fa آسیب شناسی ورزشی و حرکات اصلاحی Sport injury and corrective exercises پژوهشي Research <b>Purpose:</b> The purpose of the present study was to evaluate the association of ultrasonography findings with pain, range of motion, disability, and pressure pain threshold in patients with upper trapezius myofascial pain syndrome.&nbsp; <div><b>Methods:</b> A total of 60 subjects with upper trapezius myofascial pain syndrome (mean age: 25.90&plusmn;4.47 y mean weight: 63.53&plusmn;7.76 kg mean height: 166.55&plusmn;5.65 cm and pain duration: 9.75&plusmn;6.04 month) were selected with nonprobability convenient sampling method and examined. After methodological study, all participants were evaluated regarding their pain, cervical range of motion, functional disability, pressure pain threshold (PPT), maximum muscle and fascia thickness as well as strain ratio by the following instruments, respectively: visual analogue scale, goniometry, neck disability index, algometer, sonography, and sonoelastography.&nbsp;</div> <div><b>Results:</b> The ICC values for intra- and inter-examiner reliability of variables were high to very high (0.72-0.96). The correlation coefficients between pain (r=0.22), range of motion (r=0.11), disability (r=0.13), PPT (r=0.32), and maximum thickness of muscle were moderate. The correlation coefficients between pain (r=0.13), range of motion (r=0.23), disability (r=0.17), PPT (r=0.23) and maximum thickness of fascia were low. The correlation coefficients between pain (r=-0.65), range of motion (r=-0.23), disability (r=-0.41), PPT (r=0.71) were high. Values of &beta; for strain ratio and pain were -0.35 (P=0.01), range of motion, -0.14, (P=0.03) disability, -0.19, (P=0.03) and PPT, 0.41 (P<0.001).&nbsp;</div> <div><b>Conclusion: </b>Strain ratio of upper trapezius muscle in subjects with myofascial pain syndrome has strong correlation with pain, disability, and PPT. However, maximum muscle thickness and fascia of the upper trapezius are correlated with these variables poorly. PPT is the highly correlated factor with strain ratio.</div> Myofascial pain syndrome, Sonography, Disability, Strain ratio 221 227 http://ptj.uswr.ac.ir/browse.php?a_code=A-10-245-1&slc_lang=fa&sid=1 Behnam Akhbari Behnamakhbari@gmail.com No Organization Mahyar Salavati Mahyarsalavati@gmail.com No Organization Ismail Ebarahimi Ebrahimi.pt@gmail.com No Organization Kamran Ezzati Ez_kamran@yahoo.com Yes Department of Physiotherapy, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. Hamidreza Haghighat Khah Drhrhaghighatkhah@yahoo.com No Organization