Gastrocnemius Activity Research Articles

PERIPHERAL AND CENTRAL DEMANDS OF REPEATED-SPRINT EXERCISE WITH CONTINUOUS BLOOD FLOW RESTRICTION FOR TEAM-SPORT PLAYERS

INTRODUCTION & AIMS Team-sport players’ repeated-sprint ability improves following repeated-sprint training with systemic hypoxia (reduced fraction of inspired oxygen) through enhanced metabolic demands compared to sea-level training. Localised hypoxia (i.e., blood flow restriction; BFR) presents a limb-specific alternative strategy, though central and peripheral demands during multiple-set repeated-sprint BFR exercise have not been quantified for team-sport players. Therefore, this study aimed to assess the impact of BFR during repeated-sprint exercise on performance, metabolic, neuromuscular, and perceptual responses for team-sport players. METHODS Twenty-six semi-professional and amateur team-sport players performed cycling repeated-sprint exercise (three sets of five 5-second sprints with 25 seconds of passive recovery) with continuous BFR at 45% arterial occlusion pressure or without. Power output, vastus lateralis muscle oxygenation, and cardiorespiratory responses were continuously monitored. Surface electromyography examined vastus lateralis, biceps femoris, and lateral gastrocnemius activation, and root mean square was calculated over eight consecutive cycle revolutions. Exercise-related sensations and blood lactate concentration were assessed following sets. Linear mixed models compared differences in dependent variable means between conditions and sets or repetitions. RESULTS Mean, peak power output, and oxygen consumption decreased (p < .01) with BFR (-5.0%, -4.5%, and -6.3%, respectively) compared to without. Vastus lateralis tissue saturation index reduced (p < .001) during sprints and recovery periods for BFR (-6.9% and -5.9%, respectively). Electromyography root mean square decreased (p < .01) for biceps femoris and lateral gastrocnemius muscles with BFR (-2.8% and -8.9%, respectively), but remained unchanged for the vastus lateralis. Perceived limb discomfort increased (p < .001) for BFR, though blood lactate concentration and rating of perceived exertion did not differ between conditions (p > .05). CONCLUSION Repeated-sprint exercise with BFR for team-sport players reduced performance and likely increased the physiological and perceptual stimulus for the periphery with greater reliance on anaerobic glycolysis, despite comparable or decreased central demands.

Usability of the novel ankle training equipment with spring resistance-based plantar press exercises in the standing position: A focus on chronic stroke patients with hemiplegic gait.

To improve gait disability in patients with chronic stroke, ankle muscle strengthening and calf muscle stretching exercises are required. However, currently available ankle training equipment limit ankle exercises based on the position. Recently developed ankle training equipment enables spring resistance-based plantar press exercises to be performed in the standing position with weight support. To conduct a usability test of the ankle training equipment in the standing position by stroke patients with hemiplegic gait and verify its effects on ankle movements. The ankle training equipment was applied to five patients with chronic stroke and hemiplegic gait. In the standing position, the patients performed forefoot and rearfoot press exercises in the affected side with a day's interval at 20 repetitions maximum (RM). During the exercises, surface electromyography (sEMG) was used to measure the maximum voluntary isometric contraction (%MVIC) of the leg muscles. The System Usability Scale (SUS) was used to assess the ankle training equipment. Wilcoxon signed-rank test was used to evaluate the differences in muscle activity between the two exercises. Forefoot and rearfoot press exercises increased the %MVIC in the biceps femoris. Additionally, the tibialis anterior and medial gastrocnemius activity was significantly different between the two exercises. The SUS was 78.75% (SD 12.7). The usability test of the passive-control foot press trainer (PFPT) that with improvements in the structure and functions for convenience, it could be commercialized. PFPT could be an alternative to the ankle rehabilitation robot that necessitates a sitting position.

