Search Results (33)

Background/Objectives: Bruxism has been associated with dysregulation of the autonomic nervous system (ANS). Visceral manual therapy (VMT) has shown beneficial effects on the vagal tone and modulation of ANS activity. This study aimed to evaluate the immediate and short-term effects of VMT in individuals with clinically based bruxism. Methods: A single-blind randomized controlled trial was conducted including 24 individuals with clinically based bruxism. Participants received two sessions of either VMT or a sham placebo technique. Outcome measures included heart rate variability (HRV), both normal-to-normal intervals (HRV-SDNN), and the root mean square of successive normal-to-normal intervals (HRV-RMSSD), as well as muscle tone and stiffness and pressure pain thresholds (PPTs). Measurements were made at T1 (baseline), T2 (post-first intervention), T3 (pre-second intervention), T4 (post-second intervention), and T5 (4-week follow-up). Results: A significant time*group interaction was observed for HRV-SDNN (p = 0.04, η² = 0.12). No significant changes were found for muscle tone or stiffness. PPTs significantly increased at C4 after the second session (p = 0.049, η² = 0.16) and at the left temporalis muscle after the first session (p = 0.01, η² = 0.07). Conclusions: The findings suggest that two sessions of VMT may lead to significant improvements in HRV-SDNN compared to the placebo, suggesting a modulatory effect on autonomic function. No consistent changes were observed for the viscoelastic properties of the masticatory muscles. Isolated improvements in pressure pain sensitivity were found at C4 and the left temporalis muscle. Further research with larger sample sizes and long-term follow-up is needed to determine the clinical relevance of VMT in the management of signs and symptoms in individuals with bruxism. Full article

Medical phantoms are essential to imaging calibration, clinician training, and the validation of therapeutic procedures. However, most ultrasound phantoms prioritize acoustic realism while neglecting the viscoelastic and anisotropic properties of fibrous soft tissues. This gap limits their effectiveness in modeling realistic biomechanical behavior, especially in wave-based diagnostics and therapeutic ultrasound. Current materials like gelatine and agarose fall short in reproducing the complex interplay between the solid and fluid components found in biological tissues. To address this, we developed a soft, anisotropic composite whose dynamic mechanical properties resemble fibrous biological tissues such as skin and skeletal muscle. This material enables wave propagation and vibration studies in controllably anisotropic media, which are rare and highly valuable. We demonstrate the tunability of damping and stiffness aligned with fiber orientation, providing a versatile platform for modeling soft-tissue dynamics and validating biomechanical simulations. The phantoms achieved Young’s moduli of 7.16–11.04 MPa for skin and 0.494–1.743 MPa for muscles, shear wave speeds of 1.51–5.93 m/s, longitudinal wave speeds of 1086–1127 m/s, and sound absorption coefficients of 0.13–0.76 dB/cm/MHz, with storage, loss, and complex moduli reaching 1.035–6.652 kPa, 0.1831–0.8546 kPa, and 2.138–10.82 kPa. These values reveal anisotropic response patterns analogous to native tissues. This novel natural fibrous composite system affords sustainable, low-cost ultrasound phantoms that support both mechanical fidelity and acoustic realism. Our approach offers a route to next-gen tissue-mimicking phantoms for elastography, wave propagation studies, and dynamic calibration across diverse clinical and research applications. Full article

Polymeric composite solutions (PCSs) reinforced with carbon nanotubes sponges (CNT-sponges) have attracted interest in material science and engineering due to their physicochemical properties. Understanding the influence of CNT-sponges content (0.1 wt.%, 0.3 wt.% and 0.5 wt.%) on rheological behavior of poly(styrene-co-acrylonitrile) P(S:AN) (0:100, 20:80, 40:60 and 50:50, wt.%:wt.%) solutions synthesized by emulsion polymerization can predict the viscoelastic parameters for their possible application in electrospinning processes. The obtained nanofibers can be used as sensors, textiles, purifying agents or artificial muscles and tissues. For this, amplitude and frequency sweeps were performed to measure the viscosity (η), storage (G’) and loss (G”) moduli and loss factor (tan δ). Most PCSs showed a shear thinning behavior over the viscosity range of 0.8 < η/Pa·s < 20. At low CNT-sponges concentration in the polymer matrix, the obtained loss factor indicated a liquid-like behavior, while as CNT-sponges content increases, the solid-like behavior predominated. Then, the polymeric solutions were successfully electrospun; however, some agglomerations were formed in materials containing 0.5 wt.% of CNT-sponges attributed to the interaction forces generated within the structure. Finally, the rheological analysis indicates that the PCS with a low percentage of CNT-sponges are highly suitable to be electrospun. Full article

