Search Results (458)

Objective: This study investigated the effects of hopping speed and distance on ankle joint moments, power, and muscle activation during repeated lateral hopping tasks. Methods: Twelve trained male athletes involved in team sports performed repeated lateral hop tasks at varying speeds (slow and fast) and hop widths (30 and 45 cm). Kinematics, kinetics, and muscle activation were recorded using ten optoelectronic cameras, two force platforms, and four channels of electromyography at the peroneus longus, tibialis anterior, lateral gastrocnemius, and soleus muscles. A two-way repeated-measures ANOVA assessed the effects of speed and distance, and secondary outcomes were adjusted for multiple comparison using the false discover rate procedure. Result: Hopping speed significantly influenced ankle joint moment (p < 0.05) and produced selective altered joint power and muscle activation (p < 0.05), while distance affected ankle joint moment and range of motion in the frontal plane (p < 0.05), but not muscle activation. Several of these effects remained significant after correction for multiple comparisons. A significant speed × distance interaction was observed for frontal plane peak ankle moment (p < 0.05). Conclusions: Hopping speed modulates ankle joint moment most consistently, with more variable changes in joint power and relative muscle activation, while distance manipulation selectively affects mechanical loading without altering muscle activation. Faster hopping increased ankle joint loading and altered relative muscle activation, while wider hopping distances could progressively load frontal plane structures. The results may inform progressive loading strategies for multidirectional sport training in healthy athletes, though clinical applicability remains to be confirmed. Full article

Sprint performance improves throughout adolescence as a result of both structural and neuromuscular development. In particular, increases in body height, lower limb length, and muscle volume have been consistently linked to improvements in sprint performance. However, allometric scaling of force, speed, and power remain lower in adolescents compared to adults even after structural differences are accounted for, implicating neural factors as independent contributors to performance development. The purpose of this study was to investigate differences in neuromuscular activation patterns of the lower limb muscles during maximal sprinting between youth male athletes across two age groups (U19: 17–19 years; U16: 13–16 years). Eighteen athletes performed a 50 m maximal sprint. Spatiotemporal variables (running speed, step frequency, step length) were measured over 30–50 m using a high-speed camera (240 Hz) and timing gates. Electromyographic (EMG) signals were recorded simultaneously from ten lower limb muscles using wireless EMG sensors (2000 Hz): rectus femoris (RF), biceps femoris (BF), semitendinosus (ST), gluteus maximus (Gmax), gluteus medius (Gmed), vastus lateralis (VL), vastus medialis (VM), tibialis anterior (TA), gastrocnemius (GAS), and soleus (SOL). Root mean square (RMS) amplitude was calculated across four gait phases (contact, early-swing, mid-swing, late-swing) and normalised to maximal voluntary Isometric contraction (%MVIC). The U19 group demonstrated significantly greater running speed (U19: 9.49 ± 0.39 vs. U16: 8.67 ± 0.25 m·s⁻¹, p < 0.001), step frequency (U19: 4.49 ± 0.12 vs. U16: 4.35 ± 0.16 Hz, p = 0.004), and step length (U19: 2.12 ± 0.12 vs. U16: 1.99 ± 0.06 m, p = 0.010) than U16. The overall pattern of lower limb muscle activation across the gait cycle was broadly similar between groups; however, a significant group × phase interaction was observed for RF (p = 0.003, F = 5.257, η² = 0.247), with post hoc analysis revealing greater RF activation during early swing in U19 (p = 0.033). These findings may indicate that sprint-specific training in youth athletes is associated with not only structural but also neuromuscular differences, specifically reflecting enhanced RF recruitment during the phase-critical moment of early swing—a window in which high-threshold motor unit activation is most mechanically decisive. EMG-based assessment of hip flexor activation during maximal sprinting may provide a complementary tool, pending further validation, for talent identification and training prescription in youth track and field. Full article

