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Disruptions in gait function are common after concussion in adolescents; however, the neuromotor control deficits driving these gait disruptions are not well known. Fifteen concussed (age mean [SD]): 17.4 [0.6], 13 females, days since injury: 26.3 [9.9]) and 17 uninjured (age: 18.0 [0.7], 10 females) adolescents completed 3 trials each of single-task gait and dual-task gait (DT). During DT, participants simultaneously walked while completing a serial subtraction task. Gait metrics and variability in instantaneous mean frequency in lower extremity muscles were captured by inertial sensors and surface electromyography, respectively. A 2-way analysis of covariance was used to compare gait metrics across groups and conditions. Functional principal components analysis was used to identify regions of variability in instantaneous mean frequency curves. Functional principal component scores were compared across groups using a Welch statistic. Both groups displayed worse performance on gait metrics during DT condition compared to single-task, with no differences between groups (P <.001). Concussed adolescents displayed significantly greater instantaneous mean frequency, indicated by functional principal component 1, in the tibialis anterior, biceps femoris, and semitendinosus (P <.05) during single-task and DT compared with uninjured adolescents. Our observations suggest that concussed adolescents display inefficient motor unit recruitment lasting longer than 2 weeks following injury, regardless of the addition of a secondary task. [ABSTRACT FROM AUTHOR]

Context: Decreased muscle strength and balance in patients with functional ankle instability (FAI) can be effectively improved by ankle strength training. Low-load blood flow restriction (LL-BFR) training increases muscle size and strength, but there is limited evidence from studies on muscle strength and balance in FAI patients. Objective: To study the effects of LL-BFR training versus high-load training (HLT) on muscle strength and balance in FAI patients. Design: Randomized controlled trial. Participants: Forty-six young adults with a history of FAI. Interventions: Participants in the LL-BFR and HLT groups performed 4 sets (30 x 15 x 15 x 15) of ankle training at 20% to 40% of the one-repetition maximum and 70% to 85% one-repetition maximum, respectively, twice a week for 6 weeks. Main Outcome Measure(s): Plantar flexion, dorsiflexion, inversion, and eversion muscle strength, and the Y-balance test scores were assessed at baseline and after 3 and 6 weeks; the thickness of the tibialis anterior, triceps surae, and peroneus longus muscles were assessed at baseline and after 6 weeks. Results: Inversion, eversion, dorsiflexion, and plantar flexion muscle strength; tibialis anterior, triceps surae, and peroneus longus thickness; and Y-balance test scores were significantly increased in the LL-BFR group after 3 and 6 weeks compared with baseline (P < .05), with no significant difference between the LL-BFR and HLT groups after 6 weeks (P > .05). However, at the end of 3 weeks, eversion muscle strength and Y-balance test scores were significantly higher in the LL-BFR group than in the HLT group (P < .05). Conclusions: Over 6 weeks, LL-BFR training was as effective as HLT in improving ankle muscle strength, muscle thickness, and balance in FAI patients, but LL-BFR training improved the ankle eversion muscle strength and dynamic balance more than HLT did in the early stages of the intervention. This finding will provide a new intervention strategy for the clinical rehabilitation of FAI patients. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to clarify the relationships of the tibialis anterior tendon (TAT) and peroneus longus tendon (PLT) with articular cartilage degeneration on the medial cuneiform and first metatarsal. Methods: We examined 100 feet from 50 Japanese cadavers. The TAT was classified into 4 types based on attachment site area and number of fiber bundles: Type I, two fiber bundles with equal (within 20%) attachment site areas on the first metatarsal and medial cuneiform; Type II, with two fiber bundles and a larger (>20%) attachment site area on the medial cuneiform than on the first metatarsal; Type III, with two fiber bundles and a larger (>20%) attachment site area on the first metatarsal than on the medial cuneiform; and Type IV, with three fiber bundles. The PLT was classified into 2 types, following previous studies: Type I, insertion only to the base of the first metatarsal; Type II, insertion to the medial cuneiform and first metatarsal. The severity of articular cartilage degeneration was assessed in five stages using the International Cartilage Repair Society scale. Results: No significant difference in severity of articular cartilage degeneration was evident among types of TAT and PLT. Conclusion: Our results suggested that anatomical variations in the TAT and PLT might not affect joint stability, indicating that strengthening of these muscles could potentially enhance stability regardless of morphological variations in the insertions. [ABSTRACT FROM AUTHOR]

Recruitment input-output curves of transspinal evoked potentials that represent the net output of spinal neuronal networks during which cortical, spinal and peripheral inputs are integrated as well as motor evoked potentials and H-reflexes are used extensively in research as neurophysiological biomarkers to establish physiological or pathological motor behavior and post-treatment recovery. A comparison between different sigmoidal models to fit the transspinal evoked potentials recruitment curve and estimate the parameters of physiological importance has not been performed. This study sought to address this gap by fitting eight sigmoidal models (Boltzmann, Hill, Log-Logistic, Log-Normal, Weibull-1, Weibull-2, Gompertz, Extreme Value Function) to the transspinal evoked potentials recruitment curves of soleus and tibialis anterior recorded under four different cathodal stimulation settings. The sigmoidal models were ranked based on the Akaike information criterion, and their performance was assessed in terms of Akaike differences and weights values. Additionally, an interclass correlation coefficient between the predicted parameters derived from the best models fitted to the recruitment curves was also established. A Bland-Altman analysis was conducted to evaluate the agreement between the predicted parameters from the best models. The findings revealed a muscle dependency, with the Boltzmann and Hill models identified as the best fits for the soleus, while the Extreme Value Function and Boltzmann models were optimal for the tibialis anterior transspinal evoked potentials recruitment curves. Excellent agreement for the upper asymptote, slope, and inflection point parameters was found between Boltzmann and Hill models for the soleus, and for the slope and inflection point parameters between Extreme Value Function and Boltzmann models for the tibialis anterior. Notably, the Boltzmann model for soleus and the Extreme Value Function model for tibialis anterior exhibited less susceptibility to inaccuracies in estimated parameters. Based on these findings, we suggest the Boltzmann and the Extreme Value Function models for fitting the soleus and the tibialis anterior transspinal evoked potentials recruitment curve, respectively. [ABSTRACT FROM AUTHOR]

AbstractMouse models of amyotrophic lateral sclerosis (ALS) enable testing of novel therapeutic interventions. However, treatments that have extended survival in mice have often failed to translate into human benefit in clinical trials. Compound muscle action potentials (CMAPs) are a simple neurophysiological test that measures the summation of muscle fiber depolarization in response to maximal stimulation of the innervating nerve. CMAPs can be measured in both mice and humans and decline with motor axon loss in ALS, making them a potential translational read-out of disease progression. We assessed the translational potential of CMAPs and ascertained time points when human and mouse data aligned most closely. We extracted data from 18 human studies and compared with results generated from SOD1G93A and control mice at different ages across different muscles. The relative CMAP amplitude difference between SOD1G93A and control mice in tibialis anterior (TA) and gastrocnemius muscles at 70 days of age was most similar to the relative difference between baseline ALS patient CMAP measurements and healthy controls in the abductor pollicis brevis (APB) muscle. We also found that the relative decline in SOD1G93A TA CMAP amplitude between 70 and 140 days was similar to that observed in 12 month human longitudinal studies in APB. Our findings suggest CMAP amplitudes can provide a “translational window”, from which to make comparisons between the SOD1G93A model and human ALS patients. CMAPs are easy to perform and can help determine the most clinically relevant starting/end points for preclinical studies and provide a basis for predicting potential clinical effect sizes. [ABSTRACT FROM AUTHOR]

Walking patterns can differ between children and adults, both kinematically and kinetically. However, the detailed nature of the ankle pattern has not been clarified. We investigated musculature, biomechanics, and muscle activation strategies and their relevance to walking performance in preschool (PS) and school children (SC), with adults (AD) as reference. Twenty-six PS (3–5 yr), 20 SC (6–8 yr), and 17 AD (18–30 yr) participated. Tibialis anterior (TA) and medial gastrocnemius (MG) thicknesses, fascicle lengths, and maximal voluntary dorsi- and plantar flexion isometric torques were measured. Hip, knee, and ankle kinematics, ground reaction forces (GRFs), and TA and MG electromyographic activities were recorded during shod walking at each participant's preferred speed. Walking speed, step length, and cadence were correlated with age in PS. These walking performance measures were also correlated with muscle thickness and fascicle length, showing higher speed in individuals with thicker muscles and longer TA and MG fascicles (conversely, higher cadence with thinner muscles and shorter fascicles). AD demonstrated the largest values for muscle thickness (p<0.001), fascicle length (p<0.001), strength (p<0.001), and walking performance (speed p = 0.004; step length p<0.001; cadence p<0.001), followed by SC then PS. Both PS and SC exhibited higher TA activities than AD during the stance phase, resulting in a higher co-activation index. The GRFs relative to body weight were lower in both horizontal and vertical components in PS compared to SC and AD, while the relative lateral force during stance was greatest in PS followed by SC and then AD. Differences in preferred walking speed and step length were associated with age and muscle size. Children, particularly preschool-aged, employed a co-activation strategy of dorsi- and plantar flexors for stabilization, which resulted in sideways steps even at a preferred walking speed. [ABSTRACT FROM AUTHOR]