Both acute glyphosate and the aminomethylphosphonic acid intoxication decreased the acetylcholinesterase activity in rat hippocampus, prefrontal cortex and gastrocnemius muscle

It has been reported that glyphosate, one of the most common herbicides used in agriculture, impairs locomotion and cognition. Glyphosate has a variable half-life in soil up to biotic and/or abiotic factors transform the molecule in metabolites such as the aminomethylphosphonic acid (AMPA) that has a longer half-life. In this study, female Sprague Dawley rats were acutely exposed to different doses of glyphosate or AMPA (i.e. 10, 56 or 100 mg/kg) and, subsequently, the acetylcholinesterase (AChE) activity was measured in the hippocampus, prefrontal cortex (PFC) and the gastrocnemius muscle. Both glyphosate and AMPA produced a similar decrease in the AChE activity in all the tissues tested. These results suggest that interference with normal cholinergic neurotransmission may be one of the mechanisms involved in glyphosate-induced motor alterations in rats. Moreover, our results highlight the biological importance of AMPA as a molecule with anticholinesterase action in brain and skeletal muscle. To our knowledge, this is the first report showing in vivo that AMPA, the major metabolite of glyphosate, behaves as an organophosphate.

Does the Position of the Ankle Matter During the Single Gluteal Bridge in Futsal Players? An Electromyographic Analysis.

The aim of this study was to analyze the muscle activity of the hamstring muscles and the lateral gastrocnemius during different variants of the single-leg bridge (SLB) in futsal players. Cross-sectional study. Twenty-two futsal players (age = 24.8 [3.9]y) volunteered to participate in this study. The participants performed 3 variations of the SLB with the knee flexed at 45°. The first position was performed with the ankle in plantar position with flat support, the second with the ankle in dorsiflexion (DF) with heel support, and the third with the ankle in DF and external rotation (ER) with heel support. The Wilcoxon rank-sum test assessed the difference between variables for samples with the rank-biserial correlation effect size. Spearman correlation coefficients were used to examine the associations of the percentage maximal voluntary isometric contraction for each muscle with peak force and rate of force development with 3 different variances of the SLB. The variation of ankle DF and ER with heel support generated higher muscle activity in BF in concentric (P < .01, effect size [ES] = -0.613); isometric (P < .042, ES = -0.494); and eccentric (P < .005, ES = -0.668) contraction than ankle DF with heel support. In contrast, the variation of ankle DF and ER with heel support generated fewer muscle activity in lateral gastrocnemius in concentric (P < .001, ES = 0.779); isometric (P < .003, ES = 0.708); and eccentric (P < .014, ES = 0.589) contraction than ankle DF with heel support. The position of DF and ER was the best position in SLB to train the BF. It could be convenient to start rehabilitation of the BF with flat foot postition or ankle in DF with heel support and progress with the position of the ankle in DF and ER with heel support.

Treadmill running: how long before soft-tissue vibrations reach a steady state?

The aim of this study was to determine whether a steady state was reached over time in soft-tissue vibrations (STV) when running with different midsole hardness. Kinematics, kinetics and electromyography changes were also investigated in an attempt to be as comprehensive as possible. Forty-five physically active adults (17 females) with experience in treadmill running performed an 8.5 minutes trial at a self-selected speed with soft, medium and hard midsoles. STV of gastrocnemius muscle, kinetics, kinematics and electromyographic activity of gastrocnemius muscle and tibialis anterior were recorded for 30 seconds at minutes 0, 2, 4, 6 and 8. No time effects were found for STV, passive peak, loading rate and leg muscle activity. No significant footwear × time interactions were observed, suggesting that familiarisation is independent of midsole hardness. The fastest adjustments were an increase of foot inversion and active peak within the first 4 minutes respectively before reaching a steady state. Step frequency and vertical stiffness decreased and plateaued at minute 6. Duty factor and contact time increased whereas flight time decreased during the entire running trial. Results indicate that a familiarisation to midsole hardness is not needed for STV reliable measurements. Depending on the other biomechanical parameters assessed, we recommend at least a 6-minute running trial and a longer running trial for contact and flight times assessment.

Immediate Effect of a Comprehensive Foot Mobility and Strengthening Treatment on Ankle Muscle Activation in Children with Spastic Diplegia

Foot mobility and strengthening treatment (FMST) is a routinely practiced management strategy in musculoskeletal rehabilitation to improve ankle and foot alignment and muscle function, which prevents joint deformities. The FMST may contribute to improvements in foot alignment and muscle function in children with cerebral palsy (CP). However, treatment influence on muscle imbalances and strength in children with spastic diplegic CP is not yet documented. The aim of the study was to determine the effect of FMST on tibialis anterior (TA), medial gastrocnemius (MG), peroneus longus (PL), and soleus muscle activity using electromyography (EMG) in children with spastic diplegic CP. Twenty children with spastic diplegia (mean age: 7.4 years) with GMFCS levels I, II and III were included in this pre and post-experimental (preliminary) study. Muscle activation of TA, MG, PL, and soleus was recorded using surface EMG in a standing position before and after providing the intervention. Muscle activation in RMS-EMG (mV) was calculated. Findings showed a significant increase in muscle activation of TA, MG, and PL in standing position following the intervention. The increase in soleus muscle activation in standing was not statistically significant. We hypothesized that FMST could alter the muscle recruitment pattern. Our findings showed immediate improvement in muscle activation after the intervention. Future studies should consider its carryover effect on motor performance and gait using functional outcomes.

