## 4 Discussion
\begin{table}
\begin{tabular}{l c c c c c c} \hline  & & **Pre** & **Post** & **t (_p_)** & **Change** & **Cohen’s d 1** \\ \hline \multirow{4}{*}{UT} & EG & 22.73 \(\pm\) 9.88 & 19.57 \(\pm\) 10.16 & 2.483 (0.025 \({}^{\circ}\)) & \(-\)3.16 \(\pm\) 5.08 & 0.62 \\  & CG & 20.71 \(\pm\) 10.05 & 18.64 \(\pm\) 9.53 & 2.154 (0.048 \({}^{\circ}\)) & \(-\)2.07 \(\pm\) 3.84 & 0.54 \\  & t (_p_) & 0.573 (0.571) & & & \(-\)0.683 (0.500) & \\  & **Cohen’s d 1** & & & & 0.24 & \\ \hline \multirow{4}{*}{MT} & EG & 15.66 \(\pm\) 6.94 & 20.36 \(\pm\) 8.79 & \(-\)3.969 (0.011 \({}^{\circ}\)) & 4.70 \(\pm\) 4.74 & 0.99 \\  & CG & 13.03 \(\pm\) 6.03 & 15.42 \(\pm\) 6.97 & \(-\)2.293 (0.037 \({}^{\circ}\)) & 2.39 \(\pm\) 4.18 & 0.57 \\  & **Cohen’s d 1** & & & & 0.52 & \\ \hline \multirow{4}{*}{LT} & EG & 24.96 \(\pm\) 11.51 & 32.50 \(\pm\) 17.05 & \(-\)2.971 (0.010 \({}^{\circ}\)) & 7.53 \(\pm\) 10.14 & 0.74 \\  & CG & 19.63 \(\pm\) 11.32 & 26.35 \(\pm\) 13.97 & \(-\)2.847 (0.012 \({}^{\circ}\)) & 6.72 \(\pm\) 9.44 & 0.71 \\  & **t (_p_) & 1.321 (0.196) & & & 0.236 (0.815) & \\  & **Cohen’s d 1** & & & & 0.08 & \\ \hline \multirow{4}{*}{SA} & EG & 32.30 \(\pm\) 10.41 & 41.11 \(\pm\) 15.89 & \(-\)2.422 (0.029 \({}^{\circ}\)) & 8.80 \(\pm\) 14.54 & 0.61 \\  & CG & 27.46 \(\pm\) 9.06 & 34.03 \(\pm\) 13.07 & \(-\)2.340 (0.033 \({}^{\circ}\)) & 6.58 \(\pm\) 11.24 & 0.59 \\ \cline{1-1}  & t (_p_) & 1.405 (0.170) & & & 0.483 (0.632) & \\ \cline{1-1}  & **Cohen’s d 1** & & & & 0.17 & \\ \hline \end{tabular}  
* UT: upper trapezius MT: middle trapezius LT: lower trapezius SA: serratus anterior*_p_ < 0.05. 1 Mean \(\pm\) standard deviation.  
\end{table} 
Table 3: Comparison of the muscle activity of the UT, MT, LT, and SA in two groups. After 4 weeks of exercise, the activity of the UT muscle decreased, while the activities of the MT, LT, and SA muscles increased; there were significant differences in both groups regarding the values before and after the experiment. Elevation of the scapula with arm elevation is accomplished through activation and coupling of the SA and LT with the UT and rhomboids [7]. As the amount of upward rotation, external rotation, and backward inclination of the shoulder blades decrease, internal rotation and forward inclination increase. Hyperactivity of the UT muscle results in reduced MT and LT muscle activation in addition to insufficient SA muscle function; for example, reduced activity of the SA and LT muscles, thus reducing the upward rotation of the scapula. Meanwhile, decreased activity of the MT muscle leads to decreased posterior tilt inclination or increased anterior tilt of the scapula [24; 34]. Scapular stabilizer muscles, such as the MT, LT, and SA, play an important role in controlling the normal movement of the scapula during arm elevation [9; 35; 36]. It has been reported that, with excessive cervical extension, thoracic flexion, and scapula anterior tilt and downward rotation, the activity of the UT muscle is increased and that of the SA muscle is decreased [13; 21]. The SA and LT muscle activity decreased in subjects with scapular internal rotation due to overactivation of the UT muscle [37]. Previous research has demonstrated that corrective exercises and scapular-stabilization exercises can decrease activity in the UT muscle, while simultaneously enhancing activity in the SA and both the MT and LT muscles, proving to be effective [21; 38; 39]. As both groups performed scapular-stabilization exercises of the same duration and intensity, there were differences in muscle activity between the two groups before and after the experiment. Notably, there were no significant differences in muscle activity between the two groups. We considered this to be for two reasons: First, the scapular muscles--as the auxiliary muscles of respiration--can activate the activity of the SA muscle when strengthening respiratory training. Decreased activity of the UT muscle and increased activity of the SA muscle reduce abnormal muscle compensation [40; 41]. [PERSON] et al.