Search Results (918)

Type 2 diabetes mellitus (T2DM) involves progressive muscle wasting, metabolic dysregulation in peripheral tissues, chronic hyperglycemia, and insulin resistance. Momordica charantia is an antidiabetic agent often limited by bitterness. To improve palatability and efficacy, we developed EMS by combining M. charantia and Stevia rebaudiana (9:1). EMS’s antidiabetic effects were tested in streptozotocin (STZ)-induced and genetic db/db mouse models of diabetes. Mice received oral EMS at doses (40, 80, and 120 mg/kg) for six weeks, assessing glucose tolerance, insulin sensitivity, lipid profile, and hepatic markers. Additionally, muscle protein synthesis and degradation mechanisms were analyzed in gastrocnemius tissues. EMS significantly reduced fasting blood glucose and improved insulin sensitivity in both models. EMS decreased liver lipid accumulation and serum ALT and AST levels, indicating hepatic protection. EMS alleviated muscle atrophy by increasing muscle fiber area and was associated with increased expression or activity of AMPK/Sirt1/PGC-1α and IRS-1/PI3K/AKT insulin pathways. It also suppressed FOXO3a-mediated expression of Atrogin-1 and MuRF1, suggesting reduced activation of protein-degradation pathways. Moreover, EMS modulated the gut microbiota, increasing the abundance of beneficial species such as Barnesiella intestinihominis. These findings suggest EMS is a promising multitarget functional ingredient for metabolic complications and musculoskeletal decline in T2DM. Full article

Post-error slowing (PES) is commonly considered a behavioral marker of post-error adaptation. However, adaptive processes may also emerge through subtle modifications of motor preparation, particularly in combat sports such as taekwondo (TKD), where maintaining rapid motor execution is essential. This study examined post-error neuromuscular adjustments during a TKD-specific kicking task by comparing standard Go and post-error Go trials for changes in muscle onset latency, peak electromyographic amplitude, and co-contraction indices. Twenty-eight TKD athletes (14 novice and 14 advanced) performed a sport-specific Go/No-Go task while wearable wireless surface electromyography sensors recorded lower-limb neuromuscular activity from eight lower-limb muscles. Muscle onset latency, peak electromyographic amplitude, co-contraction indices, and reaction time were analyzed using linear mixed-effects models. Post-error Go trials showed significant alterations in muscle onset latency in posterior lower-limb muscles involved in propulsion and movement preparation (semitendinosus, biceps femoris, lateral gastrocnemius, and soleus), with muscle activation occurring closer to the foot take-off. No significant differences were observed in reaction time, peak electromyographic amplitude, or co-contraction indices, and expertise and age did not modulate these effects. These findings suggest that error-related motor adjustments may be expressed through changes in muscle activation timing rather than overt behavioral slowing. Full article

Background/Objectives: This study investigated kinetic performance, leg stiffness and gastrocnemius muscle (GM) activity during shod and barefoot two-legged hopping in female court athletes, while also assessing potential sport specialization-by-footwear interactions. Methods: Forty-two elite female Volleyball, Basketball, and Handball athletes (n = 14 per group) performed two-legged hopping at 130 bpm under both shod and barefoot conditions. Vertical ground reaction force (Fz) (Kistler forceplate sampling at 1000 Hz) was recorded in synchronization with GM vibromyographic intensity (TSD250, Biopac Systems, sampling at 2000 Hz). Kinetic metrics, kleg and GM activation were analyzed via repeated-measures ANOVA (alpha = 0.05, PSS 30.0). For all metrics, results indicated no significant sport-by-footwear interaction (p > 0.05). Results: Footwear significantly altered hopping kinematics; while absolute contact durations remained constant, relative total and effective contact durations were elongated and shortened, respectively. In the shod condition, kleg increased (+6.1%, p < 0.05) alongside a reduction in GM activation (−7.7%, p < 0.05). Additionally, Fz peak increased (+4.3%, p < 0.05) and occurred relatively earlier in the contact phase (−0.7%, p < 0.05). Conclusions: These findings indicate that footwear acts as a mechanical buffer, enabling a stiffer leg spring and reduced neuromuscular demand. The earlier timing of Fz peak suggests a facilitated eccentric-to-concentric transition, most likely allowing athletes to maintain efficient energy return despite the compliance of the footwear interface. Full article

