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Postinhibitory excitation is a transient overshoot of a neuron's baseline firing rate following an inhibitory stimulus and can be observed in vivo in human motoneurons. However, the biophysical origin of this phenomenon is still unknown and both reflex pathways and intrinsic motoneuron properties have been proposed. We hypothesized that postinhibitory excitation in motoneurons can be facilitated by hyperpolarization-activated inward currents (h-currents). Using an electrical circuit model, we investigated how h-currents can modulate the postinhibitory response of motoneurons. Further, we analyzed the spike trains of human motor units from the tibialis anterior muscle during reciprocal inhibition. The simulations revealed that the activation of h-currents by an inhibitory postsynaptic potential can cause a short-term increase in a motoneuron's firing probability. This result suggests that the neuron can be excited by an inhibitory stimulus. In detail, the modulation of the firing probability depends on the time delay between the inhibitory stimulus and the previous action potential. Further, the postinhibitory excitation's strength correlates with the inhibitory stimulus's amplitude and is negatively correlated with the baseline firing rate as well as the level of input noise. Hallmarks of h-current activity, as identified from the modeling study, were found in 50% of the human motor units that showed postinhibitory excitation. This study suggests that h-currents can facilitate postinhibitory excitation and act as a modulatory system to increase motoneuron excitability after a strong inhibition. Author summary: Human movement is determined by the activity of specialized nerve cells, the motoneurons. Each motoneuron activates a specific set of muscle fibers. The functional unit consisting of a neuron and muscle fibers is called a motor unit. The activity of motoneurons can be observed noninvasively in living humans by recording the electrical activity of the motor units using the electromyogram. We studied the behavior of human motor units in an inhibitory reflex pathway and found an unexpected response pattern: a rebound-like excitation following the inhibition. This has occasionally been reported for human motor units, but its origin has never been systematically studied. In non-human cells of the neural system, earlier studies reported that a specific membrane protein, the so-called h-channel, can cause postinhibitory excitation. Our study uses a computational motoneuron model to investigate whether h-channels can cause postinhibitory excitation, as observed in the experimental recordings. Using the model, we developed a method to detect features of h-channel activity in human recordings. Because we found these features in half of the recorded motor units, we conclude that h-channels can facilitate postinhibitory excitation in human motoneurons. [ABSTRACT FROM AUTHOR]

Background: Cycling workload is an essential factor in practical cycling training. Saddle height is the most studied topic in bike fitting, but the results are controversial. This study aims to investigate the effects of workload and saddle height on the activation level and coordination of the lower limb muscles during cycling. Methods: Eighteen healthy male participants with recreational cycling experience performed 15 × 2-min constant cadence cycling at five saddle heights of 95%, 97%, 100%, 103%, and 105% of greater trochanter height (GTH) and three cycling workloads of 25%, 50%, and 75% of functional threshold power (FTP). The EMG signals of the rectus femoris (RF), tibialis anterior (TA), biceps femoris (BF), and medial gastrocnemius (MG) of the right lower limb were collected throughout the experiment. Results: Greater muscle activation was observed for the RF and BF at a higher cycling workload, whereas no differences were observed for the TA and MG. The MG showed intensified muscle activation as the saddle height increased. The mean and maximum amplitudes of the EMG signals of the MG increased by 56.24% and 57.24% at the 25% FTP workload, 102.71% and 126.95% at the 50% FTP workload, and 84.27% and 53.81% at the 75% FTP workload, respectively, when the saddle height increased from 95 to 100% of the GTH. The muscle activation level of the RF was minimal at 100% GTH saddle height. The onset and offset timing revealed few significant differences across cycling conditions. Conclusions: Muscle activation of the RF and BF was affected by cycling workload, while that of the MG was affected by saddle height. The 100% GTH is probably the appropriate saddle height for most cyclists. There was little statistical difference in muscle activation duration, which might be related to the small workload. [ABSTRACT FROM AUTHOR]

Nicotinamide adenine dinucleotide (NADH) is a cofactor that serves to shuttle electrons during metabolic processes such as glycolysis, the tricarboxylic acid cycle, and oxidative phosphorylation (OXPHOS). NADH is autofluorescent, and its fluorescence lifetime can be used to infer metabolic dynamics in living cells. Fiber-coupled time-correlated single photon counting (TCSPC) equipped with an implantable needle probe can be used to measure NADH lifetime in vivo, enabling investigation of changing metabolic demand during muscle contraction or tissue regeneration. This study illustrates a proof of concept for point-based, minimally-invasive NADH fluorescence lifetime measurement in vivo. Volumetric muscle loss (VML) injuries were created in the left tibialis anterior (TA) muscle of male Sprague Dawley rats. NADH lifetime measurements were collected before, during, and after a 30 s tetanic contraction in the injured and uninjured TA muscles, which was subsequently fit to a biexponential decay model to yield a metric of NADH utilization (cytoplasmic vs protein-bound NADH, the A 1 τ 1 /A 2 τ 2 ratio). On average, this ratio was higher during and after contraction in uninjured muscle compared to muscle at rest, suggesting higher levels of free NADH in contracting and recovering muscle, indicating increased rates of glycolysis. In injured muscle, this ratio was higher than uninjured muscle overall but decreased over time, which is consistent with current knowledge of inflammatory response to injury, suggesting tissue regeneration has occurred. These data suggest that fiber-coupled TCSPC has the potential to measure changes in NADH binding in vivo in a minimally invasive manner that requires further investigation. [ABSTRACT FROM AUTHOR]

The attenuation of sensory inputs via various methods has been demonstrated to impair balance control and alter locomotor behavior during human walking; however, the effects of attenuating foot sole sensation under distinct areas of the foot sole on lower extremity motor output remains poorly understood. Thus, the purpose of this study was to attenuate cutaneous feedback via regional hypothermia under five different areas of the foot sole and investigate the resultant modulation of kinematic and muscle activity during level walking. Electromyography from eight lower leg muscles, kinematics, and location of center of pressure was recorded from 48 healthy young adults completing walking trials with normal and reduced cutaneous sensation from bilateral foot soles. The results of this study highlight the modulatory response of the tibialis anterior in terminal stance (propulsion and toe-off) and medial gastrocnemius muscle throughout the entire stance phase of gait. The topographical organization of foot sole skin in response to the attenuation of cutaneous feedback from different areas of the foot sole significantly modified locomotor activity. Furthermore, the locomotor response to cutaneous attenuation under the same regions that we previously facilitated with tactile feedback do not oppose each other, suggesting different physiological changes to foot sole skin generate unique gait behaviors. [ABSTRACT FROM AUTHOR]

This research aims to provide a better understanding of the swimming push-off specificity comparing force production and electromyographic (EMG) activity on squat-jumps (SJ) and countermovement-jumps (CMJ) performed underwater (similar to swimming turns push-off) and dryland conditions on two different level of expertise participants (swimmers and non-swimmers). Thirteen male swimmers and nine non-trained male sport sciences students participated in this study. Each subject carried out 10 CMJ and 10 SJ jumps in dryland (vertical) and underwater (horizontal). During these trials, force production was recorded by force platforms and muscular activity of Vastus Lateralis, Biceps Femoris, Gastrocnemius Medialis and Tibialis Anterior was analysed through EMG. A three-way ANOVA showed that swimmers increased the differences in values obtained from SJ to CMJ between dry and underwater conditions during the first impulse phase—Impulse 1 (p < 0.01), the second phase of impulse—Impulse 2 (p < 0.001) and duration from peak force to take off (p < 0.001) in contrast to non-swimmers. Patterns relating to force production and EMG were non-consistent between muscles. Jumping performance was not significantly correlated between dry land and underwater conditions; nevertheless, results emphasise that environmental constraints are decisive to define the neuro-motor response to apparently similar tasks performed in different contexts. [ABSTRACT FROM AUTHOR]

