Binder-Macleod S A, Lee S C, Russ D W, Kucharski L J
Department of Physical Therapy, University of Delaware, Newark, USA.
Muscle Nerve. 1998 Sep;21(9):1145-52. doi: 10.1002/(sici)1097-4598(199809)21:9<1145::aid-mus5>3.0.co;2-7.
Variable-frequency stimulation trains (VFTs) that take advantage of the catchlike property of skeletal muscle have been shown to augment the force production of fatigued muscles compared with constant-frequency trains (CFTs). The present study is the first to report the force augmentation produced by VFTs after fatiguing the muscle with VFTs versus fatiguing the muscle with CFTs. Data were obtained from the human quadriceps femoris muscles of 12 healthy subjects. Each subject participated in three experimental sessions. Each session fatigued the muscle with one of three protocols: CFTs with 70-ms interpulse intervals (CFT70); CFTs with 55.5-ms interpulse intervals (CFT55.5); or VFTs. Following each fatiguing protocol the muscles were tested with all three stimulation patterns (i.e., CFT55.5, CFT70, and VFT). At the end of the fatiguing protocol the VFT produced force-time integrals and peak forces approximately 18% and 32% greater than the CFT70, respectively. The testing trains showed that the VFT produced approximately 25-35% greater force-time integrals than either CFT and approximately 35-47% greater peak forces than the CFT70. For each testing train, approximately 10-15% greater force-time integrals were seen when the muscles were fatigued with the CFTs than when fatigued with the VFTs. These results support suggestions that VFTs may be useful during clinical applications of electrical stimulation.
利用骨骼肌类似捕捉特性的变频刺激序列（VFTs）已被证明与恒频刺激序列（CFTs）相比，能增强疲劳肌肉的力量产生。本研究首次报告了用VFTs使肌肉疲劳后与用CFTs使肌肉疲劳后VFTs产生的力量增强情况。数据取自12名健康受试者的股四头肌。每位受试者参加三个实验环节。每个环节用以下三种方案之一使肌肉疲劳：脉冲间隔70毫秒的CFTs（CFT70）；脉冲间隔55.5毫秒的CFTs（CFT55.5）；或VFTs。在每个疲劳方案之后，用所有三种刺激模式（即CFT55.5、CFT70和VFT）对肌肉进行测试。在疲劳方案结束时，VFT产生的力-时间积分和峰值力分别比CFT70大约大18%和32%。测试刺激序列表明，VFT产生的力-时间积分比任何一种CFT大约大25%-35%，峰值力比CFT70大约大35%-47%。对于每个测试刺激序列，当用CFTs使肌肉疲劳时，力-时间积分比用VFTs使肌肉疲劳时大约大10%-15%。这些结果支持了VFTs在电刺激临床应用中可能有用的观点。
