Ervilha Ulysses F, Farina Dario, Arendt-Nielsen Lars, Graven-Nielsen Thomas
Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D-3, 9220, Aalborg, Denmark.
Exp Brain Res. 2005 Jul;164(2):215-24. doi: 10.1007/s00221-005-2244-7. Epub 2005 Jun 11.
This study investigated the effect of muscle pain on muscle activation strategies during dynamic exercises. Ten healthy volunteers performed cyclic elbow flexion/extension movements at maximum speed for 2 min after injection of (1) hypertonic (painful) saline in the biceps brachii, (2) hypertonic saline in both biceps brachii and triceps brachii, and (3) isotonic (nonpainful) saline in the biceps brachii muscle. Surface electromyographic (EMG) signals were collected from the upper trapezius, biceps brachii, triceps brachii, and brachioradialis muscles (to estimate EMG amplitude) and with an electrode arrays from biceps brachii (to estimate muscle fiber conduction velocity [CV]). In all conditions, the acceleration of the movement decreased throughout the exercise, and kinematic parameters were not altered by pain. With respect to the control condition, pain induced a decrease of the biceps brachii (mean +/- SE, -23+/-4%) and brachioradialis (-10+/-0.4%) integrated EMG (IEMG) in the beginning of the exercise, and an increase (45+/-3.5%) of the upper trapezius IEMG at all time points during the exercise. The biceps brachii IEMG decreased over time during the nonpainful exercises (-11+/-0.6%) while it remained constant in the painful condition. Biceps brachii CV decreased during painful conditions (-12.8+/-2.2%) while it remained constant during the nonpainful condition. In conclusion, muscle pain changes the motor control strategy to sustain the required dynamic task both in the relative contribution between synergistic muscles and in the motor unit activation within the painful muscle. Such a changed motor strategy may be highly relevant in models of occupational musculoskeletal pain conditions.
本研究调查了肌肉疼痛对动态运动期间肌肉激活策略的影响。十名健康志愿者在肱二头肌注射（1）高渗（疼痛）盐水、（2）肱二头肌和肱三头肌均注射高渗盐水以及（3）肱二头肌注射等渗（无痛）盐水后，以最大速度进行2分钟的周期性肘部屈伸运动。从斜方肌上部、肱二头肌、肱三头肌和肱桡肌采集表面肌电图（EMG）信号（以估计EMG幅度），并从肱二头肌用电极阵列采集信号（以估计肌肉纤维传导速度[CV]）。在所有情况下，运动过程中运动加速度均下降，且运动学参数未因疼痛而改变。与对照条件相比，疼痛在运动开始时导致肱二头肌（平均值±标准误，-23±4%）和肱桡肌（-10±0.4%）的积分肌电图（IEMG）降低，且在运动期间的所有时间点斜方肌上部IEMG均增加（45±3.5%）。在无痛运动期间肱二头肌IEMG随时间下降（-11±0.6%），而在疼痛条件下保持不变。在疼痛条件下肱二头肌CV下降（-12.8±2.2%），而在无痛条件下保持不变。总之，肌肉疼痛会改变运动控制策略，以维持所需的动态任务，这在协同肌肉之间的相对贡献以及疼痛肌肉内的运动单位激活方面均如此。这种改变的运动策略在职业性肌肉骨骼疼痛状况模型中可能高度相关。
