far25 lifting tasks in the maximum left trapezius and the 10U lifting task differed from all other lifting tasks for the maximum right trapezius activities. There were increases in the maximum thoracolumbar velocities in the lateral bending and twisting planes for lifts incurring a MII across all lifting conditions when comparing successful lifts. These data suggest that performing tasks in moving environments will place an operator at an increased risk for musculoskeletal injuries, particularly when the rate of MII is high.

In most genuine industrial settings, it is not yet feasible to directly measure in vivo tissue loads, nor is it practical to estimate dynamic load-time histories using biomechanical models. Thus, data extrapolation techniques are often used for obtaining occupational estimates of shift or daily cumulative low-back load exposures. These techniques are reliant on the assumption that the observed duty cycle of apparently stereotypical work is consistent over long working durations. This investigation evaluated the validity of this assumption using a controlled laboratory-based repetitive lifting task. Nine men performed 30-minutes of sagittal plane repetitive lifting tasks. Upper body kinematics were captured during the tasks, and a two-dimensional dynamic biomechanical model was used to generate peak and cumulative estimates of low-back loads. Over the course of the 30-minute testing sessions, kinematic adaptations at the elbow were responsible for an 8% reduction in duty cycle duration while peak low-back load magnitudes remained consistent. Combining reductions in duty cycle duration with negligible changes in peak loading contributed to a small decrease (≪ 10%) in cumulative low-back load over the final 20-minutes of lifting. However, when data extrapolation was incorporated to estimate a shift exposure it was found that these changes could overestimate occupational cumulative low-back loading exposures by 10–27% inferences made regarding the risk of low-back pain or injury reporting associated with exposure.

The purpose of this study was to measure operator exposure to whole-body vibration (WBV) and to determine health risks associated with the operation of heavy-lift transporters (HLT; n=2), pot haulers (n=3), hoists (n=4) and loaders (n=2) used within the steel manufacturing industry. Anecdotal evidence suggested operators of the above equipment were suffering from vibration-induced injury; however, typical exposure data was not available in the literature. A tri-axial seat-pad accelerometer was used to measure vibration at the operator/seat interface. Health risk to operators was determined based on criteria established in the ISO 2631-1 standard. The calculated 8-hour daily equivalent vibration dose value placed all pot haulers and one HLT, one hoist and one loader above the health guidance caution zone (HGCZ). Therefore, interventions aimed at reducing vibration exposure below the ISO 2631-1 HGCZ should be implemented. Caution must be applied when generalizing exposure data to other industries; however, exposure data reported in this study does represent the first published data for pot-haulers and HLTs in steel production.