Compared to the determination of exercise thresholds based on systemic changes in blood lactate concentrations or gas exchange data, the determination of breakpoints based on muscle oxygen saturation offers a valid alternative to provide specific information on muscle-derived thresholds. Our study explored the profiles and timing of the second muscle oxygenation threshold (MOT2) in different muscles. Twenty-six cyclists and triathletes (15 male: age = 23 ± 7 years, height = 178 ± 5 cm, body mass = 70.2 ± 5.3 kg; 11 female: age = 22 ± 4 years, height = 164 ± 4 cm, body mass = 58.3 ± 8.1 kg) performed a graded exercise test (GXT), on a cycle ergometer. Power output, blood lactate concentration, heart rate, rating of perceived exertion, skinfolds and muscle oxygen saturation were registered in five muscles (vastus lateralis, biceps femoris, gastrocnemius medialis, tibialis anterior and triceps brachii) and percentage at which MOT2 occurred for each muscle was determinated using the Exponential Dmax. The results of Statistical Parametric Mapping and ANOVA showed that, although muscle oxygenation displayed different profiles in each muscle during a GXT, MOT2 occurred at a similar percentage of the GXT in each muscle (77% biceps femoris, 75% tibalis anterior, 76% gastrocnemius medialis and 72% vastus lateralis) and it was similar that systemic threshold (73% of the GXT). In conclusion, this study showed different profiles of muscle oxygen saturation in different muscles, but without notable differences in the timing for MOT2 and concordance with systemic threshold. Finally, we suggest the analysis of the whole signal and not to simplify it to a breakpoint. [ABSTRACT FROM AUTHOR]

Prosthetic gait differs considerably from the unimpaired gait. Studying alterations in the gait patterns could help to understand different adaptation mechanisms adopted by these populations. This study investigated the effects of induced stiff-knee gait (SKG) on prosthetic and healthy gait patterns and the capabilities of predictive simulation. Self-selected speed gait of two participants was measured: one healthy subject and one knee disarticulation subject using a variable-damping microprocessor controlled knee prosthesis. Both performed unperturbed gait and gait with restricted knee flexion. Experimental joint angles and moments were computed using OpenSim and muscle activity was measured using surface electromyography (EMG). The differences between the conditions were analyzed using statistical parametric mapping (SPM). Predictive models based on optimal control were created to represent the participants. Additionally, a hypothetical unimpaired predictive model with the same anthropometric characteristics as the amputee was created. Some patterns observed in the experimental prosthetic gait were predicted by the models, including increased knee flexion moment on the contralateral side caused by SKG in both participants, which was statistically significant according to SPM. With the exception of the rectus femoris muscle, we also found overall good agreement between measured EMG and predicted muscle activation. We predicted more alterations in activation of the hip flexors than other muscle groups due to the amputation and in the activation of the biceps femoris short head, quadratus femoris, and tibialis anterior due to SKG. In summary, we demonstrated that the method applied in this study could predict gait alterations due to amputation of the lower limb or due to imposed SKG. [ABSTRACT FROM AUTHOR]

Motor imagery (MI) is a mental simulation of a movement without its actual execution. Our study aimed to assess how MI of two modalities of gait (normal gait and much more posturally challenging slackline gait) affects muscle activity and lower body kinematics. Electromyography (biceps femoris, gastrocnemius medialis, rectus femoris and tibialis anterior muscles) as well as acceleration and angular velocity (shank, thigh and pelvis segments) data were collected in three tasks for both MI modalities of gait (rest, gait imagery before and after the real execution of gait) in quiet bipedal stance in 26 healthy young adults. No significant change was observed in electromyography activity and lower body kinematics when comparing MI tasks of normal gait. A significantly higher acceleration for the lower limb segments in the vertical direction and for the pelvis in the mediolateral and anteroposterior direction and angular velocity for pelvis in the frontal plane were found during MI of slackline gait after its real execution compared to rest. The results show that MI of normal gait does not lead to any significant changes, while MI of slackline gait affects lower body kinematics parameters. [ABSTRACT FROM AUTHOR]

Eccentric contractions (ECC) are accompanied by the accumulation of intracellular calcium ions ([Ca2+]i) and induce skeletal muscle damage. Suppressed muscle damage in repeated bouts of ECC is well characterized; however, whether it is mediated by altered Ca2+ profiles remains unknown. We tested the hypothesis that repeated ECC suppresses Ca2+ accumulation via adaptations in Ca2+ regulation. Male Wistar rats were divided into two groups: ECC single bout (ECC-SB) and repeated bout (ECC-RB). Tibialis anterior (TA) muscles were subjected to ECC (40 times, 5 sets) once (ECC-SB) or twice 14 days apart (ECC-RB). Under anesthesia, the TA muscle was loaded with Ca2+ indicator Fura 2-AM, and the 340/380 nm ratio was evaluated as [Ca2+]i. Ca2+ handling proteins were measured by Western blots. ECC induced [Ca2+]i increase in both groups, but ECC-RB evinced a markedly suppressed [Ca2+]i (Time: P < 0.01, Group: P = 0.0357). Five hours post-ECC, in contrast to the localized [Ca2+]i accumulation in ECC-SB, ECC-RB exhibited lower and more uniform [Ca2+]i (P < 0.01). In ECC-RB, mitochondria Ca2+ uniporter complex (MCU) components MCU and MICU2 were significantly increased pre-second ECC bout (P < 0.01), and both SERCA1 and MICU1 were better preserved after contractions (P < 0.01). Fourteen days after novel ECC, skeletal muscle mitochondrial Ca2+ regulating proteins were elevated. Following subsequent ECC, [Ca2+]i accumulation and muscle damage were suppressed and SERCA1 and MICU1 preserved. These findings suggest that tolerance to a subsequent ECC bout is driven, at least in part, by enhanced mitochondrial and sarcoplasmic reticulum Ca2+ regulation. NEW & NOTEWORTHY: We demonstrated a reduced [Ca2+]i profile with suppressed muscle damage after a repeated bout of ECC in vivo: the ECC-induced immediate [Ca2+]i increase was suppressed and the persistence of increased [Ca2+]i with localized accumulation was diminished after repeated ECC. This effect occurred consonant with the upregulation of the mitochondrial Ca2+ uniporter complex and better preservation of SERCA1 and MICU1. These findings suggest that the mechanistic bases for repeated bout protection involve adaptation of Ca2+ regulation. [ABSTRACT FROM AUTHOR]

Background: Falls in the elderly have become an significant public health issue. Approximately 30% of the older population falls once a year, with greater risk for older women. WHO addresses the situation as a public health issue because falls lead to injuries and fractures. It is known that during quiet standing, sway of entire body is correlated highly with the ankle joint rotation and this explains why muscles crossing the ankle joint are able to provide sensory information necessary to maintain upright standing. The ankle strategy is particularly effective in responding to the small and slow perturbations, and these muscles play a crucial role in the fine-tuned adjustments needed for postural control during activities such as standing, walking, or other weight-bearing tasks. Electromyographic (EMG) biofeedback serves as precious physiotherapy tool in enhancing and optimizing the ankle strategy, particularly in the environment of balance and postural control. With the use of EMG-biofeedback, elderly individuals can be taught to manipulate previously uncontrollable or unfelt events by modifying the signals that are shown. Method: Total 84 subjects participated in the study. Subjects were screened according to the inclusion and exclusion criteria. Baseline outcome measures which included the MiniBEST test and functional reach test were assessed. MiniBEST test is used for dynamic balance and functional mobility, it contains 14 items whereas functional reach test was used to assess static balance with outstretched hand. Subjects were randomly allotted into three groups. Group 1 was given balance protocol. Group 2 was given EMG Biofeedback with balance exercises. The group 3 was given only EMG Biofeedback, outcome measures were reassessed post intervention. This study showed that statistical and clinical significance was observed in all the intra-groups(p<0.05). Within the group the study showed greater improvement clinically and statistically in Group 2. ANNOVA test showed Group 3 being more affective compared to other 2 groups. Conclusion: The study concluded that EMG Biofeeback training should be included in along with exercise protocol to improve balance. [ABSTRACT FROM AUTHOR]

