## 3 Results
The variability among effects is presented in the forest plot in Figure 4.  
\begin{table}
\begin{tabular}{l l l l l l l} \hline \hline
**Group** & **Studies** & **SMD** & **SMD (95\% CI)** & \(\mathbf{I^{2}}\) & **t** & \(\boldsymbol{p}\)**-Value** \\ \hline
**Grip Width** & & & & & & & \\ _Normal vs. narrow_ & & & & & & & \\ _Lavicular_ & [66], [23]\({}^{1,2,4}\) & \(-\)0.38 & \(-\)1.85; 1.10 & 59.6 & \(-\)0.82 & 0.473 \\ Sternal & [23]\({}^{5,6,8}\), [57; 60] & 0.49 & \(-\)0.15; 1.14 & 32 & 2.12 & 0.101 \\
**Angle of inclination** & & & & & & \\ _Horizontal vs. declined_ & & & & & & \\ _Sternal_ & [50]\({}^{4,8}\), [35]\({}^{4,6}\), [53]\({}^{3,6}\) & \(-\)0.75 & \(-\)1.85 a 0.36 & 74.9 & \(-\)1.74 & 0.143 \\ Clavicular & [50]\({}^{2,6}\), [35]\({}^{2}\), [53]\({}^{8,11}\) & 2.03 & \(-\)2.03; 6.53 & 90.6 & 1.46 & 0.218 \\ _Horizontal vs. inclined_ & & & & & & \\ _Sternal_ & [50]\({}^{3,7}\), [35]\({}^{3,5}\), [53]\({}^{1,2,4,5,12,13}\) & 1.80 & 0.40;3.19 & 87.6 & 2.87 & 0.017 \\ Clavicular & [50]\({}^{1,5}\), [35]\({}^{1}\), [53]\({}^{7,9}\) & 0.36 & \(-\)3.03; 3.74 & 92.6 & 0.26 & 0.81 \\
**Stability condition** & & & & & & \\ _Stable vs. unstable_ & & & & & & \\ _Concentric_ & [51]\({}^{1,2}\), (52 1.2), (41.2) & \(-\)0.18 & \(-\)0.35; \(-\)0.03 & \(-\)0 & \(-\)3.02 & 0.029 \\ Eccentric & [51]\({}^{3,4}\), (52 3), (41 3.4) & 0.02 & \(-\)0.34; 0.37 & \(-\)0 & 0.12 & 0.911 \\ Complete & [59]\({}^{1,2}\), [59]\({}^{2}\), [54]\({}^{1,2}\), & \(-\)0.047 & \(-\)0.29; 0.20 & 8.3 & \(-\)0.43 & 0.675 \\
**Type of exercise** & & & & & & \\ _Bench press vs. other variants type_ & & & & & & \\ _Sternal_ & [30]\({}^{1-18}\), [39; 50]\({}^{2,4}\), [60]\({}^{1-4}\) & 4.04 & 1.74; 6.35 & 98 & 3.62 & 0.001 \\ Clavicular & & [50]\({}^{13,5}\), [58; 62] & 4.53 & \(-\)4.22; 13.27 & 94.9 & 1.65 & 0.198 \\ _Bench Press vs. all push up variants_ & & & & & & \\ _Bench Press vs. other variants no push up_ & & & & & & \\ _Bench Press vs. all push up variants_ & & & & & & \\ _Bench Press vs. other variants no push ups_ & & & & & & \\ _Send_ & [30]\({}^{1-5,7-11,13-17}\), [48; 62] & 3.01 & 0.46; 5.57 & 98.4 & 2.52 & 0.023 \\
**Type of exercise** & & & & & & \\ _Bench press vs. other variants type_ & & & & & & \\ _Sternal_ & [30]\({}^{1-18}\), [39; 50]\({}^{2,4}\), [60]\({}^{1-4}\) & 4.53 & 1.40; 7.65 & 95.9 & 3.09 & 0.001 \\ Clavicular & & [50]\({}^{13,5}\), [58; 62] & 4.53 & \(-\)4.22; 13.27 & 94.9 & 1.65 & 0.198 \\ _Bench Press vs. all push up variants_ & & & & & & \\ _Bench Press vs. other variants no push ups_ & & & & & & \\ _Bench Press vs. all push up variants_ & & & & & & \\ _Bench Press vs. other variants no push ups_ & & & & & & \\ _Send_ & [30]\({}^{1-5,7-11,13-17}\), [48; 62] & 3.01 & 0.46; 5.57 & 98.4 & 2.52 & 0.023 \\
**Type of exercise** & & & & & & \\ _Bench press vs. other variants type_ & & & & & & \\ _Send_ & [30]\({}^{6,12,18}\), [50]\({}^{1-4}\), [55]\({}^{5,58}\), [58], [60]\({}^{1-4}\), [55]\({}^{5,58}\), [60]\({}^{1-4}\), [55]\({}^{5,58}\), [60]\({}^{1-4}\), [61]\({}^{1,2}\), [55]\({}^{5,58  
In relation to the analysis comparing the activation of the pectoral muscle in a stable situation vs. an unstable situation, Figure 5A shows the analysis for the activation of the pectoral muscle in the concentric phase, Figure 5B for the eccentric phase and Figure 5C for all joint action. Six studies compare the original option of BP with an unstable exercise variant [50; 51; 54; 56; 59; 64]. No difference in chest activation was shown for eccentric phase or complete exercise; however, an unstable condition produced significantly more activation during the concentric phase than performing the exercise in a stable situation (SMD = \(-\)0.18; 95%CI \(-\)0.33 to 3.74; \(p\) = 0.029). In relation to the analysis on the activation of the pectoralis, comparing the PB exercise with any other exercise, in Figure 6A the activation of the clavicular pectoralis is shown and in Figure 6B the activation of the sternal pectoralis.