Background and Purpose: Weight‐bearing exercises can help improve physical function; however, they may be difficult to perform in patients with neurological issues or lower limb fractures. The purpose of this study was to evaluate the activity of the leg muscles during squatting when using a new exercise aid designed to help patients with difficulty in performing squats, termed the sliding tilt table, at different knee angles and to estimate the squat level for each angle. Methods: This study was a cross‐sectional, observational study performed in the general community. Participants comprised 30 healthy adult men. Squats were performed by setting the knee joints at 30, 60, and 90° and the tilt table angles to 15, 30, and 45°. The muscle activity of the vastus medialis, tibialis anterior, and gastrocnemius was measured using surface electromyography. Results: As the tilt table and knee joint angle increased, the %maximal voluntary isometric contraction increased. Similar patterns were found in both legs. Conclusions: Weight‐bearing exercises, such as squats, are important exercise elements in patients who require lower limb rehabilitation. Therefore, it is necessary to provide efficient lower limb rehabilitation exercises by adjusting the squat level according to the patient's ability, which can be achieved using a sliding tilt table. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) and calcium ions (Ca2+) are functional regulators of skeletal muscle contraction and metabolism. Although H2O2 is one of the activators of the type-1 ryanodine receptor (RyR1) in the Ca2+ release channel, the interdependence between H2O2 and Ca2+ dynamics remains unclear. This study tested the following hypotheses using an in vivo model of mouse tibialis anterior (TA) skeletal muscle. 1) Under resting conditions, elevated cytosolic H2O2 concentration ([H2O2]cyto) leads to a concentration-dependent increase in cytosolic Ca2+ concentration ([Ca2+]cyto) through its effect on RyR1; and 2) in hypoxia (cardiac arrest) and muscle contractions (electrical stimulation), increased [H2O2]cyto induces Ca2+ accumulation. Cytosolic H2O2 (HyPer7) and Ca2+ (Fura-2) dynamics were resolved by TA bioimaging in young C57BL/6J male mice under four conditions: 1) elevated exogenous H2O2; 2) cardiac arrest; 3) twitch (1 Hz, 60 s) contractions; and 4) tetanic (30 s) contractions. Exogenous H2O2 (0.1-100 mM) induced a concentration-dependent increase in [H2O2]cyto (+55% at 0.1 mM; +280% at 100 mM) and an increase in [Ca2+]cyto (+3% at 1.0 mM; +8% at 10 mM). This increase in [Ca2+]cyto was inhibited by pharmacological inhibition of RyR1 by dantrolene. Cardiac arrest-induced hypoxia increased [H2O2]cyto (+33%) and [Ca2+]cyto (+20%) 50 min postcardiac arrest. Compared with the exogenous 1.0 mM H2O2 condition, [H2O2]cyto after tetanic muscle contractions rose less than one-tenth as much, whereas [Ca2+]cyto was 4.7-fold higher. In conclusion, substantial increases in [H2O2]cyto levels evoke only modest Ca2+ accumulation via their effect on the sarcoplasmic reticulum RyR1. On the other hand, contrary to hypoxia secondary to cardiac arrest, increases in [H2O2]cyto from muscle contractions are small, indicating that H2O2 generation is unlikely to be a primary factor driving the significant Ca2+ accumulation after, especially tetanic, muscle contractions. NEW & NOTEWORTHY We developed an in vivo mouse myocyte H2O2 imaging model during exogenous H2O2 loading, ischemic hypoxia induced by cardiac arrest, and muscle contractions. In this study, the interrelationship between cytosolic H2O2 levels and Ca2+ homeostasis during muscle contraction and hypoxic conditions was revealed. These results contribute to the elucidation of the mechanisms of muscle fatigue and exercise adaptation. [ABSTRACT FROM AUTHOR]

Although studies on terrain identification algorithms to control walking assistive devices have been conducted using sensor fusion, studies on transition classification using only electromyography (EMG) signals have yet to be conducted. Therefore, this study was to suggest an identification algorithm for transitions between walking environments based on the entire EMG signals of selected lower extremity muscles using a deep learning approach. The muscle activations of the rectus femoris, vastus medialis and lateralis, semitendinosus, biceps femoris, tibialis anterior, soleus, medial and lateral gastrocnemius, flexor hallucis longus, and extensor digitorum longus of 27 subjects were measured while walking on flat ground, upstairs, downstairs, uphill, and downhill and transitioning between these walking surfaces. An artificial neural network (ANN) was used to construct the model, taking the entire EMG profile during the stance phase as input, to identify transitions between walking environments. The results show that transitioning between walking environments, including continuously walking on a current terrain, was successfully classified with high accuracy of 95.4 % when using all muscle activations. When using a combination of muscle activations of the knee extensor, ankle extensor, and metatarsophalangeal flexor group as classifying parameters, the classification accuracy was 90.9 %. In conclusion, transitioning between gait environments could be identified with high accuracy with the ANN model using only EMG signals measured during the stance phase. [ABSTRACT FROM AUTHOR]

Background: We compared rates of successful polyethylene glycol (PEG) nerve fusion between two epineural suture repairs (2SR) and five epineural suture repairs (5SR) in a rat sciatic nerve transection neurorrhaphy model. We hypothesise that the two and five epineural neural suture repair groups will achieve a similar rate of PEG fusion. Methods: Twenty-five Lewis rats underwent bilateral sciatic nerve transection. Primary neurorrhaphy (PN) consisting of 2SR in one hind limb and 5SR in the contralateral hind limb was performed utilizing PEG fusion. Successful PEG fusion was confirmed by a distal muscle twitch after nerve stimulation proximal to the nerve fusion site. Sciatic nerve conduction velocity (SNCV) across the repair site and the force generated by tibialis anterior muscle (TAM) contraction were also compared between the 2SR and 5SR groups. Results: Success rates were 100% for the 2SR and the 5SR groups. No statistically significant differences in SNCV (P = 0.444) or isometric tetanic TAM contractile force (P = 0.820) were observed between 2SR and 5SR in the setting of PEG fusion. Conclusion: These findings demonstrate no significant difference in successful PEG fusion between the 2SR and 5SR groups. In addition, the findings demonstrate no statistically significant differences in SNCV or isometric tetanic TAM contractile force following sciatic nerve transection when performing a 2SR or 5SR PN in the setting of PEG fusion. Successful PEG fusion can be achieved acutely with either a two or five-epineural suture repair in a rat model. [ABSTRACT FROM AUTHOR]

Objectives: Few studies have examined motor function in determining the suitability of patients with stroke to resume driving a car. Patients with hemiplegia usually control car pedals with the unaffected lower limb. However, motor control on the unaffected side is also impaired in patients with stroke. This study aimed to clarify the neurophysiological characteristics of pedal switching control during emergency braking in patients with hemiplegia. Methods: The study participants consisted of 10 drivers with left hemiplegia and 10 age-matched healthy drivers. An experimental pedal was used to measure muscle activity and kinematic data during braking, triggered by the light from a light-emitting diode placed in front of the drivers. Results: The patient group took the same reaction time as the healthy group. However, from the visual stimulus to the release of the accelerator pedal, the patient group had higher muscle activity in the tibialis anterior and rectus femoris and had faster angular velocities of hip and knee flexion than the healthy group. In addition, the patient group had higher co-contraction activities between flexors and extensors. From the accelerator pedal release to brake contact, the patient group had slower angular velocities of hip adduction, internal rotation, ankle dorsiflexion, internal return, and internal rotation than the healthy group. Conclusions: Patients with hemiplegia exhibited poor control of pedal switching using their unaffected side throughout the pedal-switching task. These results indicate that the safety related to car-pedal control should be carefully evaluated while deciding whether a patient can resume driving a car after a stroke. [ABSTRACT FROM AUTHOR]

Background: In this study, cadavers of 5 adult Aksaray Malakli breed dogs were used to examine the structure of the lumbosacral plexus, which provides innervation of the hindlimb and pelvic region. Objectives: This study aimed to determine the nerve root composition of the lumbosacral plexus, determine the branching patterns, map the nerve directions macro-anatomically, and collect data for future comparisons with similar breeds. Methods: The corpses were kept in a formaldehyde pool (10%) for 14 days. After this period, the anatomical area was dissected using appropriate techniques to identify the lumbosacral plexus nerves and roots. The course and origin of the nerves forming the plexus were identified and photographed. Results: In all 5 cadavers, the lumbosacral plexus originated from the L4-S3 nerves. The plexus comprised n. ischiadicus, n. tibialis, n. obturatorius, n. femoralis, n. saphenous, n. pelvini, n. pudendus, n. cutaneus femoris caudalis, n. peroneus communis, and n. gluteus caudalis. Conclusion: It was determined that n. femoralis was formed from the ventral branches of the L4 and L5 nerves and the cranial branch of the L6 nerve. N. obturatorius originated from the caudal branch of L5 and the ventral branch of L6. It was determined that n. ischiadicus originated from the L6 caudal, L7 and ventral branch of S1 nerves. The femur branched into n. tibialis and n. peroneus communis (n. fibularis) at the level of extremitas distalis. [ABSTRACT FROM AUTHOR]

