Aging effects on posture-related modulation of stretch reflex excitability in the ankle muscles in humans
Aging effects on posture-related modulation of stretch reflex excitability in the ankle muscles in humans
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DOI：
10.1016/j.jelekin.2011.10.009
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发表时间：
2012-02-01
影响因子：
2.5
通讯作者：
Nakazawa, Kimitaka
中科院分区：
文献类型：
--
作者：
Obata, Hiroki;Kawashima, Noritaka;Nakazawa, Kimitaka
本研究的目的是研究年龄对踝关节伸肌、比目鱼肌（SOL）和屈肌、胫前肌（TA）拉伸反射兴奋性的姿势相关变化的影响。14名神经正常的老年人（平均68 +/- 6岁）和12名年轻人（平均27 +/- 3岁）参与研究。在直立站立（STD）和坐姿（SIT）两种姿势条件下，施加快速的踝关节背/足底屈曲引起SOL/TA肌的拉伸反射肌电图（EMG）反应。SIT条件下，受试者保持与STD条件下相同的SOL背景肌电信号水平。在SOL肌中，两组在坐姿转变为STD时，短潜伏期拉伸反射（SLR）反应显著增强；在TA肌中，年轻组在坐姿转变为STD时，中潜伏期（MLR）和长潜伏期拉伸反射（LLR）反应显著增强；在老年组中没有观察到这种调节。由于年轻组和老年组在STD条件下的TA拉伸反射反应具有可比性，因此老年组TA肌缺乏姿势相关调节可能与SIT条件下拉伸反射兴奋性增强有关。目前的结果表明,(1)溶胶单反响应调制在年轻人和老年人的姿势改变时从坐到性病,(2)助教高钙和LLR反应没有调制在老年人改变姿势时从坐到性病,而每个响应相同的年轻人和老年人之间的性病,和(3)老化的影响姿势引起溶胶和TA肌肉牵张反射不同。(C) 2011 Elsevier Ltd.版权所有。
The purpose of this study was to examine the effects of aging on posture-related changes of the stretch reflex excitability in the ankle extensor, soleus (SOL), and flexor, tibialis anterior (TA) muscles. Fourteen neurologically normal elderly (mean 68 +/- 6 years) and 12 young (mean 27 +/- 3 years) subjects participated. Under two postural conditions, upright standing (STD) and sitting (SIT), stretch reflex electromyographic (EMG) responses in the SOL/TA muscle were elicited by imposing rapid ankle dorsi-/plantar-flexion. Under the SIT condition, subjects were asked to keep the SOL background EMG level, which is identical to that under the STD condition. In the SOL muscle, both groups showed significant enhancement of the short-latency stretch reflex (SLR) response when the posture changed from SIT to STD. In the TA muscle, the young group showed significant enhancement of the middle-(MLR) and long-latency stretch reflex (LLR) when the posture changed from SIT to STD; no such modulation was observed in the elderly group. Since the TA stretch reflex responses under the STD condition were comparable in the young and elderly groups, the lack of posture-related modulation of the TA muscle in the elderly group might be explained by augmented stretch reflex excitability under the SIT condition. The present results suggest that the (1) SOL SLR responses are modulated both in the young and elderly subjects when the posture is changed from SIT to STD, (2) TA MLR and LLR responses are not modulated in the elderly subjects when the posture is changed from SIT to STD, while each response is same between the young and elderly in STD, and (3) the effect of aging on the posture-related stretch reflex differs in the SOL and TA muscles. (C) 2011 Elsevier Ltd. All rights reserved.