Effects of a passive upper-body exoskeleton on whole-body kinematics, leg muscle activity, and discomfort during a carrying task.

To compare whole-body kinematics, leg muscle activity, and discomfort while performing a 10-min carrying task with and without a passive upper-body exoskeleton (CarrySuitⓇ), for both males and females. Diverse commercial passive exoskeletons have appeared on the market claiming to assist lifting or carrying task. However, evidence of their impact on kinematics, muscle activity, and discomfort while performing these tasks are necessary to determine their benefits and/or limitations. Sixteen females and fourteen males carried a 15kg load with and without a passive exoskeleton during 10-min over a round trip route, in two non-consecutive days. Whole-body kinematics and leg muscle activity were evaluated for each condition. In addition, leg discomfort ratings were quantified before and immediately after the task. The gastrocnemius and vastus lateralis muscle activity remained constant over the task with the exoskeleton. Without the exoskeleton a small decrease of gastrocnemius median activation was observed regardless of sex, and a small increase in static vastus lateralis activation was observed only for females. Several differences in sagittal, frontal, and transverse movements' ranges of motion were found between conditions and over the task. With the exoskeleton, ROM in the sagittal plane increased over time for the right ankle and pelvis for both sexes, and knees for males only. Thorax ROMs in the three planes were higher for females only when using the exoskeleton. Leg discomfort was lower with the exoskeleton than without. The results revealed a positive impact on range of motion, leg muscle activity, and discomfort of the tested exoskeleton.

A focus on exercise prescription and assessment for a safe return to sport participation following a patellar tendon reconstruction in a soccer player

Purpose: The aim of this study was to analyse a 6-month kinesiological intervention after patellar tendon reconstruction. The kinetics, kinematics, and neuromuscular differences between operated (OL) and non-operated limbs (N-OL) were examined over time in a soccer player. Methods: The assessment took place at three months (T0) and nine months (T1) after the reconstruction. This comprised an assessment of the range of motion (ROM), gait analysis through angle-angle diagrams, postural control, neuromuscular assessment during whole-body vibration (WBV), and unilateral-bilateral maximal voluntary isometric contractions (MVICs) synchronised with surface electromyography (sEMG). Results: The angle-angle diagrams at T1 show that the area and perimeter of the N-OL and OL diagrams increased, especially the area and perimeter of the knee-ankle diagram in OL. Furthermore, the postural control at T1 indicated an increase in different conditions. The root mean square (RMS) of sEMGRMS obtained during WBV revealed a significant alteration in the neuromuscular patterns in the OL at T1. The increase in the vastus lateralis (VL) and lateral gastrocnemius (LG) activities was accompanied by a decrease in the biceps femoris (BF) and tibialis anterior (TA). The peak of force and the rate of force development during MVICs showed a slight difference between OL and N-OL at T1. Furthermore, sEMGRMS activity synchronised with MVICs showed a slight difference between the OL and N-OL in the extensors (VL, VM, and RF) and flexors (BF) muscles at T1. Conclusions: The kinetic, kinematic, and neuromuscular variables have shown improvements at T1 compared to T0. Anyway, a 6-month individualised kinesiological intervention, following a patellar tendon reconstruction, reveals that minor alterations in the neuromuscular pattern remain in the OL. These results help kinesiologists manage the functional recovery after patellar tendon reconstruction.