Background. Muscle dysfunction is an early complication of diabetic peripheral neuropathy (DPN). As a convenient and low-cost tool, muscle ultrasound has been used to assess muscle quality and muscle mass. However, the relationship between different muscle ultrasound parameters and DPN is unclear. Objectives. This study was designed to investigate the relationship between ultrasound parameters of different muscles and DPN among patients with type 2 diabetes mellitus, including the rectus femoris (RF), tibialis anterior (TA), and medial head of gastrocnemius (MG). Materials and Methods. The research enrolled 90 patients with type 2 diabetes mellitus (T2DM). All images were attained from both sides. Muscle measurements contained muscle thickness (MT), cross-sectional area (CSA), echo intensity (EI), and corrected EI. The binary logistic regression and multiple linear regression were used to investigate the association between muscle ultrasound parameters and DPN or vibration perception threshold (VPT). Results. EI, corrected EI, MT of MG, and EI of TA were associated with DPN separately after adjusting other clinical variates. Among these muscle parameters, the EI of MG had a better predictive value (OR: 1.114, 95% CI: 1.039, 1.196) of DPN. Combined with CSA of RF, peripheral artery disease (PAD), and sex, the corrected EI of MG was associated with the vibration perception threshold (VPT) (standard β = 0.242 , p < 0.001), better than the EI of MG (standard β = 0.215 , p = 0.002). Conclusions. MG (MT, EI, and corrected EI) and TA (EI) were associated with DPN, respectively. CSA of RF and corrected EI or EI of MG combined with PAD and sex were associated with VPT significantly, which supported that muscle ultrasound might be a substantial quantitative tool for detecting the exercise benefits for DPN. [ABSTRACT FROM AUTHOR]

We investigated the effect of eldecalcitol on disuse muscle atrophy. C57BL/6J male mice aged 6 weeks were randomly assigned to control, tail suspension (TS), and TS-eldecalcitol–treated groups and were injected intraperitoneally twice a week with either vehicle (control and TS) or eldecalcitol at 3.5 or 5 ng for 3 weeks. Grip strength and muscle weights of the gastrocnemius (GAS), tibialis anterior (TA), and soleus (SOL) were determined. Oxidative stress was evaluated by malondialdehyde, superoxide dismutase, glutathione peroxidase, and catalase. Bone microarchitecture was analyzed using microcomputed tomography. The effect of eldecalcitol on C2C12 myoblasts was analyzed by measuring myofibrillar protein MHC and the atrophy markers Atrogin-1 and MuRF-1 using immunofluorescence. The influence of eldecalcitol on NF-κB signaling pathway and vitamin D receptor (VDR) was assessed through immunofluorescence, (co)-immunoprecipitation, and VDR knockdown studies. Eldecalcitol increased grip strength (P < 0.01) and restored muscle loss in GAS, TA, and SOL (P < 0.05 to P < 0.001) induced by TS. An improvement was noted in bone mineral density and bone architecture in the eldecalcitol group. The impaired oxidative defense system was restored by eldecalcitol (P < 0.05 to P < 0.01 vs. TS). Eldecalcitol (10 nM) significantly inhibited the expression of MuRF-1 (P < 0.001) and Atrogin-1 (P < 0.01), increased the diameter of myotubes (P < 0.05), inhibited the expression of P65 and P52 components of NF-κB and P65 nuclear location, thereby inhibiting NF-κB signaling. Eldecalcitol promoted VDR binding to P65 and P52. VDR signaling is required for eldecalcitol-mediated anti-atrophy effects. In conclusion, eldecalcitol exerted its beneficial effects on disuse-induced muscle atrophy via NF-κB inhibition. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effect of inducing post‐activation potentiation (PAP) during prolonged low‐frequency force depression (PLFFD) on motor unit (MU) firing rates. In 10 participants, grouped firing rates of 3027 MUs from the tibialis anterior were recorded with tungsten microelectrodes. Baseline MU firing rates at 25% isometric maximal voluntary contraction (MVC) were ∼14 Hz. A 1 min dorsiflexion MVC reduced torque and maximal MU firing rates (36 Hz) by 49% and 52%, respectively. Following task completion, firing rates at 25% of baseline MVC torque and torque in response to electrically evoked (single twitch, 10 Hz and 50 Hz) stimulation were assessed before and after a 5 s MVC (to induce PAP) every 10 min for 60 min. From 10 to 60 min after task completion, the torque ratios (twitch:50 Hz and 10:50 Hz) were depressed (∼30%) relative to baseline (P < 0.001), indicating PLFFD; and firing rates were higher by ∼15% relative to baseline (P < 0.001). This occurred despite recovery of MVC rates (∼99%) and torque (∼95%) by 10 min (P > 0.3). Inducing PAP during PLFFD increased both low to high torque ratios (twitch and 10:50 Hz) by ∼200% and ∼135%, respectively (P < 0.001) and firing rates were ∼18% lower relative to PLFFD rates (P < 0.001), despite a speeding of evoked contractile properties (P = 0.001). Thus, firing rates appear strongly matched to alterations in torque, rather than contractile speed when modified by contractile history, and lower rates during PAP may be a mechanism to mitigate effects of PLFFD. The effect of activation history on contractile function demonstrates acute compensatory responses of motoneuron output. Key points: Prolonged low frequency force depression (PLFFD) following a sustained 1 min isometric maximal voluntary contraction causes an increase in submaximal mean motor unit (MU) firing rates.Inducing post‐activation potentiation (PAP) during PLFFD, however, causes a reduction in mean submaximal MU firing rates to a level below those at baseline.The mean firing rate reduction during PAP occurs despite a speeding of evoked contractile properties and thus firing rates are more strongly matched to alterations in torque, rather than contractile speed when modified by various contractile histories.The reductions in firing rates during PAP may mitigate the effects of PLFFD during voluntary contractions.These results demonstrate that firing rates are highly responsive to opposing influences on the contractile state and can make rapid compensatory rate adjustments dependent on the active state of the muscle. [ABSTRACT FROM AUTHOR]

This study analyzed muscle activity during the stand-up paddle stroke, considering the paddling side and the adjacent and opposing muscles relative to the position of the arms during paddling. Methods: Fourteen male paddleboarders performed three trials covering 195 m in which surface electromyography of the upper trapezius, biceps brachii, triceps brachii, tibialis anterior, and gastrocnemius medialis were recorded (four-cycle strokes on each side). The data were processed according to percentage of maximum voluntary contraction (% MVC). The MVC activation values (µV) for each muscle were then calculated and presented as percentage MVC (% MVC). Results: The recovery phase accounted for 60% of the paddle cycle, while the pull phase represented 39%. During right-side paddling, higher % MVC was found in the opposite-side upper trapezius (24.35%, p < 0.01) during the pulling phase and in the adjacent biceps brachii (8.36%, p < 0.03) during the recovery phase. In left-side paddling, greater % MVC was found in the opposite-side upper trapezius (27.60%, p < 0.01) during the pulling phase and in the opposite-side triceps brachii (42.25%, p < 0.04) during the recovery phase. Furthermore, the pulling phase exhibited higher MVC in the opposite-side upper trapezius compared to the recovery phase, both in the right-side (24.35%, p < 0.03) and left-side (27.60%, p < 0.01) paddling. Conclusions: these findings help establish the muscular activity of both sides of the paddling technique and the differences between the upper and lower limbs. [ABSTRACT FROM AUTHOR]

The adverse effects of microgravity exposure on mammalian physiology during spaceflight necessitate a deep understanding of the underlying mechanisms to develop effective countermeasures. One such concern is muscle atrophy, which is partly attributed to the dysregulation of calcium levels due to abnormalities in SERCA pump functioning. To identify potential biomarkers for this condition, multi-omics data and physiological data available on the NASA Open Science Data Repository (osdr.nasa.gov) were used, and machine learning methods were employed. Specifically, we used multi-omics (transcriptomic, proteomic, and DNA methylation) data and calcium reuptake data collected from C57BL/6 J mouse soleus and tibialis anterior tissues during several 30+ day-long missions on the international space station. The QLattice symbolic regression algorithm was introduced to generate highly explainable models that predict either experimental conditions or calcium reuptake levels based on multi-omics features. The list of candidate models established by QLattice was used to identify key features contributing to the predictive capability of these models, with Acyp1 and Rps7 proteins found to be the most predictive biomarkers related to the resilience of the tibialis anterior muscle in space. These findings could serve as targets for future interventions aiming to reduce the extent of muscle atrophy during space travel. [ABSTRACT FROM AUTHOR]