Background: Branched-chain amino acids (BCAAs) regulate muscle protein metabolism, yet the systematic characterization of their dose-dependent morphological effects on exercised skeletal muscle remains limited. This study investigated the dose–response relationship between BCAA supplementation and skeletal muscle adaptations in exercise-trained mice. Methods: Seventy male Kunming mice were randomly assigned to seven groups (n = 10): a background group (no exercise), a control group (exercise + saline), and five exercise groups receiving BCAAs at 1–5 g/kg/day via intragastric gavage. Mice in the exercise groups performed 45 min of swimming daily (6 days/week) for 50 days. Gastrocnemius muscles were processed using hematoxylin–eosin staining, Masson trichrome staining, Gomori aldehyde fuchsin staining, and transmission electron microscopy. Data were analyzed using one-way ANOVA with Dunnett’s post hoc test. Results: BCAA supplementation increased gastrocnemius wet weight-to-body weight ratios and promoted denser fiber packing in a dose-dependent manner up to 3–4 g/kg/day. Deep-staining fiber proportion (putatively type II-like) increased progressively with BCAA concentration, plateauing at doses ≥ 3 g/kg/day, while elastic fiber content continued to rise through 5 g/kg/day. Mitochondrial size decreased as mitochondrial number increased; membrane and cristae thickness peaked at 3 g/kg/day. Sarcomere length, myofibril diameter, sarcoplasmic reticulum size, and transverse tubule diameter exhibited increasing trends. Conclusions: These findings establish a parameter-specific dose–response framework for BCAA-induced muscle remodeling. A supplemental dose of 3 g/kg/day above background dietary intake represents an effective threshold for maximizing indices of hypertrophic gains and mitochondrial structural maturation potentially indicative of functional enhancement. Higher doses (≥4 g/kg/day) elicited additional benefits in fiber density, mitochondrial proliferation, and elastic fiber content. Supplemental BCAA dosing strategies above constant background intake should be tailored to target specific structural outcomes, with functional validation required to confirm physiological relevance. Full article

This study compared the effects of variable-resistance compound training versus constant-resistance compound training on lower-limb explosive power in judo athletes, aiming to identify an effective and safe training method. Methods: Sixteen judo athletes were randomized into VRT (n = 8) or RT (n = 8) groups for a 6-week, twice-weekly intervention. Outcomes included rate of force development (RFD), counter movement jump (CMJ), squat jump (SJ), eccentric utilization ratio (EUR), reactive strength index (RSI), squat 1RM, muscle architecture, and Special Judo Fitness Test (SJFT). After 6 weeks of training intervention, the time × group interaction effects were significant between the variable-resistance compound training group and the constant-resistance compound training group in the following parameters: CMJ (p < 0.01, η² = 0.605), SJ (p < 0.01, η² = 0.391), EUR (p < 0.01, η² = 0.308), RSI (p < 0.01, η² = 0.306), RFD (p < 0.01, η² = 0.401), squat 1RM (p < 0.01, η² = 0.328), SJFT index (p < 0.01, η² = 0.537), femoral rectus feather angle (p < 0.05, η² = 0.380), femoral rectus thickness (p < 0.05, η² = 0.288), femoral rectus cross-sectional area (p < 0.01, η² = 0.868), gastrocnemius feather angle (p < 0.05, η² = 0.274), and gastrocnemius thickness (p < 0.05, η² = 0.390). No significant group effects were observed for any of the parameters (p > 0.05). Conclusion: Both variable-resistance training (VRT) and constant-resistance training (CRT) are effective in enhancing lower-body power in judo athletes; both training methods can be regarded as effective options for developing lower-body power in judo athletes, although VRT may offer a slight advantage in specific performance domains. Full article