Predictive simulations identify potential neuromuscular contributors to idiopathic toe walking

BackgroundMost cases of toe walking in children are idiopathic. We used pathology-specific neuromusculoskeletal predictive simulations to identify potential underlying neural and muscular mechanisms contributing to idiopathic toe walking. MethodsA musculotendon contracture was added to the ankle plantarflexors of a generic musculoskeletal model to represent a pathology-specific contracture model, matching the reduced ankle dorsiflexion range-of-motion in a cohort of children with idiopathic toe walking. This model was employed in a forward dynamic simulation controlled by reflexes and supraspinal drive, governed by a multi-objective cost function to predict gait patterns with the contracture model. We validated the predicted gait using experimental gait data from children with idiopathic toe walking with ankle contracture, by calculating the root mean square errors averaged over all biomechanical variables. FindingsA predictive simulation with the pathology-specific model with contracture approached experimental ITW data (root mean square error = 1.37SD). Gastrocnemius activation was doubled from typical gait simulations, but lacked a peak in early stance as present in electromyography. This synthesised idiopathic toe walking was more costly for all cost function criteria than typical gait simulation. Also, it employed a different neural control strategy, with increased length- and velocity-based reflex gains to the plantarflexors in early stance and swing than typical gait simulations. InterpretationThe simulations provide insights into how a musculotendon contracture combined with altered neural control could contribute to idiopathic toe walking. Insights into these neuromuscular mechanisms could guide future computational and experimental studies to gain improved insight into the cause of idiopathic toe walking.

Effects of facilitatory and inhibitory Kinesio taping on lateral gastrocnemius muscle activity, motor neuron excitability, and countermovement jump height in university athletes from multiple sports: A randomized controlled trial

ObjectivesThis study aims to investigate the temporal effects of two Kinesio Taping (KT) techniques on lateral gastrocnemius muscle activity, motor neuron excitability, and countermovement jump height in university athletes from hockey, football, basketball, and volleyball. Additionally, it investigates whether the athletes' playing positions—either attacker or defender—influence these outcomes following the KT application. MethodsForty-eight subjects were randomly assigned to one of three groups: Group A (n = 16), Group B (n = 16), and Group C (n = 16). All groups were further subdivided into attackers and defenders. Adhesive Kinesio tape was applied to the lateral gastrocnemius using the Y-shaped technique for three days. Facilitatory KT was applied from the origin to the insertion of the lateral gastrocnemius, while inhibitory KT was applied from the insertion to the origin. Motor neuron excitability, electromyographic activity, and countermovement jump height were tested at baseline, as well as after KT application, to evaluate if the dependent variables had changed. One-way ANOVA was used for baseline comparison, and mixed ANOVA was applied to assess post-interventional effects on the outcome measures. ResultsSignificant group effects for lateral gastrocnemius activation were found, measured using percentage of maximum voluntary isometric contraction (% MVIC) average root mean square (RMS). In motor neuron excitability, maximal M-wave (Mmax) was significantly improved in group comparison. Further, there was also a significant increase in countermovement jump height. There was no significant difference in outcome measures based on playing position (attacker and defender). ConclusionBoth KT techniques effectively influenced the lateral gastrocnemius muscle's activity, motor neuron excitability, and jump height when compared with the control group. Additionally, there is no effect of playing position, specifically attacker or defender, on the examined variables following KT application.

EMG Analysis During Static Balance in Chronic Ankle Instability, Coper and Controls.

Patients with chronic ankle instability (CAI) consistently display postural control alterations, which may result from sensorimotor dysfunction. This study aimed to compare muscle activity in the lower extremity and postural control among individuals with CAI, copers and uninjured controls during a static balance test. A total of 57 physically active participants were categorized into three groups (CAI, copers and controls) and performed a single-leg balance test with two visual conditions: eyes open and eyes closed. Muscle activity in six lower extremity muscles and center of pressure (CoP) variables were recorded and analyzed. Patients with CAI exhibited greater muscle activity in the medial gastrocnemius and gluteus maximus compared to controls or copers, regardless of the visual condition. Copers displayed increased gluteus medius activity compared to controls. Additionally, all groups demonstrated increased muscle activity and CoP variables when visual feedback was disrupted. These findings suggest that patients with CAI may have less effective recruitment of motor units during static balance. On the other hand, greater muscle activity in the gluteus medius in copers may represent a coping mechanism to avoid further ankle injuries. Further research on muscle activity during dynamic postural control is warranted to explore sensorimotor alterations in patients with CAI.

Ankle Biomechanics During Multidirectional Landings in Athletes With Chronic Ankle Instability.

