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. Relevance The device may help to investigate the relationship between lumbar pain and curvature, and to evaluate the lumbar curvature in sedentary work.