Introduction: Long-term weakness is common in survivors of COVID-19-associated acute respiratory distress syndrome (CARDS). We longitudinally assessed the predictors of muscle weakness in patients evaluated 6 and 12months after intensive care unit discharge with in-person visits. Methods: Muscle strength was measured by isometric maximal voluntary contraction (MVC) of the tibialis anterior muscle. Candidate predictors of muscle weakness were follow-up time, sex, age, mechanical ventilation duration, use of steroids in the intensive care unit, the compound muscle action potential of the tibialis anterior muscle (CMAP-TA-S100), a 6-min walk test, severe fatigue, depression and anxiety, post-traumatic stress disorder, cognitive assessment, and body mass index. We also compared the clinical tools currently available for the evaluation of muscle strength (handgrip strength and Medical Research Council sum score) and electrical neuromuscular function (simplified peroneal nerve test [PENT]) with more objective and robust measures of force (MVC) and electrophysiological evaluation of the neuromuscular function of the tibialis anterior muscle (CMAP-TA-S100) for their essential role in ankle control. Results: MVC improved at 12 months compared with 6 months. CMAP-TA-S100 (P = 0.016) and the presence of severe fatigue (P = 0.036) were independent predictors of MVC. MVC was strongly associated with handgrip strength, whereas CMAP-TA-S100 was strongly associated with PENT. Discussion: Electrical neuromuscular abnormalities and severe fatigue are independently associated with reduced MVC and can be used to predict the risk of long-term muscle weakness in CARDS survivors. [ABSTRACT FROM AUTHOR]

Although osteoarthritis (OA) is regarded as a disease of the articular cartilage, recent research has demonstrated alterations in periarticular muscles that surround the affected joint. Here, we investigated changes in periarticular muscle during the progression of OA, as well as the cause-and-effect relationship between muscle weakness and OA, in a mouse model of OA by destabilization of the medial meniscus (DMM). Pathological phenotypes in the periarticular muscles were assessed in the early and late stages of OA by DMM. OA pathology and pain behavior in the mice after DMM induction were examined in response to periarticular muscle weakness induced by multiple rounds of barium chloride (BaCl2) injections. The examinations were also performed in myostatin knockout mice with strengthened muscle phenotypes by muscle hypertrophy. Morphological alterations in the tibialis anterior (TA) and quadriceps muscles in DMM mice included variations in muscle-fiber size, aberrant extracellular matrix (ECM) deposition, inflammatory cell infiltration, and decreased muscle mass. Periarticular muscle fibers isolated from DMM mice showed reductions in the number of satellite cells and myogenic capacity of primary myoblast, as well as proliferation. DMM + muscle injury mice also showed exacerbated joint degeneration compared to the DMM vehicles. Myostatin knockout mice were characterized by attenuated OA and the complete abrogation of pain behavior after DMM. Our results suggest an association between muscle weakness and OA progression and pain. [ABSTRACT FROM AUTHOR]

Visual–motor illusion (VMI) elicits kinesthetic sensation from visual stimulation. We have previously performed ankle motion VMI with resistance applied to the ankle joint on the paralyzed side (power-VMI (P-VMI)) and ankle motion VMI without resistance (standard-VMI (S-VMI)) to activate the tibialis anterior (TA) muscle in stroke-paralyzed patients and compared sit-to-stand (STS) durations, but these studies did not measure TA activity during the STS movement. The purpose of this study was to evaluate the effects of different intensities of visual stimuli presented during VMI on TA and STS movement. Healthy right-footed adults (n = 18) observed two different VMI videos of ankle dorsiflexion, including S-VMI and P-VMI, with an observation time of 2 min each. STS movement was evaluated before and after watching each video. Each participant performed both S-VMI and P-VMI interventions on the same day. Only P-VMI enhanced the integrated electromyogram of the TA, increased the angular velocities of the trunk forward inclination and the ankle dorsiflexion, and shortened the STS duration. Our results indicate that P-VMI facilitates the activation of TA during STS, and we believe that we have clarified the intervention mechanism of VMI. [ABSTRACT FROM AUTHOR]

Resistance training with low loads in combination with blood flow restriction (BFR) facilitates increases in muscle size and strength comparable with high-intensity exercise. We investigated the effects of BFR on single motor unit discharge behavior throughout a sustained low-intensity isometric contraction. Ten healthy individuals attended two experimental sessions: one with, the other without, BFR. Motor unit discharge rates from the tibialis anterior (TA) were recorded with intramuscular fine-wire electrodes throughout the duration of a sustained fatigue task. Three 5-s dorsiflexion maximal voluntary contractions (MVC) were performed before and after the fatigue task. Each participant held a target force of 20% MVC until endurance limit. A significant decrease in motor unit discharge rate was observed in both the non-BFR condition (from 13.13 ± 0.87 Hz to 11.95 ± 0.43 Hz, P = 0.03) and the BFR condition (from 12.95 ± 0.71 Hz to 10.9 ± 0.75 Hz, P = 0.03). BFR resulted in significantly shorter endurance time and time-to-minimum discharge rates and greater end-stage motor unit variability. Thus, low-load BFR causes an immediate steep decline in motor unit discharge rate that is greater than during contractions performed without BFR. This shortened neuromuscular response of time-to-minimum discharge rate likely contributes to the rapid rate of neuromuscular fatigue observed during BFR. [ABSTRACT FROM AUTHOR]

Corticospinal drive during walking is reduced in older adults compared with young adults, but it is not clear how this decrease might compromise one’s ability to adjust stepping, particularly during visuomotor adaptation. We hypothesize that age-related changes in corticospinal drive could predict differences in older adults’ step length and step time adjustments in response to visual perturbations compared with younger adults. Healthy young (n = 21; age 18–33 yr) and older adults (n = 20; age 68–80 yr) were tested with a treadmill task, incorporating visual feedback of the foot position and stepping targets in real-time. During adaptation, the visuomotor gain was reduced on one side, causing the foot cursor and step targets to move slower on that side of the screen (i.e., split-visuomotor adaptation). Corticospinal drive was quantified by coherence between electromyographic signals in the beta-gamma frequency band (15–45 Hz). The results showed that 1) older adults adapted to visuomotor perturbations during walking, with a similar reduction in error asymmetry compared with younger adults; 2) however, older adults showed reduced adaptation in step time symmetry, despite demonstrating similar adaptation in step length asymmetry compared with younger adults; and 3) smaller overall changes in step time asymmetry was associated with reduced corticospinal drive to the tibialis anterior in the slow leg during split-visuomotor adaptation. These findings suggest that changes in corticospinal drive may affect older adults’ control of step timing in response to visual challenges. This could be important for safe navigation when walking in different environments or dealing with unexpected circumstances. NEW & NOTEWORTHY Corticospinal input is essential for visually guided walking, especially when the walking pattern must be modified to accurately step on safe locations. Age-related changes in corticospinal drive are associated with inflexible step time, which necessitates different locomotor adaptation strategies in older adults. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate whether caffeine consumption would change persistent inward current (PIC) contribution to motoneuron firing at increased contraction intensities and after repetitive sustained maximal contractions. Before and after the consumption of 6 mg·kg−1 of caffeine or placebo, 16 individuals performed isometric triangular-shaped ramp dorsiflexion contractions (to 20% and 40% of peak torque), followed by four maximal contractions sustained until torque production dropped to 60% of maximum, and consecutive 20% triangular-shaped contractions. Tibialis anterior motor unit firing frequencies were analyzed from high-density surface electromyograms. PIC contribution to motor unit firing was estimated by calculating the delta frequency (ΔF) using the paired motor unit technique. Motoneuron peak firing frequencies at 20% and 40% contractions and total torque-time integral during the repetitive sustained maximal contractions were also assessed. ΔF increased 0.69 peaks per second (pps) (95% CI = −0.98, −0.405; d = −0.87) from 20% to 40% contraction intensities and reduced 0.85 pps (95% CI = 0.66, 1.05; d = 0.99) after the repetitive sustained maximal contractions, regardless of caffeine consumption. Participants produced 337 Nm·s (95% CI = 49.9, 624; d = 0.63) more torque integral during the repetitive sustained maximal contractions after caffeine consumption. A strong repeated-measures correlation (r = 0.61; 95% CI = 0.49, 0.69) was observed between reductions of ΔF and peak firing frequencies after the repetitive sustained maximal contractions. PIC contribution to motoneuron firing increases from 20% to 40% contraction intensities, with no effect of caffeine (on rested tibialis anterior). Repetitive sustained maximal contractions reduced PIC contribution to motoneuron firing, regardless of caffeine or placebo consumption, evidencing that changes in intrinsic motoneuron properties contributed to performance loss. Caffeine-attenuated reduction of torque production capacity was unlikely mediated by PICs. NEW & NOTEWORTHY Persistent inward current (PIC) contribution to motoneuron firing increases with contraction intensities and is reduced after repetitive sustained maximal contractions, regardless of caffeine consumption. Reductions of PIC contribution to motoneuron firing and peak firing frequencies were largely associated, evidencing a novel mechanism underpinning decrements in maximal torque production capacity following repetitive sustained maximal contractions. Caffeine consumption attenuated neuromuscular performance reductions—allowing higher time-torque integral production during repetitive sustained maximal contractions. This was unlikely mediated by PIC. [ABSTRACT FROM AUTHOR]

