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Learn more: PMC Disclaimer | PMC Copyright Notice Health Sci Rep . 2026 Apr 14;9(4):e71925. doi: 10.1002/hsr2.71925 Search in PMC Search in PubMed View in NLM Catalog Add to search The Effects of Corrective Exercises and Respiratory Biofeedback on the Kyphosis Angle and Electrical Activity of Trapezius Muscles in Male Adolescents With Kyphosis: A Randomized Controlled Trial Shahla Hasheminezhad Shahla Hasheminezhad 1 Department of Physical Education and Sport Science, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran Find articles by Shahla Hasheminezhad 1 , Aliyeh Daryabor Aliyeh Daryabor 2 Physiotherapy Research Center, Department of Orthotics and Prosthetics, School of Rehabilitation Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Find articles by Aliyeh Daryabor 2 , Hassan Safikhani Hassan Safikhani 1 Department of Physical Education and Sport Science, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran Find articles by Hassan Safikhani 1, ✉ , Negin Ghorbani Negin Ghorbani 3 Department of Physiotherapy, Tabriz University of Medical Sciences, Tabriz, Iran Find articles by Negin Ghorbani 3 Author information Article notes Copyright and License information 1 Department of Physical Education and Sport Science, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran 2 Physiotherapy Research Center, Department of Orthotics and Prosthetics, School of Rehabilitation Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran 3 Department of Physiotherapy, Tabriz University of Medical Sciences, Tabriz, Iran * Correspondence: Hassan Safikhani ( [email protected] ) ✉ Corresponding author. Revised 2025 Dec 4; Received 2025 Mar 9; Accepted 2026 Feb 19; Collection date 2026 Apr. © 2026 The Author(s). Health Science Reports published by Wiley Periodicals LLC. This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc-nd/4.0/ License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made. PMC Copyright notice PMCID: PMC13077658 PMID: 41988394 ABSTRACT Background and Aims Thoracic kyphosis is a prevalent postural abnormality among adolescents, which can impair musculoskeletal alignment and affect neuromuscular function. Despite the known benefits of corrective exercises, limited attention has been given to the role of respiratory biofeedback. This study aimed to investigate the effects of corrective exercises and respiratory biofeedback on the kyphosis angle and the electrical activity of the trapezius muscles in male adolescents with kyphosis. Methods A randomized clinical trial was conducted on 45 male adolescents with postural kyphosis, randomly assigned into three groups: corrective exercises ( n = 15), respiratory biofeedback ( n = 15), and control ( n = 15). The interventions were delivered for 8 weeks. The control group did not receive any intervention during the study period. Kyphosis angle was measured using a flexible ruler, and surface electromyography was used to assess the electrical activity of upper, middle, and lower trapezius muscles in two stages of pre‐test and post‐test. Data were analyzed using two‐way mixed repeated measures ANOVA and Bonferroni post hoc tests at significance level of 0.05. Results Both the corrective exercise and respiratory biofeedback groups showed significant reductions in kyphosis angle and trapezius muscle activity after the intervention ( p < 0.001), whereas the control group showed no significant change ( p > 0.05). No significant differences were observed between the two intervention groups. However, both were significantly better than the control group in improving postural alignment and muscle activity ( p < 0.05). Conclusion Eight weeks of corrective exercises or respiratory biofeedback training significantly improved spinal curvature and muscle activity of trapezius muscle in adolescents with kyphosis. These interventions are recommended as effective non‐invasive approaches to address postural abnormalities in young populations. Keywords: corrective exercises, electrical activity, Kyphosis, respiratory biofeedback, trapezius 1. Introduction Movement or activity is one of the most essential needs of the body, especially for the growth and strengthening of muscles. Low physical activity over time can lead to muscle weakness and atrophy, and then the body does not have the necessary strength and endurance and is exposed to various physical injuries [ 1 , 2 ]. Most of the physical deformities are gradual and are usually caused by poor movement habits and environmental conditions during childhood and adolescence [ 3 ]. Kyphosis is one of the relatively common abnormalities of the spine. The most common upper‐body anomaly among students is determined to be kyphosis. This abnormality is more common among female students due to appearance and poor mobility [ 4 , 