Motor variability: within-subject correlations during separate and simultaneous contractions.
Motor variability: within-subject correlations during separate and simultaneous contractions.
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运动变异性：单独和同时收缩期间的受试者内相关性。
DOI：
10.1007/s00221-008-1412-y
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发表时间：
2008
影响因子：
2
通讯作者：
Welsh,SethJ
中科院分区：
文献类型：
--
作者：
Tracy,BrianL;Dinenno,DevinV;Jørgensen,Bjørn;Welsh,SethJ
为了确定近端肌肉运动变异性的相似性，年轻人和老年人分别（SEP；最大值的 2.5%、30% 和 65%）和同时（SIM；最大值的 2.5% 和 30%）进行稳定的肘屈肌 (EF) 和膝伸肌 (KE) 收缩，有 (VIS) 和没有 (NVIS) 视觉反馈。根据并发力记录计算波动幅度（力的 SD、CV）、基于时间的互相关性（CC）、力功率谱和基于频率的相干性（COH）值的肌肉间相关性。力、SEP/SIM 和视力条件之间的波动幅度相关性范围为 r= 0.34 至 0.86（P<0.05），但对于 2.5% NVIS 不存在相关性。 SIM 相对较低的 CC 值 (r= 0.22–0.33) 对于老年人来说比年轻人更强。所有记录中力波动的绝大多数功率均<4 Hz。对于老年人，仅观察到弱的 COH 峰值 <2 Hz；对于年轻人，观察到 3 至 4 Hz 之间的弱 COH 峰值；对于 30% MVC 目标力，在低于 3 Hz 的老年人中，COH 稍强。力波动幅度的相关性表明 EF 和 KE 运动神经元池类似地改变振荡突触输入并且可能相互影响。互相关性表明，远程运动神经元池在时间上受到共同激励源的类似影响，对于低频的老年人来说可能更加连贯。
To determine the similarity of motor variability in proximal muscles, young and elderly adults performed steady elbow flexor (EF) and knee extensor (KE) contractions separately (SEP; at 2.5, 30, and 65% of maximum) and simultaneously (SIM; at 2.5 and 30% of maximum), with (VIS) and without (NVIS) visual feedback. Between-muscle correlations of fluctuation amplitude (SD, CV of force), time-based cross-correlations (CC), force power spectra, and frequency-based coherence (COH) values were computed from the concurrent force records. Correlations of fluctuation amplitude ranged fromr= 0.34 to 0.86 (P< 0.05) across forces, SEP/SIM, and vision conditions, but were absent for 2.5% NVIS. The relatively low CC values for SIM (r= 0.22–0.33) were stronger for elderly than young adults. The vast majority of the power in the force fluctuations was <4 Hz for all records. Weak COH peaks were only observed <2 Hz for elderly and between 3 and 4 Hz for young, and COH was slightly stronger for elderly below 3 Hz for the 30% MVC target force. The correlations in force fluctuation amplitude suggest that the EF and KE motor neuron pools similarly transform the oscillating synaptic input and may influence each other. The cross-correlations suggest the remote motor neuron pools are influenced similarly in time by a common source of excitation, perhaps more coherently for elderly adults at low frequencies.