Assessing and understanding the control of the ankle during multidirectional jump landings in athletes with chronic ankle instability (CAI) would help health professionals develop interventions to reduce the risk of recurrent injuries. The aim of this study was to investigate the angle, angular velocity, and movements of the ankle joint, and the muscle activity of peroneus longus (PL), tibialis anterior (TA), and gastrocnemius (GAS) muscles during multidirectional landings in athletes with CAI. Nineteen athletes with CAI (≤25 Cumberland Ankle Instability Tool-Thai Score) participated. A Vicon Nexus motion analysis system synchronously collected data with an AMTI force plate and surface electromyography (EMG) to capture kinematics, kinetics, and muscle activity, respectively. Participants were asked to perform single-leg jump-landing tests in forward (0°), 30° diagonal, 60° diagonal, and lateral (90°) directions. Ankle joint kinematics, kinetics, and muscle activity of PL, TA, and GAS were analyzed. Repeated measure ANOVA (analysis of variance) and Friedman tests were used to analyze the main effects of the jump-landing direction. Athletes with CAI exhibited significant differences in ankle angles, angular velocities, ankle movements, and average muscle activity of GAS between directions. Greatest average EMG of GAS muscle was observed during landing in the lateral direction compared with the forward and 30° diagonal directions. Lateral and diagonal direction movements showed the greatest risks associated with recurrent ankle sprains. Impairments of neuromuscular control in both pre-landing and landing phases were observed in athletes with CAI when considered alongside previously published data. Laboratory-based observational study.

Effects of Neurodynamics Versus Neurodynamic Sustained Natural Apophyseal Glide in Lumbosacral Radiculopathy

Lumbosacral radiculopathy is a frequently reported health issue in middle-aged people, with a prevalence varying fromabout 2.2% to 8%. Neurodynamic mobilization (NM) and Neurodynamic sustained natural apophyseal glide (N-SNAG) techniqueswere proven effective for Lumbosacral radiculopathy. But controversies are prevalent regarding the effectiveness of their treatmentin previous studies. N-SNAG is also a comparatively new technique that is clinically being used around, but more literature is neededto analyze its effectiveness. Hence, we aimed to evaluate the efficacy of N-SNAG in comparison with NM and conventional generalexercises in treating lumbosacral radiculopathy on pain, mobility, disability, muscle activation, and health-related quality of life(HRQL). One hundred and twenty-seven patients aged between 30 and 50 years were randomly allocated into 3 different treatmentgroups, where the first and second groups received N-SNAG and NM with general exercises, and the third (control) group receivedgeneral exercises only. Range of motion of lumbar and hip flexion, active straight leg raising, low back pain, radiculopathy pain, muscleactivation of biceps femoris and gastrocnemius muscles, disability, and HRQL were evaluated at baseline, and the end of 1st week, 2ndweek, 7th week and 18th week for all the groups. Two-way repeated measure ANOVA with Bonferroni’s t-test revealed significant(p&lt;0.05) improvement in the range of lumbar and hip flexion, LBP, radiculopathy pain, active SLR, disability, and HRQL in both withingroups and between groups. Muscle activation of biceps femoris and gastrocnemius also improved significantly (p&lt;0.05) in all threegroups, but no significant (p&gt;0.05) differences were seen between groups. The study concludes that N-SNAG is more efficient thanNM and general exercise in improving pain, lumbar and hip flexion range, SLR, disability, Muscle activation, and HRQL in Lumbosacralradiculopathy patients.

The interrelationship between lower limb movement, muscle activity, and joint moment during half squat and gait

Joint moment is the resultant force of limb movements. However, estimation methods for joint moments using surface electromyography frequently use joint angles instead of limb angles. The limb angle in joint moment estimation using electromyography could clarify the effects of muscle activity on the limbs: acceleration, deceleration, or stabilization. No study has quantified the comprehensive relationship between limb movement, muscle activity, and joint moment. This study aimed to determine the influencing factors for ankle-joint moment and knee-joint moment in the sagittal plane among muscle activities and parameters related to limb movements during half squat and gait. This study included 29 healthy adults (16 female participants, 21.1 ± 2.09 years). Using inertial measurement units, thigh, shank, and foot inclination angles and angular accelerations were calculated as the parameters of limb movements. Muscle activations of the biceps femoris long head, rectus femoris, gastrocnemius, and tibialis anterior were measured. Ankle joint moment and knee-joint moment were measured using a three-dimensional motion capture system and two force plates. Regression models showed high accuracy in measuring ankle-joint moment during a half squat and gait (R2f = 0.92, 0.97, respectively) and knee-joint moment during a half squat (R2f = 0.98), but not knee-joint moment during gait (R2f = 0.63). However, only a maximum of five parameters were selected from muscle activities and limb angular information. Tibialis anterior and gastrocnemius activity were the largest contributors to ankle-joint moment during a half squat and gait, respectively, while muscle activities were not directly reflected in the knee-joint moment during either movement. Consideration of the interrelationships among limb movement, muscle activity, and joint moment is required when adjusting joint movements according to the target and aim of the therapeutic interventions.

