A Finite Element Model Study on the Role of Trunk Muscles in Generating Intra-Abdominal Pressure

The significant economic costs and human suffering due to work related low-back disorders have motivated many scientists from diverse disciplines to search for mechanisms of injury and the associated risk factors.Prevention strategies are predicated on the premise that risk factors can be identified, controlled or eliminated by appropriately designed interventions.The nature of spinal loading (in terms of its magnitude, direction , repetition and duration) has been associated with the development and aggravation of work-related low back disorders (19)(20)(21)(22)(26)(27)(28)33,34,36,38).Hence , the spine has been the focus of many biomechanical evaluations on how external loads are carried and shared by the trunk muscles and osteoligamentous spine .Historically, the limitations in modeling of spinal musculature have led the investigators to search for auxiliary mechanisms assisting the extensor muscles in satisfying the equilibrium conditions (1,3,8,13,18,(26)(27)(28)30).The detailed description of these theories and their biomechanical evaluations (testing the validity of claims regarding the unloading function of the intra-abdominal pressure and utilization of lumbodorsal fascia) can be found in a recent review by McGill and Norman (28).It is now recognized that the stability and equilibrium conditions of spine must be simultaneously insured by proper neuromuscular functions of various components of spine (1,4,7,8,12,15,17,330,(33)(34)(35)(36)40).