The Effects of a Short-Term Isometric Exercise Program Targeting Tongue, Jaw, and Trunk Muscles on Muscle Strength and Synergistic Relationships in Post-Stroke Patients: A Single-Group Pre-Post Study

The Effects of a Short-Term Isometric Exercise Program Targeting Tongue, Jaw, and Trunk Muscles on Muscle Strength and Synergistic Relationships in Post-Stroke Patients: A Single-Group Pre-Post Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The Effects of a Short-Term Isometric Exercise Program Targeting Tongue, Jaw, and Trunk Muscles on Muscle Strength and Synergistic Relationships in Post-Stroke Patients: A Single-Group Pre-Post Study Neslihan Altuntaş Yılmaz, Sami Küçükşen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7751845/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract Background: This study aimed to investigate the effects of a short-term tongue-jaw-back isometric exercise program on these muscle groups and their interrelationships in the post-stroke period. Methods: Twelve post-stroke patients were included in the study. A 14-day exercise program, consisting of two daily sessions targeting the tongue, jaw, and back muscles, was administered. Anterior and posterior tongue muscles, jaw muscles, and back muscle strength were assessed before and after the exercise program. Tongue pressure was measured using the Iowa Oral Performance Instrument (IOPI), chewing strength with a hand-held dynamometer, and back strength with a stabilizing pressure biofeedback unit. Results: After the 14-day isometric exercise program, anterior tongue strength (p = 0.025), posterior tongue strength (p = 0.021), and back muscle strength (p = 0.005) showed significant increases compared to pre-treatment values. No significant change was observed in jaw strength (p = 0.475). Spearman correlation analysis revealed no significant relationships between tongue muscles and jaw or back muscles before treatment, and simple correlations after treatment also did not reach significance. However, partial correlation analysis showed that the relationship between tongue muscles was significantly influenced by jaw strength (p = 0.040) and back strength (p = 0.038) after the intervention. Conclusions: Short-term isometric exercises targeting tongue, jaw, and back muscles in post-stroke patients effectively increased tongue and back muscle strength and enhanced the synergistic relationship among these muscle groups. Trial registration: This study was retrospectively registered with ClinicalTrials.gov on 2025-11-21 (ID: NCT07261462). Back muscles Muscle synergy Post-stroke Tongue strength Rehabilitation Background Stroke is a leading cause of death and long-term disability globally, frequently leading to a wide range of motor, sensory, and cognitive impairments [1]. A major complication of stroke is dysphagia (swallowing difficulty), which affects more than half of stroke patients and poses significant risks such as aspiration pneumonia, malnutrition, and dehydration [2]. Therefore, dysphagia management is a critical component of post-stroke rehabilitation and aims to improve patients' functional independence. Swallowing is a complex action that requires coordinated muscle activity, including that of the tongue, cheeks, lips, and masticatory muscles [3]. Weakness or discoordination of these muscles can lead to dysphagia. Specifically, tongue muscle strength is vital for initiating the swallow and propelling the food bolus posteriorly, while the masticatory muscles (masseter and temporalis muscles) play a crucial role in preparing food for swallowing [4]. Studies have shown that targeted exercises for these muscle groups can effectively improve swallowing function [5]. However, post-stroke muscle weakness is not limited to the oropharyngeal region; it also commonly affects truncal muscles, compromising postural stability. Truncal muscle strength is a crucial indicator of overall body muscle strength [6, 7]. In traditional stroke rehabilitation, priority is often given to strengthening truncal and lower extremity muscles to regain fundamental functions like walking and postural balance [8]. Yet, oropharyngeal muscles, which are critical for vital functions such as swallowing and eating, can be overlooked in this comprehensive approach. The focus on a patient's general condition and trunk control in the acute phase can cause the rehabilitation of tongue and masticatory muscles to be deprioritized. However, addressing swallowing function early is crucial for reducing aspiration risk and expediting the patient's transition to oral feeding [9]. Given this context, it is important to investigate the synergistic relationship between tongue, masticatory, and back muscle strength and to evaluate the efficacy of an integrated exercise program targeting these muscle groups. The limited number of studies that have examined this multi-faceted relationship highlights a significant knowledge gap. Therefore, this study aims to investigate the relationship among tongue pressure, chewing muscle strength, and back muscle strength in acute stroke patients and to examine the effects of a short-term isometric exercise program on these parameters. The findings are expected to contribute a new perspective to the development of holistic rehabilitation approaches for post-stroke dysphagia. Methods This study was designed as a single-group pre-post trial. A total of 12 post-stroke patients were included. All participants underwent a 14-day isometric exercise program targeting the tongue, jaw, and trunk muscles, with two daily sessions. Study Design and Ethical Approval This study was designed as a prospective, single-center research project conducted at the Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Necmettin Erbakan University. Ethical approval for the study was obtained from the Necmettin Erbakan University Health Sciences Scientific Research Ethics Committee with decision number 2021/13-71. All participants included in the study provided informed voluntary consent. The study was conducted with a single group, and all participants received the exercise intervention. Assessments were performed by the researcher, and no blinding was applied. The study was retrospectively registered in the clinical trials registry on October 8, 2025, ID no NCT07261462. Participants Twelve patients with a diagnosis of acute ischemic or hemorrhagic stroke, who were hospitalized in the Physical Medicine and Rehabilitation service between February 2022 and December 2022, were enrolled in the study. Inclusion criteria were: being within the first 30 days of stroke onset; being between 18 and 80 years of age; having experienced their first stroke; undergoing inpatient physical therapy and rehabilitation; and voluntarily consenting to participate. Exclusion criteria were: cognitive impairment, severe aphasia or communication difficulties, a history of other neurological diseases, a history of surgery in the oral or jaw region, and refusal to participate. Outcome Measures The participants' sociodemographic data (age and stroke duration) were recorded. The following clinical and functional assessments were performed both before and after the 14-day program: Motor Functional Status: Brunnstromm stages were used to evaluate motor recovery levels (upper extremity, hand, and lower extremity) of the hemiplegic side [10]. Functional Independence Status: The Barthel Index was used to determine the participants' level of independence in daily living activities [11]. Dysphagia Assessment: The Eating Assessment Tool-10 (EAT-10) score was used to determine the severity of swallowing difficulty [12].. Tongue Pressure Measurement: The Iowa Oral Performance Instrument (IOPI) was used to assess tongue muscle strength [13]. For Anterior Tongue Pressure (ATP), the IOPI bulb was placed longitudinally along the hard palate, behind the alveolar ridge. For Posterior Tongue Pressure (PTP), the bulb was positioned at the posterior border of the hard palate. Both measurements were repeated three times, and the mean values were recorded. Chewing Muscle Strength Measurement: Chewing muscle strength, representing masticatory force, was measured using a hand-held dynamometer [14]. Participants were instructed to perform a jaw-opening movement against the dynamometer placed under the chin. This measurement was repeated three times, and the average value was used for analysis. Back Muscle Strength