Falla Deborah, Farina Dario, Kanstrup Dahl Marlene, Graven-Nielsen Thomas
Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7, D-3, DK-9220 Aalborg, Denmark.
J Electromyogr Kinesiol. 2008 Dec;18(6):938-46. doi: 10.1016/j.jelekin.2007.05.007. Epub 2007 Jul 13.
This study investigated whether pain-induced changes in cervical muscle activation affect myoelectric manifestations of cervical muscle fatigue. Surface EMG signals were detected from the sternocleidomastoid and splenius capitis muscles bilaterally from 14 healthy subjects during 20-s cervical flexion contractions at 25% of the maximal force. Measurements were performed before and after the injection of 0.5 ml of hypertonic (painful) or isotonic (control) saline into either the sternocleidomastoid or splenius capitis in two experimental sessions. EMG average rectified value and mean power spectral frequency were estimated throughout the sustained contraction. Sternocleidomastoid or splenius capitis muscle pain resulted in lower sternocleidomastoid EMG average rectified value on the side of pain (P < 0.01). However, changes over time of sternocleidomastoid EMG average rectified value and mean frequency (myoelectric manifestations of fatigue) during sustained flexion were not changed during muscle pain. These results demonstrate that pain-induced modifications of cervical muscle activity do not change myoelectric manifestations of fatigue. This finding has implications for interpreting the mechanisms underlying greater cervical muscle fatigue in people with neck pain disorders.
本研究调查了疼痛引起的颈部肌肉激活变化是否会影响颈部肌肉疲劳的肌电表现。在14名健康受试者以最大力量的25%进行20秒的颈部前屈收缩过程中，双侧检测胸锁乳突肌和头夹肌的表面肌电信号。在两个实验环节中，分别向胸锁乳突肌或头夹肌注射0.5毫升高渗（疼痛）或等渗（对照）盐水前后进行测量。在持续收缩过程中估计肌电平均整流值和平均功率谱频率。胸锁乳突肌或头夹肌疼痛导致疼痛侧胸锁乳突肌肌电平均整流值降低（P<0.01）。然而，在持续前屈过程中，胸锁乳突肌肌电平均整流值和平均频率（疲劳的肌电表现）随时间的变化在肌肉疼痛期间并未改变。这些结果表明，疼痛引起的颈部肌肉活动改变不会改变疲劳的肌电表现。这一发现对于解释颈部疼痛障碍患者颈部肌肉疲劳加剧的潜在机制具有重要意义。