Low-intensity pulsed ultrasound (LIPUS) is a kind of therapeutic ultrasound. It can help improve bone fracture repair and soft tissue healing. Our previous study found that LIPUS treatment could halt the chronic kidney disease (CKD) progression in mice; unexpectedly, we observed the improvement of CKD-reduced muscle weights by LIPUS treatment. Here, we further tested the protective potential of LIPUS on CKD-associated muscle wasting/sarcopenia using the CKD mouse models. Mouse models of both unilateral renal ischemia/reperfusion injury (IRI) with nephrectomy and adenine administration were used to induce CKD. LIPUS with condition of 3MHz, 100mW/cm², 20 min/day was applied to the kidney of CKD mice. LIPUS treatment significantly reversed the increased serum BUN/creatinine levels in CKD mice. LIPUS effectively prevented the decrease in grip strength, muscle weight (soleus, tibialis anterior, and gastrocnemius muscles), cross-section areas of muscle fibres, and muscular phosphorylated Akt protein expression by immunohistochemistry, and the increase in muscular atrogenes Atrogin1 and MuRF1 protein expression by immunohistochemistry in CKD mice. These results indicated that LIPUS could help improve weak muscle strength, muscle mass loss, muscle atrophy-related protein expression, and Akt inactivation. LIPUS application may be an alternative non-invasive therapeutic intervention on the management of CKD-associated muscle wasting. [ABSTRACT FROM AUTHOR]

Asymmetrically impaired standing control is a prevalent disability among stroke patients; however, most of the neuromuscular characteristics are unclear. Therefore, the main purpose of this study was to investigate between-limb differences in intermuscular coherence during quiet standing. Consequently, 15 patients who had sub-acute stroke performed a quiet standing task without assistive devices, and electromyography was measured on the bilateral tibialis anterior (TA), soleus (SL), and medial gastrocnemius (MG). The intermuscular coherence of the unilateral synergistic (SL–MG) pair and unilateral antagonist (TA–SL and TA–MG) pairs in the delta (0–5 Hz) and beta (15–35 Hz) bands were calculated and compared between the paretic and non-paretic limbs. The unilateral synergistic SL–MG coherence in the beta band was significantly greater in the non-paretic limb than in the paretic limb (p = 0.017), while unilateral antagonist TA–MG coherence in the delta band was significantly greater in the paretic limb than in the non-paretic limb (p < 0.01). During quiet standing, stroke patients showed asymmetry in the cortical control of the plantar flexor muscles, and synchronous control between the antagonistic muscles was characteristic of the paretic limb. This study identified abnormal muscle activity patterns and asymmetrical cortical control underlying impaired standing balance in patients with sub-acute stroke using an intermuscular coherence analysis. [ABSTRACT FROM AUTHOR]

Purpose: Compartment syndrome is a surgical emergency that can occur in any part of the body and can cause cell necrosis when maintained over time. The resulting defects can affect the nerves, muscle cells, bone tissue, and other connective tissues inside the compartment, and fasciotomy has to be performed. The anatomical and histological characteristics of the leg make acute, chronic, and exertional compartment syndrome more likely in this limb. For these reasons, knowledge of the ultrasound, anatomical, and histological features of the crural fascia can help in the treatment of leg compartment syndrome. Methods: Twenty-one cryopreserved lower limbs from adult cadavers and from one 29-week-old fetus were obtained from the dissection room. They were examined by ultrasound and a subsequent anatomical dissection and microscopy to study the crural fascia and its relationship with the different muscles. Anthropometric measurements were taken of the distances from the head of the fibula and lateral malleolus to the origin of the tibialis anterior muscle in the crural fascia, the exit of the superficial fibular nerve, and the fascia covering the deep posterior muscles of the leg. Results: The crural fascia has very important clinical relationships, which can be identified by ultrasound, as the origin of the tibialis anterior muscle at 16.25 cm from the head of the fibula and the exit of the superficial fibular nerve that crosses this fascia at 21.25 cm from the head of the fibula. Furthermore, the presence of a septum that fixes the deep posterior muscles of the leg and the vessels and nerve can be seen by ultrasound and can explain the possible development of a posterior compartmental syndrome of the leg. Awareness of these features will help to keep these structures safe during the surgical treatment of compartment syndrome. Conclusion: The ultrasound study allows identification of anatomical structures in the leg and, thus, avoids damage to them during surgery for compartmental syndromes. [ABSTRACT FROM AUTHOR]

Objective The objective of this scoping review was to characterize and identify knowledge gaps about the changes in skeletal muscle fiber type proportion and cross-sectional area (CSA) after stroke. Methods This scoping review followed previously proposed frameworks. A systematic search was conducted for articles examining muscle fiber type proportion and CSA in individuals with stroke in EMBASE, MEDLINE, PsycINFO, CINAHL, SPORTDiscus, and Web of Science databases from inception to December 20, 2022. Two independent authors screened and extracted the data. Results were discussed using theories proposed by the authors of the included studies. Results Of 13 studies (115 participants), 6 (46%) were case studies or case series, 6 (46%) were cross-sectional studies, and 1 (8%) was an experimental study. Studies had small sample sizes (1–23 participants) and various muscle sampling sites (6 different muscles). All 13 studies examined muscle fiber type distributions, and 6 (46%) examined CSA. Ten (77%) studies examined differences between paretic and nonparetic muscles, and 5 (38%) compared people with stroke to people without stroke. Results from 9 of 13 studies (69%) supported a greater proportion of type II muscle fibers in the paretic limb. Of those, 4 studies (42 participants), 3 studies (17 participants), and 1 study (1 participant) saw no differences, preferential type II and type I CSA loss between limbs, respectively. Conclusion Of the limited available evidence, stroke appears to result in a shift to a higher proportion of type II muscle fibers in the paretic muscles. There are mixed results for effects on muscle fiber CSA, but there is some evidence of specific atrophy of type II muscle fibers. Impact Changes in paretic skeletal muscle fibers of individuals with stroke may explain, in part, the substantial losses in strength and power in this population. Interventions to restore type II muscle fiber size may benefit people with stroke. [ABSTRACT FROM AUTHOR]

In some compound muscle action potentials (M waves) recorded using the belly–tendon configuration, the tendon electrode makes a noticeable contribution to the M wave. However, this finding has only been demonstrated in some hand and foot muscles. Here, we assessed the contribution of the tendon potential to the amplitude of the vastus lateralis, biceps brachii and tibialis anterior M waves, and we also examined the role of this tendon potential in the shoulder‐like feature appearing in most M waves. M waves were recorded separately at the belly and tendon locations of the vastus lateralis, biceps brachii and tibialis anterior from 38 participants by placing the reference electrode at a distant (contralateral) site. The amplitude of the M waves and the latency of their peaks and shoulders were measured. In the vastus lateralis, the tendon potential was markedly smaller in amplitude (∼75%) compared to the belly M wave (P = 0.001), whereas for the biceps brachii and tibialis anterior, the tendon and belly potentials had comparable amplitudes. In the vastus lateralis, the tendon potential showed a small positive peak coinciding in latency with the shoulder of the belly–tendon M wave, whilst in the biceps brachii and tibialis anterior, the tendon potential showed a clear negative peak which coincided in latency with the shoulder. The tendon potential makes a significant contribution to the belly–tendon M waves of the biceps brachii and tibialis anterior muscles, but little contribution to the vastus lateralis M waves. The shoulder observed in the belly–tendon M wave of the vastus lateralis is caused by the belly potential, the shoulder in the biceps brachii M wave is generated by the tendon potential, whereas the shoulder in the tibialis anterior M wave is caused by both the tendon and belly potentials. New Findings: What is the central question of this study?Does a tendon electrode make a noticeable contribution to the belly–tendon M wave in the vastus lateralis, biceps brachii and tibialis anterior muscles?What is the main finding and its importance?Because the patellar tendon potential is small in amplitude, it hardly influences the amplitude and shape of the belly–tendon M wave of the vastus lateralis. However, for the biceps brachii and tibialis anterior muscles, the potentials at the tendon sites show a large amplitude, and thus have a great impact on the corresponding belly–tendon M waves. [ABSTRACT FROM AUTHOR]

