## 3 Results
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Mechanical** & \multirow{2}{*}{**NSP (\(\textit{n}\) = 20)**} & \multirow{2}{*}{**RSP (\(\textit{n}\) = 20)**} & **Calculated** & \multirow{2}{*}{**d (LCI, UCD)**} & \multirow{2}{*}{\(\textit{p}\)**} \\
**Parameters** & & & & & \\ \hline \multicolumn{6}{c}{Tone (Hz)} \\ UT & 18.6 \(\pm\) 4.7 & 14.7 \(\pm\) 1.8 & t (38) = 3.5 & 1.1 (0.4 to 1.8) & 0.002 \\ MT & 13.9 \(\pm\) 2.3 & 18.2 \(\pm\) 6.0 & t (38) = \(-\)3.0 & 1.0 (\(-\)1.6 to \(-\)0.3) & 0.006 \\ PM & 20.1 \(\pm\) 4.0 & 12.4 \(\pm\) 3.1 & t (38) = 6.9 & 2.2 (1.4 to 3.0) & \textless{}0.001 \\ PD & 16.0 \(\pm\) 2.2 & 18.0 \(\pm\) 3.8 & t (38) = \(-\)1.9 & 0.6 (\(-\)1.2 to 0.0) & 0.060 \\  & \multicolumn{6}{c}{Stiffness (N/m)} \\ UT & 350.4 \(\pm\) 72.0 & 323.8 \(\pm\) 71.4 & t (38) = 1.1 & 0.3 (\(-\)0.2 to 0.9) & 0.248 \\ MT & 282.0 \(\pm\) 62.9 & 337.0 \(\pm\) 111.9 & t (38) = \(-\)1.9 & 0.6 (\(-\)1.2 to 0.0) & 0.065 \\ PM & 235.9 \(\pm\) 11.7 & 201.1 \(\pm\) 45.8 & t (38) = 3.2 & 1.0 (0.3 to 1.6) & 0.003 \\ PD & 309.9 \(\pm\) 70.7 & 348.15 \(\pm\) 68.7 & t (38) = \(-\)1.7 & 0.5 (\(-\)1.1 to 0.0) & 0.046 \\  & \multicolumn{6}{c}{Elasticity (log DEC)} \\ UT & 1.2 \(\pm\) 0.3 & 1.6 \(\pm\) 0.2 & t (38) = \(-\)3.8 & \(-\)1.2 (\(-\)1.8 to \(-\)0.5) & 0.001 \\ MT & 1.7 \(\pm\) 0.3 & 1.0 \(\pm\) 0.08 & t (38) = 9.4 & 2.9 (2.0 to 3.9) & \textless{}0.001 \\ PM & 1.1 \(\pm\) 0.5 & 0.9 \(\pm\) 0.2 & t (38) = 1.5 & 0.4 (\(-\)0.15 to 1.1) & 0.143 \\ PD & 1.5 \(\pm\) 0.1 & 1.4 \(\pm\) 0.6 & t (38) = 1.0 & 0.3 (\(-\)0.2 to 0.9) & 0.302 \\ \hline \hline \end{tabular} All values are shown in mean \(\pm\) SD. D—[PERSON]’s effect size; NSP—normal shoulder posture; RSP—rounded shoulder posture; ICI and UCI—lower and upper (95%) confidence interval, respectively; SD—standard deviation; UT—upper trapezius; MT—middle trapezius; PM—pectorails major; PD—posterior deltoid.  
\end{table} 
Table 2: Mechanical parameters of RSP. are (M = 20.1, SD = 4.0) and HSP group are (M = 14.0, SD = 4.8), t (38) = 4.3, \(p\leq 0.001\), and PD scores for the NSP group are (M = 16.0, SD = 2.2) and HSP group are (M = 22.2, SD = 5.0), t (38) = \(-\)4.9, \(p\leq 0.001\), but UT is not statistically significant, \(p=0.731\). Hence, the test revealed that the NSP and HSP groups do have an effect on the muscle tone of MT, PD, and PM; however, they exhibit no effect on the UT muscles. As for stiffness, all muscles are statistically significant (\(p<0.05\)). The UT scores for the NSP group are (M = 350.4, SD = 72.0) and HSP group are (M = 278.6, SD = 69.6), t (38) = 3.2, \(p=0.003\) and \(p<0.001\) for MT, PM, and PD muscles. This shows that the NSP and HSP groups had a significant impact on UT, MT, PM, and PD stiffness. Concerning elasticity, MT and PM are statistically significant (\(p<0.05\)). The MT scores for the NSP group are (M = 1.7, SD = 0.3) and HSP group are (M = 2.0, SD = 0.2), t (38) = \(-\)3.4, \(p=0.001\). In addition, the PM scores for the NSP group are (M = 1.1, SD = 0.6) and RSP group are (M = 1.6, SD = 0.1) t (38) = \(-\)3.1, \(p=0.005\). On the other hand, UT and PD are not statistically significant, \(p=0.0993\) and \(p=0.0.877\), respectively. Therefore, the results indicate that the NSP and RSP groups do have an effect on MT and PM, whereas they exhibit no effect on UT and PD muscles. In summary, these results show that among both NSP and RSP participants (Figure 2), the highest elasticity values were recorded in the PM muscle. Simultaneously, the highest tone values were observed in the MT muscle and the highest stiffness values in the PD muscle during RSP. The RSP participants showed considerable variations in the biomechanical characteristics of the muscles studied. Tone and stiffness were statistically significant in the UT and MT muscles, whereas elasticity was significant in the PM and PD muscles.