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首页> 外文期刊>Gait & posture >Aging effects on postural responses to self-imposed balance perturbations.
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Aging effects on postural responses to self-imposed balance perturbations.

机译：衰老对姿势对自我施加的平衡扰动的反应的影响。

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摘要

The present study investigated how young and older individuals organize their posture in response to self-induced balance perturbations evoked by oscillatory single limb movements. Eleven old (70.1+/-4.3 years) and nine young (20.1+/-2.4 years) participants performed repeatedly for 5s hip flexion/extension movements using full range of motion and maximum velocity. Two-dimensional joint kinematics (sampling rate: 60Hz), center of pressure (CoP) and EMG activity of tibialis anterior (TA), medial gastrocnemius (MGAS) rectus femoris (RF) and, semitendinosus (ST) in the stance limb were recorded and analysed. Cross-correlation function (CCF) analysis was used to identify the degree of coupling between the swinging limb (SL), center of gravity (CoG) and CoP motions. Old adults significantly limited SL, CoG and CoP range of anterior/posterior (A/P) motion in response to the forceful leg swinging. In the stance limb, significantly lower levels of ankle muscle activity resulted in reduced hip and knee joint excursions and increased ankle instability. By contrast, young performers produced sufficient ankle muscle activity to stabilize the foot to the ground while progressively increasing joint range of motion from the ankle to the hip. Center of pressure and SL movements were strongly correlated in an anti-phase relationship in both age groups. In older adults, however, the relationship between CoG-SL and CoG-CoP movements was neither strong nor synchronous, reflecting a weaker coupling and lack of coordination between component movements. It is concluded that insufficient ankle muscle activity, central integration deficits and increased anxiety to postural threat are important factors implicated for the weaker postural synergies and freezing of degrees of freedom seen in the elderly during performance of single limb oscillations.
机译：本研究调查了年轻人和老年人如何响应摆动的单肢运动引起的自我诱导的平衡扰动来组织其姿势。 11名年龄（70.1 +/- 4.3岁）和9名年轻（20.1 +/- 2.4岁）的参与者反复进行了5s髋屈曲/伸展运动，并使用了最大范围的运动范围和最大速度。记录二维关节运动学（采样率：60Hz），胫骨前（TA），腓肠肌内侧（MGAS），股直肌（RF）和半腱肌（S​​T）的压力中心（CoP）和EMG活动并进行分析。使用互相关函数（CCF）分析来确定摆动肢体（SL），重心（CoG）和CoP运动之间的耦合程度。老年人因有力的腿部摆动而明显限制前/后（A / P）运动的SL，CoG和CoP范围。在站姿肢体中，踝部肌肉活动水平明显降低，导致髋和膝关节偏移减少，踝部不稳定性增加。相比之下，年轻的表演者产生了足够的踝部肌肉活动，以使脚稳定到地面，同时逐渐增加了从脚踝到臀部的关节活动范围。在两个年龄组中，压力中心和SL运动呈反相关关系。然而，在老年人中，CoG-SL和CoG-CoP运动之间的关系既不牢固也不同步，这反映了组件运动之间的耦合较弱且缺乏协调。结论是，踝关节肌肉活动不足，中枢神经系统整合缺陷和对姿势威胁的焦虑增加是与老年人在单肢摆动过程中看到的较弱的姿势协同作用和自由度冻结有关的重要因素。

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