Muscle Tone Assessment by Machine Learning Using Surface Electromyography.

Muscle tone is defined as the resistance to passive stretch, but this definition is often criticized for its ambiguity since some suggest it is related to a state of preparation for movement. Muscle tone is primarily regulated by the central nervous system, and individuals with neurological disorders may lose the ability to control normal tone and can exhibit abnormalities. Currently, these abnormalities are mostly evaluated using subjective scales, highlighting a lack of objective assessment methods in the literature. This study aimed to use surface electromyography (sEMG) and machine learning (ML) for the objective classification and characterization of the full spectrum of muscle tone in the upper limb. Data were collected from thirty-nine individuals, including spastic, healthy, hypotonic and rigid subjects. All of the classifiers applied achieved high accuracy, with the best reaching 96.12%, in differentiating muscle tone. These results underscore the potential of the proposed methodology as a more reliable and quantitative method for evaluating muscle tone abnormalities, aiming to address the limitations of traditional subjective assessments. Additionally, the main features impacting the classifiers' performance were identified, which can be utilized in future research and in the development of devices that can be used in clinical practice.

The Effects of Foam Rolling at Different Speeds on Mechanical Properties of Quadriceps Femoris.

Foam rolling have gained popularity among elite athletes, but the effect of the speed parameter of foam rolling has not yet been determined. Our objective was to investigate the impact of different application speeds of foam roller on the mechanical properties of the quadriceps femoris muscle. Eighteen male professional basketball athletes (age 23 ± 4 years, body mass index 24.43 ± 1.59 kg/m2) participated in this study. We used a crossover design to randomize the order of the treatment speeds (30 beats per minute-FAST, 15 beats per minute-SLOW, and a self-determined speed-SELF) with a one-week washout period between each session. We measured dominant quadriceps femoris muscle tone, elasticity, and stiffness using the Myoton device before and after the interventions. We found that the average rate for SELF was 33±10 beats per minute, making SELF the fastest. All application speeds showed similar results in pre-intervention measurements of the mechanical properties of the tissues (P > 0.05). However, post hoc analysis revealed that a decrease was evident in SLOW compared to SELF in muscle tone in post-intervention measurements (P = 0.037). Also, we noted that comparison of pre- and post-intervention on FAST and SLOW showed a significant reduction in muscle tone (P = 0.002, P = 0.008). Slower foam rolling prior to training or competition may lead to a delay in the reaction time due to the reduction in tonus, that can increase the injury risks. Alternatively, the significant reduction in tonus may be useful in regulating the increased tonus after training and competition.

Specific tension of human muscle in vivo: a systematic review.

The intrinsic force production capability of human muscle can be expressed as "Specific Tension," or, the maximum force generated per cross-sectional area of muscle fibers. This value can be used to determine, for example, whether muscle quality changes during exercise, atrophy, disease, or hypertrophy. A value of 22.5 N/cm2 for mammalian muscle has generally become accepted based on detailed studies of small mammals. Determining the specific tension of human muscle is much more challenging as almost all determinations are indirect. Calculation of human muscle specific tension requires an understanding of that muscle's contribution to joint torque, its activation magnitude, tendon compliance, and joint moment arm. Determining any of these parameters is technically challenging in humans and thus, it is no surprise that human specific tension values reported vary from 2 to 73 N/cm2. In this systematic review, we screened 1,506 published papers and identified the 30 studies published between 1983 and 2023 that used appropriate methods and which reported 96 human specific tension values. We weighted each parameter based on whether it was directly measured, estimated, or calculated based on the literature, with decreasing weighting used, the more indirect the methods. Based on this exhaustive review of the relevant human literature, we suggest that the most accurate value that should be used for human muscle specific tension is 26.8 N/cm2.

Factors influencing airway smooth muscle tone: a comprehensive review with a special emphasis on pulmonary surfactant.

