Low back pain is a major public health problem in European Countries. In France, about 50% of population is suffering of this pathology every year [Fassier, 2011]. Because of health care cost and sick leave [Fassier, 2011], [Leclerc, 2009], low back pain as both societal and economic adverse consequences. Concerning medical devices, such as lumbar belts, several clinical trials have shown their efficiency [Calmels, 1999]. It might be essential to know which parameters are important so as to increase the efficiency of their medical effects on patients. Nevertheless, both mechanical and physiological effects of lumbar belts remain unclear. In this study, a parametrical method is used in order to identify which parameters are more important than others through numerical simulation. This study is indispensable to design lumbar belts.