Background: Pain manifestations as well as increased muscle tone and stiffness noted in the course of delayed-onset muscle soreness (DOMS) are reflected in altered values of the biomechanical and visco-elastic parameters of muscles. This study aimed to compare the effects of soft tissue mobilization with foam rolling and percussive massage on symptoms of DOMS induced by a standardized muscle fatigue protocol. Methods: Healthy volunteers (n = 60) were divided into three groups: FR group—foam rolling (n = 20), PM group—percussive massage (n = 20) and CON group—control/passive rest (n = 20). The fatigue protocol for the gastrocnemius muscle was carried out for development of DOMS in subsequent days. Therapeutic procedures were applied to participants for 3 consecutive days. The results of therapy were assessed by means of myotonometry, performed five times (before, three times during the treatment procedure, and after the end of the procedure). Results: Foam rolling significantly reduced the onset and duration of increased muscle tone (p = 0.006) and stiffness (p < 0.001), unlike percussive massage. The control group exhibited higher tone and stiffness after 48 h, at the peak of DOMS-related pain symptoms. Only foam rolling improved elasticity (decrement, p < 0.001), while visco-elastic properties (relaxation, creep) varied inversely with tone and stiffness. Foam rolling led to significantly lower stiffness (day 2) and reduced decrement and relaxation (day 4) compared to the control. Neither therapy was more effective than passive rest for pain relief during the observation period. Conclusions: Foam rolling and percussive massage accelerate recovery of muscle tone, stiffness, and elasticity after DOMS as compared to passive rest but offer no added benefit for pain relief. Full article

Background/Objectives: Alkaptonuria (AKU) is a rare genetic disorder characterized by elevated levels of circulating homogentisic acid (HGA), which accumulates in connective tissues. The musculoskeletal system is particularly susceptible to HGA deposition, often resulting in severe ochronotic osteoarthropathy, especially in the hips, shoulders, knees, and spine. However, little is known about the effects of AKU on skeletal muscle tissue. The study aimed to evaluate changes in lower limb muscles associated with AKU. Methods: This case report describes the treatment of ochronotic osteoarthropathy in the knee of a 73-year-old male patient. Muscle properties were assessed using the MyotonPRO device. The rectus femoris, vastus medialis, and patellar tendon were examined both preoperatively and three months postoperatively. Results: Following total knee arthroplasty (TKA) of the right knee, the patient demonstrated significant improvement in functional outcomes. The MyotonPRO assessment revealed measurable differences in muscle properties between the operated and non-operated limbs. Postoperative measurements indicated improvements in muscle tone, elasticity, and viscoelastic parameters in the treated limb. Conclusions: This case report supports the effectiveness of TKA as a treatment for ochronotic osteoarthropathy. Furthermore, it is the first study to use the MyotonPRO to assess muscle and tendon properties in a patient with AKU. These findings highlight the need for further research into the muscular effects of this rare metabolic disorder. Full article

