Comparison of pectoralis major and serratus anterior muscle activities during different push-up plus exercises in subjects with and without scapular winging.

To examine the differences between men 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: (a) the standard push-up plus (SPP), (b) the knee push-up plus (KPP), and (c) the wall push-up plus (WPP), and to determine which exercise induced the lowest PM/SA ratio in each group. Twenty-eight men participated in this study (13 scapular winging group: age, 21.8 ± 2.1 years; 15 control group: age, 23.3 ± 2.0 years). 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 the scapular winging group was significantly greater than that in the control group (79.16 ± 6.65 %RVC vs. 39.66 ± 6.19 %RVC, p ≤ 0.05). The normalized SA activity was significantly lower in the scapular winging group compared with the control group (39.80 ± 4.09 %RVC vs. 56.28 ± 3.81 %RVC, p ≤ 0.05) and was significantly decreased in the following order: SPP > KPP > WPP; 77.09 ± 5.12 %RVC > 39.48 ± 3.38 %RVC > 27.55 ± 3.07 %RVC, p < 0.016). The PM/SA EMG ratio was significantly greater in the scapular winging group compared with that in the 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 < 0.016). Greater PM activity was found in the scapular winging group, and the SPP is an optimal exercise for subjects with scapular winging, where maximum SA activation with minimal PM activation is desired.