Changes in electromyographic activity in infraspinatus due to dry needling of its myofascial trigger points

M.Tech.Objective: The purpose of this study was to determine the immediate effects of dry needling therapy (DNT) on the surface electromyograph (sEMG) of infraspinatus muscle and thereby assess the possible effect of DNT on muscle function. Study Design: 100 patients were examined for painful myofascial trigger points (MTrPs) within the infraspinatus muscle. Surface EMG measurements were performed using a bipolar electrode configuration before treatment and immediately after treatment. The sEMG measurements that were taken were average sEMG microvolts during maximum voluntary contraction (MVC), average sEMG peak microvolts during MVC, average sEMG microvolts during rest and average sEMG minimum microvolts during rest. The differences in these measurements were statistically analyzed by STATKON at the University of Johannesburg. The difference in the study subgroup where a latent twitch response (LTR) was elicited and the study subgroup where there was visible bleeding was analyzed separately. Setting: Patients in the study were examined and treated at the University of Johannesburg’s Chiropractic day clinic. Subjects: 100 patients volunteered for the study and were randomly separated into a control and a study group. There were 50 patients in the control group and 50 patients in the study group. All patients had a painful MTrP in infraspinatus muscle, were between the ages of 18-45, had a BMI of less than 30, had no needle phobia and had activity levels of more than 3 hours a week. Method: All patients were examined for painful MTrP within the infraspinatus muscle. All patients performed a MVC pre treatment and a MVC post treatment. The average MVC was calculated by performing 5 separate isometric maximum voluntary contractions of the infraspinatus muscle. Between each contraction the patient fully relaxed the infraspinatus muscle. The contractions were of 5 seconds duration each and the rest periods were of 10 seconds duration each. Thus an average baseline sEMG was established for the patient. DNT was then performed on the 50 patients in the study group. Only the most painful MTrP within the infraspinatus muscle of the patients in the study group was treated for a total of 7minutes