A thin film of pulmonary surfactant lines the surface of the airways and alveoli, where it lowers the surface tension in the peripheral lungs, preventing collapse of the bronchioles and alveoli and reducing the work of breathing. It also possesses a barrier function for maintaining the blood-gas interface of the lungs and plays an important role in innate immunity. The surfactant film covers the epithelium lining both large and small airways, forming the first line of defense between toxic airborne particles/pathogens and the lungs. Furthermore, surfactant has been shown to relax airway smooth muscle (ASM) after exposure to ASM agonists, suggesting a more subtle function. Whether surfactant masks irritant sensory receptors or interacts with one of them is not known. The relaxant effect of surfactant on ASM is absent in bronchial tissues denuded of an epithelial layer. Blocking of prostanoid synthesis inhibits the relaxant function of surfactant, indicating that prostanoids might be involved. Another possibility for surfactant to be active, namely through ATP-dependent potassium channels and the cAMP-regulated epithelial chloride channels [cystic fibrosis transmembrane conductance regulators (CFTRs)], was tested but could not be confirmed. Hence, this review discusses the mechanisms of known and potential relaxant effects of pulmonary surfactant on ASM. This review summarizes what is known about the role of surfactant in smooth muscle physiology and explores the scientific questions and studies needed to fully understand how surfactant helps maintain the delicate balance between relaxant and constrictor needs.

Effect of Single-Dose Imipramine on Anal Sphincter Tone in Healthy Women: A Randomized, Placebo-Controlled Study Using Anal Acoustic Reflectometry.

INTRODUCTION AND HYPOTHESIS: Despite the high prevalence of fecal incontinence, existing treatment options may be inadequate. Drugs that enhance the tone of the anal sphincter complex could potentially be an effective pharmacological approach. This study investigated the effect of the tricyclic antidepressant imipramine on anal sphincter tone in healthy women, employing anal acoustic reflectometry as the evaluating method. METHODS: In a double-blind, randomized, placebo-controlled crossover study, 16 healthy female volunteers were randomized to one of two treatment sequences. The participants attended two study visits separated by at least 7 days' washout. At each visit, they received a single dose of 50 mg imipramine or matching placebo, in alternating order. We assessed the anal opening pressure under the resting state and during voluntary squeezing of the pelvic floor. Measurements were performed pre-dose and 1 h after drug administration, corresponding to the estimated time of peak plasma concentration of imipramine. RESULTS: All participants completed the study. In total, 44% of the participants reported at least one adverse effect, primarily anticholinergic. Compared with placebo, imipramine increased anal opening pressure by 15.2 cmH2O (95% confidence interval [CI] 2.0-28.2 cmH2O, p = 0.03) in the resting state and 15.1 (95% CI 4.2-26.0 cmH2O, p = 0.01) cmH2O during squeezing. CONCLUSIONS: The findings indicate that imipramine increases anal sphincter tone in healthy women. However, further research is required to evaluate its clinical impact on individuals with fecal incontinence. This research also demonstrates the effectiveness of using anal acoustic reflectometry for assessing pharmacological effects on anal sphincter function.

Impact of Standing and Sitting Postures on Spinal Curvature and Muscle Mechanical Properties in Young Women: A Photogrammetric and MyotonPro Analysis.

BACKGROUND This study aimed to evaluate the effect of standing and sitting positions on spinal curvatures evaluated using projection moire and muscle tone and stiffness using the MyotonPRO hand-held device in young women. MATERIAL AND METHODS Thirty-three healthy women, aged 21 to 23 years, volunteered in the study. We used the projection moire method to examine spinal curvatures in both positions and the MyotonPRO device to measure the tone and stiffness of muscles in 3 regions. We evaluated the effects of positions (standing vs sitting), regions (cervical, thoracic, and lumbar), and side factor (right vs left) using multivariate analysis. RESULTS The sitting position significantly decreased the lumbosacral and thoracolumbar angles (P<0.001), but had no effect on the superior thoracic angle. Muscle tension and stiffness were the highest (P<0.001) in the cervical region and did not differ between positions (P>0.05) in this region. We found significantly higher muscle tone and stiffness in the thoracic and lumbar regions during sitting than during standing (P<0.001). There was symmetry in the muscle tone and the stiffness between the right and left sides of the spine. CONCLUSIONS The sitting posture decreased lumbosacral and thoracolumbar angles but increased muscle tension and stiffness in the lumbar and thoracic regions only. The symmetry of muscle tone and transverse stiffness in both positions was the normative value. This study provides insight into the adaptive physiological changes in spinal curvature and muscle mechanical properties in young women and serves as an important reference point for clinical studies of women.