Background: This study aimed to investigate the acute changes in muscle and tendon viscoelastic properties in response to a progressive treadmill VO₂max test among professional male soccer players. Methods: Bilateral assessments at five sites—the Achilles tendon (AT), biceps femoris, semitendinosus, rectus femoris (RF), and sternocleidomastoid (SCM)—measured tone (oscillation frequency), dynamic stiffness, logarithmic decrement (elasticity), stress relaxation time, and creep. Each site was probed five times and values averaged. Repeated-measures ANOVA (Time × Side) with Bonferroni correction tested pre- to post-exercise changes; Pearson’s r examined associations with VO₂max. Results: Significant Time effects (all p < 0.05) were observed for RF frequency (η_p² = 0.226), RF creep (η_p² = 0.144), AT stiffness (η_p² ≈ 0.035), AT frequency (η_p² = 0.035), and SCM frequency (η_p² = 0.037). Post-exercise, right AT stiffness fell by 65 ± 14 N/m (p = 0.015), while left AT stiffness rose by 22 ± 9 N/m (p = 0.015). RF stiffness decreased by 28 ± 6 N/m (p < 0.001) and tone by 1.2 ± 0.3 Hz (p < 0.001), with creep (+0.08 ± 0.02; p < 0.001) and relaxation time (+1.5 ± 0.7 ms; p < 0.001) increasing. SCM tone declined by 0.8 ± 0.4 Hz (p = 0.010). Baseline RF properties—frequency (r = −0.597), stiffness (r = −0.59), relaxation time (r = 0.53), and creep (r = 0.48)—correlated moderately with VO₂max (all p < 0.05). Conclusions: These findings suggest that viscoelastic adaptations to exhaustive aerobic exercise are tissue- and side-specific, and that rectus femoris viscoelastic properties may serve as potential indicators of endurance readiness. Full article

Background: Adequate hamstring flexibility is crucial for musculoskeletal health as increased muscle tone can lead to stretch-type injuries, muscle weakness, dysfunctional neuromuscular control, postural changes, and lower back pain. The aim was to compare the effectiveness of a program based on Electrical Muscle Elongation (EME), Proprioceptive Neuromuscular Facilitation (PNF), and no intervention in improving flexibility and viscoelastic properties of hamstring and quadriceps muscles in active young adults with functional hamstring disorder (type 2B according to the Munich Consensus). Methods: Sixty-five participants (45 male, 20 female) were randomly assigned to three groups: the EME group (n = 21) received a simultaneous combination of interferential current and stretching, the PNF group (n = 22) underwent active stretching, and the Control group (n = 22) received no intervention. Hamstring and quadricep flexibility and muscle stiffness were measured in both limbs at baseline, post-intervention, and at the 4-week follow-up. Results: The EME group showed significant improvements in hamstring flexibility in the left limb compared to the Control group and in some myotonometric variables of the quadriceps muscle compared to the PNF and Control groups (p < 0.05). Within-groups differences indicated higher improvements in the EME group. Conclusions: This study suggests that EME may offer greater benefits than PNF stretching in young adults with functional hamstring disorder. Full article

As an electrically driven artificial muscle, dielectric elastomer actuators (DEAs) are notable for their large deformation, fast response speed, and high energy density, showing significant potential in soft robots. The paper discusses the working principles of DEAs, focusing on their reversible deformation under electric fields and performance optimization through material and structural innovations. Key applications include soft grippers, locomotion robots (e.g., multilegged, crawling, swimming, and jumping/flying), humanoid robots, and wearable devices. The challenges associated with DEAs are also examined, including the actuation properties of DE material, material fatigue, viscoelastic effects, and environmental adaptability. Finally, modeling and control strategies to enhance DEA performance are introduced, with a perspective on future technological advancements in the field. Full article

The temporomandibular joint (TMJ) is essential for chewing and speaking functions, as well as for making facial expressions. However, this joint can be affected by disorders, known as temporomandibular disorders (TMDs), induced by complex causes that lead to limitations in daily activities. Building on the methodology and findings from our previous study on TMJ function, our research aims to apply the established criteria and norms to patients with TMDs. The primary goal is to evaluate the applicability and clinical relevance of these reference norms in predicting the severity and progression of TMJ disorders within a clinical population. Using non-invasive myotonic measurements, we evaluated 157 subjects, including both non-TMD-affected and TMD-affected individuals. To achieve optimal results, five primary parameters (frequency, stiffness, decrement, relaxation time, and creep) were analyzed using statistical–physical tools, providing quantitative functionality degrees across different previously examined clinical groups. The obtained results identified significant quantitative markers for early diagnosis and personalized treatment of TMJ disorders. This interdisciplinary approach leads to a deeper understanding of TMJ dysfunctions and makes a meaningful contribution to clinical practice, providing more precise tools for managing and treating this complex condition. Full article

