Motor unit discharge and force tremor in skill- and strength-trained individuals
Motor unit discharge and force tremor in skill- and strength-trained individuals
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DOI：
10.1007/s002210050316
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发表时间：
1998-03-01
影响因子：
2
通讯作者：
Nordstrom, MA
中科院分区：
文献类型：
--
作者：
Semmler, JG;Nordstrom, MA
我们检测了5名音乐家（技能训练）、5名举重运动员（力量训练）和6名未训练的受试者在低力等距外展食指时第一背骨间肌（FDI）的运动单元（MU）放电特性（平均峰间间隔、ISI、放电变异性、短期同步、共同驱动）和力震颤。技能训练组的平均MU ISI略短于未训练组。FDI MUs的流量变异性在组间无显著差异。技能训练组（0.22 +/- 0.02 s(-1)， 162 MU对）、非训练组（0.32 +/- 0.02 s(-1)， 199 MU对）和力量训练组（0.44 +/- 0.03 s(-1)， 183 MU对）的平均MU同步强度（以机会以上的额外同步放电频率表示）存在差异。FDI - MU同步性较弱，在受过技能训练的受试者和未受过训练的受试者的主要（熟练）手中都具有相同的强度。未训练组非优势手FDI - MU同步性与力量训练组双手FDI - MU同步性相当。在一组MU对中评估了共同激发率的调节程度（共同驱动），技能训练的受试者（0.30 +/- 0.04,n=14）比未训练的受试者（0.43 +/- 0.3,n=14）和力量训练的受试者（0.48 +/- 0.03,n=21）弱。在目标力为0.5 N和3.5 N时，对同一受试者的每只手进行力震颤量化。在目标力为3.5 N时，技能训练组的力频谱震颤的均方根振幅和峰值功率显著低于力量训练组。三组患者的最高震颤频率相似。在技能训练的受试者中，相对更独立的FDI MUs对放电不是导致这些受试者震颤幅度降低的原因。在同一实验期间获得的FDI肌肉的MU同步和共同驱动的总体程度与震颤测量之间的相关性均不显著。中央下降指令信号的差异最有可能解释训练有素的手更独立地释放FDI MUs，而神经或外周肌肉因素可能导致较弱的震颤。
We examined motor unit (MU) discharge properties (mean interspike interval, ISI, discharge variability, short-term synchronization, common drive) and force tremor in the first dorsal interosseous (FDI) muscle of five musicians (skill-trained), five weight-lifters (strength-trained) and six untrained subjects during low-force isometric abduction of the index finger. Mean MU ISI was slightly shorter in skill-trained subjects than in untrained subjects. Discharge variability of FDI MUs did not differ significantly between groups. The mean strength of MU synchronization (expressed as the frequency of extra synchronous discharges above chance) was different in skill-trained (0.22 +/- 0.02 s(-1), 162 MU pairs), untrained (0.32 +/- 0.02 s(-1), 199 MU pairs) and strength-trained subjects (0.44 +/- 0.03 s(-1), 183 MU pairs). FDI MU synchrony was weak and of equivalent strength in both hands of skill-trained subjects and the dominant (skilled) hand of untrained subjects. The stronger FDI MU synchrony in the non-dominant hand of untrained subjects was equivalent to that found in both hands of strength-trained subjects. The extent of common modulation of firing rates (common drive) was assessed for a subset of MU pairs and was weaker in skill-trained subjects (0.30 +/- 0.04, n=14) than untrained (0.43 +/- 0.3, n=14) and strength-trained (0.48 +/- 0.03, n=21) subjects. Force tremor was quantified for each hand in the same subjects during isometric index finger abduction at target forces of 0.5 N and 3.5 N. Tremor rms amplitude and peak power in the force frequency spectrum were significantly lower in skill-trained subjects than strength-trained subjects with the 3.5-N target force. The peak tremor frequency was similar in the three groups. The relatively more independent discharge of pairs of FDI MUs in skill-trained subjects was not responsible for the reduced tremor amplitudes in these subjects. Correlations between the overall extent of MU synchrony and common drive in FDI muscles and tremor measures obtained during the same experimental session were all non-significant. Differences in the central descending command signals are the most likely explanation for the more independent discharge of FDI MUs in skill-trained hands, while neural or peripheral muscular factors may be responsible for the weaker tremor.