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Evaluation of an intervention to reduce trunk flexion among stud workers.

Fethke-N; Grant-L
Silver Spring, MD: CPWR-The Center for Construction Research and Training, 2010 Feb; :1-29
Introduction. Low back pain continues to be an important occupational health problem among workers in the construction trades. Ironworkers engaged in welding shear stud connectors are exposed to prolonged, extreme trunk flexion, a risk factor for low back pain. We investigated the effect of an intervention system designed to reduce exposure to extreme trunk flexion among stud welders on measures of trunk inclination, muscle activity, and estimated spinal compression. Methods. Participants included 10 male, journeyman ironworkers experienced with stud welding techniques and presently employed in the St. Louis metropolitan area. Inclinometry and electromyography (EMG) were used to ascertain trunk posture and activity levels of the erector spinae and upper trapezius muscle groups. For each participant, data were collected for one-half of a work day while using traditional stud welding equipment and for the other half of the same work day while using the intervention system. Paired t-tests were used to compare summary measures related to trunk inclination angle and muscle activation levels between the traditional equipment and the intervention system. Results. The mean trunk inclination angle was reduced from 34.4 degrees (sd = 10.4 degrees) during use of the traditional equipment to 9.7 degrees (sd = 7.0 degrees) during use of the intervention system. The percentage of time with trunk inclination angles greater than 60 degrees was reduced from 40.0 percent (sd = 10.1 percent) during use of the traditional equipment to 4.7 percent (sd = 5.7 percent) during use of the intervention system. In general, use of the intervention system resulted in less desirable summary measures of upper trapezius muscle activity as compared to use of the traditional equipment. Conclusions. The intervention system appears to be effective in reducing exposure to prolonged, extreme trunk flexion among stud welders. Continued development of the system should explore features designed to reduce shoulder forces and improve productivity. Future research efforts should focus on increasing the sample size and including construction site type (i.e., bridge versus building) as an independent variable. In addition, the intervention system should be evaluated for the potential to reduce exposure to welding fume among stud welders.
Construction; Construction-equipment; Construction-industry; Construction-workers; Musculoskeletal-system; Back-injuries; Iron-workers; Biomechanics; Ergonomics; Human-factors-engineering; Welders; Welding-equipment; Men; Muscle-function; Spinal-cord; Electrophysiological-measurements; Posture; Measurement-equipment; Equipment-design; Exposure-assessment; Body-mechanics
The Center for Construction Research and Training (CPWR), 8484 Georgia Avenue, Suite 1000, Silver Spring, MD 20910
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Book or book chapter
Funding Type
Construction; Cooperative Agreement
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Source Name
Evaluation of an Intervention to Reduce Trunk Flexion among Stud Workers
Performing Organization
CPWR-The Center for Construction Research and Training, Silver Spring, Maryland