Background/Objectives: Overtraining (OT) syndrome occurs when an athlete’s training load exceeds the athlete’s ability to recover, leading to a performance decrement. The use of nutritional interventions to increase resiliency to OT is a topic of interest for maximizing performance adaptations. The purpose of this study was to determine whether an essential amino acid (EAA) supplementation administered intraperitoneally and orally can mitigate performance decrements and inflammatory responses in an animal model of resistance training-induced overtraining. Methods: Thirty-two C57BL/6J mice were randomly assigned to four groups (n = 8 per group). One group served as a control (CTL), while the other three groups performed a 5-week resistance training ladder climb program. One group trained three days per week for the duration of the program (RT), while the training frequency of the other two groups doubled to six days per week to cause the OT stress. One group of animals were provided with EAA (RTOEAA), while the other received a sham (RTO). Changes (∆) in maximal carrying load (MCL) were assessed. Results: RTO experienced a greater decrease in ∆MCL than RT (p = 0.002) and RTOEAA (p = 0.029). No differences (p = 0.254) were noted between RT and RTOEAA. In addition, TNF-α expression within the plantaris muscle was significantly elevated in RTO compared to all other groups. Significant decreases in the androgen receptor were also noted for RTO in the soleus compared to RT and CTL. Conclusions: Results demonstrated that EAA supplementation was able to increase resiliency and reduce the inflammatory response to the volume overload stress. Full article

Background and Clinical Significance: Severe pediatric spastic equinovarus may significantly impair positioning, orthotic tolerance, hygiene management, caregiver-assisted mobilization, and assisted standing activities. In children with severe cerebral palsy, clinically meaningful outcomes frequently include reduction in caregiver burden and facilitation of daily care rather than restoration of autonomous gait. Ultrasound-guided cryoneurolysis has recently emerged as a minimally invasive option for focal spasticity management, although procedural workflow and tolerability remain challenging in severe deforming patterns. Case Presentation: We report a CARE-compliant same-patient bilateral technical comparison in a 9-year-old child with severe spastic cerebral palsy and bilateral dynamic equinovarus refractory to intensive rehabilitation and repeated botulinum toxin treatment. Baseline severity was consistent with GMFCS level IV. One lower limb was treated using the proposed posterior single-window ultrasound-guided cryoneurolysis approach through a single posterior proximal-calf window, whereas the contralateral limb underwent a conventional multi-point supine strategy. The posterior single-window approach enabled sequential targeting of multiple motor branches through a single posterior access corridor under continuous ultrasound guidance. The procedure required approximately 1 mL of 2% lidocaine without additional sedation and was completed in approximately 4 min, whereas the conventional supine strategy required multiple access points, repeated probe repositioning, minimal conscious sedation with midazolam, and approximately 20 min. At follow-up, lower-limb spasticity improved from approximately MAS 3 toward MAS 2, passive ankle angle, measured as the tibia–foot angle with 90° corresponding to the neutral ankle position, improved from approximately 80° to 95°, and semitendinosus-related hypertonia was reduced. Clinically meaningful improvement in positioning, hygiene management, assisted standing, and rehabilitation handling was observed. Caregiver-reported satisfaction and procedural tolerability were qualitatively perceived as better with the posterior single-window approach. Conclusions: The proposed posterior single-window cryoneurolysis strategy may represent a technically simplifying and clinically relevant minimally invasive approach for severe pediatric spastic equinovarus. Further prospective studies are required to confirm reproducibility, safety, and long-term outcomes. Full article

