Abstract: BACKGROUND: Traditional monotherapy (such as medication and physical therapy) for neck and shoulder myofascial pain syndrome has high recurrence rates and limited improvement in deep myofascial adhesions. Shock wave therapy combined with facilitated stretching may be more effective in restoring muscle function through mechanical and metabolic regulation, but there is currently a lack of dynamic assessment evidence on neuromuscular activation characteristics in patients with different pain levels.
OBJECTIVE: To observe the effect of shockwave therapy combined with facilitated stretching on the electromyographic characteristics of the upper trapezius muscle in patients with varying degrees of neck and shoulder pain. 
METHODS: A total of 120 patients with neck and shoulder pain admitted to the Second Affiliated Hospital of Hainan Medical University from January 2019 to December 2023 were selected as the research subjects and randomly divided into a control group (60 cases) and an observation group (60 cases). The observation group was treated with shock wave therapy combined with facilitated stretching, while the control group was treated with facilitated stretching alone. All treatments were given thrice a week for 6 consecutive weeks. Both groups underwent tests for neck pain and disability index, visual analogue scale for subjective pain assessment, and surface electromyography before and after treatment. 
RESULTS AND CONCLUSION: (1) The clinical efficacy rate of patients with different pain levels in the observation group was higher than that in the control group (P < 0.05). (2) Compared with before treatment, both groups showed a downward trend in neck pain and disability index and visual analogue scale scores after treatment, with the observation group being lower than the control group (P < 0.05); the shoulder joint function scores (Constant-Murley scores) in both groups showed an upward trend after treatment, with the observation group being higher than the control group (P < 0.05). (3) The resting absolute and relative values of surface electromyography showed a downward trend after treatment, with the observation group being lower than the control group (P < 0.05); the frequency domain indicators of muscle fatigue, median frequency and mean power frequency, increased after treatment, with the observation group being higher than the control group (P < 0.05). (4) The analysis of electromyographic indicators using the generalized estimating equation model at different time points, in different groups, and with different levels of pain showed that the therapeutical effect of the observation group was superior to that of the control group for patients with different pain levels. (5) There was a negative correlation between the resting absolute and relative values of surface electromyography and visual analogue scale (P < 0.05), and between mean power frequency and median frequency with visual analogue scale score (P < 0.05). In conclusion, shock wave therapy combined with facilitated stretching can effectively alleviate muscle tension in the upper trapezius of patients with varying degrees of neck and shoulder pain, and thereby relieve shoulder pain.

Key words: neck and shoulder pain, shock wave therapy, facilitated stretching, electromyographic characteristics, generalized estimating equation