Goldish G D, Quast J E, Blow J J, Kuskowski M A
Department of Physical Medicine and Rehabilitation, Veterans Administration Medical Center, Minneapolis, MN 55417.
Arch Phys Med Rehabil. 1994 Mar;75(3):324-7. doi: 10.1016/0003-9993(94)90037-x.
When lifting heavy loads, trunk muscle contraction converts the abdominal and thoracic cavities into a nearly rigid-walled cylinder that provides increased extrinsic stability and allows partial transfer of load away from the spine. Because twisting is a common mechanism of low-back injuries, this study was undertaken to determine if trunk rotation results in a decrease in the extrinsic stability of the spine. We studied the effects of changes in trunk posture on intra-abdominal pressure generated during a maximum effort Valsalva's maneuver (IAP max) in eight healthy volunteers. IAP max during standing combined with trunk rotation was found to be significantly lower than IAP max during standing straight (p < 0.05). IAP max during forward flexion combined with trunk rotation was significantly lower than during forward flexion (p < 0.01). The results of our study indicate that trunk rotation adversely effects the ability to perform a Valsalva's maneuver. We conclude that extrinsic stability of the spine is at a biomechanical disadvantage when the trunk is rotated and thus may be a contributing factor to twisting-type back injuries.
在搬运重物时，躯干肌肉收缩会将腹腔和胸腔转变为一个近乎刚性壁的圆柱体，这可提供更高的外在稳定性，并使部分负荷从脊柱转移。由于扭转是下背部损伤的常见机制，因此进行本研究以确定躯干旋转是否会导致脊柱外在稳定性降低。我们研究了八名健康志愿者在最大用力瓦尔萨尔瓦动作（最大腹内压）过程中，躯干姿势变化对所产生的腹内压的影响。发现站立并伴有躯干旋转时的最大腹内压显著低于直立站立时的最大腹内压（p < 0.05）。前屈并伴有躯干旋转时的最大腹内压显著低于单纯前屈时的最大腹内压（p < 0.01）。我们的研究结果表明，躯干旋转对进行瓦尔萨尔瓦动作的能力有不利影响。我们得出结论，当躯干旋转时，脊柱的外在稳定性处于生物力学劣势，因此可能是扭转型背部损伤的一个促成因素。
