Age-associated changes in motor unit physiology: observations from the Baltimore Longitudinal Study of Aging.
Age-associated changes in motor unit physiology: observations from the Baltimore Longitudinal Study of Aging.
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DOI：
10.1016/j.apmr.2008.09.565
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发表时间：
2009-07
影响因子：
4.3
通讯作者：
Metter EJ
中科院分区：
文献类型：
--
作者：
Ling SM;Conwit RA;Ferrucci L;Metter EJ
检查与老化相关的运动单位特征(大小和发电率)。横截面，观察性的。社区。对102名年龄在22.2-94.1岁的老年人进行了巴尔的摩纵向研究。不适用。每个受试者在伸膝时最大等长自主收缩(MVC)的10%、20%、30%和50%时，从股内侧肌收集表面代表的运动单位大小和放电率。MVC随年龄增长而下降(P<；.0001)。对MVC的差异进行了调整，在生命的第六个十年，发射速度和每牛顿力产生的电机单元大小都开始增加。每牛顿力的马达单位尺寸的增加幅度大于点火速度。75岁以上的人也激活了明显更大的单位力量运动单位(P=0.04)。相对于所产生的力量，运动单位大小的平均射击率在57.8±3.4岁和50.2-56.4岁(±4岁)之间开始增加。运动单位的大小和射击率随着年龄的增长而变化，特别是在中年之后。这些变化是否发生在与年龄相关的肌肉结构和收缩特性改变之前、之后或同时发生尚不清楚。
To examine motor unit characteristics (size and firing rate) associated with aging. Cross-sectional, observational. Community. Baltimore Longitudinal Study of Aging participants (N = 102), aged 22.2 to 94.1 years, were studied. Not applicable. Surface-represented motor unit size and firing rate were collected from the vastus medialis during knee extension at 10%, 20%, 30%, and 50% of each subject’s maximum isometric voluntary contraction (MVC). MVC declined with older age (P <.0001). Adjusting for differences in MVC, both firing rate and motor unit size per newton force generated began to increase in the 6th decade of life. Motor unit size increased per newton force to a greater extent than firing rate. Those over the age of 75 years also activated significantly larger motor units per unit force (P = .04). Relative to force generated, the average firing rate began increasing at 57.8 ± 3.4 years and between 50.2 and 56.4 years (±4y) for motor unit size. The size of motor units and firing rates used to achieve a given force changes with age, particularly after middle age. Whether these changes precede, follow, or occur concurrent to age-related modifications in muscle structure and contractile properties or sarcopenia is not known.