Relationship between comfort and back posture and mobility in sitting-posture.

The objective of this work is to analyze the causes of lumbar discomfort while sitting on a chair, by analyzing the relationship of lumbar curvature, pelvic inclination and their mobilities with discomfort. An experiment has been performed with healthy subjects, in which comfort, postural and mobility parameters have been measured. Their relationship has been analyzed with multivariate analysis. Factorial analysis has been used to represent all the correlated variables measured. Logistic regression and discriminant analyses have been used to classify discomfort/absence of discomfort. The results show that great changes of posture are a good indicator of discomfort, and that lordotic postures with forward leaned pelvis and low mobility are the principal causes of the increase of discomfort.