Measurement: Back muscle strength was measured with a stabilizing pressure biofeedback unit [15]. Individuals were asked to lie supine on a treatment table with their head turned to one side and knees flexed. These measurements were repeated three times, and the mean value was recorded. Exercise Program All participants received isometric strengthening exercises twice daily for 14 days, with each session lasting approximately 30-40 minutes. Each exercise was performed for 15 repetitions, with each repetition held for 5 seconds followed by a rest. The exercise program included the following: Isometric Exercises for Tongue Muscles: Using a tongue depressor, patients were instructed to press their tongue forward, upward, downward, and to the sides against the depressor. These exercises aim to increase the strength of the tongue muscles, which play a critical role in swallowing function [16]. Isometric Exercises for Jaw Muscles : Patients were asked to perform a chin tuck while in a supine position by tucking their chin toward their chest. Additionally, they were asked to place a soft ball under their chin and press against it to create an isometric contraction. These exercises target the muscles that facilitate swallowing [3]. Isometric Exercises for Back Muscles : Patients who could not sit with proper balance performed the exercises in a supine position with a soft ball placed under their back. They were asked to press their back against the ball to perform an isometric contraction. Patients with sufficient sitting balance were instructed to sit upright, pressing their backs against a chair to engage their trunk muscles. Strengthening the trunk muscles in this manner supports overall postural control and swallowing stability [17]. Statistical Analysis The study's sample size was determined by a power analysis performed using G*Power 3.1.9.4 software. Based on a similar single-group, pre-post study that showed a significant effect on tongue muscle strength [18], a large effect size (d=0.8) was assumed. For a statistical power of 80% and a significance level (alpha) of 5%, the minimum required sample size for a single-group, pre-post design was calculated to be 14 individuals. However, due to the high patient attrition rate and restrictive inclusion criteria for acute stroke patients, the study was completed with 12 participants. This limitation will be addressed in the discussion section. Statistical analysis of the data was performed using SPSS 25.0 software (IBM Corp., Armonk, NY, USA). The distribution of numerical variables was examined using the Shapiro-Wilk test. Since the data showed a non-parametric distribution, the Wilcoxon test was used to compare the pre- and post-treatment measurements. The relationships between parameters were evaluated using Spearman's correlation analysis, including partial correlation to control for the effect of confounding variables. The level of statistical significance was set at p<0.05. Results The sociodemographic and clinical characteristics of the 12 stroke patients who participated in the study are summarized in Table 1. The mean age of the patients was 59.08±10.15 years, with a mean stroke duration of 18.00±19.60 months. Brunnstromm stages and Barthel Index scores indicate that the patients had moderate motor and functional limitations. The mean pre-treatment EAT-10 score was 11.91±10.42, suggesting the presence of dysphagia risk. The effects of the 14-day isometric exercise program are shown in Table 2. Analysis results revealed a statistically significant increase in anterior tongue muscle strength (p=.025), posterior tongue muscle strength (p=.021), and back muscle strength (p=.005) between pre- and post-treatment measurements. However, no statistically significant change was observed in jaw muscle strength (p=.475). Spearman's correlation analysis was used to evaluate the relationships between the measured parameters before and after treatment. A very strong, positive, and statistically significant relationship was found between anterior and posterior tongue muscle strength both before (r=.922,p<.001) and after treatment (r=.762,p=.004). Furthermore, the relationship between tongue muscle strength and jaw and back muscle strength was examined. Before treatment, no statistically significant correlation was found between tongue muscle strength and the jaw and back muscles (Table 3). This finding suggests that there was no natural synergy between the swallowing muscles and other muscle groups prior to the intervention. After treatment, the simple correlations between tongue muscle strength and jaw and back muscle strength still did not reach a statistically significant level (Table 4). In addition to these findings, a partial correlation analysis was conducted to understand the extent to which the relationship between the tongue muscles was influenced by jaw and back muscle strength. In the pre-treatment period, the correlation between the tongue muscles did not change significantly when controlling for jaw and back muscle strength. However, after treatment, the relationship between the tongue muscles was found to be statistically significantly influenced by both jaw muscle strength (p=.040) and back muscle strength (p=.038). This finding indicates that the exercise program established a synergistic connection between these muscle groups (Table 5). Discussion This study is one of the pioneering investigations examining the effects of a short-term isometric exercise program on oropharyngeal and trunk muscle strength in the post-stroke period. The main aim was to investigate the effects of a 14-day isometric exercise program targeting tongue, jaw, and trunk muscles on swallowing and general motor functions in post-stroke patients. The findings support the study hypotheses, showing statistically significant improvements in anterior tongue strength (p = .025), posterior tongue strength (p = .021), and trunk muscle strength (p = .005). Notably, while the anterior and posterior tongue muscles strengthened, the force relationship between them was also significantly influenced by jaw and trunk muscle strength (p = .040, p = .038). These results suggest that swallowing function depends not only on local muscle strength but also on trunk stability. The results are consistent with previous studies. Robbins et al. [19] demonstrated that eight weeks of isometric tongue exercises increased tongue pressure, expanded tongue volume, and improved airway protection mechanisms in post-stroke patients. Similarly, Park et al. [20] reported that tongue resistance exercises significantly increased anterior and posterior tongue strength and improved oral phase swallowing scores. McKenna et al. [21], in a systematic review, indicated that isometric tongue strengthening programs increase tongue pressure in both healthy individuals and those with dysphagia, though effects on swallowing function were heterogeneous. These findings suggest that differences in protocol duration, intensity, and measurement methods may affect outcomes. Studies comparing different tongue resistance training protocols have shown that both pressure-timing-focused exercises and strength-accuracy-focused exercises improve tongue strength and reduce vallecular residue, although penetration-aspiration scores did not show significant changes [22]. This indicates that increases in tongue strength alone may not be sufficient to enhance swallowing safety. Our findings also emphasize the importance of trunk muscles. Park et al. [6] highlighted the critical role of trunk muscles in postural control. Similarly, Shimizu et al. [23] found that individuals with greater trunk muscle mass demonstrated better oral intake function (FOIS) and independent feeding at discharge. In our study, increased trunk muscle strength indirectly supported swallowing function by enhancing postural stability. Conversely, no significant change was observed in jaw muscle strength, suggesting that the duration or intensity of exercises targeting these muscles may have been insufficient. Oh et al. [24] emphasized the role of masticatory muscles in food preparation, noting that short-term interventions may not produce noticeable changes in these muscles. Thus, longer and progressive jaw exercises may be necessary. Long-term tongue strengthening protocols are also important for functional gains. Park et al. [25] reported significant improvements in FOIS