5 ]. The lack of awareness of the correct physical condition and its complications leads to people's not seeking to correct it; while physical abnormalities can be corrected with minimal cost and time if identified quickly and intervened on time [ 6 ]. The longer the interval between the onset of abnormality and the initiation of treatment, the more severe vulnerability will follow. These abnormalities can lead to permanent disabilities in more severe cases, for which correction may be highly complicated or even bordering on the impossible. Therefore, timely correction of these abnormalities is very important [ 7 ]. The natural alignment of the spine depends on the function of its muscular, bone, and joint structures. Therefore, the weakness of the muscles supporting the spine can disrupt the static and dynamic balance of a person's stature, which is generally called postural abnormalities [ 8 ]. Skeletal abnormalities can occur due to lack of movement, receiving environmental stimuli, and inappropriate movement patterns and leave adverse effects on people's psychological, social, and physiological functioning [ 9 ]. The normal level of kyphosis is 20°–40°. If this angle exceeds 40°, it is known as Deformity. In terms of correction, kyphoses are divided into two functional and structural types. Functional types can be corrected with corrective movements and different corsets, and structural types require surgery for correction [ 10 , 11 ]. In our schools and universities, many students have many physical problems, all of which indicate a very high prevalence of spinal deformity, however, most teachers, parents or themselves are less aware of it [ 12 , 13 ]. Researches have shown that increasing the kyphosis angle in adults is related to reduced physical performance, balance disorder, reduced walking speed and climbing stairs, reduced functional ability, and also reduced ability to do daily household chores. According to this, the angle of kyphosis is correlated with the strength of the muscles that open the chest [ 14 , 15 ]. Therefore, it seems that strength and stretching exercises can reduce the amount of kyphosis angle by synchronizing the positive and negative muscle groups. However, the results of various studies have shown that corrective exercises are effective on the back kyphosis angle of people with kyphosis [ 16 ]. Generally, spinal deformities are treated and corrected using a variety of corrective approaches, of which manipulation, postural retraining, employing braces and orthosis, and exercise therapy are among the most highly‐rated approaches to the treatment of spinal complications. Exercise therapy or corrective movements is one of the most common methods of correcting postural deformities in the spine and is introduced as an established attempt for correcting abnormal postures by coordinating the opposing muscle groups using stretch and strength training. Corrective exercises include stretching exercises, strength exercises, and proprioceptive neuromuscular facilitation (PNF) exercises [ 17 , 18 ]. In addition to conventional corrective methods (stretching or strength exercises), one of the behavioral therapy methods is respiratory biofeedback, which is used to treat and correct kyphosis. Respiratory biofeedback is a non‐pharmacological method that can be used to treat kyphosis, a complication that is directly related to physical and physiological disorders. It is usually done visually and verbally by presenting physiological parameters (including blood pressure and heart rate among others. This knowledge, in turn, can help them gradually understand these physiological states [ 19 ]. The more research has focused on the effect of corrective movements on the angle of kyphosis, the more widely the effect of the aforementioned exercise on muscles and their electrical activity has been neglected. The studies have also largely failed to determine the muscle groups with the highest benefit from such exercises [ 20 , 21 ]. It is safe to argue that studies on the electrical activity of the muscles involved in kyphosis and the efficacy of physical exercise on the electrical activity of the muscles subjected to this disorder have been very few and far between [ 20 ]. Therefore, considering the increasing prevalence of kyphosis in teenagers and students on the one hand and the limitations of the studies conducted in the field of the effect of exercises corrections and exercises and respiratory biofeedback on kyphosis in Iran on the other hand, the present study was designed and carried out with the aim of examining the effects of pre‐devised corrective exercises and respiratory biofeedback on the kyphosis kyphosis angle and electrical activity of trapezius muscles in male adolescents. 