There are examples of common clinical conditions that clinical signals are related to alterations in muscle tone, including myofascial pain syndrome. OBJECTIVE: to discuss the application of surface EMG to detect effect of miofascial trigger point (MTP) on neuromuscular activity at rest and maximum voluntary contraction of the trapezoid muscle. METHODS: Fifty-six subjects participated in the study and were divided into two groups: Healthy group (n = 28), with subjects who necessarily did not present MTP, and PAIN group (n = 28), with subjects who necessarily had MTP. RESULTS: The EMG signal was significantly higher in the muscle portion containing MTP than in the healthy muscle portion in PAIN group and than Healthy group (26,56 ± 44,54, 5,39 ± 6,29 and 1,56 ± 0,76, respectively, p = 0,0001) during rest. In addition, a higher intensity of the EMG signal was observed in subjects with active MTP than in latent MTP (17,85 ± 30,25 versus 3,74 ± 1,52, p = 0,04. Besides, the subjects who presented autonomic phenomena had higher EMG signal than those who had no autonomic phenomena (16,78 ± 28,44 versus 3,51 ± 3,65. CONCLUSION: The surface EMG is reliable to measure the muscular activity of the MTP, mainly at rest condition.
Electromyography (EMG); myofascial trigger point (mtp); muscle tone
