The Impact Of Pelvic Support On Scapular Muscles An Electromyography Study

Many scapular muscles are attached to the spine; therefore, alterations in spinal alignment might have a direct impact on shoulder and scapular positioning, and muscle activity. Clinicians use external support or stimuli to provide external trunk support and facilitate core stability. PURPOSE: This study aimed to investigate and compare muscle activity of the upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA) muscles during prone shoulder exercises, with/without pelvic belt support (PBS). METHODS: 30 healthy physically active participants (Tegner score of 5 and higher), were included (age: 23 ± 2.65 years, BMI: 22.2 ± 1.81 kg/m2). The UT, LT, and SA muscle activity was measured randomly against a fixed belt. Synchronously, isometric muscle strength was measured with an isometric dynamometer placed between the strap and the relevant body part. To provide pelvic support, individuals were strapped to the bed with a belt placed around their pelvis. UT and SA MVICs were measured in 1800 abduction in the prone position with/without PBS. LT MVIC was measured in the prone position with/without PBS and in the external rotation position with the arm at 1400 abduction. MVIC was given as % root mean square (RMS), and muscle strength as kg. Since the data were not normally distributed, Wilcoxon analysis was used. RESULTS: No significant difference was observed in muscle activity and muscle strength values during exercise by conditions (ps > 0.05) (Table 1). CONCLUSION: Muscle activity and strength did not change during prone shoulder exercises with the PBS. In clinical settings, pelvic stabilization with external support does not positively affect muscle activation, and therefore, prone shoulder exercises can be utilized without PBS. Table 1. - Muscle activity and Muscle Strength Values Condition 1400 abduction 1800 abduction Parameters Without PBS (X ± SD) With PBS(X ± SD) p Without PBS (X ± SD) With PBS(X ± SD) p UT (RMS%) 86 ± 44.7 84 ± 42.8 0.2 88 ± 43 91.9 ± 45.5 0.79 LT (RMS%) 71.7 ± 45.9 66.9 ± 39.7 0.15 68.9 ± 39.3 68.7 ± 39.5 0.2 SA (RMS%) 18.5 ± 25.5 22.4 ± 28.4 0.07 27.2 ± 27.3 31.7 ± 32.9 0.15 MS (kg) 12.73 ± 5 12.5 ± 4.8 0.5 12.8 ± 4.6 12.5 ± 3.7 0.8