Critical illness myopathy (CIM) is linked to mechanical ventilation and complete mechanical muscle silencing in intensive care unit (ICU) patients. Limb muscles show atrophy and declined specific single fibre force through altered protein turnover and diminished myosin-to-actin ratios. A rat ICU model reproducing preferential myosin loss and specific force decline in limb muscle was used to assess myofibrillar remodelling. After 5 or 10 days of ICU intervention, single extensor digitorum longus (EDL) and soleus muscle fibres were imaged using label-free, Second Harmonic Generation (SHG) microscopy, followed by quantitative 3D morphometry. The degree and severity of deranged myofibrillar architecture was assessed through (i) 2D and 3D Cosine Angle Sums (CAS2D/CAS3D) and (ii), Vernier Densities (VD) parameters. A progressively declining myofibrillar order was seen by dropping CAS2D/3D and increasing VD values during ICU intervention, reflecting angular and axial register deviations. Effects of chaperone co-inducer BGP-15, dissociative glucocorticoid Vamorolone (VBP-15) or its parent compound Prednisolone on myofibrillar architecture were explored. Both BGP-15 and VBP-15 modulated the progression of myofibrillar disorder seen during ICU intervention alone: For soleus fibres, BGP-15 maintained structural integrity at day 5 but not at day 10, while even worsening myofibrillar order in the EDL. VBP-15 reversed atrophy at day 10 in soleus but not in EDL fibres. Our study is the first to quantify myofibrillar remodelling in limb muscle fibres during ICU intervention in 3D and provides exploratory assessment of BGP-15 and VBP-15 treatments on aberrant remodelling in CIM. Full article

Neurogenic atrophy is the most severe type of muscle atrophy. It can be caused by injury or disease of the nerve that connects to the muscle. Damage to the sciatic nerve (nervus ischiadicus) initiates molecular processes that lead to the transformation of muscle dysfunction into an atrophic state. Oxidative stress is one of the key factors that initiates skeletal muscle atrophy. Therefore, this study evaluates the effects of oral administration of water-soluble C₆₀ fullerenes (daily dose: 1 mg/kg), as powerful antioxidants, on the contraction dynamics of the rat musculus soleus on days 15, 30, and 45 following neurogenic atrophy induced by transection of the nervus ischiadicus. Using biophysical (tensometric), biochemical, and histological analyses, we evaluated the biomechanical parameters of musculus soleus contraction (time of onset of muscle force response, integrated muscle power, maximum and minimum contraction forces), blood biochemical markers (concentrations of C-reactive protein, lactate, creatinine, and reduced glutathione, as well as superoxide dismutase and catalase activities), as well as histological and morphometric indicators of muscle damage in rats on days 15, 30, and 45 after injury induction. It was found that the use of water-soluble C₆₀ fullerenes improves the contractile activity of the musculus soleus after neurogenic atrophy and has a time-dependent nature. Specifically, by day 45 of the experiment, the maximum therapeutic effect reached 23–35 ± 2% for the biomechanical parameters of muscle contraction, and the biochemical blood parameters have nearly approached the control values. Finally, histological analysis confirmed a significant reduction in signs of destruction in muscle fibers and the level of fibrosis in the musculus soleus. These findings suggest the potential application of water-soluble C₆₀ fullerenes in the treatment of pathological conditions of the muscular system arising from peripheral nerve injury. 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: Deep squatting is essential for daily activities and sports; however, it is often limited after ankle fracture surgery, and the contributions of posterior ankle soft tissues, including the soleus muscle (SOL), Achilles tendon (AT), flexor hallucis longus muscle (FHL), and Kager’s fat pad (KFP), to this limitation remain unclear. This study aimed to determine the relationship between posterior ankle soft tissue properties (including stiffness and echo intensity [EI]) and deep squatting ability after ankle fracture surgery. Methods: This cross-sectional study included 53 patients (49.5 ± 16.1 years, 26 men) who underwent ankle fracture surgery. We measured the shear modulus of the SOL and AT, and the EI of the FHL and Kager’s fat pad; ankle range of motion and strength were evaluated. Deep squatting ability was also assessed. Multiple regression and receiver operating characteristic (ROC) analyses were performed to identify predictors of squatting limitation and evaluate discriminative performance. Results: Participants with a deep squatting limitation showed a higher shear modulus in the SOL and AT and higher EI in the FHL compared with those without limitations. SOL and AT shear modulus and FHL EI were significant independent predictors of ankle dorsiflexion angle during deep squatting. ROC analysis showed good discriminative ability for SOL shear modulus and AT shear modulus and modest discriminative ability for FHL EI. Conclusions: Increased stiffness and EI of the SOL, AT, and FHL were associated with reduced deep squatting ability after ankle fracture surgery. Targeted assessment and interventions addressing these tissues may improve postoperative function. Full article