A proper source of stem cells is key to muscle injury repair. Dental pulp stem cells (DPSCs) are an ideal source for the treatment of muscle injuries due to their high proliferative and differentiation capacities. However, the current myogenic induction efficiency of human DPSCs hinders their use in muscle regeneration due to the unknown induction mechanism. In this study, we treated human DPSCs with Noggin, a secreted antagonist of bone morphogenetic protein (BMP), and discovered that Noggin can effectively promote myotube formation. We also found that Noggin can accelerate the skeletal myogenic differentiation (MyoD) of DPSCs and promote the generation of Pax7+ satellite‐like cells. Noggin increased the expression of myogenic markers and the transcriptional and translational abundance of satellite cell (SC) markers in DPSCs. Moreover, BMP4 inhibited Pax7 expression and activated p‐Smad1/5/9, while Noggin eliminated BMP4‐induced p‐Smad1/5/9 in DPSCs. This finding suggests that Noggin antagonizes BMP by downregulating p‐Smad and facilitates the MyoD of DPSCs. Then, we implanted Noggin‐pretreated DPSCs combined with Matrigel into the mouse tibialis anterior muscle with volumetric muscle loss (VML) and observed a 73% reduction in the size of the defect and a 69% decrease in scar tissue. Noggin‐treated DPSCs can benefit the Pax7+ SC pool and promote muscle regeneration. This work reveals that Noggin can enhance the production of satellite‐like cells from the MyoD of DPSCs by regulating BMP/Smad signaling, and these satellite‐like cell bioconstructs might possess a relatively fast capacity for muscle regeneration. [ABSTRACT FROM AUTHOR]

The study aimed to determine if virtual reality (VR) games could enhance neuromuscular control and improve anticipatory and compensatory strategies in ball-kicking for soccer players. It was a single-blind randomized clinical trial involving 32 male soccer players with chronic ankle instability. Participants were divided into two groups: VR games and balance training. The primary outcomes measured were the amplitude and onset time of muscle activities in the peroneus longus (PL), tibialis anterior (TA), soleus (SOL), rectus femoris (RF), biceps femoris (BF), and gluteus medius (GM) in three phases: anticipatory (APA), compensatory 1 (CPA1), and compensatory 2 (CPA2). Secondary outcomes included the Y-balance test and perceived ankle instability. Evaluations were done before and after treatment. Both groups underwent 12 sessions, three times a week, each lasting 60 min. In the VR games group, there was a significant decrease in SOL muscle activity amplitude during CPA2 after treatment (P = 0.033), and the BF muscle activated earlier (P = 0.043). The balance training group showed a significant increase in GM muscle activity amplitude during APA (P = 0.037) and earlier activation of the GM muscle post-treatment (P = 0.050). Additionally, this group demonstrated significant decreases in RF activity during CPA1 and PL activity in CPA1 and CPA2 (P = 0.048, P = 0.030, and P = 0.050, respectively). Between-group comparisons indicated a significant increase in GM muscle activity amplitude during APA and a reduction during CPA1 for the balance training group compared to the VR games group (P = 0.050 and P = 0.012, respectively). Both groups showed significant reductions in perceived ankle instability (VR group: P = 0.002, balance training group: P < 0.001) and improvements on the Y-balance test (VR group: P < 0.021, balance training group: P < 0.033), although neither group showed significant improvement in the anterior direction. Overall, both VR games and balance training effectively enhanced perceived ankle stability and dynamic postural control, with neither approach showing clear superiority. Both groups exhibited improvements in muscle activation timing, though neither outperformed the other. While both interventions led to increased muscle activity amplitude during the anticipatory and compensatory phases, the balance training group achieved somewhat greater improvements. These results suggest that both VR games and balance training are effective rehabilitation approaches for chronic ankle instability, providing comparable benefits for enhancing ankle stability and neuromuscular control, without a distinct advantage of one over the other. RCT Registration: On the Iranian Registry of Clinical Trials (IRCT20230124057197N1). Registration date: 30/06/2023 [ABSTRACT FROM AUTHOR]

Background: A dorsal bunion may occur in nonambulatory adolescents with cerebral palsy (CP) and a Gross Motor Function Classification System (GMFCS) level of IV or V. The deformity can cause pain, skin breakdown, and difficulty wearing shoes and braces. A consensus on the biomechanics and surgical management of dorsal bunions in persons with severe CP has not been established. Methods: This retrospective cohort study included 23 nonambulatory adolescents with CP, GMFCS level IV or V, and symptomatic dorsal bunions requiring surgery. The median age at surgery was 17 years, and the median follow-up was 56 months. Reconstructive surgery included the excision of a 2 to 3-cm segment of the tibialis anterior tendon to correct the elevation of the first metatarsal. The fixed deformity of the first metatarsophalangeal joint was managed with use of corrective arthrodesis and dorsal plate fixation. Clinical and radiographic outcomes were assessed preoperatively and postoperatively at the transition to adult services. Results: There were significant improvements in the clinical and radiographic outcome measures (p < 0.001). Pain was relieved, and there were no further episodes of skin breakdown. The elevation of the first metatarsal was corrected from a mean of 3° of dorsiflexion to a mean of 19° of plantar flexion. The deformity of the first metatarsophalangeal joint was corrected from a mean of 55° of plantar flexion to a mean of 21° of dorsiflexion. Six patients had complications, all of which were grade I or II according to the modified Clavien-Dindo system. Conclusions: The surgical reconstruction of a dorsal bunion via soft-tissue rebalancing of the first ray and corrective arthrodesis of the first metatarsophalangeal joint resulted in favorable medium-term clinical and radiographic outcomes in nonambulatory adolescents with CP. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Background: Despite their ability to regenerate as well as autografts, the use of nerve allografts is limited by the need for immunosuppression and the risk of disease transmission. Further, decellularized allografts lacking Schwann cells limit axonal regeneration in long nerve defects. This study evaluated sciatic nerve regeneration in rats implanted with cold- or cryopreserved allografts, and examined the effects of FK506, an immunosuppressant that targets calcineurin function, on motor recovery. Methods: Sixty-five male Lewis rats were divided into five groups of 13, each with a 10-mm sciatic nerve gap. Group I received an autograft, whereas Groups II and III received allografts pretreated with cryopreservation and cold preservation, respectively. Groups IV and V were also implanted with cryo- and cold-preserved allografts, but were treated with a low dose of FK506. Motor regeneration was assessed at 20 weeks by the measurement of ankle contracture, compound muscle action potential, maximal isometric tetanic force, wet muscle weight of the tibialis anterior, peroneal nerve histomorphometry, and immunohistochemistry of the reconstructed sciatic nerve. Results: Similar motor recovery was observed between the autografts and both types of allografts. The groups treated with FK506 showed improved recovery, particularly in terms of ankle angle and tibialis anterior muscle weight. Histomorphometry revealed a superior myelinated fiber area and nerve ratio in the cold-preserved allograft group, while Group II displayed a less well-organized morphology. Conclusion: This study demonstrates that cold- or cryopreserved nerve allografts represent effective alternatives to autografts for peripheral nerve reconstruction, with low-dose FK506 enhancing motor recovery without necessitating immunosuppression. Level of Evidence I: Basic Science Level I. [ABSTRACT FROM AUTHOR]

Background: Gait initiation (GI) can be divided into three sections according to the center of pressure (COP) trace (S1, S2, and S3). Almost all studies do not separate each phase of the GI profile in postural control assessment and muscular investigation, whereas differences in the COP and muscles are found in each phase of the GI profile in people with gait problems. Methods: Twenty individuals with CAI and twenty healthy controls were included in the present study. A force plate synchronized with Qualisys motion analysis, MEGAWIN electromyography, and a pair of auditory cues were used for data capture. The participants carried out five trials of GI with the affected leg (dominant leg). The peak and mean COP excursions; the mean and maximum velocities of COP excursion during S1, S2,, S3, and the total phases in the mediolateral (ML) and anterior‒posterior (AP) directions; the root mean square (RMS); and the onset activity of the Tibialis Anterior (TA) and Soleus (SOL) muscles for both legs were used for statistical analysis. Independent t tests and Mann‒Whitney U tests were used for statistical analysis on the basis of a significance level of ≤ 0.05. Results: Compared with those of healthy controls, independent t tests revealed a significant decrease in the peak COP excursion in the AP direction during S2 (P = 0.021) and in the mean velocity of COP excursion in the AP direction during S1 (P = 0.044) in the CAI group. Additionally, there was a significant increase in the duration of S1 in the GI profile (P = 0.045) in the CAI group compared with the healthy control group. There was no significant difference in the other COP variables, TA or SOL RMS or onset activity for either leg during S1, S2, or S3 between the two groups (P > 0.065). Conclusion: Individuals with CAI exhibit increased stiffness in the AP direction in the injured ankle. This leads to a reduction in the velocity and peak of COP excursion, as well as an increase in the time required for postural control adjustment. These findings highlight the challenges individuals with CAI may face in meeting postural demands when trying to unload the affected foot. Ethical code: IR.SBMU.RETECH.REC.1402.095, 2023–5-28. [ABSTRACT FROM AUTHOR]