Exploring the link between occupationally relevant whole body vibration and headache and neck pain: is elevated muscle tension an intermediary factor?

Whole body vibration (WBV) is linked to short- and longer-term adverse health outcomes, including cognitive impairment, stress and memory loss, loss of balance, reduced proprioception, visual and vestibular disturbances, gastrointestinal problems, and musculoskeletal disorders. Epidemiological evidence supports the link between WBV and headache and head discomfort, but few experimental studies have examined this relationship, particularly with increased muscle tension, as an intermediary. This study aimed to investigate the relationship between muscle tension and vibration intensity, between perceived neck pain and headache/head discomfort and vibration intensity, and between muscle tension and reported neck pain and headache symptoms from simulated WBV based on field measurements of all-terrain vehicle operation on farm terrain. We observed significantly higher electromyography amplitude in the High condition (equivalent to EU Directive's Exposure Limit Value) compared to both Low (equivalent to EU Directive's Exposure Action Value) and Control (quiet sitting) conditions at the left upper trapezius muscle but there were no significant time effects. Neck pain and headache/head discomfort significantly increased after both Low (91% increase from baseline) and High (154% increase from baseline) vibration conditions but there were no significant differences between conditions. Based on simple regression modeling, the relationship between muscle activity and neck pain or headache was very weak (R2 = 0-0.093). Given the possibility of multiple factors contributing to headache symptoms, future research should not only consider the role of muscle tension but also sensory conflict, excessive noise, biodynamic responses, and a combination of these factors.

Effects of stretching exercises on muscle tension, fatigue, strength, and lactic acid accumulation: A pre-experimental study among fish transport workers.

Fish transport workers in Indonesia lift loads more than the specified limits, both in weight and frequency. This could cause lactic acid accumulation, fatigue and reduced physical performance. The aim of this study was to assess the effect of stretching intervention on muscle tension, fatigue, strength, and lactic acid level in fish transport workers in Indonesia. A pre-experimental study design with one group (pre- and post-test) design was conducted among male fish transport workers at the Tawang fish auction, Weleri, Central Java, Indonesia, in June 2022 for two weeks. We created a 1.5-minute stretching exercise video based on the University of New Castle's Manual Handling guideline, involving hand, feet, and shoulder movements. Participants performed these exercises independently before and during work every two hours, guided by the video. Data on lactic acid, muscle tension, fatigue, and strength were collected before and after the 2-week intervention. Data analysis was performed using Wilcoxon and paired Student t-tests to compare the outcome between post- and pre-intervention. A total of 18 fish transport workers were included in the study. The results showed a statistically significant increase in lactic acid levels following the intervention (p=0.016). However, the increase in muscle tension was not statistically significant (p=0.292). There was a significant increase in fatigue levels after the intervention (p=0.000). This could suggest that the stretching intervention may have had an unintended effect of increasing fatigue among the participants. On the other hand, there was a statistically significant decrease in muscle strength after the intervention (p=0.003). In conclusion, this study suggests that while stretching exercises can affect lactic acid accumulation, fatigue, and muscle strength, they do not influence muscle tension. Therefore, it is advised for workers to incorporate stretching exercises into their daily routine to mitigate potential injury risks.

Is sleep bruxism in obstructive sleep apnea only an oral health related problem?