2. Materials and Methods 2.1. Study Design This research was a clinical trial conducted in three groups with a pre‐test and a post‐test. 2.2. Research Population and Statistical Sample The statistical population of this study is all students diagnosed with kyphosis in Kermanshah. Initially, the researcher visited Kermanshah education department to receive the required documents, then by referring to different schools and meeting with principals and parents of students, 45 individuals with kyphosis—determined by the flexible ruler—were randomly selected and divided into three groups, namely control ( n = 15), selected exercises ( n = 15) and respiratory biofeedback exercises ( n = 15). Written permission obtained from all acknowledged individuals. Prior to the full data collection, a power analysis was performed using G*Power 3.1 based on preliminary data from the first five participants in each group, using the kyphosis angle as the primary outcome. The analysis estimated that 15 participants per group would be required to achieve a statistical power of 0.80 with α = 0.05, thus justifying the final sample size used in this study. Simple randomization was employed using a computer‐generated random number sequence. Allocation concealment was ensured through sealed, opaque envelopes prepared by an independent researcher not involved in participant recruitment or assessment. Participants were assigned to groups sequentially as they met the inclusion criteria, with group allocation revealed only after baseline measurements were completed. 2.3. Data Collection In this study, a researcher‐made health and medical history questionnaire was employed to collect the information regarding the prospective complications of the participants. A standard flexible ruler was used to assess kyphosis abnormalities [ 22 ]. The reliability of the flexible ruler has been previously established. The intraclass correlation coefficient (ICC) between the measurements from the Cobb and flexicurve methods was 0.906 [ 23 ]. To use a flexible ruler to measure kyphosis, first the C7 spine appendage and the L5‐S1 junction were identified and marked, and the kyphosis angle was calculated using the trigonometric formula, that is: θ = 4 ( Arctang ( 2 h / l ) ) In this technique, the subject is placed in a standing position, requiring him to be completely comfortable and natural with bare feet to perform the test. He was then required to spread his legs shoulder‐width apart and look forward. The researcher gets behind the subject to find reference points and take the necessary measurements [ 24 ]. Surface electromyography (EMG) was used to record the electrical activity of the upper, middle, and lower portions of the trapezius muscle. A wireless 8‐channel EMG system (Myon aktos, Myon AG, Switzerland) was employed. Bipolar surface electrodes were placed bilaterally over each portion of the trapezius according to SENIAM recommendations, with an inter‐electrode distance of 2 cm. Prior to electrode placement, the skin was shaved, lightly abraded, and cleaned with alcohol to reduce impedance. EMG signals were sampled at 1000 Hz, band‐pass filtered between 20 and 450 Hz, and full‐wave rectified. To determine the onset timing of muscle activation, a threshold‐based algorithm was applied. The relative timing of activation between the three portions of the trapezius was calculated to assess their coordination during the movement task. The recorded EMG data were analyzed using MegaWin software (Mega Electronics, Finland), which was used for signal visualization, processing, and extraction of relevant variables. Pro Camp2 Neurofeedback and respiratory biofeedback was used to perform respiratory biofeedback exercises. This device is designed with the goals of offering the lowest cost, providing easy use, no unnecessary complexity, and high efficacy and efficiency. It makes use of a sensor that is fastened on the abdomen just above the navel to detect abdominal breathing. The AD620 instrumentation is used in the upper parts to receive the differential amplifier signal. In this device, two PIC16f 877A microcontrollers are used to adjust different modes, which are responsible for gauging the respiration rate, plotting the pattern and offering feedback. The abdominal breathing sensor is designed in two different sensitivity modes, by which the person, who may not have proper abdominal control at the initial levels, can gradually get equipped with the necessary skills using the light mode, after which the harder mode can be employed to increase the skills in abdominal breathing. Biofeedback was performed with this device according to the training protocol in each session for half an hour. In the first session, the individual's respiratory pattern was examined and recorded, based on which, the treatment session of each patient was tailored. In this way, after connecting the abdominal breathing sensor to the individual, a visual pattern was presented to the patient according to his previous pattern, according to which the patient was tasked to breathe. Once the person had mastered the breathing pattern, a more rigorous pattern was presented and therefore, he could finally breathe at the lowest breathing rate with a 6:4 inhale‐to‐exhale ratio abdominal breathing, without having to suffer from dizziness, drowsiness, fatigue, and stress [ 25 ]. 