• Our ultrasound protocol detected ≥1 affected muscle(s) in 94% of the FSHD cohort. • The trapezius and rectus femoris muscles were most severely and most often affected. • Muscle ultrasound scores show strong correlations with clinical outcome measures. • Our study provides a solid base to establish muscle ultrasound as FSHD biomarker. Facioscapulohumeral muscular dystrophy (FSHD) is a hereditary muscle disease, that causes weakness and wasting of skeletal muscles. In this cross-sectional cohort-study on FSHD patients, we assessed muscle ultrasound findings and their relation to clinical outcome measures, evaluating the role of ultrasound as biomarker in FSHD. We included 115 genetically confirmed FSHD patients (52% males, age-range 22–80 years). They were subjected to a standardized muscle ultrasound protocol of seven truncal and upper- and lower extremity muscles bilaterally. Muscle images were scored using the Heckmatt scale. Muscle echogenicity was quantified using z-scores. Compound echogenicity and Heckmatt scores were calculated. Nearly all patients (94%) had one or multiple muscles with an increased echogenicity z-score. The trapezius muscle was most severely affected, followed by the rectus femoris muscle. Both compound ultrasound scores strongly with multiple clinical outcome measures (ρ 0.68–0.79, p < 0.001). While most muscles showed a high level of agreement between the echogenicity z-score and Heckmatt score (>95%), the tibialis anterior and gastrocnemius muscle showed lower levels of agreement (82 and 92%). In conclusion, our study confirms the use of muscle ultrasound as clinical severity biomarker and provides a solid base for future longitudinal studies to establish ultrasound as a monitoring biomarker in FSHD. [ABSTRACT FROM AUTHOR]

Objectives: To describe the morphological characteristics of subfascial intermuscular adipose tissue (IMATS) in the anterior compartment of the leg, considering its developmental and functional relationship with the crural fascia. Methods: In twenty formalin-fixed cadaveric legs (13 males, 7 females), after removal of the skin and crural fascia, the IMATS was exposed and classified into four types according to its shape. Leg length was divided into eight regions. The length, width at the widest point, closest distances of the upper and lower ends to the intermalleolar line and the anterior margin of the tibia, as well as the thickness of the skin-subcutaneous tissue complex, limb and leg lengths were measured for IMATS. Results: The most common type of IMATS was the short-large type. The largest point of IMATS was located in zone 3 or 4, and this point was located in the two zones closest to the lower end of IMATS in 75% of cases. In all cases, one to three connecting vessels piercing the crural fascia (80% were in zones 2, 3 or 4) connected to the IMATS in a slightly lateral to medial oblique course of the IMATS from top to bottom. The IMATS was superficially located in the tendinous and muscular parts of the extensor digitorum longus and/or tibialis anterior muscles, loosely attached to the muscles and crural fascia, but not between the muscle fibers. Although the largest point (p=0.041) and the distance from the distal end to the anterior margin of the tibia were found to be greater in males (p=0.049), the gender difference disappeared when normalized for limb length. Conclusion: No data on IMATS morphometry could be found in the literature. A remarkable finding of the study, which is open to interpretation in terms of the function of the IMATS, is that the location of the IMATS overlaps with the crural fascia region, which is reported to be biomechanically stiffer in the transverse direction. Our data that a connecting vessel is always connected to the IMATS by a fixed spatial relationship strengthens the argument that the developmental history of both structures may intersect. [ABSTRACT FROM AUTHOR]

Background and objectives: Oculopharyngodistal myopathy (OPDM) is an autosomal dominant myopathy clinically characterized by distal muscle weakness. Even though the identification of four causative genes, LRP12, GIPC1, NOTCH2NLC and RILPL1, it is unclear whether the myopathy progressed similarly among OPDM subtypes. We aimed to establish diagnostic clues in muscle imaging of OPDM in comparison with clinicopathologically similar oculopharyngeal muscular dystrophy (OPMD). Methods: Axial muscle CT and/or T1-weighted MRI data from 54 genetically confirmed patients with OPDM (OPDM_LRP12; n = 43, OPDM_GIPC1; n = 6, OPDM_NOTCH2NLC; n = 5) and 57 with OPMD were evaluated. We scored the degree of fat infiltration in each muscle by modified Mercuri score and performed hierarchical clustering analyses to classify the patients and infer the pattern of involvement on progression. Results: All OPDM subtypes showed a similar pattern of distribution in the affected muscles; soleus and medial gastrocnemius involved in the early stage, followed by tibialis anterior and extensor digitorum longus. For differentiating OPDM and OPMD, severely affected gluteus medius/minimus and adductor magnus was indicative of OPMD. Discussion: We identified a diagnostic muscle involvement pattern in OPDM reflecting its natural history. The results of this study will help in the appropriate intervention based on the diagnosis of OPDM, including its stage. [ABSTRACT FROM AUTHOR]

COL6 (collagen type VI)-related myopathies (COL6-RM) are a distinct group of inherited muscle disorders caused by mutations of COL6 genes and characterized by early-onset muscle weakness, for which no cure is available yet. Key pathophysiological features of COL6-deficient muscles involve impaired macroautophagy/autophagy, mitochondrial dysfunction, neuromuscular junction fragmentation and myofiber apoptosis. Targeting autophagy by dietary means elicited beneficial effects in both col6a1 null (col6a1–/–) mice and COL6-RM patients. We previously demonstrated that one-month per os administration of the nutraceutical spermidine reactivates autophagy and ameliorates myofiber defects in col6a1–/– mice but does not elicit functional improvement. Here we show that a 100-day-long spermidine regimen is able to rescue muscle strength in col6a1–/– mice, with also a beneficial impact on mitochondria and neuromuscular junction integrity, without any noticeable side effects. Altogether, these data provide a rationale for the application of spermidine in prospective clinical trials for COL6-RM. Abbreviations: AChR: acetylcholine receptor; BTX: bungarotoxin; CNF: centrally nucleated fibers; Colch: colchicine; COL6: collagen type VI; COL6-RM: COL6-related myopathies; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; NMJ: neuromuscular junction; Spd: spermidine; SQSTM1/p62: sequestosome 1; TA: tibialis anterior; TOMM20: translocase of outer mitochondrial membrane 20; TUNEL: terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling. [ABSTRACT FROM AUTHOR]

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Context: Dynamic balance exercises are commonly utilized during ankle sprain and chronic ankle instability (CAI) rehabilitation. Blood flow restriction (BFR) has been used to enhance muscle activity during exercise and improve outcomes of traditional rehabilitation exercises in clinical populations. Objective: Examine the effects of BFR on lower-extremity muscle activation during dynamic balance exercises in individuals with CAI. Design: Crossover study design. Setting: Laboratory. Patients or Other Participants: Twenty-five (N = 25) young adults with a history of CAI. Interventions: Participants performed dynamic balance reaching exercises during 2 randomized order conditions, BFR, and control. For each condition, participants performed 2 trials of balance exercises. Each trial included 4 sets (30 × 15 × 15 × 15) of reaches in anterior, posteromedial, and posterolateral directions. For the BFR condition, the authors placed a cuff around the proximal thigh at 80% of arterial occlusion pressure. For the control condition, no cuff was worn. Main Outcome Measure(s): The authors recorded normalized electromyography muscle activation of the vastus lateralis, soleus, tibialis anterior, and fibularis longus during balance exercise trials and recorded participants' ratings of perceived postural instability and exertion after each trial of balance exercises. Results: The authors observed greater vastus lateralis (P <.001, d = 0.86 [0.28 to 1.44]) and soleus (P =.03, d = 0.32 [−0.24 to 0.87]) muscle activation during balance exercises with BFR than control. The authors observed no differences in tibialis anterior (P =.33, d = 0.09 [−0.46 to 0.65]) or fibularis longus (P =.13, d = 0.06 [−0.50 to 0.61]) muscle activation between the conditions. The authors observed greater ratings of perceived postural instability (P =.004) and exertion (P <.001) during balance exercises with BFR than control. Conclusions: Individuals with CAI demonstrated large increases in vastus lateralis and small increases in soleus muscle activation during dynamic balance exercises with BFR. The BFR had no effect on fibularis longus and tibialis anterior muscle activation. Individuals with CAI perceived greater postural instability and exertion during dynamic balance exercises with BFR. [ABSTRACT FROM AUTHOR]