BACKGROUND: The etiology of sleep bruxism in obstructive sleep apnea (OSA) patients is not yet fully clarified. This prospective clinical study aimed to investigate the connection between probable sleep bruxism, electromyographic muscle tone, and respiratory sleep patterns recorded during polysomnography. METHODS: 106 patients with OSA (74 males, 31 females, mean age: 56.1 ± 11.4 years) were divided into two groups (sleep bruxism: SB; no sleep bruxism: NSB). Probable SB were based on the AASM criteria: self-report of clenching/grinding, orofacial symptoms upon awakening, abnormal tooth wear and hypertrophy of the masseter muscle. Both groups underwent clinical examination for painful muscle symptoms aligned with Temporomandibular Disorders Diagnostic Criteria (DC/TMD), such as myalgia, myofascial pain, and headache attributed to temporomandibular disorder. Additionally, non-complaint positive muscle palpation and orofacial-related limitations (Jaw Functional Limited Scale-20: JFLS-20) were assessed. A one-night polysomnography with electromyographic masseter muscle tone (EMG) measurement was performed. Descriptive data, inter-group comparisons and multivariate logistic regression were calculated. RESULTS: OSA patients had a 37.1% prevalence of SB. EMG muscle tone (N1-N3, REM; P = 0.001) and the number of hypopneas (P = 0.042) were significantly higher in the sleep bruxism group. While measures like apnea-hypopnea-index (AHI), respiratory-disturbance-index (RDI), apnea index (AI), hypopnea-index (HI), number of arousals, and heart rate (1/min) were elevated in sleep bruxers, the differences were not statistically significant. There was no difference in sleep efficiency (SE; P = 0.403). Non-complaint masseter muscle palpation (61.5%; P = 0.015) and myalgia (41%; P = 0.010) were significant higher in SB patients. Multivariate logistic regression showed a significant contribution of EMG muscle tone and JFLS-20 to bruxism risk. CONCLUSION: Increased EMG muscle tone and orofacial limitations can predict sleep bruxism in OSA patients. Besides, SB patients suffer more from sleep disorder breathing. Thus, sleep bruxism seems to be not only an oral health related problem in obstructive apnea. Consequently, interdisciplinary interventions are crucial for effectively treating these patients. TRIAL REGISTRATION: The study was approved by the Ethics Committee of Philipps-University Marburg (reg. no. 13/22-2022) and registered at the "German Clinical Trial Register, DRKS" (DRKS0002959).

Chloroquine and cinchonine affect rat vascular smooth muscle tonus through calcium channels - in silico and in vitro approaches.

BACKGROUND: In the present study, two structurally similar alkaloids from trees of Cinchona genus, chloroquine and cinchonine, were examined for their vasorelaxant effects in a model of phenylephrine-induced smooth muscle contractions. METHODS: Potential mechanisms of action associated with endothelial vasorelaxant compounds, voltage-gated Ca2+ channels (LTCCs), and inositol triphosphate receptors were examined in isolated rat aortic rings. Also, an in silico approach was used to predict the activity of the two test compounds. RESULTS: Experimental results revealed that both chloroquine and cinchonine significantly decrease phenylephrine-induced smooth muscle contractions, although to a different extent. Evaluated mechanisms of action indicate that endothelium is not involved in the vasorelaxant action of the two tested alkaloids. On the other hand, voltage-gated Ca2+ channels were found to be the dominant way of action associated with the vasorelaxant action of chloroquine and cinchonine. Finally, IP3R is found to have only a small impact on the observed activity of the tested compounds. CONCLUSION: Molecular docking studies predicted that chloroquine possesses a significant activity toward a suitable model of LTCCs, while cinchonine does not. The results of the present study point to the fact that great caution should be paid while administering chloroquine to vulnerable patients, especially those with cardiovascular disorders (Tab. 3, Fig. 3, Ref. 28).

Rehabilitation Treatment Specification System: Content and Criterion Validity Across Evidence-Based Voice Therapies for Muscle Tension Dysphonia.

