CHANGES IN FIRING RATE OF HUMAN MOTOR UNITS DURING LINEARLY CHANGING VOLUNTARY CONTRACTIONS
CHANGES IN FIRING RATE OF HUMAN MOTOR UNITS DURING LINEARLY CHANGING VOLUNTARY CONTRACTIONS
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DOI：
10.1113/jphysiol.1973.sp010193
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发表时间：
1973-01-01
影响因子：
5.5
通讯作者：
YEMM, R
中科院分区：
文献类型：
--
作者：
MILNERBR.HS;STEIN, RB;YEMM, R
1.人类受试者使用手的第一背侧骨间肌产生近似线性增加或减少的自愿等长收缩。 2. 单运动单位开始以 8·4±1·3 脉冲/秒（观察的平均值±标准差）发射，并且对于自主力每变化 100 g，其发射速率增加 1·4±0·6 脉冲/秒。这些值与募集运动单位的阈值力无关。 3. 在随意增加和减少中等速率（每 10 秒一个完整的周期）时，单个运动单元的放电速率在所研究的整个力范围内随力呈线性变化。然而，在随意力缓慢增加的过程中，发射率趋于达到稳定水平，而在快速增加的过程中，观察到初始脉冲序列的速率大致恒定。 4. 确定了招募和增加发射率作为增加自愿收缩力的机制的相对重要性。只有在武力水平较低的情况下，招募才是主要机制。如果考虑到整个生理范围，增加的发射频率成为中间力量水平下更重要的机制，并且贡献了大部分力量。
1. Human subjects generated approximately linearly increasing or decreasing voluntary, isometric contractions using the first dorsal interosseus muscle of the hand. 2. Single motor units began firing at 8·4±1·3 impulses/sec (mean ± S.D. of an observation) and increased their firing rate 1·4±0·6 impulses/sec for each change of 100 g in voluntary force. These values were independent of the threshold force for recruiting motor units. 3. At intermediate rates of increasing and decreasing voluntary force (one complete cycle every 10 sec) the firing rate of single motor units varied linearly with force over the entire range of forces studied. However, during slow increases in voluntary force, the firing rate tended to reach a plateau, while during rapid increases an initial train of impulses at a roughly constant rate was observed. 4. The relative importance of recruitment and increased firing rate, as mechanisms for increasing the force of voluntary contraction, was determined. Only at low levels of force is recuitment the major mechanism. Increased firing rate becomes the more important mechanism at intermediate force levels and contributes the large majority of force if the entire physiological range is considered.