## 4 Discussion  
The present study revealed that adding AE to PT improved the outcomes related to widespread PS in patients with myogenic TMD. The analysis showed differences between groups for the Achilles PPT and CSI in favor of the PT + AE group at T2. In the PT + AE group, higher PPT values compared to the PT group were observed in the Achilles tendons of both legs, as well as a lower ICS. This difference could be attributed to having performed AE. The addition of AE to a PT treatment seemed to have additional benefits on myogenic TMD by improving their widespread PS. The effect sizes achieved between groups in the Achilles PPT, and on the CSIs at T1 (Left Achilles: d = 1.3; Right Achilles: d = 0.9; CSI: d = 2.3) and T2 (Left Achilles: d = 2.5; Right Achilles: d = 0.9; CSI: d = 1.7) suggested that AE had positive effects on widespread PS. AE at submaximal intensity had already shown hypoalgesic effects on other chronic musculoskeletal conditions with widespread PS [17]. It has been suggested that AE increases the blood supply and metabolic resources, allowing a mechanical reorganization of muscle fibers [16]. Additionally, when the AE is performed at submaximal intensities, lactate is secreted. This secretion appears to have an important role in chronic pain, as studies show alterations in the structural properties of the brain where the demand for lactate is greater [44; 45; 46]. Accordingly, global resistance training, as well as AE training, could compensate for this lack of lactate by stimulating its production [47; 48]. The PPT was evaluated in areas close to the TMJ. Differences between groups were found only for the PPT of the right masseter at T2, with a significant difference between the groups in favor of the PT + AE (\(p<0.01\)). No significant differences were found between groups for the secondary outcomes. However, intragroup improvements were observed, although they were not analyzed as it was not the objective of the study. It is necessary to mention that the improvements observed in both groups in jaw opening and anxiety are smaller than those observed in previous studies [15]. This may be due to the small sample size of our study and the lack of experience of the physiotherapist responsible for the intervention. Despite the lack of significant differences between groups for these variables, the effect sizes showed that the PT + AE group had better improvements than the PT group. In fact, it has been shown that in patients with chronic non-specific neck pain, AE reduces neck pain and headaches [49; 50]. Furthermore, in patients with mixed and myogenic TMD, AE improves headaches [26], pain perception [27; 28], anxiety [28], oral health-related quality of life [26], and the activation and strength of masticatory muscles [27]. Finally, a systematic review and meta-analysis by [PERSON] et al. [51] showed that AE is effective for reducing anxiety. As previous studies have shown [52], there is a moderate to strong correlation between anxiety/depression and CSI. Therefore, the significant improvements in HADS and CSI scores in the AE group may demonstrate this relationship between both variables. Therefore, AE could reduce widespread PS as well as myofasical pain. Given that myogenic TMD tends to become chronic and there is usually a PS in local and remote areas, AE could be a beneficial treatment. The results presented should be interpreted with caution, as this study has some limitations. Firstly, there is no gold standard to assert the existence of central sensitization, thus we can only suspect its presence through assessments with CSI and sensorial quantitative tests [53]. Secondly, the data presented are from a preliminary study with a small sample size, therefore, we do not know if these results would be replicable in a larger sample with myogenic TMD. Furthermore, it is important to note that widespread PS is commonly present in patients with a tendency toward chronicity, so it will be essential to conduct a long-term follow-up.