scores, large effect sizes in tongue pressure, and reduced vallecular residue after 12 weeks of resistance tongue training. However, other swallowing parameters did not show significant changes. This indicates that the effects of short-term programs may be limited, while long-term exercises may yield more pronounced improvements. Our study aligns with this literature, demonstrating that a short-term isometric exercise program significantly increased tongue and trunk muscle strength and enhanced synergy between muscle groups.. Clinically, the study’s most important contribution is providing a holistic perspective to dysphagia rehabilitation. Early post-stroke interventions targeting not only tongue and swallowing muscles but also trunk muscles may reduce aspiration risk and facilitate the transition to oral feeding. This approach may complement conventional rehabilitation protocols and enhance functional independence. Nevertheless, this study has some limitations. First, the sample size was smaller than that calculated in the power analysis, limiting generalizability. Second, only a 14-day short-term exercise program was applied; longer-term studies with follow-up measurements are needed to assess the durability of changes. Furthermore, swallowing function was assessed only with the EAT-10; objective methods such as videofluoroscopic swallowing evaluation were not included. Future studies should examine the effectiveness of exercise protocols of varying durations and intensities in larger samples, using objective measures of swallowing function. In addition, biomechanical and neurophysiological studies elucidating the contribution of trunk muscles to swallowing function would help further develop rehabilitation programs. In conclusion, this study demonstrates that a short-term isometric exercise program can improve tongue and trunk muscle strength and enhance synergy between muscle groups in post-stroke patients. Holistic approaches targeting both oropharyngeal and trunk muscles may provide valuable contributions to clinical practice in dysphagia rehabilitation. Conclusion This study demonstrated that a 14-day short-term isometric exercise program can significantly improve tongue, jaw, and trunk muscle strength in post-stroke patients while enhancing synergy between muscle groups. These findings suggest that swallowing function depends not only on oropharyngeal muscle strength but also on trunk stability. Clinically, combining exercises targeting both oropharyngeal and trunk muscles may accelerate the transition to oral feeding, reduce aspiration risk, and improve functional independence in post-stroke patients. Future research should involve larger sample sizes and examine the long-term effects of exercise programs, comparing protocols of varying intensity, duration, and frequency. Additionally, swallowing function should be assessed using objective measures (such as videofluoroscopic or fiberoptic endoscopic swallowing evaluations), and biomechanical and neurophysiological studies are needed to clarify the contribution of trunk muscles to swallowing. These efforts will further enhance rehabilitation strategies. Abbreviations ATP: Anterior Tongue Pressure PTP: Posterior Tongue Pressure IOPI: Iowa Oral Performance Instrument EAT-10: Eating Assessment Tool-10 FOIS: Functional Oral Intake Scale SPSS: Statistical Package for the Social Sciences CI: Confidence Interval p: Significance Level (Probability) mmHg: Millimeters of Mercury kg: Kilogram %: Percent Declarations Ethics approval and consent to participate This study was designed as a prospective, single-center research project conducted at the Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Necmettin Erbakan University. Ethical approval for the study was obtained from the Necmettin Erbakan University Health Sciences Scientific Research Ethics Committee with decision number 2021/13-71. Written informed consent was obtained from all individual participants included in the study. This study was conducted in accordance with the principles of the Declaration of Helsinki. Consent for publication Not applicable Availability of data and materials The datasets generated and/or analysed during the current study are not publicly available due to ethical restrictions but are available from the corresponding author on reasonable request ( [email protected] ). Competing interests The authors declare no competing interests. Funding No funding was received for this study. Authors' contributions NAY conceptualized and designed the study, SK supervised the research. Both authors contributed to data analysis, manuscript writing, and approved the final version. Acknowledgements The authors would like to thank the administration of Necmettin Erbakan University Meram Medical Faculty Hospital for granting permission to conduct this study. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Authors' information [email protected] References Feigin VL, Stark BA, Brien P. Global, regional, and national burden of stroke and its risk factors, 1990–2019: A systematic analysis for the Global Burden of Disease Study 2019. Lancet Neurol. 2021;20(8):646–78. Hansen T, Sivertsen S, Bjerre M. The prevalence of dysphagia in stroke patients: A systematic review. Int J Environ Res Public Health. 2021;18(23):12693. Guggenbichler V, Kriechbaum B, Pittermann T. The role of masseter and temporal muscle strength in stroke patients with dysphagia. Dysphagia. 2022;37(2):263–71. Oh JC, Park E, Choi J. Effects of masticatory muscle training on chewing and swallowing function in elderly individuals. Dysphagia. 2020;35(6):935–43. Do JY, Jung JY, Lee DH. Effects of tongue strengthening exercise on dysphagia in post-stroke patients: A systematic review and meta-analysis. J Clin Neurol. 2021;17(1):1–9. Park SM, Han JY, Lee JS. The relationship between trunk muscle strength and upper extremity function in chronic stroke patients. J Phys Ther Sci. 2022;34(3):253–7. Park H, Lee S, Kim Y. The role of trunk control in swallowing function among patients with stroke. Clin Rehabil. 2022;36(5):651–9. Liao CH, Tseng PC, Lin JH, Yang YR. Effects of core stability training on balance and mobility in stroke patients: A systematic review and meta-analysis. Gait Posture. 2020;80:233-41. Sasegbon A, Hamdy S. The role of cortical neuroplasticity in the recovery of swallowing after stroke. Neurogastroenterol Motil. 2017;29(1):e12932. Brunnstrom S. Motor testing procedures in hemiplegia: based on stroke rehabilitation. Phys Ther. 1966;46(3):227-45. Shah S, Vanclay F, Cooper B. Improving the sensitivity of the Barthel Index for stroke rehabilitation. J Clin Epidemiol. 1989;42(8):707-14. Belafsky PC, Mouadeb DA, Rees CJ, Pryor JC, Postma GN, Allen J, et al. Validity and reliability of the Eating Assessment Tool (EAT-10). Ann Otol Rhinol Laryngol. 2008;117(12):919-24. Robin B, Gozdzikowska M, Mąka A. The use of the Iowa Oral Performance Instrument (IOPI) for the evaluation of tongue strength and its application in dysphagia rehabilitation: A literature review. Rehabil Speech Swallowing. 2019;10(1):1-8. Igarashi R, Tsubaki R, Yamagishi A, Sato M, Takeda T. A novel method for measuring maximum occlusal force using a digital force gauge with a single-arm bite fork. J Oral Rehabil. 2021;48(5):589-96. Cuesta-Vargas AI, Gabel P, O'Leary S. The measurement of back muscle activity using a pressure biofeedback unit: A systematic review. J Back Musculoskelet Rehabil. 2017;30(2):273-86. Logemann JA. Evaluation and treatment of swallowing disorders. 2nd ed. Pro-Ed; 1998. Bae SH, Park JS, Lee DR, Kim HY. Effects of back muscle strengthening exercise on swallowing function in stroke patients with dysphagia. J Clin Neurol. 2017;13(3):253-61. Kim HD, Choi JB, Yoo SJ, Chang MY, Lee SW, Park JS. Tongue-to-palate resistance training improves tongue strength and oropharyngeal swallowing function in subacute stroke survivors with dysphagia. J Oral Rehabil. 2017;44(1):59-64. Robbins J, Kays SA, Gangnon RE, Hind JA, Hewitt AL, Gentry LR, et al. The effects of lingual exercise in stroke patients with dysphagia. Arch Phys Med Rehabil. 2007;88(2):150-8. Park JS, An DH, Oh DH, Chang MY. Effect of tongue strength training using the Iowa Oral Performance Instrument in stroke patients with dysphagia. J Phys Ther Sci. 2019;31(1):75-8. McKenna VS, Zhang B, Haines MB, Kelchner LN. A systematic review of isometric lingual strength-training programs in adults with and without dysphagia. Am J Speech Lang Pathol. 