Validation of a fibre-optic goniometer system to investigate the relationship between sedentary work and low back pain

To date, sedentary occupational (biomechanical) risk factors for low back pain have not been measured using sufficiently precise tools, partly due to technological limitations. The purpose of this study was to validate a new fibre-optic goniometer (FOG) system designed to identify sedentary work activities and measure their lumbar postural characteristics. The system was first validated using data from simulated work activities; 10 student subjects wore the FOG system on their hip and lumbar spine for 8 min whilst alternating between sitting, standing and walking. The behaviour of all subjects was simultaneously recorded on a video camera, and Observer Software® was used to time-code the activities, enabling second by second comparison with the FOG record. High minimum sensitivity (Smin) and predictive values (PV) were evident for the detection of sitting (99% and 98%), standing (97% and 95%), and walking (94% and 96%). Five sedentary workers then wore the FOG system (whilst being recorded on video camera) for 4 h each during a normal working shift, and the system was re-validated against the Observer record. Smin and PV were similar for sitting (99% and 99%), but reduced for standing (96% and 91%), and walking (89% and 94%). For simulated and actual work the FOG system accurately reported lumbar postural characteristics for each activity (mean position, mean angular velocity, standard deviation). The occurrence (K=1) and duration of seated (lordotic/kyphotic) lumbar postures were also correctly identified. The FOG system can accurately measure exposure to sedentary work activities and certain biomechanical factors.Relevance to industryThe relationship between sedentary work and low back pain is unclear. This study validates a dynamic new system that could be worn by sedentary workers throughout the day to investigate biomechanical risk factors for low back pain in sedentary work environments.