Pathologies in neck and masticatory muscles affect muscle tone and biomechanical and viscoelastic properties, necessitating precise assessment for treatment. This study evaluated the impact of two guided interventions—relaxing exercises targeting the neck and masticatory muscles (“Exercise”) and heavy chewing using six chewing gums (“Chewing”)—on the masseter and upper trapezius muscles. Twelve participants (aged 19–40 years) underwent myotonometric assessment pre- and post-intervention, measuring tone, stiffness, decrement, relaxation time, and creep. The results showed significant changes in the masseter muscle after exercise, with increased stiffness (14.46%, p < 0.001) and tone (7.03%, p < 0.001) but decreased creep (−9.71%, p < 0.001) and relaxation time (−11.36%, p < 0.001). Conversely, chewing decreased stiffness (−8.82%, p < 0.001) and tone (−5.53%, p < 0.001), while it increased creep (9.68%, p < 0.001) and relaxation time (9.98%, p < 0.001). In the trapezius muscles, tone decreased after both interventions (Exercise: −7.65%, p < 0.001; Chewing: −1.06%, p = 0.003), while relaxation increased (Exercise: 1.78%, p < 0.001; Chewing: 2.82%, p < 0.001). These findings reveal the distinct effects of exercise and chewing on muscle properties, emphasising the complexity of their therapeutic potential and the need for further investigation. Full article

Background/Objectives: To compare the lumbopelvic muscle mechanical properties (MMPs) of women with and without multiple sclerosis (MS) and explore relationships between these properties and sociodemographic/clinical characteristics. Methods: This cross-sectional observational study included 22 women with MS and 22 age- and BMI-matched women without MS. MMPs (frequency, stiffness, decrement, relaxation, and creep) of pelvic floor and lumbar paravertebral muscles were assessed using a MyotonPRO device. Sociodemographic and clinical data related to pelvic floor health were also collected. Results: Women with MS showed significant differences in pelvic floor MMPs, including higher frequency (3.26 Hz; 95% CI [2.12, 4.41]), stiffness (90 N/m; 95% CI [55.09, 124.91]), and decrement (0.2; 95% CI [0.09, 0.31]), and lower relaxation (6.15 ms; 95% CI [8.26, 4.05]) and creep (0.24; 95% CI [0.34, 0.13]) compared to women without MS. For lumbar paravertebral muscles, differences were observed only on the right side, with lower frequency (2.15 Hz; 95% CI [0.28, 4.02]) and stiffness (62.17 N/m; 95% CI [10.7, 113.65]) in women with MS. Correlation patterns between MMPs and clinical characteristics differed by group, with moderate correlations found only in the MS group (e.g., EDSS: r = 0.57; p = 0.006; PFDI-20: r = 0.47; p = 0.026). Conclusions: Women with MS exhibit altered pelvic floor MMPs, characterized by reduced tone and stiffness and increased elasticity and viscoelasticity, while lumbar paravertebral differences are minimal. These findings highlight the need for objective MMP assessments in women with MS to guide preventive and therapeutic interventions. Full article

Background: One of the methods used in malocclusion treatment is the use of fixed appliances. Research conducted so far has revealed that changes in bite force occurring over the course of orthodontic treatment are directly related to the functional status of the masticatory muscles. It is therefore advisable to find out how the biomechanical parameters of the masseter muscles change after treatment with the application of fixed appliances. Methods: The study material comprised 74 individuals, divided into the study group (n = 37) treated by means of fixed orthodontic appliances over the average time of 12.27 months and the control group (n = 37) consisting of individuals did not undergo orthodontic treatment. The biomechanical properties of the masseter muscles were examined by means of myotonometry. Results: Upon completion of orthodontic treatment, the values of the parameters of tension, stiffness, and elasticity of masseter muscles located on both sides did not statistically significantly differ between patients from the study group who were treated by means of fixed orthodontic appliances and patients from control group who did not undergo orthodontic treatment. Conclusions: Treatment of malocclusions with the use of fixed appliances does not affect the biomechanical and visco-elastic properties of the masseter muscles (stiffness, tension, and elasticity) assessed by means of myotonometry and it appears safe for masticatory muscles. Full article

