Fatigability and variable-frequency train stimulation of human skeletal muscles
Fatigability and variable-frequency train stimulation of human skeletal muscles
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DOI：
10.1093/ptj/83.4.366
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发表时间：
2003-04-01
期刊：
影响因子：
3.2
通讯作者：
Dudley, GA
中科院分区：
文献类型：
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作者：
Bickel, CS;Slade, JM;Dudley, GA
背景和目的。股四头肌（QF）和胫骨前肌（TA）肌肉通常通过物理治疗师使用电刺激来激活。这两种肌肉在其纤维类型组成方面有着根本的不同。使用给定肌肉开发的协议是否可以应用于另一种肌肉很少受到质疑，即使它们的纤维类型不同。本研究的目的是测试以下假设：与疲劳状态下的恒频序列（CFT）刺激相比，在变频序列（VFT）刺激期间的扭矩增加在这些肌肉之间没有差异，即使TA肌肉相对于每块肌肉的整体组成比QF肌肉具有50%相对更多的慢纤维。科目10名娱乐活跃且无下肢病理史的男性参与了本研究（平均年龄= 25岁，SD=4，范围=19-31;平均身高=179 cm，SD=5，范围=170-188;平均体重=80 kg，SD=15，范围=63-111）。方法.受试者的TA和QF肌肉用CFTs（6个200微秒的方波，间隔70毫秒）或VFT（第一个脉冲间隔=5毫秒）刺激，引起等长收缩。结果增强后，VFT和CFT刺激的扭矩-时间积分和峰值扭矩没有差异。TA肌肉的上升时间长于QF肌肉，CFT刺激的上升时间长于VFT刺激的上升时间（均约为40%）。在180次CFT（50%占空比）后，峰值扭矩总体下降了56%，肌肉之间没有差异。增强扭矩时间积分（25%）VFIF刺激疲劳QF和TA肌肉之间没有什么不同。扭矩增加是由于VFT刺激引起的峰值扭矩比CFT刺激高27%，上升时间减慢较少（15% vs 30%）。讨论和结论。结果表明，QF肌肉可能不一定比TA肌肉疲劳。结果表明，VFTs增加的力量疲劳，人骨骼肌纤维类型无关。
Background and Purpose. The quadriceps femoris (QF) and tibialis anterior (TA) muscles are often activated through the use of electrical stimulation by physical therapists. These 2 muscles are fundamentally different in regard to their fiber-type composition. Whether protocols developed using a given muscle can be applied to another muscle has seldom been questioned, even if they differ in fiber type. The purpose, of this study was to test the hypothesis that torque augmentation during variable-frequency train (VFT) stimulation as compared with constant-frequency train (CFT) stimulation in the fatigued state would not differ between these muscles, even though the TA muscle has 50% relatively more slow fibers than the QF muscle relative to each muscle's overall composition. Subjects. Ten recreationally active men with no history of lower-extremity pathology participated in the study (mean age = 25 years, SD=4, range=19-31; mean height=179 cm, SD=5, range=170-188; mean body mass=80 kg, SD=15, range=63-111). Methods. The subjects' TA and QF muscles were stimulated with CFTs (six 200-microsecond square waves separated by 70 milliseconds) or VFTs (first interpulse interval=5 milliseconds) that evoked an isometric contraction. Results. After potentiation, the torque-time integral and peak torque were not different for the VFT and CFT stimulation. Rise time was longer for the TA muscle than for the QF muscle and for CFT stimulation versus VFT stimulation (both approximately 40%). After 180 CFTs (50% duty cycle), peak torque decreased 56% overall, with no differences between muscles. Enhancement of the torque-time integral (25%) by VFIF stimulation was not different between fatigued QF and TA muscles. Torque augmentation was due to the VFT stimulation evoking 27% greater peak torque and less slowing of rise time than the CFT stimulation (15% versus 30%). Discussion and Conclusion. The results indicate that the QF muscle may not necessarily fatigue more than the TA muscle. The results suggest that VFTs augment the force of fatigued, human skeletal muscle irrespective of fiber type.