2017;26(2):524–39. Steele CM, Bailey GL, Chau T, Molfenter SM, Oshalla M, Waito AA, et al. Outcomes of tongue-pressure strength and accuracy training for dysphagia following acquired brain injury. Int J Speech Lang Pathol. 2016;18(6):578–91. Shimizu A, Maeda K, Tanaka K, Wakabayashi H, Mori N. Trunk muscle mass index is positively associated with swallowing function in patients with stroke. Nutrition. 2022;100:111674. Oh JC, Park E, Choi J. Effects of masticatory muscle training on chewing and swallowing function in elderly individuals. Dysphagia. 2020;35(6):935–43. Park JS, An DH, Oh DH, Lee MM. Effects of an 8-week tongue-strengthening exercise program on tongue strength and swallowing-related outcomes in patients with dysphagia after stroke: A randomized controlled trial. J Oral Rehabil. 2023;50(7):623–32 Tables Table 1. Demographic and Clinical Characteristics of Patients Variable Min. Max. Mean SD Sociodemographic Data Age (years) 39.00 75.00 59.08 10.15 Stroke Duration (months) 2.00 72.00 18.00 19.60 Clinical Assessment Brunnstromm Upper Extremity 1.00 6.00 3.58 1.72 Brunnstromm Hand 1.00 5.00 3.41 1.44 Brunnstromm Lower Extremity 3.00 5.00 4.00 0.85 Barthel Index 0.00 75.00 36.66 21.77 EAT-10 0.00 26.00 11.91 10.42 Muscle Strength Measurements (Pre-Post) Anterior Tongue Muscle Strength (Pre) 12.00 47.00 25.91 11.71 Anterior Tongue Muscle Strength (Post) 10.00 56.00 30.41 14.33 Posterior Tongue Muscle Strength (Pre) 10.00 28.00 19.33 6.66 Posterior Tongue Muscle Strength (Post) 12.00 36.00 23.08 7.45 Jaw Muscle Strength (Pre) 3.40 12.00 5.94 2.19 Jaw Muscle Strength (Post) 4.20 7.20 5.65 0.94 Back Muscle Strength (Pre) 42.00 84.00 49.75 11.33 Back Muscle Strength (Post) 46.00 88.00 56.66 11.57 SD: Standard Deviation. Table 2. Comparison of Muscle Strength Differences Before and After Treatment (Wilcoxon Test) Pre-Treatment – Post-Treatment Z p Anterior Tongue Muscle Strength -4.50 −2.242 0.025* Posterior Tongue Muscle Strength (2-tailed) -3.75 −2.316 0.021* Jaw Muscle Strength 0.29 −0.714 0.475 Back Muscle Strength -6.91 −2.831 0.005* The Z value is the test statistic from the Wilcoxon signed-rank test. p<0.05 indicates a statistically significant difference. Table 3. Pre-Treatment Correlation Between Tongue, Jaw and Back Muscle Strength Variable Anterior Tongue Muscle Strength Posterior Tongue Muscle Strength Jaw Muscle Strength r=0.244(p=0.445) r=0.233(p=0.466) Back Muscle Strength r=0.059(p=0.856) r=−0.028(p=0.930) Results from Spearman's correlation analysis. Values in parentheses represent two-tailed p-values. Table 4. Post-Treatment Correlation Between Tongue, Jaw, and Back Muscle Strength Variable Anterior Tongue Muscle Strength Posterior Tongue Muscle Strength Jaw Muscle Strength r=0.228 (p=0.476) r=0.336 (p=0.285) Back Muscle Strength r=−0.067 (p=0.836) r=0.143 (p=0.658) Results from Spearman's correlation analysis. Values in parentheses represent two-tailed p-values. Table 5. Post-Treatment Partial Correlation Analysis (Influence of Jaw and Back Muscle Strength on the Relationship Between Tongue Muscles) Variable Control Variable r P Anterior Tongue Muscle Strength Jaw Muscle Strength 0.626 0.040* Posterior Tongue Muscle Strength Back Muscle Strength 0.629 0.038* p<0.05. The table shows how the relationship between anterior and posterior tongue muscle strength changes when jaw and back muscle strength are controlled. Additional Declarations No competing interests reported. Supplementary Files Tables.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 18 Jan, 2026 Reviewers agreed at journal 16 Jan, 2026 Reviewers agreed at journal 12 Jan, 2026 Reviewers invited by journal 09 Jan, 2026 Editor invited by journal 10 Dec, 2025 Editor assigned by journal 05 Dec, 2025 Submission checks completed at journal 04 Dec, 2025 First submitted to journal 04 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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07:58:02","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":15749,"visible":true,"origin":"","legend":"","description":"","filename":"Tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-7751845/v1/7d2007de684acd05b1be74b6.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Effects of a Short-Term Isometric Exercise Program Targeting Tongue, Jaw, and Trunk Muscles on Muscle Strength and Synergistic Relationships in Post-Stroke Patients: A Single-Group Pre-Post Study","fulltext":[{"header":"Background","content":"\u003cp\u003eStroke is a leading cause of death and long-term disability globally, frequently leading to a wide range of motor, sensory, and cognitive impairments [1]. A major complication of stroke is dysphagia (swallowing difficulty), which affects more than half of stroke patients and poses significant risks such as aspiration pneumonia, malnutrition, and dehydration [2]. Therefore, dysphagia management is a critical component of post-stroke rehabilitation and aims to improve patients' functional independence.\u003c/p\u003e\n\u003cp\u003eSwallowing is a complex action that requires coordinated muscle activity, including that of the tongue, cheeks, lips, and masticatory muscles [3]. Weakness or discoordination of these muscles can lead to dysphagia. Specifically, tongue muscle strength is vital for initiating the swallow and propelling the food bolus posteriorly, while the masticatory muscles (masseter and temporalis muscles) play a crucial role in preparing food for swallowing [4]. Studies have shown that targeted exercises for these muscle groups can effectively improve swallowing function [5].\u003c/p\u003e\n\u003cp\u003eHowever, post-stroke muscle weakness is not limited to the oropharyngeal region; it also commonly affects truncal muscles, compromising postural stability. Truncal muscle strength is a crucial indicator of overall body muscle strength [6, 7]. In traditional stroke rehabilitation, priority is often given to strengthening truncal and lower extremity muscles to regain fundamental functions like walking and postural balance [8]. Yet, oropharyngeal muscles, which are critical for vital functions such as swallowing and eating, can be overlooked in this comprehensive approach. The focus on a patient's general condition and trunk control in the acute phase can cause the rehabilitation of tongue and masticatory muscles to be deprioritized. However, addressing swallowing function early is crucial for reducing aspiration risk and expediting the patient's transition to oral feeding [9].\u003c/p\u003e\n\u003cp\u003eGiven this context, it is important to investigate the synergistic relationship between tongue, masticatory, and back muscle strength and to evaluate the efficacy of an integrated exercise program targeting these muscle groups. The limited number of studies that have examined this multi-faceted relationship highlights a significant knowledge gap. Therefore, this study aims to investigate the relationship among tongue pressure, chewing muscle strength, and back muscle strength in acute stroke patients and to examine the effects of a short-term isometric exercise program on these parameters. The findings are expected to contribute a new perspective to the development of holistic rehabilitation approaches for post-stroke dysphagia.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis study was designed as a single-group pre-post trial. A total of 12 post-stroke patients were included. All participants underwent a 14-day isometric exercise program targeting the tongue, jaw, and trunk muscles, with two daily sessions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy Design and Ethical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was designed as a prospective, single-center research project conducted at the Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Necmettin Erbakan\u0026nbsp; University. Ethical approval for the study was obtained from the Necmettin Erbakan\u0026nbsp; \u0026nbsp;University Health Sciences Scientific Research Ethics Committee with decision number 2021/13-71. All participants included in the study provided informed voluntary consent. The study was conducted with a single group, and all participants received the exercise intervention. Assessments were performed by the researcher, and no blinding was applied.\u0026nbsp;The study was retrospectively registered in the clinical trials registry on October 8, 2025, ID no \u0026nbsp;NCT07261462.