PURPOSE: Systematically improving voice therapy outcomes is challenging as the clinician actions (i.e., active ingredients) responsible for improved patient functioning (i.e., targets) are relatively unknown. The theory-driven Rehabilitation Treatment Specification System (RTSS) and standard, voice-specific terminology based on the RTSS (RTSS-Voice) may help address this problem. This qualitative study evaluated if the RTSS and RTSS-Voice can describe four evidence-based voice therapies for muscle tension dysphonia without missing critical aspects (content validity) and identify commonalities and differences across them (criterion validity). METHOD: Qualitative interviews were completed between the clinicians (protocol experts) who developed and/or popularized the vocal function exercises, laryngeal reposturing, circumlaryngeal massage, and conversation training therapies as well as RTSS experts to produce RTSS specifications that met two consensus criteria: (a) The protocol expert agreed that the specification represented their treatment theory, and (b) the RTSS experts agreed that the specifications correctly adhered to both the RTSS framework and the RTSS-Voice's standard terminology. RESULTS: The RTSS and RTSS-Voice comprehensively described voice therapy variations across and within the four diverse treatment programs, needing only the addition of one new target: overall auditory-perceptual severity. CONCLUSIONS: The RTSS and RTSS-Voice exhibited strong content validity. The standard RTSS-Voice terminology helped identify, for the first time, commonalities and differences in treatment ingredients, targets, and mechanisms of action across four treatments developed for the same patient population. In the long term, the RTSS and RTSS-Voice could provide the framework for an ever-growing collection of clinically meaningful and evidence-based therapy algorithms with potential to improve research, education, and clinical care. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.25537624.

Myotonometry in machinery operators and its relationship with postural ergonomic risk.

OBJECTIVES: To analyze the association between occupational ergonomic risk, personal characteristics, and working conditions with the biomechanical properties of stiffness and muscular tone in the paravertebral muscles of electric pallet jack and forklift operators in the industrial sector. METHODS: A total of 75 industrial sector machine operators were evaluated in 2021. Personal characteristics and working conditions were assessed through a questionnaire. Ergonomic risk was assessed using the Rapid Entire Body Assessment (REBA) method, and biomechanical properties of stiffness and muscular tone were obtained using the Myoton Pro device. Stiffness in paravertebral muscles was compared based on the operated machine and observed ergonomic risk. A multilevel linear regression model was employed to quantify the relationship, with mean differences and 95% CI calculated. RESULTS: Very high ergonomic risk was found in 75% of the electric pallet truck drivers. In this group with the highest ergonomic risk, an association between biomechanical properties and older workers was observed. Additionally, among electric pallet truck drivers, stiffness (mean difference 335.9 N/m, 95% CI: 46.4 (3.4 to 110.0), P < 0.05) and paravertebral muscle tone (mean difference 17.5 Hz, 95% CI: 1.4 (0.1 to 3.4), P < 0.05) showed statistically significant differences in the very high ergonomic risk category compared to the high-risk category. No significant differences were observed in any of the analyzed variables among forklift drivers. CONCLUSIONS: Workers operating electric pallet trucks with very high ergonomic risk according to the REBA method and aged over 40 yr are associated with increased muscle stiffness and tone.

Muscle Tension Dysphagia: An Expanded Investigation of Clinical Presentations and Swallowing Kinematics.

PURPOSE: This study retrospectively examined patient-reported symptoms, quality of life, and swallowing kinematics in individuals with presumed muscle tension dysphagia (MTDg). METHOD: Twenty-six individuals met the inclusion criteria. Data were gathered from patient-reported outcome measures (PROs), symptomology, clinician reports of palpation, and hyolaryngeal and hyoid movements measured on a 20-ml thin liquid bolus during videofluoroscopic swallowing studies. RESULTS: All PROs were outside of typical limits, except for the Voice Handicap Index-10. Mean hyoid excursion was 1.52 cm (SD = 0.46, range: 0.76-2.43), and hyolaryngeal excursion was 0.77 cm (SD = 0.44, range: -0.42-1.68). A minority of participants (4%-19%) demonstrated atypical hyoid and/or hyolaryngeal excursion compared to the available normative reference value sets. CONCLUSIONS: Individuals demonstrated abnormalities in the clinical evaluation of the areas of palpation and reported perilaryngeal discomfort and symptoms of laryngeal hyperresponsiveness, with a negative impact on their quality of life across various PROs. Atypical hyoid and/or hyolaryngeal excursion during swallowing was rare when compared to available normative reference values. The clinical evaluation of MTDg may be enhanced by including components related to muscle tension and laryngeal hyperresponsiveness in order to differentiate MTDg from idiopathic functional dysphagia and lead the patient to the otolaryngology/speech-language pathology clinic for intervention and management.

