Abstract
Objectives. Electrogoniometers are used to collect continuous information on postural distributions among workers. Enormous quantities of data are generated that have to be reduced to meaningful parameters: angle, duration and frequency. This study 1) shows the patterns of lumbar movements among nurses and office workers; and 2) investigates whether the patterns are associated with back problems.
Methods. A direct registration of the lumbar posture in the sagittal plane was made during a working day with an inclinometer. An exposure variation analysis (Mathiassen and Winkel, 1991) was used to summarize information on angle, duration and percentage of working time in a data matrix. A statistical model which takes exposure level, duration, and frequency into account simultaneously was used to analyze these data matrixes and compare exposure patterns between nurses and office workers and between workers with back problems and those without.
Results. Nurses spent a higher percentage of their working time in lumbar postures with angles between 40–70 degrees (p<0.03) than office workers. The percentage of the working time spent in a given lumbar posture for periods of 5 seconds or more is less among nurses than among office workers (p<0.01). Among both nurses and office workers, subjects with back problems in the previous 12 months spent less working time in postures sustained for 10 seconds or more in comparison with those without back problems.
Conclusion. The exposure patterns of lumbar posture of nurses and office workers discriminated best for working time in trunk flexion over 40 degrees. This implies that observations of flexion at 20 degrees were irrelevant. Furthermore, nurses show a more dynamic exposure pattern than office workers. The findings with respect to back problems indicate that back problems may interfere with posture during work.