Background: Migraine diagnosis is mainly clinically based on symptomatology. The objectives of this study were (1) to determine the ability of pain thresholds to differentiate between women with and without migraines and (2) to determine the ability of clinical, psychological and psychophysical variables to differentiate between women with episodic and chronic migraines. A diagnostic accuracy study was conducted. Methods: Pressure-pain thresholds (PPTs) at one trigeminal (temporalis muscle) and one extra-trigeminal (cervical spine) and two distant-pain free (second metacarpal and tibialis anterior muscle) areas, as well as dynamic pain thresholds (DPTs), were bilaterally assessed in 100 women with migraines, recruited from tertiary hospitals (50% episodic, 50% chronic), and 50 comparable women without headaches. Migraine pain features (headache diary), migraine-associated burden (HDI), anxiety and depressive levels (HADS) and state (STAI-S)–trait (STAI-T) anxiety were also evaluated. The area under the receiver operating characteristic (ROC) curve, with optimal cut-off points, as well as the sensitivity, specificity and positive/negative likelihood ratios (LR) for each variable, were calculated. The women with migraines showed lower PPTs and DPTs than those without migraines. Results: The women with chronic migraines showed lower PPTs in the temporalis muscle than the women with episodic migraines. No clinical, psychological or psychophysical variables exhibited acceptable ROC values (≥0.7) for differentiating between women with and without migraines or between women with episodic and chronic migraines. Conclusions: Although the women with migraines had widespread pressure-pain hyperalgesia, neither the clinical, psychological nor psychophysical (pain threshold) variable exhibited the proper diagnostic accuracy to distinguish between women with and without migraines or between women with episodic and chronic migraines. New studies should clarify the clinical relevance of the findings of the current study. [ABSTRACT FROM AUTHOR]

(1) Background: the objective of this study was to examine the impact of defatted mealworm hydrolysate (DMH), formulated through protein hydrolysis, on muscle protein synthesis in C2C12 cells and rats; (2) Methods: C2C12 cells were treated with dexamethasone and DMH, and cell viability was quantified using the MTT assay. Twenty-four Sprague–Dawley rats were divided into three groups (control, DEX, and DEX + DMH) and treated for 8 weeks. The DEX and DEX + DMH groups were administered intraperitoneal injections of DEX at a concentration of 2.25 mg/kg over a 3-d period. The control and DEX groups were fed a control diet, whereas the DMH group had part of the protein composition of the control diet replaced with 3.5% of DMH. The impact of DMH on muscle protein synthesis was evaluated through the measurement of grip strength, gastrocnemius and tibialis anterior muscle weights, and the investigation of muscle protein synthesis and degradation factor mRNA expression utilising the real-time PCR method; (3) Results: in vitro experiments demonstrated that treatment with DMH at concentrations greater than 5 mg/mL markedly alleviated DEX-induced injury in C2C12 cells. In vivo experiments demonstrated that the mRNA expression levels of myogenin and myoblast determination proteins, which promote muscle protein synthesis, were significantly increased. Furthermore, rats fed DMH exhibited significantly enhanced grip strength and tibialis anterior weight; (4) Conclusions: these findings indicate that DMH may serve as a functional material capable of promoting muscle protein synthesis and that the utilization of proteolytic enzymes is advantageous for the effective utilization of mealworms. [ABSTRACT FROM AUTHOR]

Movements are performed by motoneurons transforming synaptic inputs into an activation signal that controls muscle force. The control signal emerges from interactions between ionotropic and neuromodulatory inputs to motoneurons. Critically, these interactions vary across motoneuron pools and differ between muscles. To provide the most comprehensive framework to date of motor unit activity during isometric contractions, we identified the firing activity of extensive samples of motor units in the tibialis anterior (129 ± 44 per participant; n=8) and the vastus lateralis (130 ± 63 per participant; n=8) muscles during isometric contractions of up to 80% of maximal force. From this unique dataset, the rate coding of each motor unit was characterised as the relation between its instantaneous firing rate and the applied force, with the assumption that the linear increase in isometric force reflects a proportional increase in the net synaptic excitatory inputs received by the motoneuron. This relation was characterised with a natural logarithm function that comprised two stages. The initial stage was marked by a steep acceleration of firing rate, which was greater for low-than medium- and high-threshold motor units. The second stage comprised a linear increase in firing rate, which was greater for high- than medium- and low-threshold motor units. Changes in firing rate were largely non-linear during the ramp-up and ramp-down phases of the task, but with significant prolonged firing activity only evident for medium-threshold motor units. Contrary to what is usually assumed, our results demonstrate that the firing rate of each motor unit can follow a large variety of trends with force across the pool. From a neural control perspective, these findings indicate how motor unit pools use gain control to transform inputs with limited bandwidths into an intended muscle force. [ABSTRACT FROM AUTHOR]

The use of minimalist shoes can lead to enhanced foot somatosensory activation and postural stability but can also increase the incidence of overuse injuries during high-impact or prolonged activities. Therefore, it appears useful to explore new strategies that employ minimalist shoes to effectively facilitate the somatosensory activation of the foot while minimizing acute and cumulative joint stress and risk of injury. To this purpose, this study introduces a novel exercise paradigm: walking for three minutes in ultra-minimalist shoes on artificial flat surfaces designed to mimic highly rugged natural terrains. The activity of foot muscles and lumbar multifidus, pain perception level, and stabilometric parameters were recorded and analyzed to characterize the novel exercise, comparing it to walking barefoot or in conventional shoes on the same rugged surface. Compared to being barefoot, ultra-minimalist shoes effectively filter nociceptive stimuli from the rugged surface, while compared to conventional shoes, they enhance the somatosensory input supporting static stability. Walking with ultra-minimalist and conventional shoes yielded higher gastrocnemius activity and lower tibialis anterior and multifidus activity compared to barefoot walking. This study highlights a practical and safe framework for enhancing foot somatosensory activation and postural stability. The new intervention is suitable for people of all ages, requires minimal time commitment, and can be performed in controlled environments such as homes, gyms, and healthcare facilities. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to identify the contribution of the common synaptic drives to motor units during obstacle avoidance, using coherence analysis between a-pair electromyography (EMG) signals (EMG-EMG coherence). Materials and Methods: Fourteen healthy volunteers walked on a treadmill with and without obstacle avoidance. During obstacle gait, subjects were instructed to step over an obstacle with their right leg while walking that would randomly and unpredictably appear. Surface EMG signals were recorded from the following muscles of the right leg: the proximal and distal ends of tibialis anterior (TAp and TAd), biceps femoris (BF), semitendinosus (ST), lateral gastrocnemius (LG), and medial gastrocnemius (MG). Beta-band (13–30 Hz) EMG-EMG coherence was analysed. Results: Beta-band EMG-EMG coherence of TAp-TAd during swing phase and BF-ST during pre and initial swing phase when stepping over an obstacle were significantly higher compared to normal gait (both p < 0.05). Beta-band EMG-EMG coherence of TAp-TAd, BF-ST, and LG-MG during stance phase were not significantly different between the two gait conditions (all p > 0.05). Conclusions: The present findings suggest increased common synaptic drives to motor units in ankle dorsiflexor and knee flexor muscles during obstacle avoidance. It also may reflect an increased cortical contribution to modify the gait patterns to avoid an obstacle. [ABSTRACT FROM AUTHOR]

Background: Previous studies have found that inhibitory priming with continuous theta burst stimulation (cTBS) can enhance the effect of subsequent excitatory conditioning stimuli with intermittent theta burst stimulation (iTBS) in the upper limbs. However, whether this combined stimulation approach elicits a comparable compensatory response in the lower extremities remains unclear. This study aimed to investigate how cTBS preconditioning modulated the effect of iTBS on motor cortex excitability related to the lower limb in healthy individuals. Methods: Using a randomised cross-over design, a total of 25 healthy participants (19 females, mean age = 24.80 yr) were recruited to undergo three different TBS protocols (cTBS + iTBS, sham cTBS + iTBS, sham cTBS + sham iTBS) in a random order. Each TBS intervention was administered with one-week intervals. cTBS and iTBS were administered at an intensity of 80% active motor threshold (AMT) delivering a total of 600 pulses. Before intervention (T0), immediately following intervention (T1), and 20 min after intervention (T2), the corticomotor excitability was measured for the tibialis anterior muscle of participants' non-dominant leg using a Magneuro100 stimulator and matched double-cone coil. The average amplitude of the motor-evoked potential (MEP) induced by applying 20 consecutive monopulse stimuli at an intensity of 130% resting motor threshold (RMT) was collected and analysed. Results: Compare with T0 time, the MEP amplitude (raw and normalised) at T1 and T2 showed a statistically significant increase following the cTBS + iTBS protocol (p < 0.01), but no significant differences were observed in amplitude changes following other protocols (sham cTBS + iTBS and sham cTBS + sham iTBS) (p > 0.05). Furthermore, no statistically significant difference was found among the three protocols at any given time point (p > 0.05). Conclusions: Preconditioning the lower extremity motor cortex with cTBS prior to iTBS intervention can promptly enhance its excitability in healthy participants. This effect persists for a minimum duration of 20 min. [ABSTRACT FROM AUTHOR]

