Latash M, Kalugina E, Nicholas J, Orpett C, Stefoski D, Davis F
Center for Multiple Sclerosis, Rush-Presbyterian St. Luke's Medical Center, Chicago, IL 60612, USA.
Mult Scler. 1996 Feb;1(4):236-41.
Short episodes of electrical stimulation were applied to the right quadriceps muscle of patients with multiple sclerosis (MS) and healthy subjects at different times during 60 sec sustained voluntary muscle contractions at 0 to 100% levels of maximal voluntarily generated joint torque. The amplitude of electrically induced increments of torque (delta T) has been shown to depend upon both the level of muscular contraction and time from the beginning of the contraction. The dependence of delta T upon the time from the beginning of contraction has been assumed to reflect muscle fatigue. Patients with MS demonstrated an apparent involvement of central neurogenic mechanisms in fatigue manifested as a drop in muscle torque during sustained contractions at 75 and 100% levels when electrical stimulation was able to induce considerable increments in muscle torque. These patients also demonstrated a dependence of delta T upon the contraction level suggesting that they did not produce maximal voluntary contraction torque in the pre-trial. Fatigue in MS is due to central, neurogenic factors and does not seem to involve any myogenic factors such as might be related to secondary muscle changes due to the long-standing disorder. The subjective feeling of tiredness ('fatigue') may be related to a dissociation between central motor commands ('effort') and their mechanical consequences.
在最大自主产生关节扭矩的0%至100%水平下，对多发性硬化症（MS）患者和健康受试者的右股四头肌进行60秒持续自主肌肉收缩，在不同时间施加短时间电刺激。电诱发扭矩增量（δT）的幅度已被证明取决于肌肉收缩水平和收缩开始后的时间。δT对收缩开始后时间的依赖性被认为反映了肌肉疲劳。MS患者在75%和100%水平的持续收缩过程中，当电刺激能够引起肌肉扭矩显著增加时，表现出中枢神经源性机制明显参与疲劳，表现为肌肉扭矩下降。这些患者还表现出δT对收缩水平的依赖性，表明他们在试验前未产生最大自主收缩扭矩。MS中的疲劳是由中枢神经源性因素引起的，似乎不涉及任何肌源性因素，例如可能与长期疾病导致的继发性肌肉变化有关的因素。主观疲劳感（“疲劳”）可能与中枢运动指令（“努力”）与其机械后果之间的分离有关。