Background: Exercise plays a crucial role in the prevention and management of type 2 diabetes. During self-motion, optic flow provides visual information about heading direction and influences postural control. This study investigated postural responses and muscle activation in individuals with type 2 diabetes exposed to optic flow stimuli simulating self-motion, and examined whether these responses varied according to habitual physical activity over 12 months. Methods: Surface electromyographic (EMG) and stabilometric data were collected from 23 individuals during quiet standing under different visual motion conditions. Participants were classified as physically active or inactive based on standardized criteria. EMG activity was recorded bilaterally from the tibialis anterior and soleus muscles at baseline, 6, and 12 months. Center of pressure (COP) displacement was measured using two force platforms. Results: Stabilometric analysis revealed a significant effect of visual stimulus on COP displacement in both antero-posterior and medio-lateral directions, as well as on COP speed, indicating that optic flow modulates postural control. COP speed changes over time differed by sex, while medio-lateral sway showed time-dependent variations across sides and physical activity groups. EMG analysis showed a significant effect of visual stimulus on soleus activation, with no consistent effects for tibialis anterior. Conclusions: Optic flow significantly modulated postural control and lower-limb muscle activation in individuals with type 2 diabetes. Preliminary differences in response profiles associated with habitual physical activity level were observed, though these should be interpreted cautiously given the exploratory nature of the study. Larger, adequately powered studies are warranted to further investigate these associations. Full article

Objective: We aimed to determine whether sexual experience modulates the soleus H-reflex in male rats and to assess the specific contribution of vermis lobules 6a and 7 to cerebellar-dependent spinal plasticity. Methods: Thirty-six male Wistar rats were divided into sexually inexperienced (SI) and sexually experienced (SE) groups and assigned to one of three cerebellar conditions: intact control, lobule 6a lesion, or lobule 7 lesion. SE rats underwent repeated mating sessions until they achieved efficient copulatory performance. Subsequently, targeted electrolytic lesions were made, and electromyographic recordings of the soleus H-reflex were obtained under urethane anesthesia to quantify H-wave amplitude and temporal parameters. Results: The global linear mixed model yielded no significant main effects of sexual experience, cerebellar condition, or their interaction on H-wave amplitude. Planned contrasts revealed a near-significant trend toward higher H-wave amplitude in sexually experienced intact animals compared with inexperienced controls (p = 0.061, Cohen’s d = 0.592, 95% CI [−1.44, 0.04] V), and significant amplitude reductions following lobule 6a (p = 0.029, d = 1.450, 95% CI [0.13, 2.33] V) and lobule 7 (p = 0.002, d = 2.256, 95% CI [0.74, 3.08] V) lesions specifically in sexually experienced animals. Neither sexual experience nor lesions significantly affected H-wave latency or duration, suggesting that modulation primarily targets synaptic excitability rather than axonal conduction. M-wave latency showed a significant effect of sexual experience (p = 0.026, d = 1.405, 95% CI [0.03, 0.45] ms). Conclusions: Sexual experience appears to be associated with cerebellar-dependent modulation of soleus H-reflex excitability; lobules 6a and 7 of the cerebellar vermis contribute to this effect specifically in experienced animals. Shorter M-wave latency in experienced animals suggests parallel peripheral motor reorganization. Adequately powered confirmatory studies are needed to characterize the mechanisms underlying this association. Full article