Complete skeletal muscle regeneration after traumatic injuries remains a challenge due to impaired regenerative capability and dysregulated microenvironments. Autophagy plays a crucial role in the muscle regeneration process by regulating myogenic and non-myogenic cells. Herein, we report a bioactive MXene hydrogel (FPGM) capable of upregulating autophagy and increasing muscle innervation to restore skeletal muscle structure and function. FPGM possessed excellent electrical conductivity, tissue adhesive ability and antioxidation, which could eliminate excess reactive oxygen species to reduce oxidative stress and decrease the secretion of pro-inflammatory cytokine. FPGM upregulated the autophagy level of myoblasts and promoted the migration and tube formation of endothelial cells as well as myogenic differentiation with negligible toxicity. FPGM accelerated muscle fiber formation and skeletal muscle regeneration by improving autophagy, which could regulate microenvironment through raising M2 macrophages to alleviate excessive inflammation, facilitating angiogenesis and decreasing fibrous scar tissue formation in vivo. Importantly, FPGM could efficiently restore muscle function by improving muscle innervation, tibialis anterior compound muscle action potential amplitude and neuromuscular conduction. This work demonstrates that bioactive MXene hydrogel should be a promising candidate for complete skeletal muscle regeneration. [ABSTRACT FROM AUTHOR]

This study is a cross-sectional study and aims to determine the differences in lower limb muscle activation and variability at preferred, slow, and fast walking speeds according to age and fall risk. We divided 301 participants into groups based on fall risk (fall-risk vs. non-fall-risk). We measured muscle activation and its coefficients of variation (CV) for the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius muscle (GCM) at speeds 20% slower, 20% faster, and 40% faster than the preferred speed (PS). When compared by fall risk, fall-risk older adults had significantly lower GCM activity and higher CVs of RF, BF, TA, and GCM in PS. With changes in gait speed, fall-risk older adults had significantly increased CVs of RF, BF, and GCM. Our findings provide new evidence that variability rather than muscle activity increases with walking speed in older adults at risk of falls, highlighting the importance of decreasing muscle activity variability in preventing fall risk. [ABSTRACT FROM AUTHOR]

Studies suggest heterogeneity in cancer cachexia (CC) among models and biological sexes, yet examinations comparing models and sexes are scarce. We compared the transcriptional landscape of skeletal muscle across murine CC models and biological sexes during early and late CC. Global gene expression analyses were performed on gastrocnemius [Lewis lung carcinoma (LLC)], quadriceps (KPC-pancreatic), and tibialis anterior [Colon-26 (C26)-colorectal and ApcMin/+] muscles across biological sexes. Differentially expressed genes (DEGs) were identified using an adj-P value of <0.05, followed by pathway and computational cistrome analyses. Integrating all controls, early and late stages of all models and sexes revealed up to 68% of DEGs and pathways were enriched at early and late CC, indicating a conserved transcriptional profile during CC development. Comparing DEGs and pathways within sexes and across models, in early CC, the transcriptional response was highly heterogeneous. At late stage, 11.5% of upregulated and 10% of downregulated genes were shared between models in males, whereas 18.9% of upregulated and 7% of downregulated DEGs were shared in females. Shared DEGs were enriched in proteasome and mitophagy/autophagy pathways (upregulated), and downregulation of energy metabolism pathways in males only. Between sexes, though the proportion of shared DEGs was low (<16%), similar pathway enrichment was observed, including proteasome and mitophagy at late-stage CC. In early CC, oncostatin M receptor (Osmr) upregulation was the only commonality across all models and sexes, whereas CLOCK and ARNTL/BMAL1 were predicted transcriptional factors associated with dysregulations in all three male models. This study highlights sex and model differences in CC progression and suggests conserved transcriptional changes as potential therapeutic targets. NEW & NOTEWORTHY: This study is among the first to integrate and compare the skeletal muscle transcriptional landscape across multiple preclinical models and biological sexes. We highlight that 1) early CC transcriptional changes are two-thirds conserved at late stages, 2) DEGs are largely model and sex specific, and 3) transcriptional factors including CLOCK and ARNTL/BMAL1, which influence early CC gene expression, might represent a global therapeutic target with a chance of efficacy across various cancer types. [ABSTRACT FROM AUTHOR]

Objectives: The aim of the study was to evaluate foot posture and the mechanical properties of extrinsic foot muscles in fibromyalgia. Methods: Patients with fibromyalgia (n = 86) and age- and gender-matched controls (n = 41) were included in the study. Foot Posture Index (FPI), Beighton and Brighton criteria were used to evaluate static foot posture, joint hypermobility, and benign joint hypermobility syndrome (BJHS), respectively. Tonus, elasticity, and stiffness of the extrinsic foot muscles including gastrocnemius medialis, tibialis anterior, and peroneus longus were measured by the MyotonPRO® device. Foot function, quality of life, and physical activity level were assessed by the Foot Function Index (FFI), Short Form-36 (SF-36), and the International Physical Activity Questionnaire-Short Form (IPAQ-SF), respectively. Results: The frequency of abnormal foot posture in the fibromyalgia and control groups was 68.6% versus 39%, respectively; and neutral foot posture was approximately twice as prevalent in the control group compared to the fibromyalgia group (p = 0.006). Pronated foot posture was the most common abnormality in fibromyalgia (61.6%) and observed in 85.5% of the patients with joint hypermobility and in 87.1% of those meeting BJHS criteria. The elasticity of peroneus longus at rest and the elasticity of tibialis anterior in the standing position were significantly different between the fibromyalgia group and the control group [1.08 (0.22) vs. 1.02 (0.25), p = 0.037 and 0.92 (0.29) vs. 0.87 (0.24), p = 0.011, respectively]. Regarding the fibromyalgia group, no difference was detected among foot posture groups in terms of myotonometric data. Conclusions: Pronation foot posture is common in fibromyalgia with a much higher frequency in fibromyalgia patients with hypermobility. In daily clinical practice for fibromyalgia, particular attention should be given to foot alignment. [ABSTRACT FROM AUTHOR]

Horizontal decelerations are frequently performed during team sports and are closely linked to sports performance and injury. This study aims to provide a comprehensive description of the kinetic demands of decelerations at the whole-body, structural, and tissue-specific levels of the musculoskeletal system. Team-sports athletes performed maximal-effort horizontal decelerations whilst full-body kinematics and ground reaction forces (GRFs) were recorded. A musculoskeletal model was used to determine whole-body (GRFs), structural (ankle, knee, and hip joint moments and contact forces), and tissue (twelve lower-limb muscle forces) loads. External GRFs in this study, especially in the horizontal direction, were up to six times those experienced during accelerated or constant-speed running reported in the literature. To cope with these high external forces, large joint moments (hip immediately after touchdown; ankle and knee during mid and late stance) and contact forces (ankle, knee, hip immediately after touchdown) were observed. Furthermore, eccentric force requirements of the tibialis anterior, soleus, quadriceps, and gluteal muscles were particularly high. The presented loading patterns provide the first empirical explanations for why decelerating movements are amongst the most challenging in team sports and can help inform deceleration-specific training prescription to target horizontal deceleration performance, or fatigue and injury resistance in team-sports athletes. [ABSTRACT FROM AUTHOR]

Background: Drop foot is common post-stroke, elevating fall risks and mobility limitations. It is caused by weakness and lack of control of the tibialis anterior muscle (TA), for which various rehabilitation treatments are used. A reliable objective estimate of changes in TA muscle morphology and composition can enhance treatment optimization. Objectives: We aimed to ascertain 3D freehand ultrasound (3DfUS) reliability in measuring TA muscle volume, length, and echo intensity in stroke patients and healthy controls and its validity by comparing these features across legs, between patients and controls, and between clinical subgroups (i.e. patients with and without ankle contracture, spastic muscle overactivity, and foot dorsiflexor paresis). Methods: We included 9 stroke patients and 9 healthy controls to define reliability and 26 stroke patients and 28 healthy controls to define validity. For reliability, data were collected and processed by 2 different operators and processors. For inter- and intra-rater reliability, intra-class correlation coefficient (ICC) and standard error of measurement (SEM) were used. For validity, Wilcoxon-Signed-Ranked and Mann-Whitney U tests were used for comparisons between groups and subgroups. Results: All measurements showed good to excellent inter- and intra-rater reliability (ICC: 0.816 to 0.997, SEM: 0.5% to 7.8%). Comparison analyses revealed no differences in muscle features among legs, groups, or subgroups. Conclusion: While the 3DfUS is a reliable method to define TA morphology and composition, its clinical validity needs further investigation into factors influencing muscle property changes across various age groups and post-stroke time points. MeSH terms: Stroke; Skeletal muscle morphology; muscle composition; 3D freehand ultrasonography, Anterior Tibial Muscle [ABSTRACT FROM AUTHOR]