Cannabidiol (CBD) has proven clinical benefits in the treatment of seizures, inflammation, and pain. The recent legalization of CBD in many countries has caused increased interest in the drug as an over-the-counter treatment for athletes looking to improve recovery. However, no data on the effects of CBD on the adaptive response to exercise in muscle are available. To address this gap, we eccentrically loaded the tibialis anterior muscle of 14 rats, injected them with a vehicle (n = 7) or 100 mg/kg CBD (n = 7), and measured markers of injury, inflammation, anabolic signaling, and autophagy 18 hr later. Pro-inflammatory signaling through nuclear factor kappa B (NF-kB) (Ser536) increased with loading in both groups; however, the effect was significantly greater (36%) in the vehicle group (p <.05). Simultaneously, anabolic signaling through ribosomal protein S6 kinase beta-1 (S6K1) (Thr389) increased after eccentric contractions in both groups with no difference between vehicle and CBD (p =.66). The ribosomal protein S6 phosphorylation (240/244) increased with stimulation (p <.001) and tended to be higher in the CBD group (p =.09). The ubiquitin-binding protein p62 levels were not modulated by stimulation (p =.6), but they were 46% greater in the CBD compared with the vehicle group (p =.01). Although liver weight did not differ between the groups (p =.99) and levels of proteins associated with stress were similar, we did observe serious side effects in one animal. In conclusion, an acute dose of CBD decreased pro-inflammatory signaling in the tibialis anterior without blunting the anabolic response to exercise in rats. Future research should determine whether these effects translate to improved recovery without altering adaptation in humans. [ABSTRACT FROM AUTHOR]

Context: The improvement of hip joint stability can significantly impact knee and rearfoot mechanics. Individuals with pes planus have a weak abductor hallucis (AbdH), and the tibialis anterior (TA) may activate to compensate for this. As yet, no studies have applied isometric hip abduction (IHA) for hip stability during short-foot exercise (SFE). Objective: To compare the effects of IHA on the muscle activity of the AbdH, TA, peroneus longus (PL), and gluteus medius (Gmed), as well as the medial longitudinal arch (MLA) angle during sitting and standing SFE. Design: Two-way repeated analyses of variance were used to determine the statistical significance of AbdH, TA, PL, and Gmed electromyography activity, as well as the change in MLA angle. Setting: University research laboratory. Participants: Thirty-two Participants : pes planus. Intervention(s ). The participants performed SFE with and without isometric hip abduction in sitting and standing positions. Main Outcome Measures: Surface electromyography was used to measure the activity of the AbdH, TA, PL, and Gmed muscles, and Image J was used to measure the MLA angle. Results: Significant interactions between exercise type and position were observed in terms of the PL muscle activity and in the change in MLA angle only, while other muscles showed significant main effects. The IHA during SFE significantly increased the AbdH muscle activity, while the TA muscle activity was significantly lower. The muscle activity of Gmed and PL was significantly increased in the standing position compared with sitting, but there was no significant difference with or without IHA. The change in the MLA angle was significantly greater in SFE with IHA in a standing position than in the other SFE conditions. Conclusions: IHA may be an effective method for reducing compensatory TA activity and increasing AbdH muscle activity during SFE for individuals with pes planus. [ABSTRACT FROM AUTHOR]

Liwei Wang,1,&ast; Yinyin Qu,1,&ast; Ying Deng,1 Jun Li,1 Yanqing Liu,2 Changyi Wu1 1Department of Anesthesiology, Peking University Third Hospital, Peking University, Beijing, 100191, People’s Republic of China; 2Department of Orthopaedics, Peking University Third Hospital, Peking University, Beijing, 100191, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Changyi Wu, Department of Anesthesiology, Peking University Third Hospital, 49 North Garden Road, Haidian District, Beijing, 100191, People’s Republic of China, Tel +86-13522028771, Email wuchangyitougao@sina.com Yanqing Liu, Department of Orthopaedics, Peking University Third Hospital, 49 North Garden Road, Haidian District, Beijing, 100191, People’s Republic of China, Tel +86-13611346532, Email yanqing_liu@sohu.comPurpose: The location of the sciatic nerve deep within the thigh tissue makes it challenging to locate while the patient is in a supine position. The posterior intermuscular septum of the thigh, which encircles the posterior surface of the adductor magnus muscle (AMM), is where the sciatic nerve is located. Our hypothesis was that administering local anesthetic injections into this area could block the sciatic nerve. Therefore, our aim was to evaluate the effectiveness of sciatic nerve block achieved by injecting local anesthetic into the posterior intermuscular septum of the thigh, named the AMM approach.Methods: Twenty-six patients undergoing total knee arthroplasty were included in the study. We performed an ultrasound-guided sciatic nerve block by injecting 20 mL of 0.25% ropivacaine into the posterior surface of the adductor magnus muscle, using the AMM approach. Additionally, we administered a femoral nerve block with 20 mL of 0.4% ropivacaine. We assessed the sensory and motor effects of the blockade in the operated lower limb and recorded postoperative pain scores at 0, 4, 8, 12, 24, and 48 hours after the operation.Results: The AMM approach successfully block the sciatic nerve in all 26 patients. The onset of the sensory and motor blockades was achieved within 5.4 ± 1.9 min and 8.7 ± 3.5 min, respectively. We achieved a satisfactory position with the first puncture in 19 of 26 patients (73.1%). The muscle strength of the tibialis anterior immediately after surgery was 4 (ranging from 2 to 5). Additional rescue analgesics were required in 5 of the 26 patients (19.2%) during the first 24 hours postoperatively.Conclusion: The AMM approach is an innovative and effective method for sciatic nerve block. When combined with simultaneous femoral nerve block in patients undergoing total knee arthroplasty, it provides a useful analgesic treatment option.Keywords: sciatic nerve block, adductor magnus muscle, tibialis anterior, femoral nerve block

Context: The research on the change in properties of the lower leg muscles by different intensity sinusoidal vertical whole-body vibration ( SV - WBV ) exposures has not yet been investigated. Objective: The purpose of this study was to determine effect of a 20-minute different intensity SV-WBV application to the ankle plantar flexor and dorsiflexor muscles properties and hamstring flexibility. Design: Prospective preintervention -postintervention design. Setting: Physiotherapy department. Participants: A total of 50 recreationally active collegeaged individuals with no history of a lower leg injury volunteered. Interventions: The SV-WBV was applied throughout the session with an amplitude of 2 to 4 mm and a frequency of 25 Hz in moderate-intensity vibration group and 40 Hz in a vigorousintensity vibration group . Main Outcome Measures : The gastrocnemius and tibialis anterior muscle tone was assessed with MyotonPRO, and the strength evaluation was made on the same lower leg muscles using hand-held dynamometer. The sit and reach test was used for the lower leg flexibility evaluation. Results: The gastrocnemius muscle tone decreased on the right side (d = 0.643, P = .01) and increased on the left (d= 0.593, P = .04) when vigorous-intensity vibration was applied. Bilateral gastrocnemius muscle strength did not change in both groups (P >.05). Without differences between groups, bilateral tibialis anterior muscle strength increased in both groups (P < .01). B ilateral gastrocnemius and tibialis anterior muscle tone did not change in the moderate-intensity vibration group (P> .05). Flexibility increased in both groups (P < . 01 ); however, there was no statistically significant difference between the groups ( d = 0 . 169, P = . 55 ). Conclusions: According to study results, if SV-WBV is to be used in hamstring flexibility or ankle dorsiflexor muscle strengthening, both vibration exposures should be preferred. Different vibration programs could be proposed to increase ankle plantar Rexor muscle strength in the acute results. Vigorous-intensity vibration exposure is effective in altering ankle plantar flexor muscle tone, but it is important to be aware of the differences between the lower legs. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of 8-week inspiratory muscle training on activity in the ankle muscles of athletes with chronic low-back pain. A randomized controlled trial involving 45 men and women with chronic low-back pain was carried out. Electromyography activity in the tibialis anterior, peroneus longus, gastrocnemius medialis, and gastrocnemius lateralis muscles of the dominant leg was recorded. Secondary outcomes included biopsychosocial indices, such as pain, disability, anxiety and depression, fear-avoidance beliefs, and fear of (re)injury. Static and dynamic overhead squat tests showed that inspiratory muscle training decreased activity in the tibialis anterior, peroneus longus, and gastrocnemius medialis muscles. In the static single-leg squat test and the descending phase of the dynamic equivalent, such a decrease was observed in all the 4 muscles. Inspiratory muscle training significantly reduced pain severity and activity in the tibialis anterior, peroneus longus, and gastrocnemius medialis muscles during the ascending phase of the dynamic single-leg squat test. On the basis of the findings, 8 weeks of inspiratory muscle training may constitute useful rehabilitation for reducing excessive activity in ankle joint muscles and aiding chronic low-back pain recovery. [ABSTRACT FROM AUTHOR]

