A Biomechamical Approach for Assessment of Overload on Lumbar Spine: the Effects of Different Demographic Variables on Muscle Fatigue

INTRODUCTION Spinal pathologies constitute a major factor accountable for work withdrawal. More recent data from the National Institute of Social Security (INSS) show that, in 2003, 387,905 jobrelated accidents were reported, more than 20,341 of which have been associated to the spinal region, and approximately 50% of those accidents have been recorded on INSS files as pain in this body segment(1). In common, spinal diseases account for changes in its structure and function commonly associated to presence of pain predominantly at lumbar spine(2). On the other hand, the presence of lumbar pain with no association to other orthopaedic or rheumatic disorders has been increasingly described. Called non-specific lumbar pain, this symptom has been shown to be related to muscular function changes(3,4). Static and dynamic stability of the spine is responsible for A BIOMECHAMICAL APPROACH FOR ASSESSMENT OF OVERLOAD ON LUMBAR SPINE: THE EFFECTS OF DIFFERENT DEMOGRAPHIC VARIABLES ON MUSCLE FATIGUE