Abstract: OBJECTIVE: To evaluate the sternocleidomastoid and the descending portion of the trapezius muscles in terms of electromyographic activity and pressure pain threshold in women with chronic cervical pain after acupuncture treatment.METHODS: Twenty-five women, aged 18-50 years[(31±3) years], with chronic neck and temporomandibular disorder participated in the study. The electromyographic activity of the sternocleidomastoid muscle and the descending portion of the trapezius muscle were recorded at rest, during shoulder elevation,(left and right) rotation of the neck and crucifix position. Maximum voluntary contraction was used to normalize the electromyographic activity data. The points used for acupuncture were Jiache(ST 6), Xiaguan(ST 7), Quanliao(SI 18),Tinggong(SI 19), Yifeng(TE-17), Fengchi(GB 20),Renzhong(GV 26), Yangbai(GB-14), and points of the lower and upper limbs: Tai chong(LV 3), Zusanli(ST 36), Sanyinjiao(SP 6), Kunlun(BL 60), He Gu(LI4) and Yanglingquan(GB 34). The treatment course was 10 sessions, 30 min long per session, and twice a week. The final electromyographic activity and pressure pain threshold data collection were performed 15 d after treatment completion.RESULTS: The normalized electromyographic activity and pressure pain threshold data were tabulated and submitted to statistical analysis using t-test(P < 0.05). Significant difference was observed during shoulder elevation for the left trapezius muscle,during neck rotation from the right side to the left,and pressure pain threshold for the trapezius and sternocleidomastoid muscles, bilaterally, after the acupuncture treatment.CONCLUSION: The acupuncture treatment improved the neck muscles in terms of electromyographic activity and increased the tolerance to chronic pain in women.

Key words: Acupuncture, Chronic pain, Neck muscles, Electromyography, Pain threshold