Presland Jarrod D, Dowson Martin N, Cairns Simeon P
Division of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, 1020, New Zealand.
Eur J Appl Physiol. 2005 Sep;95(1):42-51. doi: 10.1007/s00421-005-1395-3. Epub 2005 Jun 23.
The aims of this study were to (1) quantify any central fatigue that occurs following prolonged dynamic exercise, i.e. reduced muscle force caused by impaired motor drive from the central nervous system and (2) determine whether decreased cortical arousal, assessed using critical flicker fusion threshold (CFF), occurs and is related to impaired exercise performance. Fifteen healthy men cycled at 70% VO2peak until exhaustion. The peak force of maximum voluntary isometric contractions (MVC) of the quadriceps muscle group was reduced by 30% at exhaustion. The voluntary activation ratio determined using superimposed tetanic stimulation fell from 0.99 to 0.86 at exhaustion. The central fatigue (%) at exhaustion was 33+/-12% (+/- SD) (assessed via the tetanus interpolation technique) and 54+/-32% (assessed via the relative decline of MVC and peak tetanic force) of the total fatigue. The MVC only partially recovered and central fatigue persisted at 30 min post-exercise. CFF increased from 39.2+/-2.3 to 41.8+/-3.5 Hz at exhaustion, but did not correlate with central fatigue. Every subject reached the highest rating of perceived exertion (RPE) at exhaustion of 20 on the Borg scale. The time to exhaustion was related to how quickly the RPE increased and to the ability to sustain exercise at very high RPE. These data suggest that with prolonged cycling: (1) there is considerable and a persistent form of central fatigue, (2) there is an increased level of cortical arousal, and (3) exhaustion is linked to very high subjective RPE.
（1）量化长时间动态运动后出现的任何中枢性疲劳，即由中枢神经系统运动驱动受损导致的肌肉力量下降；（2）确定使用临界闪光融合频率（CFF）评估的皮质唤醒降低是否发生，以及是否与运动表现受损有关。15名健康男性以70%的最大摄氧量（VO2peak）进行骑行，直至力竭。股四头肌群最大自主等长收缩（MVC）的峰值力量在力竭时下降了30%。使用叠加强直刺激测定的自主激活率在力竭时从0.99降至0.86。力竭时的中枢性疲劳（%）通过破伤风插值技术评估为总疲劳的33±12%（±标准差），通过MVC和强直峰值力量的相对下降评估为54±32%。MVC仅部分恢复，运动后30分钟中枢性疲劳仍然存在。力竭时CFF从39.2±2.3赫兹增加到41.8±3.5赫兹，但与中枢性疲劳无关。每位受试者在力竭时达到了Borg量表上20的最高主观用力感觉等级（RPE）。力竭时间与RPE增加的速度以及在非常高的RPE水平下维持运动的能力有关。这些数据表明，长时间骑行时：（1）存在相当程度且持续存在的中枢性疲劳形式；（2）皮质唤醒水平升高；（3）力竭与非常高的主观RPE有关。