2.4. Exercise Routine and Implementation 2.4.1. Selected Correction Exercises In the first session, the basic principles of correction exercises were explained to the participants and general information on the correction exercises was provided to them. The goal of the devised program is to stretch the tightened pectoral muscles and strengthen the back muscles, particularly those of the trapezius. The program included both types of stretch‐and‐strength training. Participants were required to attend for 8 weeks, 3 sessions per week, and 60 min per session. To reduce the risk of possible injuries to the joints and muscles of the patients and to increase the mobility of the joints of the spine and shoulder girdle, a 15‐min warm‐up routine was inserted at the start of the program and a 10‐min cooling routine was added to the end of each session. After the warm‐up phase, first stretching exercises and then strengthening exercises were performed [ 26 ]. The corrective exercise program was systematically developed based on the National Academy of Sports Medicine (NASM) Corrective Exercise Continuum, which includes four sequential phases: inhibit, lengthen, activate, and integrate [ 27 ]. Inhibit Phase: Self‐myofascial release techniques using a foam roller were applied to overactive and tight muscles, specifically the pectoralis major and upper trapezius. Each muscle group received 30–60 s of foam rolling. Lengthen Phase: Static stretching was performed for shortened muscles identified during postural assessments, targeting the pectoralis major, pectoralis minor, and upper trapezius. Each stretch was held for 30 s and repeated for two sets. Activate Phase: Targeted strengthening exercises were prescribed to activate underactive muscles responsible for postural control, including the lower trapezius, middle trapezius, rhomboids, and deep cervical flexors. Exercises such as prone Y‐raises, scapular retractions, and chin tucks were performed in 2–3 sets of 10–15 repetitions. Integrate Phase: Functional, dynamic movement patterns were introduced to enhance neuromuscular coordination and postural stability. Exercises included thoracic extension with scapular retraction and wall slides, performed in a controlled manner with emphasis on posture and breathing. The entire exercise protocol was conducted three times per week for 8 weeks under the supervision of a certified corrective exercise specialist. The control group received no intervention during the study period and was assessed only at baseline and after 8 weeks. 2.4.2. Respiratory Biofeedback Exercises Participants were required to participate for 8 weeks and 3 sessions per week and 30 min per session. Meetings were scheduled every other day for each subject, and on days when the subject did not have a treatment session, he was required to perform the trained breathing tasks for 20 min. From the third session onwards, after connecting the device to the person and making the initial settings, the person was left alone with the device to practice with the device and thus did not receive any additional feedback and guidance from the executor (Figure 1 ) [ 25 ]. Figure 1. Open in a new tab Illustration of respiratory biofeedback exercises performed by participants using a home‐built abdominal breathing biofeedback device. The images demonstrate sensor placement on the abdomen just above the navel and participant positioning during biofeedback training. The device provides visual feedback to guide abdominal breathing with an inhale‐to‐exhale ratio of 6:4. Exercises were performed in a quiet sitting posture for 30 min per session, three times a week for 8 weeks. 2.5. Data Analysis Following data collection, descriptive statistics were employed to describe the data, after which the Shapiro–Wilk test was used to check the normality of the data. Descriptive statistics included means ± standard deviations for normally distributed data. Two‐way mixed repeated measure ANOVA was used to evaluate the effect of the interventions during time and Tukey's Honest Significant Difference (HSD) test was utilized for pairwise comparison between groups. Moreover, Bonferroni correction was utilized to compared difference between pre‐test and post‐test in each group separately. In this research, the version 23 of SPSS was used for data analysis with a significant level of 0.05. 