Kukulka C G, Russell A G, Moore M A
Brain Res. 1986 Jan 1;362(1):47-54. doi: 10.1016/0006-8993(86)91397-1.
Experiments were designed to evaluate changes in the electrical activation and force generating capabilities of human soleus muscle during sustained, maximum isometric contractions. Eighteen experiments were conducted on 7 healthy subjects. Surface EMG, and in select cases, intramuscular fine wire EMG recordings, were made to assess the electrical activation of soleus. Subjects performed maximum isometric plantarflexion contractions of 1-3 min during which time supramaximal electrical pulses were delivered to the tibial nerve at 5-s intervals to elicit maximum M waves. M wave areas were assessed for evidence of neuromuscular junction failure. The results revealed that, on average, maximum force declined to 80% of unfatigued maximum by 60 s of effort, 74% by 90 and 120 s, and 70% by 180 s. M waves were stable for efforts up to 3 min, thereby providing little evidence for neuromuscular junction failure. In 3 experiments, total spike counts from intramuscular recordings displayed a 50% reduction in firing by 30 s of effort, with little additional slowing for up to 3 min. Although all of the fatigue-induced electrical and mechanical alterations in muscle activation reported earlier for intrinsic hand and foot muscles were verified in these experiments on soleus, the magnitudes and time courses of these changes were quite different. All changes were consistent with a muscle designed to optimally resist fatigue.
实验旨在评估人类比目鱼肌在持续最大等长收缩过程中电激活和产生力量能力的变化。对7名健康受试者进行了18次实验。通过表面肌电图，并在某些情况下通过肌内细钢丝肌电图记录，来评估比目鱼肌的电激活情况。受试者进行1 - 3分钟的最大等长跖屈收缩，在此期间，每隔5秒向胫神经输送超强电脉冲以引出最大M波。评估M波面积以寻找神经肌肉接头功能障碍的证据。结果显示，平均而言，用力60秒时最大力量下降至未疲劳时最大值的80%，90秒和120秒时为74%，180秒时为70%。在长达3分钟的用力过程中，M波保持稳定，因此几乎没有证据表明存在神经肌肉接头功能障碍。在3次实验中，肌内记录的总尖峰计数在用力30秒时放电减少50%，在长达3分钟的时间内几乎没有进一步减慢。尽管早期报道的内在手部和足部肌肉疲劳诱导的肌肉激活方面的所有电和机械变化在这些比目鱼肌实验中都得到了验证，但这些变化的幅度和时间进程却大不相同。所有变化都与一块旨在最佳抵抗疲劳的肌肉相一致。
