Ballistic contractions in man: characteristic recruitment pattern of single motor units of the tibialis anterior muscle.
Ballistic contractions in man: characteristic recruitment pattern of single motor units of the tibialis anterior muscle.
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人体弹道收缩：胫骨前肌单个运动单位的特征募集模式。
DOI：
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发表时间：
1977
期刊：
影响因子：
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通讯作者：
E. Godaux
中科院分区：
文献类型：
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作者：
J. Desmedt;E. Godaux
1. 使用来自成年男性完整胫骨前肌的高选择性电极记录单个运动单位。对以不同力发展速率进行的不同峰值力的自愿等长收缩期间的放电模式进行了详细的参数分析。 2.在平滑跟踪斜坡力的过程中，从给定肌肉部位记录的不同运动单位以一致的顺序被招募，当肌肉产生一定水平的力时，每个单位变得活跃。一些单位在这种缓慢的斜坡收缩中的阈值超过了8公斤。相比之下，在不到 0-15 秒的时间内达到 12 公斤峰值力的快速弹道收缩中，相同的运动单位会在很大程度上先于肌肉力量的产生而短暂爆发。 3. 在慢速跟踪斜坡收缩中，单个运动单位的瞬时频率最初相当低（5-15/秒），并且随着斜坡力的增加而增加。相比之下，在（强）弹道收缩中，相同的装置在爆发初期以异常高的瞬时频率（60-120/秒）放电，此后发射频率降低。这种迄今为止未知的模式似乎是弹道收缩的特征，即使是在仅 0-4 秒内达到 12 公斤的快速跟踪斜坡收缩中也没有发现这种模式。 4. 在强烈的弹道收缩的早期爆发中，激活的不同运动单位的电位以几毫秒的间隔相当拥挤，并且对不同运动单位的激活等级的观察并不能为分析弹道收缩中单位的招募顺序提供可靠的数据。 5. 描述了一种估计单个运动单元弹道力阈值的新方法。当进行一系列峰值力范围为 0-05 至 12 kg 的快速弹道收缩时，任何给定的运动单位仅在弹道峰值力超过某个可重复值时才会激活。基于这些弹道力阈值对招募顺序的详细分析表明，它与慢速跟踪斜坡收缩中相同单位的招募顺序几乎相同（相关性= 0-95）。 6. 弹道收缩的强度分级是通过在更强的收缩中募集额外的运动单位以及通过增加其射速来进行的。讨论了这些分级机制。
1. Single motor units were recorded with highly selective electrodes from intact tibialis anterior muscle in the adult man. A detailed parametric analysis was made of the discharge patterns during voluntary isometric contractions of different peak forces carried out at various rates of force development. 2. During the smooth tracking of a ramp force, the different motor units recorded from a given muscle site were recruited in a consistant order, each unit becoming active when the muscle developed a certain level of force. The threshold of some of the units in such slow ramp contractions exceeded 8 kg. By contrast, in brisk ballistic contractions reaching a peak force of 12 kg in less than 0‐15 sec, the same motor units discharged in a transient burst which largely preceded the muscle force production. 3. In slow tracking ramp contractions, the instantaneous frequency of single motor units was initially rather low (5‐15/sec) and it increased as the ramp force augmented. By contrast, in (strong) ballistic contractions, the same units discharged at an unusually high instantaneous frequency (60‐120/sec) early in the burst and the firing frequency decreased thereafter. Such hitherto unknown pattern appears characteristic of ballistic contractions and it was not found in even fast tracking ramp contractions achieving 12 kg in only 0‐4 sec. 4. The potentials of the different motor units activated are rather crowded at intervals of a few msec in the early burst of a strong ballistic contraction and observations on the rank activation of the different motor units do not provide reliable data for the analysis of the recruitment order of units in ballistic contractions. 5. A new method is described for estimating ballistic force threshold of single motor units. When a large series of brisk ballistic contractions with peak forces ranging from 0‐05 to 12 kg was carried out any given motor unit only became active when the ballistic peak force exceeded a certain reproducible value. A detailed analysis of the recruitment order based on these ballistic force thresholds showed it to be virtually identical to the recruitment order of the same units in slow tracking ramp contractions (correlation=0‐95). 6. Ballistic contractions are graded in force both by the recruitment of additional motor units in stronger contractions, and by an increase in their rate of firing. These gradation mechanisms are discussed.