## 4 Discussion  
Among various manual treatments for MFP associated with MTrPs, the most commonly used are compression technique, myofascalial release, acupressure, muscle energy technique, and specific soft tissue mobilization techniques [14]. However, manual treatments for MTrPs have varying degrees of effectiveness and it is hard to identify the most effective rehabilitation method for MTrPs. The presented study aims to analyze the acute effect of the compression technique on active maximum mouth opening and bioelectric masticatory muscle activity in young adult women with active myofascalial trigger points in the masseter muscles. To the best of our knowledge, this is the first study to evaluate the acute effects of CT in masticatory muscles with active MTrPs using sEMG. Although the increase in the active MMO values within the study group after CT was not statistically significant, a significant difference was observed only before CT between the study and control groups. For determination of impact on masticatory muscle activity, surface electromyography was applied, by using a BioEMG III device in resting mandibular position and during maximum voluntary clenching. The main finding of the presented study was that the resting bioelectrical activity of the MM muscles with active MTrPs after CT was significantly lower than before CT. Opposite interaction was found in bioelectric MM muscle activity during maximum voluntary contraction. A significant increase in RMS values during maximum voluntary clenching was demonstrated after the application of CT concerning the bioelectrical activity of the MM muscles. The above observations seem to be in line with the pain adaptation model, hypothesizing that pain leads to changes in muscle activity aiming to limit movement and to protect tissues against further injuries by a decreased muscle activity [19]. The above \begin{table}
\begin{tabular}{c c c c} \hline  & **S1** & **S2** & **C** \\ \hline RMS TA (\(\mu\)V) & 109.91 & 103.23 & 139.06 \\ SD (\(\mu\)V) & 52.83 & 42.03 & 75.38 \\ U (S1 vs. C) & 212 & NA & 212 \\ Z (S1 vs. C) & 2.297 & NA & 2.297 \\ p (S1 vs. C) & 0.022 * & NA & 0.022 * \\ r (S1 vs. C) & 0.319 & NA & 0.319 \\ U (S2 vs. C) & NA & & 219 \\ Z (S2 vs. C) & NA & & \(-\)2.169 \\ p (S2 vs. C) & NA & & 0.03 * \\ r (S2 vs. C) & NA & & \(-\)0.301 \\ U (S1 vs. S2) & & 306 & NA \\ Z (S1 vs. S2) & & 0.576 & NA \\ p (S1 vs. S2) & & 0.577 & NA \\ r (S1 vs. S2) & & 0.08 & NA \\ \hline RMS MM (\(\mu\)V) & 110.2 & 139.06 & 153.98 \\ SD (\(\mu\)V) & 58.38 & 41.44 & 98.88 \\ U (S1 vs. C) & 255 & NA & 255 \\ Z (S1 vs. C) & 1.51 & NA & 1.51 \\ p (S1 vs. C) & 0.131 & NA & 0.131 \\ r (S1 vs. C) & 0.209 & NA & 0.209 \\ U (S2 vs. C) & NA & & 197 \\ Z (S2 vs. C) & NA & & \(-\)0.229 \\ p (S2 vs. C) & NA & & 0.01 * \\ r (S2 vs. C) & NA & & \(-\)0.032 \\ U (S1 vs. S2) & & 203 & NA \\ Z (S1 vs. S2) & & \(-\)2.461 & NA \\ p (S1 vs. S2) & & 0.014* & NA \\ r (S1 vs. S2) & & \(-\)0.341 & NA \\ \hline \end{tabular} (S1)—study group before compression technique; (S2)—study group after compression technique; (C)—control group; (r)—effect size; * Significant difference.  
\end{table} 
Table 3: Comparing means of bioelectric activity of temporalis anterior (RMS TA) and masseter muscle (RMS MM) during maximum voluntary clenching. hypothesis is in accordance with the results presented by [PERSON] et al. who showed significantly higher masticatory muscle activity during clenching tasks in TMDs-free subjects in comparison to patients diagnosed with TMDs [10]. Moreover, [PERSON] et al. reported higher resting bioelectrical activity of masticatory muscles in patients with myofasical pain [9]. The pain adaptation model seems to be also confirmed by the presented observations, which show alterations in sEMG activity due to the presence of MTrPs. Hence, the deactivation of MTrPs through CT improves muscle activity and offers the possibility of generating greater forces within the MM muscles. Both the increase in active MMO and changes in sEMG activity after CT may have a multifactorial basis.