Type 2 diabetes mellitus (T2DM) accounts for over 90% of diabetes cases, and T2DM-related sarcopenia is a growing concern. Carnosine, abundant in human skeletal muscle, helps maintain muscle quality and function. This study investigated whether carnosine deficiency contributes to T2DM-related sarcopenia and whether exogenous carnosine supplementation alleviates muscle atrophy. A mouse model of T2DM sarcopenia was established using streptozotocin combined with a high-fat diet. LC-MS metabolomics revealed a significant reduction in carnosine content in the gastrocnemius muscle of model mice. A C2C12 myotube atrophy model was induced by high-glucose (HG), and qRT-PCR showed altered expression of carnosine metabolism-related enzymes, suggesting disrupted carnosine homeostasis under T2DM conditions. Mechanistic investigations using immunofluorescence, Western blotting, transcriptome sequencing, mitochondrial staining, and molecular docking indicated that carnosine may alleviate high-glucose-induced myotube atrophy through the PI3K/AMPK/PGC-1α signaling pathway. In vivo, carnosine supplementation increased the number of mitochondria and the proportion of slow muscle fibers in gastrocnemius muscle, ameliorating the atrophic phenotype. These findings suggest that carnosine has potential as a candidate for intervention in T2DM-related sarcopenia, though further validation of its direct molecular targets is required. Full article

Although considerable research has investigated non-motorized treadmills (NMTs), most studies have focused on healthy adults or athletes. This study aimed to compare trunk and lower limb muscle activation during walking on an NMT and flat ground (FG) at different exercise intensities in patients with stroke. Eighteen patients with stroke participated in this within-subject, repeated-measures experimental study conducted at a single hospital. Participants performed walking trials under six randomized conditions, comprising both NMT and FG walking at intensities of 20%, 40%, and 60% of heart rate reserve (HRR). Muscle activation of the affected-side erector spinae, internal oblique, gluteus medius, gluteus maximus, vastus medialis oblique, biceps femoris, and lateral gastrocnemius was assessed. Walking on the NMT resulted in significantly greater overall muscle activation than walking on FG (p < 0.05). In addition, significant differences in trunk and lower limb muscle activation were observed across HRR levels during both NMT and FG walking (p < 0.05), indicating that exercise intensity influenced neuromuscular responses. These findings suggest that NMT walking, particularly at higher intensities, acutely increases neuromuscular demands, providing preliminary evidence for its potential application as a demanding walking condition for stroke rehabilitation. Full article

Objectives: Skeletal muscle architecture (SMA) defines the mechanical limits of force production. However, its associations with force–time strategy under externally loaded conditions have received little research attention. This exploratory study examined associations between vastus lateralis (VL) and lateral gastrocnemius (LG) architecture and force–time strategy, jump-height retention, and stretch–shortening cycle (SSC) transfer-efficiency in collegiate basketball players. Methods: Seventeen collegiate male basketball players completed B-mode ultrasonographic assessment of VL and LG architecture, including muscle thickness, pennation angle (PA), and fascicle length. Athletes performed the squat jump (SJ), loaded squat jump (LSJ), countermovement jump (CMJ), and loaded countermovement jump (LCMJ) on force platforms, with a 20 kg external load applied for loaded conditions. Loaded retention, defined as the percentage of jump height preserved under load, was proposed as a unified construct. Pearson’s correlations were calculated, with Benjamini–Hochberg false discovery rate (FDR) corrections applied within predefined functional groups and pooled across morphology-sensitive correlations. Results: LG PA showed a large negative association with LCMJ rate of force development (r = −0.68 [−0.87, −0.30]) and a large positive association with LCMJ time to peak force (r = 0.68 [0.29, 0.87]), both surviving within-group FDR correction. VL PA was associated with eccentric acceleration time and concentric time across jump conditions (r = 0.52 to 0.61), interpreted as exploratory. Transfer-efficiency indices showed no significant associations with SMA, except for the LCMJ/LSJ concentric time ratio, which showed a moderate negative association with LG PA (r = −0.49 [−0.79, −0.01]). Conclusions: Resting muscle architecture was associated with the temporal and rate characteristics of force expression under load, rather than with the gross preservation of jump height. Integrating architectural assessment with loaded force–time profiling warrants further investigation as a means of characterizing individual force-development strategies. Full article

