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Abstract：
OBJECTIVE: The aim of this study was to investigate the influence of the type of current and the frequency of impulses of electrical stimulation on the contraction of pelvic muscles with different fibre content.
METHODS: Electrical stimulation of complete muscles from Wistar rats was performed in vitro with a biphasic square wave current and with a bipolar mid-frequency current at frequencies between 2 and 100 Hz. The parameters of the resulting isometric contraction were determined.
RESULTS: The iliococcygeus and pubococcygeus, both with mainly fast-twitch muscle fibres, showed maximal contraction with a biphasic current with square wave pulses at 50 Hz and 60 Hz. The best result in the soleus, with mainly slow-twitch fibres, was with 33 Hz. The mid-frequency current needed a higher intensity to reach lower contraction values but was more effective at the very low frequencies.
CONCLUSIONS: Current type and frequency of electrical impulses change the electrically induced contraction in pelvic muscles substantially. This should be taken into account when designing and evaluating specific electrical stimulation of pelvic floor muscles aiming at improving either fast contraction or support, or both. From these data, optimal stimulation programmes may be proposed for mainly slow and mainly fast pelvic floor muscles, which need to be evaluated in a clinical setting.
METHODS: Electrical stimulation of complete muscles from Wistar rats was performed in vitro with a biphasic square wave current and with a bipolar mid-frequency current at frequencies between 2 and 100 Hz. The parameters of the resulting isometric contraction were determined.
RESULTS: The iliococcygeus and pubococcygeus, both with mainly fast-twitch muscle fibres, showed maximal contraction with a biphasic current with square wave pulses at 50 Hz and 60 Hz. The best result in the soleus, with mainly slow-twitch fibres, was with 33 Hz. The mid-frequency current needed a higher intensity to reach lower contraction values but was more effective at the very low frequencies.
CONCLUSIONS: Current type and frequency of electrical impulses change the electrically induced contraction in pelvic muscles substantially. This should be taken into account when designing and evaluating specific electrical stimulation of pelvic floor muscles aiming at improving either fast contraction or support, or both. From these data, optimal stimulation programmes may be proposed for mainly slow and mainly fast pelvic floor muscles, which need to be evaluated in a clinical setting.
摘要：
目的：本研究的目的是研究电刺激的电流类型和脉冲频率对不同纤维含量的骨盆肌肉收缩的影响。
方法:在体外用双相方波电流和用频率在2和100Hz之间的双极中频电流进行来自Wistar大鼠的完整肌肉的电刺激。确定了所得的等距收缩的参数。
结果：髂尾囊和耻骨尾囊，两者都主要是快速抽搐的肌肉纤维，在50Hz和60Hz的方波脉冲下，双相电流显示最大收缩。比目鱼最好的结果，主要是慢抽搐纤维，是33赫兹。中频电流需要更高的强度以达到更低的收缩值,但在非常低的频率下更有效。
结论：电脉冲的电流类型和频率实质上改变了骨盆肌肉的电诱导收缩。在设计和评估旨在改善快速收缩或支撑的盆底肌肉的特定电刺激时，应考虑到这一点。或者两者兼而有之。从这些数据来看,最佳的刺激方案可以提出主要是缓慢的和主要是快速的盆底肌肉，这需要在临床环境中进行评估。
方法:在体外用双相方波电流和用频率在2和100Hz之间的双极中频电流进行来自Wistar大鼠的完整肌肉的电刺激。确定了所得的等距收缩的参数。
结果：髂尾囊和耻骨尾囊，两者都主要是快速抽搐的肌肉纤维，在50Hz和60Hz的方波脉冲下，双相电流显示最大收缩。比目鱼最好的结果，主要是慢抽搐纤维，是33赫兹。中频电流需要更高的强度以达到更低的收缩值,但在非常低的频率下更有效。
结论：电脉冲的电流类型和频率实质上改变了骨盆肌肉的电诱导收缩。在设计和评估旨在改善快速收缩或支撑的盆底肌肉的特定电刺激时，应考虑到这一点。或者两者兼而有之。从这些数据来看,最佳的刺激方案可以提出主要是缓慢的和主要是快速的盆底肌肉，这需要在临床环境中进行评估。
