Technique to measure lumbar curvature in the ergonomic evaluation of chairs: description and validation

Objective. To describe and validate a system to record the lumbar curvature, specially designed for the ergonomic evaluation of chairs. Design. The technique consists of a flexible goniometer and requires a model of lumbar flexion (relationship between length and angle). Background. Most of the techniques do not allow using the backrest of the chair or do not record continuously. Methods. Precision, repeatability and reproducibility of the measurements have been analysed, as well as the lumbar flexion model. Results. A suitable lumbar model of flexion and the repeatability and reproducibility errors obtained are presented. Conclusions. The linear model is a good one to represent the flexion of the lumbar spine. The measurements are reproducible and the errors are similar or lower than with conventional inclinometers.