3. Results The demographic characteristics of participants are shown in Table 1 , with no significant different among groups ( p > 0.05). The results of the Shapiro–Wilk test showed that the variables such as age, height, weight, and body mass index, as well as the data of kyphosis angle and electrical activity of trapezius muscles obtained in the pre‐test and post‐test in different groups, had a normal distribution ( p > 0.05). Table 1. Demographic characteristics of participants. Group n Age (years) Height (cm) Weight (kg) BMI (kg/m²) Baseline kyphosis angle (°) Corrective exercises 15 16.2 ± 1.4 168.5 ± 8.2 58.3 ± 7.9 20.5 ± 2.1 52.4 ± 4.8 Respiratory biofeedback 15 15.9 ± 1.6 169.8 ± 7.6 59.7 ± 8.4 20.7 ± 2.3 53.1 ± 5.2 Control 15 16.1 ± 1.5 167.9 ± 8.8 57.9 ± 7.2 20.6 ± 2.0 52.8 ± 4.6 p ‐value — 0.367 0.595 0.738 0.718 0.550 Open in a new tab Levene's test indicated homogeneity of variances for all variables ( p > 0.05). The mean and standard deviation of kyphosis angle and electrical activity of trapezius muscle in three groups in pre‐test and post‐test conditions along with the results of two‐way mixed repeated measure ANOVA are presented in Table 2 . As shown in Table 2 , the main effect of time was significantly found for both variables of kyphosis angle and electrical activity of trapezius muscles, revealing the significant effect of intervention during time. Moreover, a significant interaction was found between the kyphosis angle and the electrical activity of the trapezius muscles. So, the Bonferroni correction was applied for these outcomes, revealing the interaction effect and allowing for comparison of two conditions in each group. The results of Table 3 showed that the mean of the kyphosis angle in the two groups of corrective movements and respiratory biofeedback before and after the intervention had a significant statistical difference (Figure 2 , p < 0.05). In other words, corrective exercises and respiratory biofeedback could significantly alleviate the extent of the kyphosis angle. However, the mean kyphosis angle in the control group before and after the intervention had no statistically significant difference ( p > 0.05). Moreover, the mean of the electrical activity in the two groups of corrective movements and respiratory biofeedback before and after the intervention had a significant statistical difference (Figure 3 , p < 0.05). In other words, corrective exercises and respiratory biofeedback were able to reduce the extent of electrical activity and improve the complication, an effect which was not observed in the control group ( p > 0.05) (Table 3 ). Table 2. The results of two‐way mixed repeated measure ANOVA. Corrective exercises Respiratory biofeedback Control Two‐way mixed repeated measure ANOVA①②/③④/⑤⑥ ① Pre‐Test ② Post‐Test ③ Pre‐Test ④ Post‐Test ⑤ Pre‐test ⑥ Post‐test Main effect Variables Interaction of time and group Time Group Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD p ‐value Effect size p ‐value Effect size p ‐value Effect size Kyphosis angle (°) 52.08 2.61 43.85 2.52 53.15 2.63 44.94 2.42 52.29 2.13 50.86 1.96 < 0.001 ** 0.992 < 0.001 ** 0.998 0.001 * 0.300 Electrical activity of trapezius muscles (mV) 17.97 1.47 14.60 1.33 18.88 1.47 15.02 1.45 18.24 1.11 17.42 1.03 < 0.001 ** 0.992 < 0.001 ** 0.998 0.010 * 0.197 Open in a new tab * p < 0.05 ** p < 0.001. Table 3. Bonferroni correction of pre‐test and post‐test for within‐group comparison. Group Variable Mean SD Mean difference p ‐value Corrective exercises Kyphosis angle Pre‐test 52.08 2.61 7.866 < 0.001 ** Post‐test 43.85 2.52 Electrical activity of trapezius muscles Pre‐test 17.97 1.47 3.933 < 0.001 ** Post‐test 14.60 1.33 Respiratory biofeedback Kyphosis angle Pre‐test 53.15 2.63 8.066 < 0.001 ** Post‐test 44.94 2.42 Electrical activity of trapezius muscles Pre‐test 18.88 1.47 4.066 < 0.001 ** Post‐test 15.02 1.45 Control Kyphosis angle Pre‐test 52.29 2.13 1.756 0.832 Post‐test 50.86 1.96 Electrical activity of trapezius muscles Pre‐test 18.24 1.11 1.274 0.753 Post‐test 17.42 1.03 Open in a new tab Abbreviation: SD, standard deviation. ** p < 0.001. Figure 2. Open in a new tab Comparison of kyphosis angle in 3 groups, 1: pre‐test, 2: post‐test. Figure 3. Open in a new tab Comparison of electrical activity of trapezius muscles in 3 groups, 1: pre‐test, 2: post‐test. Moreover, the main effect of group was significant for kyphosis angle and electrical activity of trapezius muscles, revealing the significant between three groups (Table 2 ). Tukey's HSD test showed that the two groups of corrective movements and respiratory biofeedback have no statistically significant difference in terms of the mean kyphosis angle after the intervention ( p > 0.05). Nevertheless, the mean kyphosis angle after the intervention in both corrective movements and respiratory