Objectives: Some young individuals participating in sports activities may encounter lower leg muscle pain and tightness, potentially indicating chronic exertional compartment syndrome (CECS). While muscle pressure measurement is typically recommended for diagnosis, it is invasive and associated with low sensitivity and specificity. Thus, there is a need for novel diagnostic approaches. Methods: This feasibility study aims to assess whether an ultrasound-guided technique can effectively measure the compressibility of the anterior tibial muscle compartment, focusing on optimal leg positioning and identifying reliable external and internal anatomical landmarks. The compressibility of the anterior tibial muscle compartment was evaluated using ultrasound images obtained at 10 mmHg and 80 mmHg external pressure, with the drop in compartment thickness used to calculate the compressibility ratio. Measurements were conducted in various leg positions and utilizing different external and internal landmarks. Results: Studies in healthy volunteers showed that knee and heel support positioning, measuring at the leg's widest circumference, and using the interosseous membrane as an internal landmark yielded the lowest measurement variability with an intra class correlation of.977 (.764–1.000; 95%-confidence interval). Conclusion: These findings suggest that ultrasound-guided techniques can feasibly determine the compressibility ratio of the anterior tibial muscle compartment, providing valuable insights for standardized protocols in future studies on suspected cases of chronic exertional compartment syndrome. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Research on muscle activity to reduce injuries during firefighting training has getting increasing attention. OBJECTIVE: The purpose of this study was to assess the activity changes in nine muscles of firefighters during the seven firefighting training programs, and to analyze the influence of different firefighting training programs on muscle activity. METHODS: Ten healthy male firefighters were recruited to measure the field surface electromyographic activities (including the percentage of Maximum Voluntary Contraction electromyography (% MVC) and the integrated electromyography value (iEMG)) during all the firefighting training programs. RESULTS: The results showed that the electromyographic activity of gastrocnemius (GA) was stronger in climbing the hooked ladder and climbing the six-meter long ladder training programs. Arms, shoulders, and lower limb muscles were more activated, myoelectric activities were more intense, and fatigue in these areas was more likely to occur during climbing five-story building with loads. Compared with other muscles, erector spine (ES) had a higher degree of activation during different postures of water shooting. The Borg scale scores of shoulders, trunk, thighs and calves were also higher. CONCLUSION: After completing all training programs, GA, tibialis anterior (TA), trapezius (TR), and ES were strongly activated, and all muscles had obvious force. The % MVC and iEMG analyses correspond well with the Borg Scale score. The results can provide certain reference for reducing the musculoskeletal injury of firefighters, carrying out scientific training and formulating effective injury prevention measures for them. [ABSTRACT FROM AUTHOR]

Ankle-foot orthoses (AFOs) have been commonly prescribed for stroke survivors with foot drop, but their impact on the contractions of paretic tibialis anterior (TA) and medial gastrocnemius (MG) has remained inconclusive. This study thus investigated the effect of AFOs on these muscle contractions in stroke survivors. The contractions of paretic TA and MG muscles were assessed in twenty stroke patients and compared between walking with and without AFOs, using a novel wearable dynamic ultrasound imaging and sensing system. The study found an increase in TA muscle thickness throughout a gait cycle (p > 0.05) and a significant increase in TA muscle surface mechanomyography (sMMG) signals during the pre- and initial swing phases (p < 0.05) when using an AFO. MG muscle thickness generally decreased with the AFO (p > 0.05), aligning more closely with trends seen in healthy adults. The MG surface electromyography (sEMG) signal significantly decreased during the initial and mid-swing phases when wearing an AFO (p < 0.05). The TA-MG co-contraction index significantly decreased during initial and mid-swing phases with the AFO (p < 0.05). These results suggest that AFOs positively influenced the contraction patterns of paretic ankle muscles during walking in stroke patients, but further research is needed to understand their long-term effects. [ABSTRACT FROM AUTHOR]

Background/Objectives: Previous studies have shown that neuromuscular electrical stimulation (NMES), while expensive, can provide some of the health benefits of exercise to people who cannot exercise their legs normally. The aim of this study was to quantify the increases in muscle metabolism in four muscles of the legs of able-bodied individuals with NMES. Methods: Healthy college-aged students were tested. NMES of four muscle groups was performed with inexpensive stimulators and reusable tin foil electrodes. The biceps femoris, vastus lateralis, medial gastrocnemius, and tibialis anterior muscles on one leg were stimulated for ten minutes with twitch stimulations at the highest comfortable stimulation current. Muscle metabolism was measured using the slope of oxygen consumption measured with near-infrared spectroscopy (NIRS) during 5 s of cuff ischemia. Results: Initial studies found fold increases in muscle metabolism above rest of 8.9 ± 8.6 for the vastus lateralis, 7.9 ± 11.9 for the biceps femoris, 6.6 ± 7.8 for the medial gastrocnemius, and 4.9 ± 3.9 for the tibialis anterior. Some participants were able to obtain large increases in muscle metabolism, while other participants had lower increases. Conclusions: The ability to produce large increases in metabolism has the potential to allow NMES to replace or augment exercise to improve health in people who cannot otherwise exercise. The devices used were inexpensive and could be adapted for easy use by a wide range of individuals. [ABSTRACT FROM AUTHOR]

Background/Objectives: The purposes of the present study were to assess gait by using a novel approach that plots two adjacent joint angles and the postural control in individuals with autism (ASD) and individuals with typical neurodevelopmental (TD). Methods: The surface electromyography (sEMG) activity was measured synchronously with the other variables. Twenty young adult men, 10 with TD and 10 with a diagnosis of ASD, took part in this study. Results: There was a significant difference between ASD and TD groups in the area described by the knee–ankle diagram (p < 0.05). The sEMG activity recorded from the lateral gastrocnemius (LG) during the contact phase of gait was significantly lower in the ASD group compared with the TD group (p < 0.05). The sEMG activity recorded in the different postural conditions showed differences in LG and tibialis anterior (TA) between the ASD and TD groups (p < 0.05). Conclusions: The knee–ankle diagram provided a sensitive and specific movement descriptor to differentiate individuals with ASD from individuals with TD. The reduced LG activation is responsible for the reduced area in the knee–ankle diagram and 'toe-walking' in individuals with ASD and represents the common denominator of an altered ankle strategy during locomotion and postural control. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusions New treatments have dramatically improved the prognosis for Hereditary Transthyretin Amyloid Polyneuropathy (ATTRv‐PN). However, there is a lack of routine follow‐up studies outside of therapeutic trials. Our aim was to report the long‐term clinical and electrophysiological evolution of a cohort of ATTRv‐PN patients and to determine which biomarkers are most sensitive to change.We retrospectively collected neuropathy impairment scale (NIS), polyneuropathy disability scale (PND), overall neuropathy limitation scale (ONLS), rash built overall disability scale (RODS), electrodiagnostic data, motor unit number index (MUNIX), troponin and N‐terminal pro‐brain natriuretic peptide levels. Electrophysiological worsening was defined as a 20% decrease in previous values.Thirty‐five patients, with a median age of 58 (interquartile ranges 42–71) years, were followed for a median of 36 (24–48) months. All patients received a transthyretin stabiliser, gene silencer or liver transplant.Overall assessment of the cohort showed clinical, biological and electrophysiological stability. However, on an individual basis, NIS worsened in 45% of patients (14/31), ONLS in 46% (13/28), PND in 28% (9/32) and RODS in 39% (11/28) at the last follow‐up. Motor amplitude sum score decreased in 33% (11/33), amplitude recorded on tibialis anterior muscle in 44% (12/27), sensory amplitude sum score in 39% (11/28) and MUNIX sum score in 27% (7/26).Overall effectiveness of ATTRv‐PN treatments in routine care is good. However, individual assessments show up to 40% deterioration over time. Electrophysiological measures are valuable monitoring tools but are not more sensitive to change than clinical scores. Results must be confirmed in larger cohorts. [ABSTRACT FROM AUTHOR]

Background: Hallux valgus is a deformity characterized by lateral deviation of the big toe and medial deviation of the first metatarsal, causing difficulty in walking and requiring various treatments. Despite its multifactorial etiology, the role of the tibialis anterior tendon in hallux valgus and its variations in the morphology of tibialis anterior tendon distal insertion sites have not been fully explored. This study aimed to evaluate the effect of such variations on hallux valgus using magnetic resonance imaging. Methods: This was a retrospective study and included 115 individuals aged 18 years and older who underwent foot radiographs and MRI. The participants were divided into a hallux valgus group of 53 patients and a control group of 62 people based on radiographic measurements. Tibialis anterior tendon distal attachment was classified into five types according to the attachment morphology. Statistical analyses were performed to evaluate the relationship between the tibialis anterior tendon types and hallux valgus severity. Results: Among the participants, patients who underwent foot radiography and MRI due to any medical indication 70.4% were female, with a mean age of 43.83 ± 15.25 years. In terms of tibialis anterior tendon distal attachment, the most common type was Type 5 (40.9%), followed by Type 2 (34.8%). Type 4 was not observed in any case. In all participants, the mean hallux valgus angle was 20.63 ± 8.42o, and the mean intermetatarsal angle was 9.69 ± 2.68o. Tibialis anterior tendon distal attachment Type 5 was significantly associated with an increased hallux valgus angle but not with the intermetatarsal angle. We found a significant relationship between the diameter of the tibialis anterior tendon and hallux valgus angle. Conclusions: This study revealed a significant association between hallux valgus and Type 5 tibialis anterior tendon distal attachment, suggesting that tibialis anterior tendon morphology influences hallux valgus severity. The findings underscore the importance of considering variations in tibialis anterior tendon distal attachment sites in the etiopathogenesis and treatment planning of hallux valgus. [ABSTRACT FROM AUTHOR]