Comparison of muscle tightness between knees in individuals with unilateral osteoarthritis and its relationship with pain and function.

BACKGROUND: Unilateral osteoarthritis (OA) affects single knees and presents a unique scenario where individuals experience varying degrees of symptoms between their affected and unaffected knees. OBJECTIVE: This study aims to investigate differences in muscle tightness between symptomatic and asymptomatic knees in individuals with unilateral knee OA while exploring the interplay among pain, functionality, and muscle tightness. METHODS: In this cross-sectional study, thirty knee OA patients underwent assessments for hamstring (Active Knee Extension, Straight Leg Raise), iliotibial band (Ober Test), and quadriceps tightness (Modified Thomas Test). Pain intensity was measured using the Visual Analog Scale (VAS), and functional limitations were evaluated via the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). RESULTS: A negative correlation was observed between participants' pain and AKE (p= 0.004, r=-0.515), ASLR (p= 0.27, r=-0.403), Ober (p= 0.010, r=-0.461) values. However, no significant correlation was found with the Modified Thomas value (p= 0.204, r=-0.239). There was also a negative correlation between participants' WOMAC scores and AKE (p= 0.019, r=-0.427), OBER (p= 0.004, r=-0.510), and Modified Thomas (p= 0.022, r=-0.416) values, while ASLR (p= 0.286, r=-0.202) values showed no significant correlation. Comparisons between AKE, Ober, and Modified Thomas values showed higher values in asymptomatic extremities (AKE: p= 0.025, Ober: p= 0.021, Modified Thomas: p= 0.030). CONCLUSION: This study emphasizes the significance of muscle tightness in the symptomatic extremities of individuals with unilateral knee OA. The results indicate that increased muscle tightness makes pain worse and limits movement. It's crucial for healthcare providers treating OA to focus on improving muscle flexibility, reducing pain, and enhancing overall function.

[Rehabilitation of patients with facial nerve neuropathy in cases of increased muscle tone on the healthy side of the face]. / Reabilitatsiya patsientov s neiropatiei litsevogo nerva pri povyshenii tonusa myshts na zdorovoi storone litsa.

OBJECTIVE: To evaluate the effectiveness of physical rehabilitation (PR) and injections of botulinum toxin type A (BTA) in the correction of muscles hypertonicity ty of the healthy side of the face or its prevention in patients with facial nerve neuropathy (FNN). MATERIAL AND METHODS: One hundred and forty-six patients with FNN of various etiologies with muscles hypertonicity of the healthy side or the risk of its development were studied. The term of treatment was 33 [10; 99] days. There are 88 women and 58 men aged 42 [34; 56] years. Diagnosis included clinical examination and stimulation electroneuromyography (ENMG, n=113; 77.4%) with assessment of M-wave amplitude asymmetry. All patients were prescribed a standard PR complex, in addition - relaxation of the muscles of the healthy side by injections of BTA (Incobotulinumtoxin A) - BTA group (n=38) or by special PR techniques - physiotherapy group (n=108). RESULTS: In both groups, patients were comparable in age, sex and severity of FNN at clinical assessment. But objectively, in the BTA group there were more symptomatic forms (63.2% vs 43.5%; p=0.038), cases of M-wave amplitude asymmetry over 90% in ≥2 branches (52.6% vs 18.5%; p=0.032). Displacement of the face midline was a factor limiting recovery (68.4% and 62%; χ2=0.495; p=0.482) in two groups. With amplitude asymmetry of more than 90% in ≥2 branches (a predictor of the risk of unfavorable outcome), a favorable outcome occurred more often in the BTA group (80% versus 45%; χ2=5.227; p=0.023). In case of amplitude asymmetry of less than 90% in all branches, a favorable outcome was observed in two groups. CONCLUSION: Indications for botulinum therapy in patients with FNN are deep prosoparesis or prosoplegia, muscles hypertonicity of the healthy side, displacement of the face midline, ENMG predictors of the risk of unfavorable outcome. PR is an effective method of prevention in patients with a favorable prognosis of outcome or treatment of mild forms.

