NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, The University of Queensland, St. Lucia, Brisbane, QLD, 4072, Australia,
Eur J Appl Physiol. 2014 May;114(5):1057-65. doi: 10.1007/s00421-014-2840-y. Epub 2014 Feb 11.
Although it appears obvious that we change movement behaviors to unload the painful region, non-systematic motor adaptations observed in simple experimental tasks with pain question this theory. We investigated the effect of unilateral pain on performance of a bilateral plantarflexion task. This experimental task clearly allowed for stress on painful tissue to be reduced by modification of load sharing between legs.
Fourteen participants performed a bilateral plantarflexion at 10, 30, 50 and 70 % of their MVC during 5 conditions (Baseline, Saline-1, Washout-1, Saline-2, Washout-2). For Saline-1 and -2, either isotonic saline (Iso) or hypertonic saline (Pain) was injected into the left soleus.
The force produced by the painful leg was less during Pain than Baseline (range -52.6 % at 10 % of MVC to -20.1 % at 70 % of MVC; P < 0.003). This was compensated by more force produced by the non-painful leg (range 18.4 % at 70 % of MVC to 70.2 % at 10 % of MVC; P < 0.001). The reduction in plantarflexion force was not accompanied by a significant decrease in soleus electromyographic activity at 10 and 30 % of MVC. Further, no significant linear relationship was found between changes in soleus electromyographic activity and change in plantarflexion force for the painful leg (with the exception of a weak relationship at 10 % of MVC, i.e., R (2) = 0.31).
These results show that when the nervous system is presented with an obvious solution to decrease stress on irritated tissue, this option is selected. However, this was not strongly related to a decrease in soleus (painful muscle) activity level.
尽管我们改变运动行为以减轻疼痛区域似乎是显而易见的，但在有疼痛的简单实验任务中观察到的非系统性运动适应质疑了这一理论。我们研究了单侧疼痛对双侧跖屈任务表现的影响。这个实验任务显然允许通过改变腿部之间的负荷分担来减轻疼痛组织的压力。
14 名参与者在 5 种条件下（基础、盐水 1、冲洗 1、盐水 2、冲洗 2）以 10%、30%、50%和 70%的最大等长收缩（MVC）进行双侧跖屈。对于盐水 1 和 2，左比目鱼肌注射等渗盐水（Iso）或高渗盐水（Pain）。
在 Pain 时，疼痛腿产生的力小于基础（范围为 10%MVC 时为-52.6%至 70%MVC 时为-20.1%；P<0.003）。这是由非疼痛腿产生的更大力量（范围为 70%MVC 时为 18.4%至 10%MVC 时为 70.2%；P<0.001）补偿的。跖屈力的降低并没有伴随着 10%和 30%MVC 时比目鱼肌肌电图活动的显著下降。此外，在疼痛腿的比目鱼肌肌电图活动变化与跖屈力变化之间没有发现显著的线性关系（除了在 10%MVC 时存在较弱的关系，即 R（2）=0.31）。
这些结果表明，当神经系统面临明显的减轻刺激组织压力的解决方案时，会选择这种方案。然而，这与比目鱼肌（疼痛肌肉）活动水平的降低并没有很强的关系。
