Postactivation potentiation of short tetanic contractions is differently influenced by stimulation frequency in young and elderly adults
Postactivation potentiation of short tetanic contractions is differently influenced by stimulation frequency in young and elderly adults
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DOI：
10.1007/s00421-008-0739-1
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发表时间：
2008-07-01
影响因子：
3
通讯作者：
Duchateau, Jacques
中科院分区：
文献类型：
--
作者：
Baudry, Stephane;Klass, Malgorzata;Duchateau, Jacques
本研究的目的是检查激活后增强（PAP）的扭矩和扭矩发展率引起的短列车的刺激在不同频率的收缩，在年轻人和老年人的影响。还分析了列车内每个电刺激的个人机械贡献。单脉冲，并在20，50，80和100 Hz的两个（PT2）和三个脉冲序列（PT3）被诱发之前和期间10分钟的时间后，6秒的条件MVC。结果表明，随着刺激频率的增加，年轻人（从对照值的184.5%增加到140.4%）和老年人（从140.5%增加到109.6%）的PT 2扭矩的PAP下降。无论刺激频率，PAP的峰值是更大的年轻人比老年人，并立即发生后，空调MVC，但延迟为100 Hz的条件下，在老年人。对于PT3，结果相似，但PAP的程度较小，在列车内的机械贡献的PAP也随着刺激频率的增加而降低。对于大多数频率高于20 Hz，PAP的峰值为每一个机械的贡献被推迟了1分钟后，空调MVC。这些结果表明，年龄和频率相关的PAP饱和度的连续机械的贡献内的一列刺激，随着时间的推移而减少。这一发现的功能含义是，与低激活率相比，高激活率时PAP效应较低且延迟。
The purpose of this study was to examine the effects of postactivation potentiation ( PAP) on the torque and rate of torque development for contractions evoked by short trains of stimuli at different frequencies, in young and elderly adults. Individual mechanical contributions to each electrical stimulus within trains were also analysed. Single pulse, and two- (PT2) and three-pulse trains (PT3) delivered at 20, 50, 80 and 100 Hz were evoked before and during a 10 min period after a 6-s conditioning MVC. The results show that PAP of the torque for PT2 decreased with the increase of the stimulation frequency for young (from 184.5 to 140.4% of control values) and elderly (from 140.5 to 109.6%). Regardless of the stimulation frequency, the peak of PAP was greater in young than in elderly and occurred immediately after the conditioning MVC but was delayed for the 100 Hz condition in elderly adults. For PT3, the results were similar although the extent of PAP was less. The PAP of the mechanical contributions within the trains also decreased with the augmentation of the stimulation frequency. For most of the frequencies above 20 Hz, the peak of PAP for each mechanical contribution was delayed by 1 min after the conditioning MVC. These results indicate an age-and frequency-related PAP saturation of the successive mechanical contributions within a train of stimuli that decrease with time. The functional implication of the findings is that PAP effect is lower and delayed at high compared with low activation rate.