The relationship between lower extremity muscle tightness and pain and disability in individuals with non-specific chronic low back pain.

BACKGROUND: Low back pain is a common health issue, and such pains are often associated with muscle tightness. Understanding the link between lower back pain and tight lower extremity muscles is essential for effective pain management and enhanced quality of life. OBJECTIVE: The objective of this study was to investigate the relationship between lower extremity muscle tightness and pain and disability in individuals with non-specific low back pain (NSLBP). METHODS: A total of 52 individuals with NSLBP were enrolled in this cross-sectional study. Lower extremity muscle tightness was assessed using various clinical tests, including the Active Knee Extension Test, Active Straight Leg Raise, Ober Test, and Modified Thomas Test. Pain intensity and disability were evaluated using the Visual Analog Scale and the Oswestry Disability Index, respectively. Statistical analyses were conducted to assess the correlation between muscle tightness, pain, and disability. RESULTS: The study found weak to moderate negative correlations between lower extremity muscle tightness and both pain intensity and disability in individuals with NSLBP (r: -0.287 to -0.526, p < 0.05). Dominant and non-dominant extremities exhibited differences in muscle flexibility, with the dominant extremity showing greater flexibility (p < 0.05). CONCLUSIONS: In individuals with NSLBP, lower extremity muscle tightness is closely related to pain severity and disability. These findings suggest that lower extremity muscle tightness plays a significant role in the severity of low back pain and disabilities. Additionally, the observed flexibility difference between dominant and non-dominant extremities warrants further investigation for more personalized treatment approaches.

Tirasemtiv enhances submaximal muscle tension in an Acta1:p.Asp286Gly mouse model of nemaline myopathy.

Nemaline myopathies are the most common form of congenital myopathies. Variants in ACTA1 (NEM3) comprise 15-25% of all nemaline myopathy cases. Patients harboring variants in ACTA1 present with a heterogeneous disease course characterized by stable or progressive muscle weakness and, in severe cases, respiratory failure and death. To date, no specific treatments are available. Since NEM3 is an actin-based thin filament disease, we tested the ability of tirasemtiv, a fast skeletal muscle troponin activator, to improve skeletal muscle function in a mouse model of NEM3, harboring the patient-based p.Asp286Gly variant in Acta1. Acute and long-term tirasemtiv treatment significantly increased muscle contractile capacity at submaximal stimulation frequencies in both fast-twitch extensor digitorum longus and gastrocnemius muscle, and intermediate-twitch diaphragm muscle in vitro and in vivo. Additionally, long-term tirasemtiv treatment in NEM3 mice resulted in a decreased respiratory rate with preserved minute volume, suggesting more efficient respiration. Altogether, our data support the therapeutic potential of fast skeletal muscle troponin activators in alleviating skeletal muscle weakness in a mouse model of NEM3 caused by the Acta1:p.Asp286Gly variant.

The mechanism of action for laryngeal manual therapies: the need for an update.