Background/Objective: Spasticity following stroke causes structural changes in the muscles and fascia, affecting the mobility and functional recovery of patients. Understanding these structural changes is critical to optimizing the rehabilitation strategies for patients. Therefore, in this study, we aimed to investigate the differences in crural and epimysial fascia thickness and muscle stiffness in the affected and unaffected lower limbs of chronic stroke patients with spasticity. Methods: A total of 88 patients with chronic stroke (mean age: 62.7 ± 10.2 years) were included in this study. Ankle range of motion, crural fascial thickness, and muscle stiffness in affected and unaffected lower limbs were assessed using ultrasound. Results: For the affected lower limbs, 59 patients (67.1%) exhibited a modified Ashworth scale score of 2, whereas 29 patients (32.9%) exhibited a score of 3. Ankle range of motion, fascia thickness, and muscle stiffness were also measured. The range of motion in ankle dorsiflexion and plantar flexion was significantly reduced on the affected side (p < 0.05). Crural fascia thickness was significantly greater in all regions of the affected side (anterior: 0.96 ± 0.14 vs. 0.72 ± 0.08 mm [p < 0.001]; lateral: 1.01 ± 0.14 vs. 0.75 ± 0.14 mm [p < 0.001]), and the epimysial fascia of the tibialis anterior muscle was similarly greater in the affected side (0.46 ± 0.07 vs. 0.34 ± 0.03 mm [p < 0.001]). However, no significant differences in muscle stiffness were observed between the affected and unaffected sides (p > 0.05). Conclusions: Overall, these findings revealed significant fascial thickening with only minimal changes in muscle stiffness on the affected side, highlighting the importance of controlling fascial changes for post-stroke spasticity management. [ABSTRACT FROM AUTHOR]

In severe skeletal muscle damage, muscle tissue regeneration process has to face the loss of resident muscle stem cells (MuSCs) and the lack of connective tissue necessary to guide the regeneration process. Biocompatible and standardized 3D structures that can be injected to the muscle injury site, conforming to the defect shape while actively guiding the repair process, holds great promise for skeletal muscle tissue regeneration. In this study, we explore the use of an injectable and porous lysine dendrimer/polyethylene glycol (DGL/PEG) hydrogel as an acellular support for skeletal muscle regeneration. We adjusted the DGL/PEG composition to achieve a stiffness conducive to the attachment and proliferation of murine immortalized myoblasts and human primary muscle stems cells, sustaining the formation and maturation of muscle fibers in vitro. We then evaluated the potential of one selected "myogenic-porous hydrogel" as a supportive structure for muscle repair in a large tibialis anterior muscle defect in rats. This injectable and porous formulation filled the defect, promoting rapid cellularization with the presence of endothelial cells, macrophages, and myoblasts, thereby supporting neo-myogenesis more specifically at the interface between the wound edges and the hydrogel. The selected porous DGL/PEG hydrogel acted as a guiding scaffold at the periphery of the defect, facilitating the formation and anchorage of aligned muscle fibers 21 days after injury. Overall, our results indicate DGL/PEG porous injectable hydrogel potential to create a pro-regenerative environment for muscle cells after large skeletal muscle injuries, paving the way for acellular treatment in regenerative muscle medicine. [ABSTRACT FROM AUTHOR]

Reciprocal inhibition (RI) between leg muscles is crucial for smooth movement. Pedaling is a rhythmic movement that can increase RI in healthy individuals. Transcutaneous spinal cord stimulation (tSCS) stimulates spinal neural circuits by targeting the afferent fibers. Pedaling with simultaneous tSCS may modulate the plasticity of the spinal neural circuit and alter neural activity based on movement and muscle engagement. This study investigated the RI changes after pedaling and tSCS and determined the phase of pedaling in which tSCS should be applied for optimal RI modulation in healthy individuals. Eleven subjects underwent three interventions: pedaling combined with tSCS during the early phase of lower extension (phase 1), pedaling combined with tSCS during the late phase of lower flexion (phase 4) of the pedaling cycle, and pedaling combined with sham tSCS. The RI from the tibialis anterior to the soleus muscle was assessed before, immediately after, 15 min, and 30 min after the intervention. RI increased immediately after phase 4 and pedaling combined with sham tSCS, whereas no changes were observed after phase 1. These results demonstrate that tSCS modulates RI changes induced by pedaling in a stimulus phase-dependent manner in healthy individuals. However, the mechanism involved in this intervention needs to be explored to achieve higher efficacy. [ABSTRACT FROM AUTHOR]

Purpose: We tested the hypothesis that heat stress influences the closed-loop cardio-postural control by an increased blood pressure (BP) drop and postural sway. Methods: Fourteen healthy individuals (eight women) performed two orthostatic tests under thermal reference (TC; ~ 24 ºC) and HOT (~ 38 ºC) conditions. The center-of-pressure (COP) displacements and the electromyography (EMG) activity of the calf muscles (medial gastrocnemius and tibialis anterior) were recorded during the initial orthostasis (ORT onset) after the supine-to-stand challenge. At the same period, BP (beat-to-beat) was continuously monitored, and supine-to-stand variations (∆%) were calculated. Sublingual temperature (Tsl) was measured as a surrogate of internal temperature. Results: Tsl increased in HOT compared to TC (TC 36.5 ± 0.3 vs. HOT 36.7 ± 0.3 ºC; p < 0.01). COP distance was greater in HOT compared to TC condition (TC 596.6 ± 242.4 vs. HOT 680.2 ± 249.1 mm; p < 0.01). EMG activity of the gastrocnemius decreased in HOT compared to TC condition (TC 95.5 ± 19.8 vs. HOT 78.4 ± 22.8%mV; p = 0.02). EMG of tibialis did not change between TC and HOT (TC 83.5 ± 42.9 vs. HOT 66.1 ± 31.9% mV; p = 0.29). BP showed a greater fall in HOT compared to TC condition (∆%TC − 24.5 ± 13.2 vs. ∆%HOT − 33.2 ± 20.2%; p = 0.01). Conclusion: Heat stress causes a greater fall in blood pressure and a reduction in musculoskeletal pump activity during orthostatic onset. These effects could be potential mechanisms that underlie augmented postural instability under a heated environment. [ABSTRACT FROM AUTHOR]

Reciprocal inhibition and coactivation are strategies of the central nervous system used to perform various daily tasks. In automatic postural responses (APR), coactivation is widely investigated in the ankle joint muscles, however reciprocal inhibition, although clear in manipulative motor actions, has not been investigated in the context of APRs. The aim was to identify whether reciprocal inhibition can be observed as a strategy in the recruitment of gastrocnemius Medialis (GM), Soleus (So) and Tibialis Anterior (TA) muscles in low- and high-velocity forward and backward perturbations. We applied two balance perturbations with a low and a high velocity of displacement of the movable platform in forward and backward conditions and we evaluated the magnitude and latency time of TA, GM and So activation latency, measured by electromyography (EMG). In forward perturbations, coactivation of the three muscles was observed, with greater activation amplitude of the GM and lesser amplitude of the So and TA muscles. For backward, the pattern of response observed was activation of the TA muscle, a decrease in the EMG signal, which characterizes reciprocal inhibition of the GM muscle and maintenance of the basal state of the So muscle. This result indicates that backward perturbations are more challenging. [ABSTRACT FROM AUTHOR]

