Department of Neurology, St Lucas Hospital, Amsterdam, The Netherlands.
J Electromyogr Kinesiol. 1996 Sep;6(3):147-57. doi: 10.1016/1050-6411(96)00031-4.
Loss of sarcolemmal excitability is an early sign of fatigue in exercising muscle. This can be determined from a decreasing muscle fibre conduction velocity (MFCV). Underlying causes are still unclear. Three McArdle's disease patients and seven healthy controls performed sustained isometric ischaemic biceps brachii exercise until exhaustion. Each subject participated in three tests: at 40%, at 80% and at 100% of the maximal voluntary contraction (MVC). Analysis was done over the period in which the force level was maintained at 40% and 80% MVC, and over the period during loss of force at all three levels. We found that, in contrast to the occurrence of an immediately starting and ongoing decrease of MFCV in controls, a delayed onset of this decrease was observed in patients with McArdle's disease. Only during the loss of force phase was the MFCV decrease similar in patients and controls. The early occurrence of an MFCV decrease in controls appears to be related to the accumulation of lactic acid, which is virtually absent in the patient group. During force loss, different (additional) mechanisms must be responsible for the MFCV decrease in patients and, most probably, in controls as well.
肌细胞膜兴奋性丧失是运动肌肉疲劳的早期迹象。这可以通过肌肉纤维传导速度（MFCV）的降低来确定。其潜在原因尚不清楚。三名 McArdle 病患者和七名健康对照者进行了持续的等长缺血肱二头肌运动，直至力竭。每位受试者参加了三项测试：40%、80%和 100%最大自主收缩（MVC）。分析在力维持在 40%和 80%MVC 的期间以及在所有三个水平的力丧失期间进行。我们发现，与对照组中 MFCV 立即开始并持续降低的情况相反，McArdle 病患者的这种降低延迟发生。只有在力丧失阶段，患者和对照组的 MFCV 降低才相似。对照组中 MFCV 降低的早期发生似乎与乳酸的积累有关，而在患者组中几乎不存在乳酸。在力丧失期间，患者和对照组的 MFCV 降低可能由不同的（附加）机制引起。
