Physical activity modulates corticospinal excitability of the lower limb in young and old adults
Physical activity modulates corticospinal excitability of the lower limb in young and old adults
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DOI：
10.1152/japplphysiol.01078.2016
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发表时间：
2017-08-01
影响因子：
3.3
通讯作者：
Hunter, Sandra K.
中科院分区：
文献类型：
--
作者：
Hassanlouei, Hamidollah;Sundberg, Christopher W.;Hunter, Sandra K.
衰老与神经肌肉功能下降有关，这可能部分归因于皮质脊髓兴奋性的改变。规律的体力活动 (PA) 可能会改善这些与年龄相关的衰退，但 PA 对皮质脊髓兴奋性的影响尚不清楚。本研究的目的是通过比较 28 名不同活动水平的年轻人（22.4 +/- 2.2 岁；14 名女性和 14 名男性）和 50 名老年人（70.2 +/- 6.1 岁；22 名女性和 28 名男性）的运动诱发电位 (MEP) 刺激反应曲线，确定年龄、性别和 PA 对皮质脊髓兴奋性的影响。使用经颅磁刺激在活跃的股外侧肌（10%最大自主收缩）中引发 MEP，刺激器强度增加 5%，直至达到最大 MEP 幅度。 MEP 振幅的刺激-响应曲线与四参数 S 形曲线拟合并计算最大斜率 (slope(max))。使用三轴加速度计对习惯性 PA 进行评估，并将参与者分为符合建议的 PA 最佳健康益处指南（> 10,000 步/天，高 PA；n = 21）或不符合指南的参与者（0.05），这表明习惯性 PA 对投射到下肢的皮质脊髓束的兴奋性的影响在年轻人和老年人中相似。这些发现提供的证据表明，达到推荐的 PA 指南以获得最佳健康可能会通过降低皮质脊髓兴奋性来调节其对神经系统的影响。新的和值得注意的经颅磁刺激用于确定达到推荐的最佳健康每天 10,000 步是否会影响投射到膝伸肌的皮质脊髓束的兴奋性。无论年龄和性别如何，每天行走超过 10,000 步的人的皮质脊髓兴奋性低于每天行走 10,000 步的人，这可能是通过降低皮质脊髓兴奋性来调节其对神经系统的影响。
Aging is associated with reduced neuromuscular function, which may be due in part to altered corticospinal excitability. Regular physical activity (PA) may ameliorate these age-related declines, but the influence of PA on corticospinal excitability is unknown. The purpose of this study was to determine the influence of age, sex, and PA on corticospinal excitability by comparing the stimulus-response curves of motor evoked potentials (MEP) in 28 young (22.4 +/- 2.2 yr; 14 women and 14 men) and 50 old adults (70.2 +/- 6.1 yr; 22 women and 28 men) who varied in activity levels. Transcranial magnetic stimulation was used to elicit MEPs in the active vastus lateralis muscle (10% maximal voluntary contraction) with 5% increments in stimulator intensity until the maximum MEP amplitude. Stimulus-response curves of MEP amplitudes were fit with a four-parameter sigmoidal curve and the maximal slope calculated (slope(max)). Habitual PA was assessed with tri-axial accelerometry and participants categorized into either those meeting the recommended PA guidelines for optimal health benefits (> 10,000 steps/day, high-PA; n = 21) or those not meeting the guidelines ( 0.05), suggesting that habitual PA influenced the excitability of the corticospinal tract projecting to the lower limb similarly in both young and old adults. These findings provide evidence that achieving the recommended PA guidelines for optimal health may mediate its effects on the nervous system by decreasing corticospinal excitability.NEW & NOTEWORTHY Transcranial magnetic stimulation was used to determine whether achieving the recommended 10,000 steps/ day for optimal health influenced the excitability of the corticospinal tract projecting to the knee extensor muscles. Irrespective of age and sex, individuals who achieved >10,000 steps/day had lower corticospinal excitability than those who performed 10,000 steps/day may mediate its effects on the nervous system by decreasing corticospinal excitability.