This study investigated the feasibility and biomechanical effects of volitional electromyography (EMG)-based control of a powered transtibial ankle prosthesis. Four male participants completed static and dynamic EMG assessments and gait analysis while using both their prescribed passive prosthesis and an EMG-controlled powered prototype during level walking at self-selected and fast speeds, as well as ramp ascent and descent. Selective activation of residual tibialis anterior and gastrocnemius muscles was quantified using a co-contraction index, and lower-limb kinematics and kinetics were compared between prosthetic conditions. Participants were able to generate task-dependent residual muscle activity, supporting the feasibility of EMG-based volitional control. However, muscle selectivity was reduced during dynamic tasks, with higher co-contraction during gait than during seated static contractions, and substantial inter-subject variability was observed. Compared to the prescribed passive prosthesis, the EMG-controlled prototype generally produced lower prosthetic-side ankle range of motion and ankle power, although ankle moments were sometimes slightly greater. These findings suggest that EMG control is feasible, but that future controller design must remain flexible to individual users’ neuromuscular abilities and dynamic control limitations. The results provide important guidance for the development and testing of more adaptive, personalized, and functionally effective EMG-controlled prosthetic ankle systems. Full article

Mineralising avian tendon is a widely used experimental model for studying collagen-guided mineralisation. Yet, the three-dimensional organisation and topology of its internal canal system have never been quantitatively characterised. We combined high-resolution micro-computed tomography (micro-CT) and scanning electron microscopy (SEM) to provide the first morphometric and topological analysis of the canalicular network in mineralised turkey gastrocnemius tendon. micro-CT revealed that unmineralised canals occupy approximately 34.6% of the mineralised tissue volume and form a single continuously connected network (99.8% of void volume), with a connectivity density of ~1.3 × 10² mm⁻³, a fractal dimension of 2.58, a degree of anisotropy DA = 0.87 [BoneJ convention, range 0–1], and a closed-loop topology. SEM revealed marked ultrastructural heterogeneity of the mineral phase across fascicle cross-sections, consistent with graded intrafibrillar-to-interfibrillar deposition. These findings establish the first quantitative morphometric framework for physiologically mineralising collagen tissue and support the use of turkey gastrocnemius tendon as a tractable model for studying mineralisation dynamics, enthesis biology, and the design of biomimetic scaffolds with controlled porosity and anisotropy. Full article

Background/Objectives: Evidence on the role of muscle mechanical (myotonic) properties in athletic performance remains limited in young adult and sub-elite populations, particularly in American football, and sex-specific patterns of association are not well understood. This study aimed to investigate the associations between lower extremity myotonic properties and performance outcomes (strength and balance) in American football athletes, with a specific focus on sex-related differences and candidate predictors. Methods: A cross-sectional design was implemented involving 35 American football athletes (17 female, 18 male). Lower extremity muscle tone, stiffness, and elasticity were assessed using MyotonPRO. Strength parameters (lower limb, handgrip, back, and shoulder internal rotation) and balance performance (static and dynamic under eyes-open and eyes-closed conditions) were evaluated using standardized measurement protocols. Pearson correlation analysis was conducted to examine bivariate associations, followed by Least Absolute Shrinkage and Selection Operator (LASSO) regression to determine candidate predictors while addressing multicollinearity. Results: Male athletes exhibited significantly greater height, body mass, and BMI (p < 0.001), alongside elevated myotonic values compared to females. Correlation analyses indicated distinct sex-specific association patterns between myotonic properties and performance metrics. LASSO regression revealed a distinct sex-specific divergence in strength prediction: female strength was predominantly driven by proximal musculature (quadriceps and hamstring elasticity/stiffness), whereas male strength was anchored by distal musculature (gastrocnemius tone/stiffness). Furthermore, rigorous penalization shrunk nearly all balance coefficients to zero in both sexes, indicating that resting myotonic properties do not independently predict dynamic or static postural control. Conclusions: While lower extremity myotonic properties are candidate predictors of multi-regional strength via sex-specific proximal and distal strategies, they do not independently predict balance performance, suggesting postural control relies primarily on active motor recruitment rather than passive resting mechanics. Given the cross-sectional design of this study, causal inferences cannot be drawn, and these findings should be interpreted accordingly. The observed sex-specific differences may support consideration of individualized, sex-informed training strategies in American football athletes. Full article

