Li Xiaoyan, Aruin Alexander S
Departments of Physical Therapy and Bioengineering, University of Illinois at Chicago, Chicago, IL 60612, USA.
Exp Brain Res. 2007 Aug;181(2):333-46. doi: 10.1007/s00221-007-0931-2. Epub 2007 Apr 12.
The purpose of the study was to investigate whether anticipatory postural adjustments (APAs) are modified with short-term changes in the body mass. Nine subjects were asked to catch a 2.2 kg load with their arms extended under conditions of no weight and when additional weights of 10 and 20% of the subject's body weight (BW) were attached to single body locations or when 20 or 40% BW were attached evenly to two locations. Attaching weights was associated with an increase of the whole body mass, but also involved changes in the vertical position of the center of mass (COM). Electromyographic activity of leg and trunk muscles and ground reaction forces were recorded and quantified within the typical time intervals of APAs. APAs were influenced by the magnitude of the weight attached to the body: an increase in the body mass was associated with anticipatory co-activation of trunk and leg muscles. The level of this co-activation increased with an increase in the magnitude of weight added to the body. At the same time, APAs were affected by the changes in the vertical position of COM. These findings suggest that in the case of short-term changes in the body mass, the CNS might prioritize information regarding the magnitude and location of the additional weight added to the body and utilize a strategy of anticipatory co-activation of postural muscles directed at the stabilization of body segments.
本研究的目的是调查预期姿势调整（APAs）是否会随着体重的短期变化而改变。九名受试者被要求在无负重以及在受试者体重（BW）的10%和20%的额外重量分别附着于身体单个部位，或者20%或40% BW均匀附着于两个部位的条件下，伸展手臂接住一个2.2千克的重物。附着重量会使全身质量增加，但也会使质心（COM）的垂直位置发生变化。在APAs的典型时间间隔内记录并量化腿部和躯干肌肉的肌电活动以及地面反作用力。APAs受到附着于身体的重量大小的影响：体重增加与躯干和腿部肌肉的预期共同激活有关。这种共同激活的程度随着添加到身体上的重量大小的增加而增加。同时，APAs受到COM垂直位置变化的影响。这些发现表明，在体重发生短期变化的情况下，中枢神经系统可能会优先处理有关添加到身体上的额外重量的大小和位置的信息，并采用一种预期姿势肌肉共同激活的策略，旨在稳定身体各部位。