biofeedback groups was statistically significant compared to the control group ( p < 0.05). Therefore, both corrective movements and respiratory biofeedback interventions can improve the kyphosis angle (Table 4 ). Table 4. Tukey's honest significant difference (HSD) test for pairwise comparison between groups. Variable Group Group Mean difference p ‐value Kyphosis angle (°) Corrective exercises Respiratory biofeedback 0.833 0.231 Control 5.166 0.001 * Respiratory biofeedback Control −2.583 0.001 * Electrical activity of trapezius muscles (mV) Corrective exercises Respiratory biofeedback 1.083 0.072 Control 4.333 0.001 * Respiratory biofeedback Control 6.25 0.001 * Open in a new tab * p < 0.05 Also, Tukey's Honest Significant Difference (HSD) Test showed that the two groups of corrective movements and respiratory biofeedback have no statistically significant difference in terms of the mean electrical activity after the intervention ( p > 0.05). However, the mean electrical activity after the intervention in both corrective movements and respiratory biofeedback groups was statistically significant compared to the control group ( p < 0.05), therefore, both corrective movements and respiratory biofeedback interventions can improve the electrical activity of the selected muscles (Table 4 ). 4. Discussion The prevalence of postural abnormalities is increasing in different age groups, especially among adolescents and young adults. These deformities can lead to adverse changes in skeletal alignment, respiratory function, and functional capacity, particularly when the thoracic spine develops excessive kyphotic curvature [ 28 , 29 ]. Impaired thoracic posture has been associated with reduced chest expansion, decreased respiratory efficiency, and limitations in movement performance [ 30 ]. Therefore, identifying effective corrective strategies for improving thoracic alignment and muscular function in adolescents is of considerable importance. The present study aimed to investigate the effects of corrective exercises and respiratory biofeedback on the kyphosis angle and trapezius muscle activity in male adolescents with postural kyphosis. The results of the present study demonstrated that both corrective exercises and respiratory biofeedback were effective in reducing the thoracic kyphosis angle. These findings are consistent with previous investigations reporting that structured corrective or postural exercise programs can meaningfully improve thoracic alignment among adolescents and adults with hyperkyphosis [ 31 , 32 , 33 ]. Similar outcomes have been documented in randomized controlled trials demonstrating significant reductions in thoracic curvature following corrective and three‐dimensional postural interventions [ 34 , 35 ]. Furthermore, a systematic review by Dimitrijević et al. [ 36 ] confirmed that corrective exercise modalities consistently decrease thoracic kyphosis across diverse populations, supporting the responsiveness of spinal curvature to targeted rehabilitation. The observed improvements may be attributed to the physiological adaptations typically associated with strength and flexibility training. Strengthening exercises targeting the spinal extensors and scapular stabilizers can increase contractile protein content, enhance neuromuscular coordination, and improve endurance [ 37 ]. Concurrently, stretching exercises of shortened anterior chain muscles—particularly the pectoral muscles—help restore muscular balance around the thoracic spine [ 38 , 39 ]. These mechanisms collectively contribute to improved alignment and reduction in kyphotic curvature. In addition to changes in posture, the present study found significant reductions in the electrical activity of the trapezius muscles following the intervention period. Early neuromuscular adaptations—including improved motor unit recruitment strategies, reduced compensatory activation, and enhanced coordination—are commonly observed during the initial weeks of corrective or resistance‐based training [ 40 , 41 ]. The decreases in trapezius activity observed in this study are consistent with earlier EMG‐based research. For example, Arshadi et al. [ 42 ] reported significant reductions in upper trapezius activation following an 8‐week corrective exercise program in individuals with upper crossed syndrome. Similarly, Seidi et al. [ 35 ] reported significant reductions in upper trapezius activation following an 8‐week corrective exercise program in individuals with upper crossed syndrome. These findings indicate that neuromuscular reorganization of the scapulothoracic musculature can occur within a relatively short period, contributing to better postural control and movement efficiency. The beneficial effects of respiratory biofeedback observed in this study may also be related to autonomic and sensorimotor