Objective: Sodium–glucose cotransporter 2 (SGLT2) inhibitors, particularly empagliflozin, have attracted considerable attention because of their cardiovascular benefits beyond glycemic control. However, the interaction between empagliflozin and exercise-induced physiological cardiac remodeling in healthy individuals remains insufficiently understood. This study investigated the effects of different swimming exercise protocols (anaerobic, aerobic, and endurance), administered alone or in combination with empagliflozin, on cardiac structure and electrophysiology. Methods: Thirty-six male Sprague–Dawley rats were randomly assigned to six groups (n = 6 per group): anaerobic (An), aerobic (Ae), endurance (En), and the corresponding exercise groups combined with empagliflozin (An + Empa, Ae + Empa, and En + Empa). Empagliflozin was administered by oral gavage at a dose of 15 mg/kg/day for 30 days. Transthoracic echocardiography, electrocardiography (ECG), and gastrocnemius electromyography were performed at baseline and at the end of the study to assess cardiac remodeling, heart rate, and neuromuscular function. The study was carried out over a 30-day intervention period following ethics committee approval on 24 July 2024. Results: No significant between-group differences were observed in echocardiographic parameters before the intervention. On day 30, significant differences were identified among the groups in interventricular septal thickness at end-diastole (IVSd) (p = 0.027), left ventricular internal diameter at end-diastole (LVIDd) (p = 0.009), and end-diastolic volume (EDV) (p = 0.014). Bonferroni-corrected post hoc analysis showed that the aerobic exercise plus empagliflozin group differed from several exercise-only groups, particularly in parameters related to ventricular size and filling volume, including LVIDd and EDV (p < 0.008). On day 30, electrocardiographic repolarization-related parameters, including QT, QTc, JT, and Tpeak–Tend intervals, also differed significantly among the groups (all p < 0.05). In post hoc analysis, the anaerobic exercise group showed significant differences in QT and JT intervals compared with the aerobic and endurance groups (p < 0.008). In the anaerobic protocol, empagliflozin was associated with a reduction in heart rate compared with the corresponding control group (p = 0.019). No significant between-group differences were observed in EMG findings. Conclusions: Different exercise protocols induce distinct patterns of adaptation in cardiac structure and electrophysiology in healthy rats. Empagliflozin (15 mg/kg/day) may modulate exercise-induced cardiac responses in a modality-dependent manner; the most pronounced echocardiographic effects were observed in the aerobic protocol, whereas the effect on heart rate was observed in the anaerobic protocol. These findings highlight the need for longer-term and mechanistic studies to further clarify the effects of SGLT2 inhibitors on physiological cardiac remodeling. Full article