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eParticipants\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTwelve patients with a diagnosis of acute ischemic or hemorrhagic stroke, who were hospitalized in the Physical Medicine and Rehabilitation service between February 2022 and December 2022, were enrolled in the study. Inclusion criteria were: being within the first 30 days of stroke onset; being between 18 and 80 years of age; having experienced their first stroke; undergoing inpatient physical therapy and rehabilitation; and voluntarily consenting to participate. Exclusion criteria were: cognitive impairment, severe aphasia or communication difficulties, a history of other neurological diseases, a history of surgery in the oral or jaw region, and refusal to participate.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOutcome Measures\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe participants' sociodemographic data (age and stroke duration) were recorded. The following clinical and functional assessments were performed both before and after the 14-day program:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMotor Functional Status:\u003c/strong\u003e Brunnstromm stages were used to evaluate motor recovery levels (upper extremity, hand, and lower extremity) of the hemiplegic side [10].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunctional Independence Status:\u003c/strong\u003e The Barthel Index was used to determine the participants' level of independence in daily living activities [11].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDysphagia Assessment:\u003c/strong\u003e The Eating Assessment Tool-10 (EAT-10) score was used to determine the severity of swallowing difficulty [12]..\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTongue Pressure Measurement:\u003c/strong\u003e The Iowa Oral Performance Instrument (IOPI) was used to assess tongue muscle strength [13]. For Anterior Tongue Pressure (ATP), the IOPI bulb was placed longitudinally along the hard palate, behind the alveolar ridge. For Posterior Tongue Pressure (PTP), the bulb was positioned at the posterior border of the hard palate. Both measurements were repeated three times, and the mean values were recorded.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eChewing Muscle Strength Measurement:\u003c/strong\u003e Chewing muscle strength, representing masticatory force, was measured using a hand-held dynamometer [14]. Participants were instructed to perform a jaw-opening movement against the dynamometer placed under the chin. This measurement was repeated three times, and the average value was used for analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBack Muscle Strength Measurement:\u003c/strong\u003e Back muscle strength was measured with a stabilizing pressure biofeedback unit [15]. Individuals were asked to lie supine on a treatment table with their head turned to one side and knees flexed. These measurements were repeated three times, and the mean value was recorded.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExercise Program\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll participants received isometric strengthening exercises twice daily for 14 days, with each session lasting approximately 30-40 minutes. Each exercise was performed for 15 repetitions, with each repetition held for 5 seconds followed by a rest. The exercise program included the following:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIsometric Exercises for Tongue Muscles:\u003c/strong\u003e Using a tongue depressor, patients were instructed to press their tongue forward, upward, downward, and to the sides against the depressor. These exercises aim to increase the strength of the tongue muscles, which play a critical role in swallowing function [16].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIsometric Exercises for Jaw Muscles\u003c/strong\u003e: Patients were asked to perform a chin tuck while in a supine position by tucking their chin toward their chest. Additionally, they were asked to place a soft ball under their chin and press against it to create an isometric contraction. These exercises target the muscles that facilitate swallowing [3].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIsometric Exercises for Back Muscles\u003c/strong\u003e: Patients who could not sit with proper balance performed the exercises in a supine position with a soft ball placed under their back. They were asked to press their back against the ball to perform an isometric contraction. Patients with sufficient sitting balance were instructed to sit upright, pressing their backs against a chair to engage their trunk muscles. Strengthening the trunk muscles in this manner supports overall postural control and swallowing stability [17].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study's sample size was determined by a power analysis performed using G*Power 3.1.9.4 software. Based on a similar single-group, pre-post study that showed a significant effect on tongue muscle strength [18], a large effect size (d=0.8) was assumed. For a statistical power of 80% and a significance level (alpha) of 5%, the minimum required sample size for a single-group, pre-post design was calculated to be 14 individuals. However, due to the high patient attrition rate and restrictive inclusion criteria for acute stroke patients, the study was completed with 12 participants. This limitation will be addressed in the discussion section.\u003c/p\u003e\n\u003cp\u003eStatistical analysis of the data was performed using SPSS 25.0 software (IBM Corp., Armonk, NY, USA). The distribution of numerical variables was examined using the Shapiro-Wilk test. Since the data showed a non-parametric distribution, the Wilcoxon test was used to compare the pre- and post-treatment measurements. The relationships between parameters were evaluated using Spearman's correlation analysis, including partial correlation to control for the effect of confounding variables. The level of statistical significance was set at p\u0026lt;0.05.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe sociodemographic and clinical characteristics of the 12 stroke patients who participated in the study are summarized in Table 1. The mean age of the patients was 59.08±10.15 years, with a mean stroke duration of 18.00±19.60 months. Brunnstromm stages and Barthel Index scores indicate that the patients had moderate motor and functional limitations. The mean pre-treatment EAT-10 score was 11.91±10.42, suggesting the presence of dysphagia risk.\u003c/p\u003e\n\u003cp\u003eThe effects of the 14-day isometric exercise program are shown in Table 2. Analysis results revealed a statistically significant increase in anterior tongue muscle strength (p=.025), posterior tongue muscle strength (p=.021), and back muscle strength (p=.005) between pre- and post-treatment measurements. However, no statistically significant change was observed in jaw muscle strength (p=.475).\u003c/p\u003e\n\u003cp\u003eSpearman's correlation analysis was used to evaluate the relationships between the measured parameters before and after treatment. A very strong, positive, and statistically significant relationship was found between anterior and posterior tongue muscle strength both before (r=.922,p\u0026lt;.001) and after treatment (r=.762,p=.004).\u003c/p\u003e\n\u003cp\u003eFurthermore, the relationship between tongue muscle strength and jaw and back muscle strength was examined. Before treatment, no statistically significant correlation was found between tongue muscle strength and the jaw and back muscles (Table 3). This finding suggests that there was no natural synergy between the swallowing muscles and other muscle groups prior to the intervention. After treatment, the simple correlations between tongue muscle strength and jaw and back muscle strength still did not reach a statistically significant level (Table 4).\u003c/p\u003e\n\u003cp\u003eIn addition to these findings, a partial correlation analysis was conducted to understand the extent to which the relationship between the tongue muscles was influenced by jaw and back muscle strength. In the pre-treatment period, the correlation between the tongue muscles did not change significantly when controlling for jaw and back muscle strength. However, after treatment, the relationship between the tongue muscles was found to be statistically significantly influenced by both jaw muscle strength (p=.040) and back muscle strength (p=.038). This finding indicates that the exercise program established a synergistic connection between these muscle groups (Table 5).