Validity study of fixed-interval observations for the assessment of body postures during construction work

Categories of body posture recorded with two observational methods were compared to measurements obtained with an electronic postural assessment system and video analysis during simulated construction tasks. The electronic postural assessment system consisted of electronic inclinometers to measure upper arm posture, knee flexion and trunk flexion, coveralls to house the inclinometer wiring, and an electrogoniometric system to measure trunk lateral bending and torsion. Video analysis included frozen-frame analysis that corresponded to the moment of observation and simulated real-time analysis. Measurements were made on five male participants who performed three of six simulated construction tasks. Overall, agreement among the observational and reference methods was high, although significant differences among the methods were found in the measured frequency of some leg and trunk postures, particularly for knee flexion, trunk lateral bending and trunk torsion. These results suggest that discrete observations can be used to obtain accurate estimates of exposure frequency for arm postures at or above shoulder height, kneeling, climbing and gross categories of trunk flexion.