Objective: This study aimed to compare the neuromuscular control characteristics of international- and national-level squash players during forehand strokes using a multichannel surface electromyography (sEMG)-based sensing framework. By integrating wearable biosignal acquisition with muscle synergy and intermuscular coherence analyses, this study sought to identify sensor-derived markers of performance-related neuromuscular control and to provide evidence for sensor-informed squash training and athlete monitoring. Methods: Participants performed standardized forehand strokes, during which multichannel sEMG signals were synchronously collected from major upper-limb, lower-limb, and trunk muscles. The recorded sensor signals were preprocessed and analyzed using non-negative matrix factorization to extract muscle synergies, including the number of synergies, muscle weightings, and synergy activation durations. In addition, time–frequency intermuscular coherence analysis was performed on the sEMG sensor data to quantify coherence differences in the α, β, and γ frequency bands between upper-limb–trunk and lower-limb–trunk muscle pairs. Results: No significant difference was found between the two groups in the number of muscle synergies, with both groups clustering into four synergy modules. However, the sEMG sensor-based analysis revealed clear between-group differences in synergy structure and coordination patterns. International-level players showed higher muscle weightings in major proximal muscles, including the deltoid, pectoralis major, erector spinae, and gluteus maximus, and lower weightings in relatively smaller or more distal muscles such as the biceps brachii and lateral gastrocnemius. In terms of synergy timing, international-level players exhibited significantly shorter activation durations in SYN1 and SYN2, but a significantly longer activation duration in SYN3, than national-level players. For intermuscular coherence, international-level players showed significantly lower coherence in the α, β, and γ bands for multiple upper-limb–trunk and lower-limb–trunk muscle pairs. Conclusions: A multichannel sEMG sensing approach was effective in detecting performance-level differences in neuromuscular control during the squash forehand stroke. International-level players exhibited more efficient and refined neuromuscular coordination, characterized by optimized proximal muscle recruitment, more task-specific synergy timing, and reduced intermuscular coherence across selected muscle pairs. These findings highlight the value of wearable EMG sensors and sensor-based neuromuscular feature extraction for quantitative athlete assessment, movement monitoring, and the development of sensor-guided training strategies in squash. Full article

Introduction: Population aging is a growing and challenging phenomenon, primarily due to its association with functional decline and sarcopenia, which increase the risk of falls. These events have significant impacts on public health and the quality of life of older adults. Regular physical activity has shown benefits in reducing falls and their consequences, with systemic vibratory therapy (SVT) emerging as a promising strategy to mitigate these adverse outcomes. However, evidence on the actual effectiveness of this therapeutic approach remains limited, as does clarity regarding optimal body position, protocol parameters, and equipment when combined with physical activity programs. Objectives: To compare the effect of systemic vibratory therapy (SVT) associated with a physical activity program on the perception of fear of falling in older adults (M01.060.116.100). As secondary outcomes, the study will assess functional physical conditioning, electromyographic activity, muscular synergy, and center of pressure oscillation in this population. Methods: A randomized controlled clinical trial with blinded outcome assessors and blinded statistical analysis will be conducted with 192 older adults participating in the UNATI/UNISUAM program. Participants will be allocated into three groups: (A) usual physical activity; (B) usual physical activity + SVT in a semi-squat position; and (C) usual physical activity + SVT in a seated position. Assessments will include sociodemographic data, concern about falling assessed using the Falls Efficacy Scale-International (FES-I), physical performance (2 min stationary march test), surface electromyography of the tibialis anterior and medial gastrocnemius muscles, along with posturography using a force platform. Results: This study will provide information on outcomes related to fall risk, balance, physical fitness, and neuromuscular variables in older adults undergoing two distinct SVT protocols. Clinical Trials Registration: Brazilian Registry of Clinical Trials RBR-68pry5j. Registered on 8 December 2025. Full article

Injuries of the gastrocnemius muscle and the common calcaneal tendon in dogs require effective stabilization of the tarsocrural joint to allow proper healing and prevent mechanical overload. This report described a novel minimally invasive technique for temporary internal tarsal stabilization using synthetic tape in two dogs. No comparison with other stabilization techniques was carried out. Both dogs presented with hindlimb lameness and partial plantigrade stance secondary to a subtotal injury of the lateral myotendinous gastrocnemius, and were treated without primary tenorrhaphy. Internal stabilization was achieved by placing polypropylene tape (Bühner’s tape) between the tibial tuberosity and the calcaneus, acting as a flexion-limiting device. A clinical, radiographic, and ultrasonographic follow-up was carried out for 5–9 months. Both dogs showed progressive clinical improvement with restoration of near-normal tarsal angles. Ultrasonography demonstrated progressive healing with fibrous tissue bridging the myotendinous junction. No major complications or radiographic signs of osteoarthrosis were observed. This technique may represent a promising option for selected cases; however, additional studies are needed to compare it with established external or rigid internal fixation methods. Full article