Background: The latissimus dorsi free flap is a workhorse for extensive lower-extremity soft tissue defects. Conventionally, the skin paddle is designed according to the anticipated defect and left in place on the muscle as a single composite unit. This report describes an alternative approach in which the skin paddle is secondarily mobilized through subcutaneous undermining and rotated as a separate propeller-type local extension flap on random-pattern vascularization, without a specifically identified perforator—a technique that has not been previously reported. Case Presentation: A 38-year-old male with a high-energy distal lower-extremity defect exposing bone, Achilles tendon, and hardware underwent free latissimus dorsi reconstruction with an empirically designed skin paddle over the constant perforator zone. The skin paddle was subsequently mobilized and rotated as a separate propeller-type extension flap to cover the Achilles region, with additional areas managed using split-thickness skin graft and a reverse soleus flap. Results: The latissimus dorsi flap and skin paddle remained viable, providing stable coverage of the defect. The additional reverse soleus flap achieved durable medial coverage, and the limb was ultimately preserved with satisfactory soft-tissue stability. Conclusion: A random-pattern latissimus dorsi skin paddle designed within the anatomically constant perforator zone can provide a feasible new option offering intraoperative flexibility in complex lower-extremity trauma when perforator mapping is impractical. Full article

Background: Spasticity is a common and disabling symptom of multiple sclerosis (MS), yet its assessment remains challenging. Clinical scales such as the Ashworth Scale (AS) evaluate resistance to passive movement, whereas neurophysiological measures (e.g., H-reflex, F-wave) provide objective indices of α-motoneuron excitability but correlate inconsistently with clinical severity. Real-time ultrasound elastography (RTE) enables semi-quantitative, in vivo assessment of muscle stiffness, while the recently introduced Muscle Elastography Multiple Sclerosis Score (MEMSs) aims to classify muscle spasticity in MS. Objective: To evaluate the utility of RTE using MEMSs for the objective assessment of muscle status in MS patients with spasticity, and to compare elastographic findings with clinical and neurophysiological measures. Methods: In this single-center study, 26 MS patients (diagnosed according to the 2017 McDonald criteria) and age- and sex-matched healthy controls (n = 27) were enrolled. Spasticity was graded using the AS. All participants underwent bilateral RTE of the gastrocnemius muscle, with images independently scored by two blinded neurologists using the 5-point MEMSs scale. Neurophysiological assessment included the soleus H-reflex, with calculation of H/M ratios. Correlations were analyzed using Pearson’s coefficient, and inter-observer reliability was assessed. Results: No consistent or statistically robust associations were found between clinical spasticity severity (AS scores) and either neurophysiological or elastographic parameters. Several MEMSs did not correlate reliably with AS grades, and neurophysiological measures showed limited discriminatory ability between MS patients and healthy controls. Correlations between neurophysiological and elastography parameters were weak to moderate (ρ ranging from −0.49 to 0.45). Inter-observer reliability of MEMSs scoring ranged from poor to moderate across the examined muscle groups, with Cohen’s κ values ranging from −0.02 to 0.54. Conclusions: RTE using MEMSs did not demonstrate sufficient validity or reproducibility for assessing muscle spasticity in MS, showing poor agreement with both clinical and neurophysiological measures. Full article

Background: Acute compartment syndrome (ACS) is a limb-threatening surgical emergency most commonly associated with fractures or high-energy trauma. Non-fracture-related ACS in athletes is uncommon and may lead to delayed diagnosis. Repetitive blunt trauma during combat sports has rarely been described as a potential mechanism. Case Methods: The case concerns a 21-year-old elite-level kickboxing athlete who developed acute compartment syndrome of the left lower leg following repeated calf kicks sustained during sparring. The patient presented with rapidly progressive calf pain, swelling, compartment firmness, paresthesias and weight bearing difficulties. CT angiography demonstrated diffuse edema of the posterior compartments associated with a large intramuscular soleus hematoma without active arterial bleeding. Results: In view of the severity of the symptoms and the characteristic clinical presentation, an emergency fasciotomy was performed in operating room. Progressive closure was achieved using the vessel loop shoelace technique, allowing gradual tension-free closure. Wound healing progressed without infection, and physiotherapy was introduced with joint mobilization. The patient achieved full functional recovery after 6 months. Conclusions: This case illustrates an atypical etiology of ACS—repetitive targeted calf strikes—and underscores the importance of early recognition even in the absence of fracture or major trauma. Clinical vigilance remains paramount, and prompt surgical intervention is critical to prevent irreversible muscle and nerve damage. Awareness of such mechanisms is particularly relevant for clinicians managing athletes in combat sports. To our knowledge, this is the first documented case of ACS secondary to repeated calf kicks in kickboxing. Full article