PURPOSE OF REVIEW: To propose a pathway for expanding the understanding of potential mechanisms of action with laryngeal-based manual therapy (LMT) for muscle tension dysphonia (MTD). This review may help determine if current LMT literature has kept up with advances in the more general manual therapy (MT) findings. RECENT FINDINGS: Studies over the past thirty years, including recently published articles, have confirmed the efficacy of various manual therapy interventions in treating MTD. However, gaps exist between current LMT literature and that being presented in the more general MT field. Instead of viewing peripheral manipulation's influences as a local cause/effect process, the MT literature paints a richer tapestry of centrally mediated impacts. SUMMARY: Evidence from outside the LMT field has introduced a broad tapestry of factors that may contribute to the efficacy of MT, extending beyond the local effects reported in LMT literature. To better understand the effect and mechanism of action touch-based interventions have on a patient's voice and to potentially improve outcomes, it is necessary to broaden investigations to include a broader range of perspectives.

Acute effects of muscle mechanical properties after 2000-m rowing in young male rowers.

Background: The mechanical properties of muscles, such as changes in muscle tone and stiffness, are related to sports performance and injuries. Rowers are at increased risk of muscle fatigue and injury during high-repetition and heavy-load cyclic muscle actions. In view of this, the aim of the present study was to investigate the acute effect on muscle tone and stiffness, as well as bilateral muscle asymmetry, in high school rowers after a 2000-meter rowing ergometer test. Methods: Twelve young male rowers (age = 17.1 ± 0.9 years, body weight = 73.5 ± 9.7 kg) were included in the study. The data of muscle tone (frequency) and stiffness of the posterior deltoids (PD), latissimus dorsi (LD), and rectus femoris (RF) (dominant and non-dominant side) before and after a 2000-m rowing ergometer test were collected using a handheld MyotonPRO device. Results: After the rowing ergometer test, the muscle tone of dominant side PD, LD, and RF were significantly increased (p < 0.05). On the other hand, the muscle stiffness of the non-dominant side LD and RF, as well as the dominant side PD, LD, and RF were significantly increased after the rowing ergometer test (p < 0.05). The muscle tone and stiffness results showed that the dominant side PD, LD, and RF were all significantly higher than the non-dominant side after the rowing ergometer test (p < 0.05), where bilateral PD and RF exhibits moderate asymmetry (5% < symmetry index < 10%). Conclusions: After a high-intensity and high-load 2000-m rowing ergometer test, PD, LD, and RF showed increases in muscle tone and stiffness, as well as changes in the symmetry of bilateral muscle mechanical properties.

Acoustic and Physiologic Correlates of Vocal Effort in Individuals With and Without Primary Muscle Tension Dysphonia.

OBJECTIVES: The aims of this study were to determine relationships between vocal effort and (a) acoustic correlates of vocal output and (b) supraglottic compression in individuals with primary muscle tension dysphonia (pMTD) and without voice disorders (controls) in the context of a vocal load challenge. METHOD: Twenty-six individuals with pMTD and 35 vocally healthy controls participated in a 30-min vocal load challenge. The pre- and postload relationships among self-ratings of vocal effort, various acoustic voice measures, and supraglottic compression (mediolateral and anteroposterior) were tested with multiple regression models and post hoc Pearson's correlations. Acoustic measures included cepstral peak prominence (CPP), low-to-high spectral ratio, difference in intensity between the first two harmonics, fundamental frequency, and sound pressure level (dB SPL). RESULTS: Regression models for CPP and mediolateral compression were statistically significant. Vocal effort, diagnosis of pMTD, and vocal demand were each significant variables influencing CPP measures. CPP was lower in the pMTD group across stages. There was no statistical change in CPP following the vocal load challenge within either group, but both groups had an increase in vocal effort postload. Vocal effort and diagnosis influenced the mediolateral compression model. Mediolateral compression was higher in the pMTD group across stages and had a negative relationship with vocal effort, but it did not differ after vocal loading. CONCLUSIONS: CPP and mediolateral supraglottic compression were influenced by vocal effort and diagnosis of pMTD. Increased vocal effort was associated with lower CPP, particularly after vocal load, and decreased mediolateral supraglottic compression in the pMTD group.