Effects of tetanic contraction of motor units of similar type on the initial stiffness to ramp stretch of the cat peroneus longus muscle.
Effects of tetanic contraction of motor units of similar type on the initial stiffness to ramp stretch of the cat peroneus longus muscle.
复制标题
类似类型运动单位的强直收缩对猫腓骨长肌斜坡拉伸初始刚度的影响。
DOI：
10.1152/jn.1990.64.6.1724
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发表时间：
1990
影响因子：
2.5
通讯作者：
Laporte,Y
中科院分区：
文献类型：
--
作者：
Petit,J;Filippi,GM;Gioux,M;Hunt,CC;Laporte,Y
1.在猫腓骨长肌中测量了斜坡拉伸初始部分期间的刚度，该肌肉处于静息状态，并且在通过增加相同类型[慢（S）、抗快速疲劳（FR）或可快速疲劳（FF）]的运动单位数量产生的最大强直收缩期间。2.该初始斜坡刚度被定义为在恒定速度延伸的有限范围内张力与长度变化之间的比率，在该范围内张力随长度变化线性上升。当其他单位保持不活动时，许多运动单位的强直收缩会降低这种僵硬度。在S、FR或FF单位产生的收缩中，减少具有不同的特征。3.两个简短的斜坡（三角形）拉伸施加在短时间内，以评估稳定的跨桥的斜坡刚度的变化的贡献。当第一次拉伸的幅度超过稳定横桥的假定弹性极限时，第二次斜坡拉伸显示初始刚度降低20-60%。这在被动肌肉和几个运动单位收缩的肌肉中都可以看到。4.当激活越来越多的相同类型的运动单元时，收缩期间传递的一对三角形拉伸中的第二个的初始斜坡刚度几乎与所产生的张力成线性地增加。这种增加的斜率是2.5倍陡峭的S单位比FR单位。这反映了这样一个事实，S单位产生的收缩比快速单位产生的收缩对拉伸的阻力成比例地更大。
1. The stiffness during the initial portion of a ramp stretch was measured in cat peroneus longus muscle at rest and during maximal tetanic contractions produced by increasing numbers of motor units of the same type [slow (S), fast fatigue resistant (FR), or fast fatigable (FF)]. 2. This initial ramp stiffness was defined as the ratio between tension and length change over the limited range of constant velocity extension during which tension rose linearly with length change. This stiffness was reduced by tetanic contraction of a number of motor units while other units remained inactive. The reduction had different characteristics in contractions produced by S, FR, or FF units. 3. Two brief ramp (triangular) stretches were applied at short intervals to evaluate the contribution of stable cross bridges to the changes in ramp stiffness. When the amplitude of the first stretch exceeded the presumed elastic limits of the stable cross bridges, the second ramp stretch showed a reduction of 20–60% in initial stiffness. This was seen both in passive muscles and in muscles in which several motor units were contracting. 4. When increasing numbers of motor units of the same type were activated, the initial ramp stiffness to the second of a pair of triangular stretches delivered during contraction increased almost linearly with the developed tension. The slope of this increase was 2.5 times steeper for S units than for FR units. This reflects the fact that contraction produced by S units causes a proportionally greater resistance to stretch than that of fast units.