Within-Subject Changes in Shoulder Girdle Muscle Activation After Soft Tissue Mobilization of the Upper Trapezius

The purpose of this study was to investigate the effect of the integrated neuromuscular inhibition technique (INIT) of the upper trapezius (UT) on shoulder muscle activity in chronic shoulder pain.

Twenty-two patients (mean age 42.5 ± 16.07) with chronic unilateral shoulder pain with UT myofascial trigger points (MTrPs) (n = 27) and scapular dyskinesis received a single session of INIT (∼15 minutes for each MTrP). The pain on the visual analog scale, along with surface electromyographic activity, maximum voluntary contraction in % (in arm raising and lowering in scapular plane), and pressure pain threshold (PPT) of 5 girdle muscles UT, lower trapezius, serratus anterior, middle deltoid, and infraspinatus were measured before and immediately after treatment. Wilcoxon signed-rank test was used for analysis (at α ≤ 0.05).

Muscle activity of all the muscles, especially the lower trapezius, was reduced during arm raising in the scapular plane (76.69%-71.14% [p = 0.003]). UT activity decreased during arm lowering also (56.70%-45.99% [p ˂ 0.001]). The intensity of shoulder pain reduced (50.50 mm to 22 mm, [p ˂ 0.001]), and PPT values of all 5 muscles improved post-treatment.

The findings of this study provide preliminary evidence for the application of a single session of INIT on UT MTrPs in reducing activity in the scapular muscles, improving shoulder pain, and PPT in chronic unilateral shoulder pain.