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study is one of the pioneering investigations examining the effects of a short-term isometric exercise program on oropharyngeal and trunk muscle strength in the post-stroke period. The main aim was to investigate the effects of a 14-day isometric exercise program targeting tongue, jaw, and trunk muscles on swallowing and general motor functions in post-stroke patients. The findings support the study hypotheses, showing statistically significant improvements in anterior tongue strength (p = .025), posterior tongue strength (p = .021), and trunk muscle strength (p = .005). Notably, while the anterior and posterior tongue muscles strengthened, the force relationship between them was also significantly influenced by jaw and trunk muscle strength (p = .040, p = .038). These results suggest that swallowing function depends not only on local muscle strength but also on trunk stability.\u003c/p\u003e\n\u003cp\u003eThe results are consistent with previous studies. Robbins et al. [19] demonstrated that eight weeks of isometric tongue exercises increased tongue pressure, expanded tongue volume, and improved airway protection mechanisms in post-stroke patients. Similarly, Park et al. [20] reported that tongue resistance exercises significantly increased anterior and posterior tongue strength and improved oral phase swallowing scores. McKenna et al. [21], in a systematic review, indicated that isometric tongue strengthening programs increase tongue pressure in both healthy individuals and those with dysphagia, though effects on swallowing function were heterogeneous. These findings suggest that differences in protocol duration, intensity, and measurement methods may affect outcomes.\u003c/p\u003e\n\u003cp\u003eStudies comparing different tongue resistance training protocols have shown that both pressure-timing-focused exercises and strength-accuracy-focused exercises improve tongue strength and reduce vallecular residue, although penetration-aspiration scores did not show significant changes [22]. This indicates that increases in tongue strength alone may not be sufficient to enhance swallowing safety.\u003c/p\u003e\n\u003cp\u003eOur findings also emphasize the importance of trunk muscles. Park et al. [6] highlighted the critical role of trunk muscles in postural control. Similarly, Shimizu et al. [23] found that individuals with greater trunk muscle mass demonstrated better oral intake function (FOIS) and independent feeding at discharge. In our study, increased trunk muscle strength indirectly supported swallowing function by enhancing postural stability.\u003c/p\u003e\n\u003cp\u003eConversely, no significant change was observed in jaw muscle strength, suggesting that the duration or intensity of exercises targeting these muscles may have been insufficient. Oh et al. [24] emphasized the role of masticatory muscles in food preparation, noting that short-term interventions may not produce noticeable changes in these muscles. Thus, longer and progressive jaw exercises may be necessary.\u003c/p\u003e\n\u003cp\u003eLong-term tongue strengthening protocols are also important for functional gains. Park et al. [25] reported significant improvements in FOIS scores, large effect sizes in tongue pressure, and reduced vallecular residue after 12 weeks of resistance tongue training. However, other swallowing parameters did not show significant changes. This indicates that the effects of short-term programs may be limited, while long-term exercises may yield more pronounced improvements. Our study aligns with this literature, demonstrating that a short-term isometric exercise program significantly increased tongue and trunk muscle strength and enhanced synergy between muscle groups..\u003c/p\u003e\n\u003cp\u003eClinically, the study’s most important contribution is providing a holistic perspective to dysphagia rehabilitation. Early post-stroke interventions targeting not only tongue and swallowing muscles but also trunk muscles may reduce aspiration risk and facilitate the transition to oral feeding. This approach may complement conventional rehabilitation protocols and enhance functional independence.\u003c/p\u003e\n\u003cp\u003eNevertheless, this study has some limitations. First, the sample size was smaller than that calculated in the power analysis, limiting generalizability. Second, only a 14-day short-term exercise program was applied; longer-term studies with follow-up measurements are needed to assess the durability of changes. Furthermore, swallowing function was assessed only with the EAT-10; objective methods such as videofluoroscopic swallowing evaluation were not included.\u003c/p\u003e\n\u003cp\u003eFuture studies should examine the effectiveness of exercise protocols of varying durations and intensities in larger samples, using objective measures of swallowing function. In addition, biomechanical and neurophysiological studies elucidating the contribution of trunk muscles to swallowing function would help further develop rehabilitation programs.\u003c/p\u003e\n\u003cp\u003eIn conclusion, this study demonstrates that a short-term isometric exercise program can improve tongue and trunk muscle strength and enhance synergy between muscle groups in post-stroke patients. Holistic approaches targeting both oropharyngeal and trunk muscles may provide valuable contributions to clinical practice in dysphagia rehabilitation.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrated that a 14-day short-term isometric exercise program can significantly improve tongue, jaw, and trunk muscle strength in post-stroke patients while enhancing synergy between muscle groups. These findings suggest that swallowing function depends not only on oropharyngeal muscle strength but also on trunk stability. Clinically, combining exercises targeting both oropharyngeal and trunk muscles may accelerate the transition to oral feeding, reduce aspiration risk, and improve functional independence in post-stroke patients.\u003c/p\u003e\n\u003cp\u003eFuture research should involve larger sample sizes and examine the long-term effects of exercise programs, comparing protocols of varying intensity, duration, and frequency. Additionally, swallowing function should be assessed using objective measures (such as videofluoroscopic or fiberoptic endoscopic swallowing evaluations), and biomechanical and neurophysiological studies are needed to clarify the contribution of trunk muscles to swallowing. These efforts will further enhance rehabilitation strategies.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eATP: Anterior Tongue Pressure\u003c/p\u003e\n\u003cp\u003ePTP: Posterior Tongue Pressure\u003c/p\u003e\n\u003cp\u003eIOPI: Iowa Oral Performance Instrument\u003c/p\u003e\n\u003cp\u003eEAT-10: Eating Assessment Tool-10\u003c/p\u003e\n\u003cp\u003eFOIS: Functional Oral Intake Scale\u003c/p\u003e\n\u003cp\u003eSPSS: Statistical Package for the Social Sciences\u003c/p\u003e\n\u003cp\u003eCI: Confidence Interval\u003c/p\u003e\n\u003cp\u003ep: Significance Level (Probability)\u003c/p\u003e\n\u003cp\u003emmHg: Millimeters of Mercury\u003c/p\u003e\n\u003cp\u003ekg: Kilogram\u003c/p\u003e\n\u003cp\u003e%: Percent\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was designed as a prospective, single-center research project conducted at the Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Necmettin Erbakan\u0026nbsp; University. Ethical approval for the study was obtained from the Necmettin Erbakan\u0026nbsp; University Health Sciences Scientific Research Ethics Committee with decision number 2021/13-71.\u0026nbsp;Written informed consent was obtained from all individual participants included in the study.\u0026nbsp;This study was conducted in accordance with the principles of the Declaration of Helsinki.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe datasets generated and/or analysed during the current study are not publicly available due to ethical restrictions but are available from the corresponding author on reasonable request ([email protected]).\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eNo funding was received for this study.