Influence of Scapular Position on the Core Musculature Activation in the Prone Plank Exercise

Abstract

Prone plank is a widely used exercise in core stability training. Research has shown that pelvic tilt plays an important role on the electromyographic (EMG) activation of core musculature. However, the influence of scapular position on EMG activation is currently unknown. Therefore, this study evaluated the influence of scapular position on the core muscles during a prone plank. Surface EMG of the rectus abdominis (RA), external oblique (EO), internal oblique (IO), and erector spinae (ES) was collected in 15 participants (10 men and 5 women). Four variations of the prone plank were evaluated: scapular abduction with anterior (ABANT) and posterior (ABRET) pelvic tilt; and scapular adduction with anterior (ADANT), and posterior (ADRET) pelvic tilt. Individual muscle EMG and overall EMG for each plank exercise was analyzed. Joint positions were controlled with a 2D kinematic analysis. Ratings of perceived exertion (RPE) were also registered. The ADRET resulted in higher overall EMG activity compared with ABANT (p = 0.04) and ADANT (p = 0.04). Moreover, ADRET resulted in greater EMG activity compared with ADANT, ABANT, and ABRET for EO (p = 0.000; p = 0.000; p = 0.035), IO (p = 0.000; p = 0.000; p = 0.005), and ES (p = 0.019; p = 0.001; p = 0.014). Regarding RA, ADRET was significantly higher compared with ADANT (p = 0.002) and ABANT (p = 0.005). Finally, ADRET provoked a higher RPE compared with ABANT (p = 0.000), ABRET (p = 0.001), and ADANT (p = 0.015). These findings demonstrate the influence of the scapular and pelvic position on the EMG response of the core muscle groups analyzed in this study, and highlight the greater contribution of these muscles to the postural stabilizing demands during posterior pelvic tilt positions, particularly when the scapulae are in adduction.