Muscle activation while running on the ground compared to artificial turf in males with pronated and supinated feet

BackgroundRunning on different surfaces, including natural and artificial surfaces, requires different gait mechanics, especially in individuals with foot deformity. Research questionHow muscle activity change during running on the ground and artificial turf in males with pronated and supinated feet? MethodsIn this quasi-experimental study, we assessed a cohort of young male subjects, classified as healthy (n = 10), and with pronated (n = 10) or supinated (n = 10) feet. An electromyographic system was used to record lower limb muscle activity while running on the ground and artificial turf at constant speed (3.2 m/s). ResultsResults demonstrated significant main effects of the "surface" factor for vastus medialis activity during the loading phase (p = 0.040, η2 =0.147). Paired comparison revealed significantly greater vastus medialis activity while running on artificial grass with respect to the ground. A significant effect of the “group” factor was found for medial gastrocnemius during loading phase (p = 0.020, η2 =0.250). Paired-wise comparison revealed significantly lower medial gastrocnemius activity in the pronated and supinated feet groups than in the healthy group. SignificanceThe healthy group may possess better neuromuscular control, allowing them to effectively coordinate the activation of the medial gastrocnemius with other muscles involved in running. Based on these findings, running on artificial turf is useful when the runner would like to strengthen vastus medialis muscle. The runner should carefully choose the running surface according to his/her state and training session goal.

Bifidobacterium bifidum and Lactobacillus paracasei alleviate sarcopenia and cognitive impairment in aged mice by regulating gut microbiota-mediated AKT, NF-κB, and FOXO3a signaling pathways

Sarcopenia is closely associated with gut dysbiosis. Probiotics alleviate gut dysbiosis. Therefore, we selected probiotics Lactobacillus paracasei P62 (Lp) and Bifidobacterium bifidum P61 (Bb), which suppressed muscle RING-finger protein-1 (MuRF1) expression and NF-κB activation in C2C12 cells, and examined their effects on muscle mass loss and dysfunction in aged mice. Oral administration of Lp, Bb, or their mix (LB) increased grip strength and treadmill running distance and time. They significantly increased muscle weight in aged mice. They also increased AKT activation, PGC1α, SIRT1, and myosin heavy chain (MyHC) expression, MyHC-positive cell population, and cell size in the gastrocnemius (GA) muscle, while FOXO3a and NF-κB activation, MuRF1, muscle atrophy F-box, and p16 expression, and NF-κB+CD11c+ cell population decreased. Furthermore, they reduced cognitive impairment-like behavior, IL-6 expression, FOXO3a activation, and NF-κB-positive cell population in the hippocampus, GA, and colon, while hippocampal brain-derived neurotropic factor expression increased. They shifted gut microbiota composition in aged mice: they increased Akkermansiaceae and Bacteroidaceae populations, which were positively correlated with total muscle weight and MyHC expression, and decreased Odoribacteraceae and Deferribacteriaceae populations, which were positively correlated with MuRF1 and IL-6 expression. LB alleviated sarcopenia- and cognitive impairment-like symptoms more potently than Lp or Bb alone. Based on these findings, probiotics, particularly Lp, Bb, and LB, can alleviate aging-dependent sarcopenia and cognitive impairment by regulating gut microbiota-mediated AKT, NF-κB, and/or FOXO3a signaling pathways.

Comparison of biomechanical analysis results using different musculoskeletal models for children with cerebral palsy.

