The Effect of External Load and Trunk Posture on Lumbar Lordosis Inclination under Static Condition

Background:Epidemiological studies have shown that low back pain after load-carrying is an important and costly disorder in muscolo-skeletal system. Lumbar curvature is an important factor in posture and body movement that may assist us to evaluate how low back pain problems may develop. Differences in lumbar inclination affect the vertebral stresses. The object of this study was evaluation of the affects of external load and trunk posture on lumbar curvature under static condition.Materials and Methods:Ten healthy female subjects with no history of low back pain were participated in this study. Two inclinometers were used to evaluate the lumbar inclination. Six static tasks while holding three levels of load (0, 6, 12 Kg) and two levels of trunk position (neutral and 30 degree of flexion) were simulated for subjects.Results:Trunk position (30 degree of flexion) and external load (6, 12 Kg) both had significant effects on lumbar inclination and reduce lumbar lordosis (p < 0.05).Conclusion:Lumbar lordosis reduced while holding load, so muscles activity and may reduce tissue injuries reduced. Increased lumbar kyphosis shown resulted in trunk flexion is a lumbar supportive factor for compressive stresses.Key words: Lumbar lordosis, load, trunk posture, static activity