This paper will develop the restoring model of a commercial pneumatic artificial muscle (PAM) based on a McKibben structure, which comprises an elastic element connected with a viscoelastic element in parallel. The elastic element is generated by compressed air inside the rubber bellow; meanwhile, the viscoelasticity is affected by the rubber material. In particular, the viscoelastic property of the rubber material is proposed based on the Maxwell model. Instead of derivative of integer orders, an equation of motion of the fractional model is introduced to better capture the amplitude- and frequency-dependent property of the viscoelasticity of the PAM. The equation expressing the hysteresis loop due to the viscoelasticity of the PAM material will then be analyzed and built. A water cycle algorithm is employed to determine the optimal set of the proposed model. To evaluate the effectiveness of the proposed model, a comparison between the simulation calculated from the proposed model and experimental data is considered under harmonic force excitation. This study’s results give potential insight into the field of system dynamic analysis with the elastic element being PAM. Full article

This study aimed to evaluate the viscoelastic properties of lower-extremity muscles in pediatric hemophilia (FVIII-IX) patients. The study included 20 severe- and moderate-type right-dominant hemophilia patients diagnosed with hemophilia A–B and 20 healthy children. Viscoelastic properties (tone, stiffness, elasticity) of the lower-extremity muscles were measured using a MyotonPRO device. The physical characteristics of the pediatric hemophilia patients (mean age: 11.9 ± 3.95 years) and the control group (mean age: 12.6 ± 3.41 years) were found to be similar. A difference was observed only in the elasticity of the right vastus lateralis (p < 0.05) by means of the viscoelastic properties of the lower-extremity muscles. The results were similar in other muscle groups (p > 0.05). The dominant-side vastus lateralis muscle elasticity (the ability of the muscle to regain its original shape after contraction or removal of an external force) of hemophilia patients was found to be lower compared to healthy children. The fact that 45% of hemarthroses occur in the knee joint and that recurrent bleeding may affect the flexibility of the vastus lateralis, which is the main muscle within the quadriceps muscle group and responsible for the stabilization of the patella, can be associated with the study results. Full article

Background: Temporomandibular joint (TMJ) disorders, which affect millions of people worldwide, have multiple etiological factors that make an accurate diagnosis and effective treatments difficult. As a consequence, the gold standard diagnostic criteria for TMJ disorders remain elusive and often depend on subjective decisions. Aim: In this context, the lack of a non-invasive quantitative methodology capable of assessing the functional physiological state and, consequently, identifying risk indicators for the early diagnosis of TMJ disorders must be tackled and resolved. Methodology: In this work, we have studied the biomechanics and viscoelastic properties of the functional masticatory system by a non-invasive approach involving 52 healthy subjects, analysed by statistical–physics analysis applied to myotonic measurements on specific points of the masticatory system designing a TMJ network composed of 17 nodes and 20 links. Results: We find that the muscle tone and viscoelasticity of a specific cycle linking frontal, temporal, and mandibular nodes of the network play a prominent role in the physiological functionality of the system. At the same time, the functional state is characterised by a landscape of nearly degenerated levels of elasticity in all links of the network, making this parameter critically distributed and deviating from normal behaviour. Conclusions: Time evolution and dynamic correlations between biomechanics and viscoelastic parameters measured on the different cycles of the network provide a quantitative framework associated with the functional state of the masticatory system. Our results are expected to contribute to enriching the taxonomy of this system, primarily based on clinical observations, patient symptoms, and expert consensus. Full article