Snijders C J, Ribbers M T, de Bakker H V, Stoeckart R, Stam H J
Department of Biomedical Physics, Faculty of Medicine and Allied Health Sciences, Erasmus University Rotterdam, The Netherlands.
J Electromyogr Kinesiol. 1998 Aug;8(4):205-14. doi: 10.1016/s1050-6411(98)00005-4.
In a biomechanical model we described that for stability of the flat sacroiliac joints (SIJ) muscle forces are required which press the sacrum between the two hip bones (self-bracing). Shear loading of these joints is caused by gravity and longitudinally oriented muscles. Protection against shearing can come from transversely oriented muscles like the internal oblique (OI) abdominal muscles. For validation we used standing postures with significantly more or less OI activity compared to activity in a standardized erect standing reference posture. OI activity decreased significantly when (a) resting on one leg (the contralateral), as can be observed at bus stops, (b) tilting the pelvic backward and (c) applying a pelvic belt. We explain this decrease of OI activity by, respectively, decrease of gravity load, decrease of load from the psoas major muscles, and a substitute of self-bracing. The outcome of this study is in line with the biomechanical model on SIJ stability. Clinical relevance of this study regards aspecific low back pain and is found in the effect of the use of a pelvic belt, of a trunk position as adopted when wearing a small rucksack and of the benefit of exercising trunk muscles in extension and torsion.
在一个生物力学模型中，我们描述了为使扁平的骶髂关节（SIJ）保持稳定，需要肌肉力量将骶骨挤压在两块髋骨之间（自我支撑）。这些关节的剪切负荷由重力和纵向肌肉引起。防止剪切力可来自横向肌肉，如腹内斜肌（OI）。为进行验证，我们采用了与标准化直立站立参考姿势相比，OI活动明显更多或更少的站立姿势。当（a）单腿（对侧）休息时，如在公交站观察到的那样，（b）骨盆向后倾斜，以及（c）使用骨盆带时，OI活动显著降低。我们分别通过重力负荷的降低、腰大肌负荷的降低以及自我支撑的替代来解释OI活动的这种降低。本研究结果与关于SIJ稳定性的生物力学模型一致。本研究的临床意义涉及非特异性下腰痛，可在使用骨盆带的效果、背小背包时所采用的躯干位置以及锻炼躯干伸展和扭转肌肉的益处中发现。