Background: Human cadaveric models provide a controlled experimental setting to investigate the anatomical basis and mechanical behaviour underlying musculoskeletal ultrasound findings. In recent years, both B-mode ultrasound and shear wave elastography have been applied in cadaveric studies to explore muscle architecture, aponeurotic structures, and passive mechanical properties under standardized conditions. Objective: The aim of this scoping review was to map and synthesize cadaveric studies using ultrasound and shear wave elastography to investigate lower-limb muscles and their aponeurotic structures, with emphasis on methodological applications, anatomical insights, and limitations relevant to clinical interpretation. Material and Methods: A scoping review was conducted according to PRISMA-ScR principles. Studies were included if ultrasound imaging (B-mode and/or shear wave elastography) was applied directly to human cadaveric lower-limb muscles or aponeurotic structures. Data were extracted and synthesized descriptively by anatomical region and ultrasound technique. Results: A total of 11 studies met the inclusion criteria and were included in the final qualitative synthesis, all of which applied ultrasound imaging, with or without shear wave elastography, directly to human cadaveric muscle tissue Among these, seven studies specifically investigated lower-limb skeletal muscles and their aponeurotic structures using ultrasound-based techniques to describe muscle architecture, internal connective tissue anatomy, or passive mechanical behaviour. These studies focused on the quadriceps femoris, hamstrings, adductor longus, and the gastrocnemius–soleus complex. The remaining four studies were considered relevant and therefore included in the scoping review because, although they did not focus on a specific lower-limb muscle group, they addressed key methodological factors influencing ultrasound and elastography-derived measurements in cadaveric muscle tissue. These investigations examined the effects of tissue layering, specimen-related characteristics, and measurement conditions, thereby providing essential methodological context for the interpretation of ultrasound-based outcomes across different anatomical regions. Conclusions: Cadaveric ultrasound studies provide essential anatomical context for interpreting musculoskeletal ultrasound, while cadaveric shear wave elastography supports controlled exploration of passive muscle mechanics. At the same time, these studies highlight important methodological sensitivities that should be acknowledged before translating elastography findings to clinical decision-making. Full article

Muscle wasting contributes substantially to inflammatory bowel disease (IBD)-related disability, but its association with colitis severity across disease stages remains poorly characterized. We therefore assessed skeletal muscle mass, fiber morphology, and voluntary wheel-running performance in Winnie mice—a spontaneous Muc2 mutant model of chronic colitis—in separate female and male homozygous mutant and WT littermate cohorts. Assessments were performed at 5 weeks, before overt colitis, and at 15 weeks, in a cohort with more pronounced colitis. Outcomes included disease activity index (DAI), fecal lipocalin-2 (LCN-2), wheel-running metrics, soleus and tibialis anterior mass, and minimal Feret’s diameter distributions. At 5 weeks, Winnie mice showed no overt disease activity and no consistent structural muscle deficit. In contrast, the 15-week cohort exhibited marked colitis in both sexes, with increased DAI and LCN-2, reduced voluntary wheel-running performance, lower soleus and tibialis anterior mass, and smaller muscle fiber diameters with left-shifted size distributions. Correlation analyses identified associations between fecal LCN-2, skeletal muscle mass and size, and wheel-running distance and velocity, supporting a link between intestinal inflammation and muscle impairment in this model. These cross-sectional data are consistent with reduced voluntary activity and structural myopathy during progression of spontaneous colitis. The Winnie mouse model therefore provides a clinically relevant preclinical platform to study IBD-associated muscle wasting and its association with intestinal inflammation. Full article