Comparison of Pectoralis Major and Serratus Anterior Muscle Activities During Different Push-Up Plus Exercises in Subjects With and Without Scapular Winging

The purpose of this study was to investigate differences between males with and without scapular winging in the electromyographic (EMG) amplitude and activity ratio between the pectoralis major (PM) and serratus anterior (SA) during 3 push-up plus exercises; the standard push-up plus (SPP), the knee push-up plus (KPP), and the wall push-up plus (WPP), and to determine which exercise induced the lowest PM/SA ratio in each group. Twenty-eight males took part in this study (13 scapular winging group, 21.8 ± 2.1 year; 15 control group, 23.3 ± 2.0 year). Surface EMG of the PM, SA and activity ratio between the PM and SA were collected during 3 push-up plus exercises, and the EMG data were expressed as a percentage of the reference voluntary contraction (% RVC). The normalized PM activity for subjects in scapular winging group was significantly higher than that in the control group (79.16±6.65 vs. 39.66±6.19 %RVC, p<.05). The normalized SA activity was significantly lower in scapular winging group compared to the control group (39.80±4.09 vs. 56.28±3.81 %RVC, p<.05), and was significantly reduced in the following order: SPP > KPP > WPP; 77.09±5.12 > 39.48±3.38 > 27.55±3.07 %RVC, p<.016). The PM/SA EMG ratio was significantly higher in the scapular winging group compared to that in control group across all exercises, and was significantly lower during SPP than that during KPP and WPP in both groups (1.13±0.58 vs. 0.53±0.25 for SPP, 3.50±2.07 vs. 0.92±0.63 for KPP, 4.04±3.13 vs. 1.19±0.66 for WPP, p<.016). Greater PM activity was seen in the scapular winging group, and the SPP is an ideal exercise for subjects with scapular winging where maximum SA activation with minimal PM activation is desired.