Relevance of adding a triangular dynamic cushion on a traditional chair: A 3D-analysis of seated schoolchildren.

Abstract

Low back pain is highly prevalent in the general population and is even reported as early as at primary school. A poor sitting position has been suggested as an etiologic factor. This study analysed, in primary schoolchildren, the influence of a triangular dynamic cushion that aims to help children maintain their physiological lumbar lordosis and to induce movement to reduce the static effect of the sitting position. Thirty 8-year-old children took part in this study. A 3D analysis combined with electromyography was used to evaluate the biomechanics and the related muscle activation in two sitting positions (with and without a triangular cushion on a horizontal stool) during a 15-minute working task. In addition, the force of the feet on the ground was assessed with a force plate. The cushion improved the trunk-thighs angle, lumbar lordosis, anterior pelvis tilt, and feet support on the ground (p<0.0001). In addition, sitting on the cushion appeared to be more dynamic (p<0.05) and induced a decrease of the lumbar paravertebral muscle activity (p<0.01). Sitting on a dynamic triangular cushion tends to favour the "ideal" siting position usually described in the literature and to decrease the level of paravertebral muscle recruitment. Seeing that sitting position is a risk factor to develop low back pain, the cushion could be a solution to prevent it.