Laurel Kincl

Postural Sway Measurements: A Potential Safety Monitoring Technique for Workers Wearing Personal Protective Equipment

This study investigated the use of postural sway measurements as a potential safety monitoring technique. Sixteen healthy male volunteers (age: 41.8+/-9.3 years) participated in this study. The level of neurophysiological strain and the ability to maintain upright balance for workers wearing personal protective equipment (PPE) were investigated. Three levels of PPE, the United States Environmental Protection Agency (USEPA)-defined levels A, B, and C, were worn in random order while performing two randomly ordered tasks, resting and a workload. After the workload task, the perceived exertion and discomfort were recorded. Postural sway, measured using a microprocessor-based force platform system, was assessed after each task. The variables of sway area and sway length were calculated from stabilograms. These measurements were taken for three sway tests: 1) Eyes open (EO), 2) Eyes closed on a four-inch foam (FC), and 3) a dynamic test with the subject reaching for a weight placed in front, lifting it to his or her chest, and lowering back to the shelf four times (RE). The heart rate was significantly higher for the workload task (p < 0.05), and the levels A and B PPE demonstrated significantly higher perceived exertion results than level C PPE (p < 0.05). The heart rate and perceived exertion were not significantly correlated with the sway measurements. Level A produced significant self-reported discomfort results for the upper back, lower back, and thighs. The sway variables showed significant differences with the PPE levels and the task. The workload task produced significantly higher sway length than the resting task (p < 0.05) for all test conditions. The PPE level B produced significantly higher sway length than PPE level A (p < 0.05) in the FC test condition. These results indicate that postural stability is altered with PPE use and with fatigued postural muscles. In summary, postural sway measurements may be used as a potential safety monitoring technique.

The impact of drywall handling tools on the low back.

Carpenters and other construction workers who install drywall have high rates of strains and sprains to the low back and shoulder. Drywall is heavy and awkward to handle resulting in increased risk of injury. The purpose of this study was to evaluate several low-cost coupling tools that have the potential to reduce awkward postures in drywall installers. Five coupling tools were evaluated using the Lumbar Motion Monitor that measures trunk kinematics and predicts probability of low back disorder group membership risk (LBD risk). Workers answered surveys about their comfort while using each tool. The results indicate that use of the 2-person manual lift and the J-handle provide the best reduction in awkward postures, motions, low back sagittal moment, and LBD risk. The two-person manual lift appears to be the safest method of lifting and moving drywall, though using the two-person J-handle also significantly reduces injury risk. Given that carpenters are skeptical about using equipment that can get in the way or get lost, a practical recommendation is promotion of two-person manual lifting. For single-person lifts, the Old Man tool is a viable option to decrease risk of MSDs.

Workday Arm Elevation Exposure: A Comparison Between Two Professions

OCCUPATIONAL APPLICATIONS Results from this study indicate that dental hygienists spent a mean of 7% of their workday with their arms elevated above 60° of humeral elevation. The majority of their workday (71%) was spent working with their arms in static positions. Compared to a separate working population (office workers), dental hygienists had more than two times greater arm elevation exposure above 60°. Dental hygienists have a high incidence of shoulder injuries, which may be related to arm elevation exposure. Based on the present study, ergonomic interventions should be based on reducing the total arm elevation exposure in dental hygiene. Further, interventions should be designed to reduce the repetitive tasks performed by dental hygienists. TECHNICAL ABSTRACT Background: The prevalence of shoulder-related musculoskeletal disorders among dental hygienists working in the United States has been reported to be between 21% and 60%. Arm elevation exposure levels above 60° have been identified as potentially harmful in other occupations. Purpose: The aim of this study was to measure arm elevation exposure in dental hygienists in a single workday and to compare these data with those from another occupation with a lower risk for shoulder impingement syndrome. Methods: Bilateral, full workday arm elevation exposure was measured for both dental hygienists and computer workers using a tri-axial accelerometer with a built in data logger (Virtual Corset®, Microstrain, Inc., VT, USA). Exposures analyzed were the percent of the workday spent above 30°, 60°, and 90° of humeral elevation. Additionally, exposure to repetitive motion, or jerk, was estimated, specifically the percent time spent moving the arm in pseudo-static (<10°/s) slow humeral motion (between 10°/s and 40°/s) and fast humeral motion (>40°/s). Results: Dental hygienists had bilateral arm elevations above 60° for approximately 7% of their workday, more than two times the exposure of office workers for the same duration of work. Dental hygienists had a mean of 71% of their work time in pseudo-static postures, which is significantly less than computer workers (78%). Dental hygienists had slow and fast arm motion during 23% and 6% of their workday, respectively, significantly higher than those for computer workers (17% and 5%). Conclusions: Arm elevation exposure levels among dental hygienists are relatively high and may contribute to upper extremity injuries within this profession. In dental hygiene work, elevation exposure above 60° and dynamic arm motions above 10°/s may be specific contributors to the risk of upper extremity disorders bilaterally.