mechanisms. Slow diaphragmatic breathing, particularly when guided through visual or auditory feedback, has been shown to influence autonomic balance by promoting parasympathetic activation, which can reduce sympathetic‐driven muscle overactivity [ 43 ]. Improved interoceptive awareness and breathing coordination may reduce tonic activation of the upper trapezius and facilitate more efficient neuromuscular patterns. Previous biofeedback‐oriented rehabilitation research has also demonstrated changes in trapezius muscle activity and improved respiratory–postural coupling following training (e.g., studies on occupational trapezius biofeedback [ 44 ]; shoulder impingement biofeedback [ 45 ]). These findings support the role of respiratory biofeedback as a complementary approach to enhance neuromuscular control and postural alignment. Given that the intervention lasted 8 weeks, the changes observed in both kyphosis angle and muscle activity likely reflect early neuromuscular and structural adaptations. However, previous studies have shown that discontinuation of corrective programs may result in regression of postural improvements over time. Therefore, continued engagement in corrective exercises and breathing training is recommended to maintain optimal alignment and prevent recurrence of postural deviations. Overall, the present findings highlight the effectiveness of both corrective exercises and respiratory biofeedback in improving thoracic posture and trapezius muscle function in adolescents with kyphosis. These interventions may be considered valuable non‐invasive strategies to address postural abnormalities in younger populations. 4.1. Limitations and Suggestions Despite the valuable findings of this study, several limitations should be acknowledged. First, the sample consisted exclusively of male adolescents, which limits the generalizability of the results to female populations and other age groups. Second, although the 8‐week intervention period was adequate to detect early neuromuscular and postural adaptations, long‐term follow‐up assessments were not performed; therefore, the durability of these improvements remains unclear. Third, surface EMG measurements were limited to the trapezius muscles, while other muscles involved in thoracic alignment—such as the spinal extensors and pectoral muscles—were not evaluated, restricting comprehensive interpretation of neuromuscular changes. Finally, potential psychological or behavioral factors, such as adherence to home‐based components or lifestyle habits, were not controlled and may have influenced the outcomes. Future studies are recommended to include larger and more diverse samples, incorporate long‐term follow‐up assessments, evaluate additional postural and respiratory muscles, and consider combining corrective exercises with other modalities such as cognitive–behavioral strategies or wearable posture‐feedback devices. Investigations comparing different intensities, frequencies, and formats of biofeedback and corrective exercise programs would also help optimize clinical protocols. 5. Conclusion The findings of the present study indicate that both corrective exercises and respiratory biofeedback lead to significant improvements in postural alignment and neuromuscular function among adolescents with thoracic kyphosis. Specifically, both interventions resulted in a meaningful reduction in the thoracic kyphosis angle as well as a decrease in trapezius muscle activity, suggesting favorable adaptations in spinal posture and scapulothoracic muscle control. Given that these methods are non‐invasive, feasible, and well tolerated in adolescents, they may be recommended as effective strategies for managing postural kyphosis in school‐aged populations. Continued engagement in corrective and breathing exercises may help maintain these improvements over time. Author Contributions Conceptualization: Hassan Safikhani. Methodology: Shahla Hasheminezhad and Hassan Safikhani. Investigation: Negin Ghorbani. Statitical analysis: Aliyeh Daryabor. Writing – original draft: Aliyeh Daryabor: Writing – review and editing: Hassan Safikhani and Shahla Hasheminezhad. Funding The authors received no specific funding for this work. Ethics Statement This study was approved by the code of ethics of Islamic Azad University Kermanshah Branch with the code IR.IAU.KSH.REC.1403.047. Although this current study was a randomized clinical trial registered in the Iranian Register of Clinical Trials (registration number: IRCT20231108059995N2). Consent All participants in the study signed an informed consent form. Written informed consent or assent (as appropriate) was obtained from all participants and their legal guardians. Conflicts of Interest The authors declare no conflicts of interest. 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