Introduction: Musculoskeletal model-based simulations have gained popularity as a tool for analyzing human movement biomechanics. However, when examining the same gait, different models with varying anatomical data and assumptions may produce inconsistent biomechanical results. This inconsistency is particularly relevant for children with cerebral palsy, who often exhibit multiple pathological gait patterns that can impact model outputs. Methods: The aim of this study was to investigate the effect of selecting musculoskeletal models on the biomechanical analysis results in children with cerebral palsy. Gait data were collected from multiple participants at slow, medium, and fast velocities. Joint kinematics, joint dynamics, and muscle activation were calculated using six popular musculoskeletal models within a biomechanical simulation environment. Results: The degree of inconsistency, measured as the root-mean-square deviation, in kinematic and kinetic results produced by the different models ranged from 4% to 40% joint motion range and 0%-28% joint moment range, respectively. The correlation between the results of the different models (both kinematic and kinetic) was good (R0.85, P 0.01), with a stronger correlation observed in the kinetic results. Four of the six models showed a positive correlation between the simulated muscle activation of rectus femoris and the surface EMG, while all models exhibited a positive correlation between the activation of medial gastrocnemius and the surface EMG (P 0.01). Discussion: These results provide insights into the consistency of model results, factors influencing consistency, characteristics of each model's outputs, mechanisms underlying these characteristics, and feasible applications for each model. By elucidating the impact of model selection on biomechanical analysis outcomes, this study advances the field's understanding of musculoskeletal modeling and its implications for clinical gait analysis model decision-making in children with cerebral palsy.

Chronic changes in muscle architecture and aponeurosis structure following calf muscle strain injuries.

Muscle strain injuries in the human calf muscles are frequent sports injuries with high recurrence. Potential structural and functional changes in the medial head of the musculus gastrocnemius (GM) and the associated aponeurosis are not well documented. To test whether a GM muscle strain injury affects muscle fascicle length, pennation angle, and the morphology of the deep aponeurosis at rest and during muscle contraction long time after the injury. Additionally, electromyography (EMG) of the GM and the soleus muscle during a unilateral heel rise was measured in the injured and uninjured calf. GM fascicle length, pennation angle, and aponeurosis thickness was analyzed on dynamic ultrasonography (US) recordings in 10 participants with a chronic calf strain. In addition, US images taken across the distal portion and mid-belly of the GM were analyzed at three different ankle positions. EMG recordings were obtained during a unilateral heel rise. The pennation angle of the injured distal GM was significantly larger compared to the uninjured GM in the contracted, but not the relaxed state. Pennation angle increased more in the injured compared to the uninjured GM during contraction. Fascicle length was shorter in the most distal portion of the injured GM. Fascicles at the distal portion of the injured GM showed a pronounced curvilinear shape as the muscle contracted and the aponeurosis was enlarged in the injured compared to the uninjured GM. The ratio between GM and soleus EMG activity showed a significantly higher relative soleus activity in the injured compared to the healthy calf. The greater change in pennation angle and curvilinear fascicle shape during contraction suggest that a long-term consequence after a muscle strain injury is that some muscle fibers at the distal GM are not actively engaged. The significantly enlarged aponeurosis indicates a substantial and long-lasting connective tissue involvement following strain injuries.

Lower limb muscle activation pattern in male soccer players with lumbar hyperlordosis

Objectivethe aim of the current study was to compare the lower limb muscle activation pattern in soccer players with and without lumbar hyperlordosis during single-leg squat performance. Methodsthirty male collegiate soccer players (15 with and 15 without lumbar hyperlordosis) performed the SLS task. Surface EMG was used to record the activation of eleven lower limb muscles. The activation of these muscles reduces to 100 points during the SLS cycle, where 50% demonstrates the maximum knee flexion, and 0% and 99% demonstrate the maximum knee extension. Resultssoccer players with lumbar hyperlordosis had higher muscle activation than those with normal lumbar lordosis in gluteus maximus, biceps femoris, and medial gastrocnemius. By contrast, they had lower gluteus medius, vastus medialis oblique, rectus femoris, soleus, and medial gastrocnemius (only in the final ascent phase of the SLS) muscle activity than the normal group during the SLS. Conclusionthis alteration may negatively affect targeted muscle performance during the SLS. Subsequent study is required to specify whether such an alteration in the lower limb muscle could be accompanied by injury in soccer players and change in their athletic performance.

Older Adults with Pre-sarcopenia/Sarcopenia have Increased Gastrocnemius Muscle Activity to Maintain Upright Postural Control at Stance Perturbation

Older Adults with Pre-sarcopenia/Sarcopenia have Increased Gastrocnemius Muscle Activity to Maintain Upright Postural Control at Stance Perturbation