Kato Tomohisa, Yamamoto Shin-ichiro, Miyoshi Tasuku, Nakazawa Kimitaka, Masani Kei, Nozaki Daichi
Faculty of Systems Engineering, Shibaura Institute of Technology, Saitama, Japan.
Departiment of Bio-Science and Engineering, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, Japan.
Gait Posture. 2014;40(1):107-12. doi: 10.1016/j.gaitpost.2014.03.006. Epub 2014 Mar 12.
Quiet standing posture in humans has often been modeled as a single inverted pendulum pivoting around the ankle joint. However, recent studies have suggested that anti-phase action between leg and trunk segments plays a significant role in stabilizing posture by reducing the acceleration of the center of mass (COM) of the body. The aim of this study is to test the hypothesis that anti-phase action is attenuated in the elderly compared to the young. The anterior-posterior movements of leg and trunk segments were measured using 4 laser displacement sensors from 22 healthy young subjects (age range, 20-35 years) and 38 healthy elderly subjects (age range, 57-80 years) standing quietly for 30s twice. To focus on the segmental action between trunk and legs, we applied constraints (i.e., wooden splints) on each segment. We found that the velocity and acceleration of the COM (standard deviation of the time series was evaluated) were significantly higher for the elderly subjects than for young subjects. The increase in the acceleration of the COM resulted not only from an increase in the angular acceleration of the segments but also from the reduction of their anti-phase relationship, as demonstrated by an index that quantifies the degree of cancelation between both segments. We conclude that the degree of anti-phase action between trunk and leg segments during quiet standing is smaller for elderly subjects than for young subjects, and that this change of the anti-phase action due to aging resulted in increased COM acceleration in the elderly subjects.
人类安静站立姿势通常被建模为围绕踝关节枢转的单摆。然而，最近的研究表明，腿部和躯干节段之间的反相作用通过降低身体重心（COM）的加速度在稳定姿势方面发挥着重要作用。本研究的目的是检验与年轻人相比老年人反相作用减弱的假设。使用4个激光位移传感器测量了22名健康年轻受试者（年龄范围20 - 35岁）和38名健康老年受试者（年龄范围57 - 80岁）安静站立30秒两次时腿部和躯干节段的前后运动。为了关注躯干和腿部之间的节段性作用，我们在每个节段上施加了约束（即木制夹板）。我们发现老年受试者的COM速度和加速度（通过评估时间序列的标准差）显著高于年轻受试者。COM加速度的增加不仅源于节段角加速度的增加，还源于它们反相关系的减弱，这通过量化两个节段之间抵消程度的指标得以证明。我们得出结论，老年受试者在安静站立时躯干和腿部节段之间的反相作用程度小于年轻受试者，并且这种由于衰老导致的反相作用变化导致老年受试者的COM加速度增加。