Purpose: Muscle activation often occurs in muscles ipsilateral to a voluntarily activated muscle and to a greater extent after stroke. In this study, we measured muscle activation in non-target, ipsilateral leg muscles and used transcranial magnetic stimulation (TMS) to provide insight into whether corticomotor pathways contribute to involuntary activation. Materials and methods: Individuals with stroke performed unilateral isometric ankle dorsiflexion, ankle plantarflexion, knee extension, and knee flexion. To quantify involuntary muscle activation in non-target muscles, muscle activation was measured during contractions from the ipsilateral tibialis anterior (TA), medial gastrocnemius (MG), rectus femoris (RF), and biceps femoris (BF) and normalized to resting muscle activity. To provide insight into mechanisms of involuntary non-target muscle activation, TMS was applied to the contralateral hemisphere, and motor evoked potentials (MEPs) were recorded. Results: We found significant muscle activation in nearly every non-target muscle during isometric unilateral contractions. MEPs were frequently observed in non-target muscles, but greater non-target MEP amplitude was not associated with greater non-target muscle activation. Conclusions: Our results suggest that non-target muscle activation occurs frequently in individuals with chronic stroke. The lack of association between non-target TMS responses and non-target muscle activation suggests that non-target muscle activation may have a subcortical or spinal origin. Non-target muscle activation has important clinical implications because it may impair torque production, out-of-synergy movement, and muscle activation timing. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease, pathologically characterized by TDP‐43 aggregates. Recent evidence has been indicated that phosphorylated TDP‐43 (pTDP‐43) is present not only in motor neurons but also in muscle tissues. However, it is unclear whether testing pTDP‐43 aggregation in muscle tissue would assist in the diagnosis of ALS. We propose three key questions: (i) Is aggregation of pTDP‐43 detectable in routine biopsied muscles? (ii) Can detection of pTDP‐43 aggregation discriminate between ALS and non‐ALS patients? (iii) Can pTDP‐43 aggregation be observed in the early stages of ALS? We conducted a diagnostic study comprising 2 groups: an ALS group in which 18 cases underwent muscle biopsy screened from a registered ALS cohort consisting of 802 patients and a non‐ALS control group, in which we randomly selected 54 muscle samples from a biospecimen bank of 684 patients. Among the 18 ALS patients, 3 patients carried pathological GGGGCC repeats in the C9ORF72 gene, 2 patients carried SOD1 mutations, and 7 patients were at an early stage with only one body region clinically affected. The pTDP‐43 accumulation could be detected in routine biopsied muscles, including biceps brachii, deltoid, tibialis anterior, and quadriceps. Abnormal aggregation of pTDP‐43 was present in 94.4% of ALS patients (17/18) compared to 29.6% of non‐ALS controls (16/54; p < 0.001). The pTDP‐43 aggregates were mainly close to the sarcolemma. Using a semi‐quantified pTDP‐43 aggregates score, we applied a cut‐off value of 3 as a diagnostic biomarker, resulting in a sensitivity of 94.4% and a specificity of 83.3%. Moreover, we observed that accumulation of pTDP‐43 occurred in muscle tissues prior to clinical symptoms and electromyographic lesions. Our study provides proof‐of‐concept for the detection of pTDP‐43 accumulation via routine muscle biopsy which may serve as a novel biomarker for diagnosis of ALS. [ABSTRACT FROM AUTHOR]

Background. This study aims to determine if Riluzole usage can change the function and excitability of motor neurons. Methods. The clinical data and indices of motor neuron excitability were assessed using high-density surface EMG parameters from 80 ALS participants. The persistent inward current was assessed using the discharge rate from paired motor units obtained from the tibialis anterior muscle. This enabled the discharge rate at recruitment, peak discharge rates and the hysteresis of the recruitment–derecruitment frequencies (also known as delta F) to be calculated. Limbs were classified according to their strength. Results. No differences in these motor neuron discharge properties were found according to whether Riluzole was used. Conclusions. The possible interpretations of this finding are discussed. [ABSTRACT FROM AUTHOR]

DUX4 is the major gene responsible for facioscapulohumeral dystrophy (FSHD). Several mouse models expressing DUX4 have been developed, the most commonly used by academic laboratories being ACTA1-MCM/FLExDUX4. In this study, molecular and histological modifications in the tibialis anterior and quadriceps muscles were investigated in this model at different time points. We investigated several changes that could be used as markers of therapeutic efficacy. Our results confirm the progressive muscular dystrophy previously described but also highlight biases associated with tamoxifen injections and the complexity of choosing the genes used to calculate a DUX4-pathway gene composite score. We also developed a comprehensive force test that better reflects the movements made in everyday life. This functional force–velocity–endurance model, which describes the force production capacities at all velocity and fatigue levels, was applied on 12–13-week-old animals without tamoxifen. Our data highlight that previously unsuspected muscle properties are also affected by the expression of DUX4, leading to a weaker muscle with a lower initial muscle force but with preserved power and endurance capacity. Importantly, this force–velocity–endurance approach can be used in humans for clinical evaluations. [ABSTRACT FROM AUTHOR]

Elevated glucocorticoids alter the skeletal muscle transcriptome to induce a myopathy characterized by muscle atrophy, muscle weakness, and decreased metabolic function. These effects are more likely to occur and be more severe in aged muscles. Resistance exercise can blunt the development of glucocorticoid myopathy in young muscle, but the potential to oppose the signals initiating myopathy in aged muscle is unknown. To answer this, young (4-mo-old) and aged (24-to 25-mo-old) male C57BL/6 mice were randomized to receive either an intraperitoneal (IP) injection of dexamethasone (DEX; 2 mg/kg) or saline as a control. Two hours postinjections, the tibialis anterior (TA) muscles of mice were subjected to unilateral high-force contractions. Muscles were harvested 4 h later. The glucocorticoid- and contraction-sensitive genes were determined by RNA sequencing. The number of glucocorticoid-sensitive genes was similar between young and aged muscle. Contractions opposed changes to more glucocorticoid-sensitive genes in aged muscle, with this outcome primarily occurring when hormone levels were elevated. Glucocorticoid-sensitive gene programs opposed by contractions were primarily related to metabolism in young mice and muscle size regulation and inflammation in aged mice. In silico analysis implied peroxisome proliferator-activated receptor gamma-1 (PPARG) contributed to the contraction-induced opposition of glucocorticoid-sensitive genes in aged muscle. Increasing PPARG expression in the TA of aged mice using adeno-associated virus serotype 9 partially counteracted the glucocorticoid-induced reduction in runt-related transcription factor 1 (Runx1) mRNA content, recapitulating the effects observed by contractions. Overall, these data contribute to our understanding of the contractile regulation of the glucocorticoid transcriptome in aged skeletal muscle. NEW & NOTEWORTHY: We establish the extent to which muscle contractions oppose changes to the glucocorticoid-sensitive transcriptome in both young and aged muscle. We also identify peroxisome proliferator-activated receptor gamma (PPARG) as a transcription factor likely contributing to contraction-induced opposition to the glucocorticoid transcriptome in aged muscle. Overall, these data contribute to our understanding of the contractile regulation of the glucocorticoid transcriptome. [ABSTRACT FROM AUTHOR]

Unloader braces are a treatment modality for medial compartment knee osteoarthritis. The functional mechanisms involved are not yet fully understood. Therefore, this two-part systematic review examines the following research questions: How is muscle activation altered by medial compartment knee osteoarthritis, and do medial tibiofemoral compartment unloader braces alter muscle activation? If so, could this alteration be part of the unloading mechanism by affecting the altered muscle activity in medial compartment knee osteoarthritis? A systematic literature search was conducted using PubMed, LIVIVO, Web of Science, Google Scholar, and CENTRAL for articles published until August 2023. The first systematic review, examining neuromuscular alterations, identified 703 articles, with a final inclusion of 20. The second systematic review, which evaluated the neuromuscular effects of unloader braces, identified 123 articles with the final inclusion of 3. Individuals with medial compartment knee osteoarthritis demonstrated increased activity and co-contraction of the periarticular knee muscles, whereas medial tibio-femoral compartment unloader braces seemed to reduce activity and co-contraction. In contrast to the belief that unloader braces result in muscle weakness as they decrease muscle activity and co-contraction, our limited insights indicate that they rather might reduce the pathological increase. This may result in joint load reduction due to lower compressive forces. However, further investigation is required. [ABSTRACT FROM AUTHOR]

Ankle fractures can lead to issues such as limited dorsiflexion, strength deficits, swelling, stiffness, balance disorders, and functional limitations, which complicate daily activities. This study aimed to describe neuromuscular adaptations at 6 and 12 months post-surgery during static and dynamic balance tasks, specifically using the Y-Balance Test (YBT). Additionally, the relationship between neuromuscular patterns, balance, and musculoskeletal deficits was evaluated. In 21 participants (14 at 6 months and 21 at 12 months) with bimalleolar fractures, hip strength, ankle dorsiflexion, ankle functionality, and static and dynamic balance were assessed using electromyography of five lower limb muscles (tibialis anterior, peroneus longus, lateral gastrocnemius, biceps femoris, and gluteus medius). A significant interaction effect (limb × proximal [hip]—distal [ankle] muscle) (F = 30.806, p < 0.001) was observed in the anterior direction of the Y-Balance Test (YBTA) at 6 months post-surgery. During the YBTA and YBT posteromedial (YBTPM), it was found that a lower dorsiflexion range of movement was associated specifically at 6 months with greater activation of the lateral gastrocnemius. However, these differences tended to diminish by 12 months. These findings suggest that neuromuscular patterns differ between operated and non-operated limbs during the YBTA at 6 months post-surgery. The Y-Balance Test, particularly its anterior direction, effectively highlighted these neuromuscular changes. This is a preliminary study; further research is needed to explore these findings in depth. [ABSTRACT FROM AUTHOR]