Fatigue and Exercise Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, East Sussex, Eastbourne, UK.
Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Northumbria, UK.
Eur J Appl Physiol. 2019 Apr;119(4):991-1005. doi: 10.1007/s00421-019-04089-7. Epub 2019 Feb 12.
The assessment of voluntary activation of the knee extensors using transcranial magnetic stimulation (VA) is routinely performed to assess the supraspinal function. Yet methodological scrutiny of the technique is scarce. The aim of the present study was to examine face validity and reliability of VA and its two main determinants (superimposed twitch during a maximal voluntary contraction [SIT] and estimated resting twitch [ERT]).
SIT ERT, and VA were measured on ten healthy males (age 24 ± 5 years) before and following intermittent isometric fatiguing exercise on two separate occasions.
The findings indicated issues regarding the accuracy of ERT and suggested a three-point relationship should not be used to determine ERT. Reliabilities for VA, SIT and ERT were acceptable pre- but much weaker post-exercise (especially for SIT). Despite statistically significant changes in main neuromuscular variables following the intermittent isometric fatiguing exercise (P < 0.05), when post-exercise reliability was considered, the exercise effect on VA was smaller than the smallest detectable change in 18 of the 20 individual tests performed, and for the whole sample for one of two visits. Finally, maximal voluntary contraction was reduced significantly following the neuromuscular assessment (NMA) pre-exercise but recovered during the NMA post-exercise.
This is the first study to demonstrate a lack of sensitivity of key neuromuscular measurements to exercise and to evidence both presence of neuromuscular fatigue following the NMA in itself, and recovery of the neuromuscular function during the NMA post-exercise. These results challenge the face validity of this routinely used protocol.
使用经颅磁刺激（VA）评估膝关节伸肌的自愿激活，通常用于评估中枢神经系统的功能。然而，该技术的方法学审查很少。本研究的目的是检验 VA 及其两个主要决定因素（最大随意收缩时的叠加 twitch[SIT]和估计的静息 twitch[ERT]）的表面有效性和可靠性。
在两次单独的间歇等长疲劳运动前后，对 10 名健康男性（年龄 24±5 岁）进行 SIT、ERT 和 VA 测量。
研究结果表明 ERT 的准确性存在问题，并表明不应使用三点关系来确定 ERT。VA、SIT 和 ERT 的可靠性在运动前是可以接受的，但在运动后要差得多（尤其是 SIT）。尽管间歇等长疲劳运动后主要神经肌肉变量发生了统计学上的显著变化（P<0.05），但考虑到运动后的可靠性，运动对 VA 的影响在 20 次单独测试中的 18 次和两次测试中的一次中都小于最小可检测变化，而对于整个样本。最后，在神经肌肉评估（NMA）前，最大随意收缩明显减少，但在 NMA 后恢复。
这是第一项研究表明，关键神经肌肉测量对运动的敏感性不足，并证明 NMA 本身存在神经肌肉疲劳，以及 NMA 后运动期间神经肌肉功能的恢复。这些结果对该常规使用的方案的表面有效性提出了挑战。