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors' contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNAY conceptualized and designed the study, SK supervised the research. Both authors contributed to data analysis, manuscript writing, and approved the final version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank the administration of Necmettin Erbakan University Meram Medical Faculty Hospital for granting permission to conduct this study. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors' information\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\[email protected]\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eFeigin VL, Stark BA, Brien P. Global, regional, and national burden of stroke and its risk factors, 1990\u0026ndash;2019: A systematic analysis for the Global Burden of Disease Study 2019. 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J Phys Ther Sci. 2022;34(3):253\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003ePark H, Lee S, Kim Y. The role of trunk control in swallowing function among patients with stroke. Clin Rehabil. 2022;36(5):651\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eLiao CH, Tseng PC, Lin JH, Yang YR. Effects of core stability training on balance and mobility in stroke patients: A systematic review and meta-analysis. Gait Posture. 2020;80:233-41.\u003c/li\u003e\n\u003cli\u003eSasegbon A, Hamdy S. The role of cortical neuroplasticity in the recovery of swallowing after stroke. Neurogastroenterol Motil. 2017;29(1):e12932.\u003c/li\u003e\n\u003cli\u003eBrunnstrom S. Motor testing procedures in hemiplegia: based on stroke rehabilitation. Phys Ther. 1966;46(3):227-45.\u003c/li\u003e\n\u003cli\u003eShah S, Vanclay F, Cooper B. Improving the sensitivity of the Barthel Index for stroke rehabilitation. J Clin Epidemiol. 1989;42(8):707-14.\u003c/li\u003e\n\u003cli\u003eBelafsky PC, Mouadeb DA, Rees CJ, Pryor JC, Postma GN, Allen J, et al. Validity and reliability of the Eating Assessment Tool (EAT-10). Ann Otol Rhinol Laryngol. 2008;117(12):919-24.\u003c/li\u003e\n\u003cli\u003eRobin B, Gozdzikowska M, Mąka A. The use of the Iowa Oral Performance Instrument (IOPI) for the evaluation of tongue strength and its application in dysphagia rehabilitation: A literature review. Rehabil Speech Swallowing. 2019;10(1):1-8.\u003c/li\u003e\n\u003cli\u003eIgarashi R, Tsubaki R, Yamagishi A, Sato M, Takeda T. A novel method for measuring maximum occlusal force using a digital force gauge with a single-arm bite fork. J Oral Rehabil. 2021;48(5):589-96.\u003c/li\u003e\n\u003cli\u003eCuesta-Vargas AI, Gabel P, O\u0026apos;Leary S. The measurement of back muscle activity using a pressure biofeedback unit: A systematic review. J Back Musculoskelet Rehabil. 2017;30(2):273-86.\u003c/li\u003e\n\u003cli\u003eLogemann JA. Evaluation and treatment of swallowing disorders. 2nd ed. Pro-Ed; 1998.\u003c/li\u003e\n\u003cli\u003eBae SH, Park JS, Lee DR, Kim HY. Effects of back muscle strengthening exercise on swallowing function in stroke patients with dysphagia. J Clin Neurol. 2017;13(3):253-61.\u003c/li\u003e\n\u003cli\u003eKim HD, Choi JB, Yoo SJ, Chang MY, Lee SW, Park JS. Tongue-to-palate resistance training improves tongue strength and oropharyngeal swallowing function in subacute stroke survivors with dysphagia. J Oral Rehabil. 2017;44(1):59-64.\u003c/li\u003e\n\u003cli\u003eRobbins J, Kays SA, Gangnon RE, Hind JA, Hewitt AL, Gentry LR, et al. The effects of lingual exercise in stroke patients with dysphagia. Arch Phys Med Rehabil. 2007;88(2):150-8.\u003c/li\u003e\n\u003cli\u003ePark JS, An DH, Oh DH, Chang MY. Effect of tongue strength training using the Iowa Oral Performance Instrument in stroke patients with dysphagia. J Phys Ther Sci. 2019;31(1):75-8.\u003c/li\u003e\n\u003cli\u003eMcKenna VS, Zhang B, Haines MB, Kelchner LN. A systematic review of isometric lingual strength-training programs in adults with and without dysphagia. Am J Speech Lang Pathol. 2017;26(2):524\u0026ndash;39.\u003c/li\u003e\n\u003cli\u003eSteele CM, Bailey GL, Chau T, Molfenter SM, Oshalla M, Waito AA, et al. Outcomes of tongue-pressure strength and accuracy training for dysphagia following acquired brain injury. Int J Speech Lang Pathol. 2016;18(6):578\u0026ndash;91.\u003c/li\u003e\n\u003cli\u003eShimizu A, Maeda K, Tanaka K, Wakabayashi H, Mori N. Trunk muscle mass index is positively associated with swallowing function in patients with stroke. Nutrition. 2022;100:111674.\u003c/li\u003e\n\u003cli\u003eOh JC, Park E, Choi J. Effects of masticatory muscle training on chewing and swallowing function in elderly individuals. Dysphagia. 2020;35(6):935\u0026ndash;43.\u003c/li\u003e\n\u003cli\u003ePark JS, An DH, Oh DH, Lee MM. Effects of an 8-week tongue-strengthening exercise program on tongue strength and swallowing-related outcomes in patients with dysphagia after stroke: A randomized controlled trial. J Oral Rehabil. 2023;50(7):623\u0026ndash;32\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1. Demographic and Clinical Characteristics of Patients\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"589\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;Variable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMin.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMax.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSociodemographic Data\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e39.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e75.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e59.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eStroke Duration (months)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e72.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e18.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e19.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eClinical Assessment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBrunnstromm Upper Extremity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBrunnstromm Hand\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBrunnstromm Lower Extremity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.85\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBarthel Index\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e75.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e36.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e21.77\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eEAT-10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e26.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10.42\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMuscle Strength Measurements (Pre-Post)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAnterior Tongue Muscle Strength (Pre)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e12.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e47.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e25.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.71\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAnterior Tongue Muscle Strength (Post)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e56.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e30.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e14.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePosterior Tongue Muscle Strength (Pre)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e28.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e19.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.66\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePosterior Tongue Muscle Strength (Post)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e12.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e36.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e23.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eJaw Muscle Strength (Pre)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e12.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eJaw Muscle Strength (Post)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBack Muscle Strength (Pre)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e42.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e84.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e49.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBack Muscle Strength (Post)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e46.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e88.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e56.