## 4 Discussion
While both methods have proven effective in other contexts, this study focused specifically on their differential effects on the frontal plane posture of high-level rhythmic gymnasts, which represents a novel contribution. Unlike prior studies centered on the sagittal plane or general flexibility, our findings address the influence of these interventions on lateral trunk control, vertebral asymmetries, and postural imbalances during frontal standing, a critical component for injury prevention and performance in this population. Notably, statistically significant differences favoring the [PERSON] group were consistently found in the upright and left frontal standing positions. These positions are particularly important in rhythmic gymnastics due to frequent lateral displacements, and the observed improvements suggest that Mezieres therapy may enhance neuromuscular control in those movements. Interestingly, the greater improvement observed on the left side may be explained by the gymnasts' dominant use of their right sides, highlighting the value of addressing postural imbalances through individualized therapy. Although [PERSON] et al. (2007) [32] explored upper limb dominance in gymnasts and noted strength differences between dominant and non-dominant arms, their findings on unilateral adaptation may partially help interpret the lateralized effects found in our sample. However, given that their focus was on scapular and shoulder control, the extrapolation of these results should be approached with caution. The decision to evaluate posture in rhythmic gymnasts experiencing LBP stemmed from the unique physical demands and biomechanical stresses associated with this sport. Rhythmic gymnastics requires an exceptional combination of flexibility, strength, and repetitive hyperextension movements of the spine, which predisposes athletes to postural deviations and musculoskeletal injuries, particularly in the lumbar region [6; 10; 14]. postural assessment is critical in this population because altered alignment or compensatory mechanisms can contribute to LBP development and persistence. By analyzing posture, it is possible to identify specific postural imbalances such as hyperlordosis, pelvic tilts, or scapular misalignments, which may exacerbate spinal loading and strain. Understanding these postural deviations enables a targeted approach for injury prevention and management, including tailored training modifications, rehabilitation protocols, and corrective exercises. Moreover, rhythmic gymnasts are a unique athletic group in which aesthetics and extreme ranges of motion are prioritized, often at the expense of spinal health. This makes them particularly vulnerable to overuse injuries such as LBP, highlighting the need for specific postural evaluation. By addressing posture-related factors, we aimed to provide actionable insights into both the prevention and treatment of LBP, ultimately enhancing athletic performance and longevity in sports. Limitations  
The sample size was small because of the high professional level and participant inclusion criteria. All participants were ranked in the top four elite national positions in 2022 Spanish competition. The lack of scientific evidence for Mezieres and isostretching treatments makes any discussion of the findings and results difficult. This additional physiotherapy has gained ground without much scientific evidence of its effectiveness. Spinal Mouse instruments are expensive and are not a common therapeutic evaluation tool found in every physiotherapy center. It is not easy to demonstrate the efficacy of a postural treatment because a long duration is the principal characteristic of this treatment. Finally, only one sex was analyzed, female elite athletes with low back pain, which hinders the adaptation of the results for all athletes of the same discipline. Study strengths  
The elite athletes were blinded to the study groups.