Millet Guillaume Y, Martin Vincent, Maffiuletti Nicola A, Martin Alain
INSERM/ERIT-M 0207 Motricité-Plasticité, Faculté des Sciences du Sport, Université de Bourgogne, BP 27 877-21078 Dijon, France.
Can J Appl Physiol. 2003 Jun;28(3):434-45. doi: 10.1139/h03-032.
The aim of this study was to characterize neuromuscular fatigue in knee extensor muscles after a marathon skiing race (mean +/- SD duration = 159.7 +/- 17.9 min). During the 2 days preceding the event and immediately after, maximal percutaneous electrical stimulations (single twitch, 0.5-s tetanus at 20 and 80 Hz) were applied to the femoral nerve of 11 trained skiers. Superimposed twitches were also delivered during maximal voluntary contraction (MVC) to determine maximal voluntary activation (% VA). EMG was recorded from the vastus lateralis muscle. MVC decreased with fatigue from 171.7 +/- 33.7 to 157.3 +/- 35.2 Nm (-8.4%; p < 0.005) while % VA did not change significantly. The RMS measured during MVC and peak-to-peak amplitude of the compound muscle action potential (PPA) from the vastus lateralis decreased with fatigue by about 30% (p < 0.01), but RMS.PPA-1 was similar before and after the ski marathon. Peak tetanus tension at 20 Hz and 80 Hz (P(0)20 and P(0)80, respectively) did not change significantly, but P(0)20.P(0)80-1 increased (p < 0.05) after the ski marathon. Data from electrically evoked single twitches showed greater peak mechanical response, faster rate of force development, and shorter contraction time in the fatigued state. From these results it can be concluded that a ski skating marathon (a) alters slightly but significantly maximal voluntary strength of the knee extensors without affecting central activation, and (b) induces both potentiation and fatigue.
本研究的目的是描述马拉松滑雪比赛后（平均±标准差持续时间 = 159.7±17.9分钟）膝伸肌的神经肌肉疲劳特征。在比赛前2天以及比赛刚结束后，对11名训练有素的滑雪者的股神经施加最大经皮电刺激（单脉冲、20赫兹和80赫兹下0.5秒的强直刺激）。在最大自主收缩（MVC）期间也施加叠加脉冲以确定最大自主激活（%VA）。从股外侧肌记录肌电图。MVC随着疲劳从171.7±33.7牛米降至157.3±35.2牛米（-8.4%；p<0.005），而%VA没有显著变化。在MVC期间测量的均方根值（RMS）以及股外侧肌复合肌肉动作电位的峰峰值幅度（PPA）随着疲劳下降了约30%（p<0.01），但RMS.PPA-1在滑雪马拉松前后相似。20赫兹和80赫兹下的最大强直张力（分别为P(0)20和P(0)80）没有显著变化，但滑雪马拉松后P(0)20.P(0)80-1增加（p<0.05）。电诱发单脉冲的数据显示，在疲劳状态下峰值机械反应更大、力量发展速率更快且收缩时间更短。从这些结果可以得出结论，滑雪马拉松（a）轻微但显著地改变了膝伸肌的最大自主力量，而不影响中枢激活，并且（b）既诱导了增强作用又导致了疲劳。