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11.57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eSD: Standard Deviation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. Comparison of Muscle Strength Differences Before and After Treatment (Wilcoxon Test)\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"568\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePre-Treatment \u0026ndash;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;Post-Treatment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eZ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAnterior Tongue Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-4.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026minus;2.242\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.025*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior Tongue Muscle Strength (2-tailed)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-3.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026minus;2.316\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.021*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eJaw Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026minus;0.714\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.475\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBack Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-6.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026minus;2.831\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.005*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe Z value is the test statistic from the Wilcoxon signed-rank test. p\u0026lt;0.05 indicates a statistically significant difference.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3. Pre-Treatment Correlation Between Tongue, Jaw and Back Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"3\" cellpadding=\"0\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eVariable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eAnterior Tongue Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior Tongue Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eJaw Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003er=0.244(p=0.445)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003er=0.233(p=0.466)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eBack Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003er=0.059(p=0.856)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003er=\u0026minus;0.028(p=0.930)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eResults from Spearman\u0026apos;s correlation analysis. Values in parentheses represent two-tailed p-values.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4.\u0026nbsp;\u003c/strong\u003ePost-Treatment Correlation Between Tongue, Jaw, and Back Muscle Strength\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"3\" cellpadding=\"0\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eVariable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eAnterior Tongue Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior Tongue Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eJaw Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003er=0.228 (p=0.476)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003er=0.336 (p=0.285)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eBack Muscle Strength\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003er=\u0026minus;0.067 (p=0.836)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003er=0.143 (p=0.658)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eResults from Spearman\u0026apos;s correlation analysis. Values in parentheses represent two-tailed p-values.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5. Post-Treatment Partial Correlation Analysis\u003c/strong\u003e \u003cstrong\u003e(Influence of Jaw and Back Muscle Strength on the Relationship Between Tongue Muscles)\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eControl Variable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003er\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAnterior Tongue Muscle Strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eJaw Muscle Strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.626\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.040*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePosterior Tongue Muscle Strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBack Muscle Strength\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.629\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.038*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003ep\u0026lt;0.05. The table shows how the relationship between anterior and posterior tongue muscle strength changes when jaw and back muscle strength are controlled.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Back muscles, Muscle synergy, Post-stroke, Tongue strength, Rehabilitation","lastPublishedDoi":"10.21203/rs.3.rs-7751845/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7751845/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003eThis study aimed to investigate the effects of a short-term tongue-jaw-back isometric exercise program on these muscle groups and their interrelationships in the post-stroke period.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eTwelve post-stroke patients were included in the study. A 14-day exercise program, consisting of two daily sessions targeting the tongue, jaw, and back muscles, was administered. Anterior and posterior tongue muscles, jaw muscles, and back muscle strength were assessed before and after the exercise program. Tongue pressure was measured using the Iowa Oral Performance Instrument (IOPI), chewing strength with a hand-held dynamometer, and back strength with a stabilizing pressure biofeedback unit.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eAfter the 14-day isometric exercise program, anterior tongue strength (p = 0.025), posterior tongue strength (p = 0.021), and back muscle strength (p = 0.005) showed significant increases compared to pre-treatment values. No significant change was observed in jaw strength (p = 0.475). Spearman correlation analysis revealed no significant relationships between tongue muscles and jaw or back muscles before treatment, and simple correlations after treatment also did not reach significance. However, partial correlation analysis showed that the relationship between tongue muscles was significantly influenced by jaw strength (p = 0.040) and back strength (p = 0.038) after the intervention.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions: \u003c/strong\u003eShort-term isometric exercises targeting tongue, jaw, and back muscles in post-stroke patients effectively increased tongue and back muscle strength and enhanced the synergistic relationship among these muscle groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration:\u003c/strong\u003e This study was retrospectively registered with ClinicalTrials.gov on 2025-11-21 (ID: NCT07261462).\u003c/p\u003e","manuscriptTitle":"The Effects of a Short-Term Isometric Exercise Program Targeting Tongue, Jaw, and Trunk Muscles on Muscle Strength and Synergistic Relationships in Post-Stroke Patients: A Single-Group Pre-Post Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-13 18:26:27","doi":"10.21203/rs.3.rs-7751845/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-01-18T18:25:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"166923373435749985093028820310665017364","date":"2026-01-16T11:11:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"284571033535099069574233541170812636333","date":"2026-01-12T10:10:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-09T08:45:53+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-10T13:03:10+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-05T09:16:04+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-04T22:03:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2025-12-04T21:58:40+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"68930cef-128d-42f8-ba1c-976a702aa8d4","owner":[],"postedDate":"January 13th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-01-13T18:26:27+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-13 18:26:27","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7751845","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7751845","identity":"rs-7751845","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}