The effects of dry needling on muscle blood flow of the infraspinatus in individuals with shoulder pain



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The presence of myofascial trigger points (MTrPs) has been associated with the chronicity of shoulder pain. In the past decade, dry needling (DN) has been used in physical therapy practice to treat MTrPs with favorable outcomes. Impaired blood flow has been proposed as an underlying pathophysiologic mechanism of MTrP in patients with shoulder-neck pain. To date, although DN has been shown to change blood flow in healthy individuals, no studies have examined whether DN would change blood flow in individuals with shoulder pathology. The primary purpose of this study was to evaluate the effects of DN on the blood flow of the infraspinatus muscle in individuals with shoulder pain. The secondary purpose of this study was to examine the effects of DN on sensitivity to pressure of the infraspinatus muscle and shoulder range of motion (ROM) in individuals with shoulder pain. This study utilized a sham-controlled design. Forty individuals with nonspecific shoulder pain and the presence of at least one MTrP in the infraspinatus muscle were randomly assigned to a real DN group or a sham DN group. Outcome measures, including blood flow parameters, pressure pain threshold (PPT), and ROMs of shoulder internal rotation and external rotation, were collected before and immediately after a single session of DN. Blood flow parameters included peak systolic velocity (PSV), end diastolic velocity (EDV), resistive index (RI), and pulsatile index (PI). The ANOVA results showed that the real DN group had a significant decrease in PSV and increases in ROMs of shoulder internal and external rotation after DN, but no significant differences in other outcome measures between the two DN groups. The results indicated that participants who received real DN exhibited a significant reduction in PSV, indicative of an improvement in blood flow to the infraspinatus. Reduced blood flow after DN suggests that DN may have vasodilation effects, leading to relief of capillary compression. DN also may affect muscle relaxation, thus contributing to motion improvement. These results may provide clinicians with further evidence for the use of DN for individuals with shoulder pain.



Biology, Physiology