Context: Lower-extremity stress fractures (SFx) are a common occurrence during load-bearing activities of jumping and landing. To detect biomechanical changes during jumping postinjury, a fatigue model could be used. Objective: To evaluate muscle activation in the lower leg and tibial accelerations (TAs) prefatigue to postfatigue following a jumping task in those with and without a history of SFx. Design: Repeated-measures. Setting: Athletic Training Research Lab. Participants: A total of 30 active college-aged students with and without a history of lower-extremity (leg or foot) SFx (15 males and 15 females; 21.5 [5.04] y, height = 173.5 [12.7] cm, weight = 72.65 [16.4] kg). Intervention: A maximal vertical jump on one leg 3 times with arms folded across the chest prefatigue to postfatigue was performed. Fatigue protocol was standing heel raises on a custom-built platform at a pace controlled by a metronome until task failure was reached. Legs were tested using a randomized testing order. Electromyographic (EMG) surface electrodes were placed on the medial gastrocnemius, soleus, and tibialis anterior following a standardized placement protocol. A triaxial accelerometer was attached to the proximal anteromedial surface of the tibia. Main Outcome Measures: Linear envelopes of the medial gastrocnemius, soleus, and tibialis anterior and peak accelerations (resultant acceleration takeoff and landing).Results: Significant interaction for leg × test for tibialis anterior with a posttest difference between SFx and control (P =.05). There were decreases in EMG linear envelope following fatigue for medial gastrocnemius (P <.01) and tibialis anterior (P =.12) pretest to posttest. At takeoff, TA was greater in the SFx contralateral leg in comparison with the control leg (P =.04). At landing, TA was greater in posttest (P <.01) and in the SFx leg compared with SFx contralateral (P =.14). Conclusion: A decrease in muscle activity and an increase in TA following fatigue were noted for all subjects but especially for those with a history of SFx. [ABSTRACT FROM AUTHOR]

Two optimization techniques, static optimization (SO) and computed muscle control (CMC), are often used in OpenSim to estimate the muscle activations and forces responsible for movement. Although differences between SO and CMC muscle function have been reported, the accuracy of each technique and the combined effect of optimization and model choice on simulated muscle function is unclear. The purpose of this study was to quantitatively compare the SO and CMC estimates of muscle activations and forces during gait with the experimental data in the Gait2392 and Full Body Running models. In OpenSim (version 3.1), muscle function during gait was estimated using SO and CMC in 6 subjects in each model and validated against experimental muscle activations and joint torques. Experimental and simulated activation agreement was sensitive to optimization technique for the soleus and tibialis anterior. Knee extension torque error was greater with CMC than SO. Muscle forces, activations, and co-contraction indices tended to be higher with CMC and more sensitive to model choice. CMC's inclusion of passive muscle forces, muscle activation-contraction dynamics, and a proportional-derivative controller to track kinematics contributes to these differences. Model and optimization technique choices should be validated using experimental activations collected simultaneously with the data used to generate the simulation. [ABSTRACT FROM AUTHOR]

Context: Unstable devices in various forms are used as therapeutic adjuncts for prevention or following an injury. A slip-over-the-shoe design with inflatable domes (STEPRIGHT® Stability Trainer) was developed to improve balance. It is unknown how this unstable device affects muscle activity during a closed-chain exercise such as the forward lunge. Objective: To compare muscle activity across 3 surfaces (STEPRIGHT®, Both Sides Up [BOSU®] Balance Trainer, and firm) during a forward lunge. Design: Within-subject, repeated measures. Setting: University physical therapy research laboratory. Participants: A total of 20 healthy, recreationally active subjects (23.4 [1.47] y, 172.7 [14.7] cm, 71.6 [16.8] kg). Intervention: Each subject performed 1 set of 10 repetitions of forward lunge exercise in random order with STEPRIGHT®, BOSU®, and firm surface. Main Outcome Measures: Surface electromyography data, normalized to maximum voluntary isometric contractions (%MVIC), was used to assess muscle activity on rectus femoris, vastus medialis oblique (VMO), biceps femoris, lateral gastrocnemius, fibularis longus, and tibialis anterior. Results: The repeated-measures analysis of variance determined that there was a significant effect for surface type. During the descent of the lunge, the STEPRIGHT® elicited higher rectus femoris (33% [27%] MVIC) compared with BOSU® (22% [14%] MVIC) and VMO (44% [15%] MVIC) on STEPRIGHT® compared with firm (38% [11%] MVIC) (P <.05). During the ascent of the lunge, the rectus femoris (38% [27%] MVIC) using STEPRIGHT® was higher than BOSU® (24% [16%] MVIC), and STEPRIGHT® elicited higher VMO (65% [20%] MVIC) versus BOSU® (56% [19%] MVIC) (P ≤.01). The STEPRIGHT® for fibularis longus was higher (descent: 51% [20%] MVIC, ascent: 52% [22%] MVIC) than BOSU® (descent: 36% [15%] MVIC, ascent: 33% [16%] MVIC) or firm (descent: 33% [12%] MVIC, ascent: 35% [15%] MVIC) (P <.001). Conclusions: Clinicians may choose to use the STEPRIGHT® for strengthening VMO and fibularis longus muscles, as these were over 41% MVIC or any of the 3 surfaces for endurance training (<25% MVIC) for biceps femoris muscle. This information may be helpful in exercise dosage for forward lunges when using STEPRIGHT®, BOSU®, or a firm surface. [ABSTRACT FROM AUTHOR]

This study investigated the effect of the time and direction preparation on the electromyographic (EMG) response of the ankle extensor to the backward translation of the support surface in stance. Fifteen healthy adult males aged 35.9 ± 6.2 years participated in this study. In the constant session, the interval between the warning cue and the onset of the backward support surface translation was constant. In the random time session, the interval was randomly assigned in each trial, but the direction was backward across the trials. In the random direction session, the direction was randomly assigned in each trial, but the interval was constant. The EMG amplitude in the time epochs 100-175 ms after translation onset in the random time session was significantly greater than that in the constant session in the soleus, gastrocnemius, and tibialis anterior muscles. The EMG amplitude in the time epochs 120-185 ms after translation onset in the random direction session was significantly greater than that in the constant session in the gastrocnemius and tibialis anterior muscles. This finding indicates that time and direction preparation reduces the late component of the ankle EMG response to backward translation of the support surface. This finding is explained by the supposed process through which uncertainty of the upcoming event causes disinhibition of response or by how time and direction preparation optimizes the magnitude of the long-latency response mediated by the transcortical pathway. [ABSTRACT FROM AUTHOR]

Background: Calcific myonecrosis is a rare entity that is considered a sequela of chronic compartment syndrome. A fusiform mass with central liquefaction and peripheral calcification replaces the affected muscle unit. Case Report: We are presenting a case of calcific myonecrosis of the tibialis anterior in a 76-year-old man. Although the mass was present for several years, the patient recently developed leg pain and foot drop. After radiological and histopathological diagnosis, patient was treated with surgical excision of the mass. Conclusion: Although calcific myonecrosis is a benign condition, due to the pressure effect on surrounding structures, it may be a source of leg pain and foot drop. Cortical erosion and scalloping of underlying major bone may be reasons for extremity pain. To relieve pain, alleviate pressure effect, and prevent pathological fracture of the underlying bone, complete surgical excision of the lesion is essential. [ABSTRACT FROM AUTHOR]

Introduction: Epidural electrical stimulation (EES) has been shown to improve motor dysfunction after spinal cord injury (SCI) by activating residual locomotor neural networks. However, the stimulation current often spreads excessively, leading to activation of non-target muscles and reducing the accuracy of stimulation regulation. Objectives: Near-infrared nerve stimulation (nINS) was combined with EES to explore its regulatory effect on lower limb muscle activity in spinal-cordtransected rats. Methods: In this study, stimulation electrodes were implanted into the rats' L3-L6 spinal cord segment with T8 cord transected. Firstly, a series of EES parameters (0.2-0.6 mA and 20-60 Hz) were tested to determine those that specifically regulate the tibialis anterior (TA) and medial gastrocnemius (MG). Subsequently, to determine the effect of combined optical and electrical stimulation, near-infrared laser with a wavelength of 808 nm was used to irradiate the L3-L6 spinal cord segment while EES was performed. The amplitude of electromyography (EMG), the specific activation intensity of the target muscle, and the minimum stimulus current intensity to induce joint movement (motor threshold) under a series of optical stimulation parameters (power: 0.0-2.0 W; pulse width: 0-10 ms) were investigated and analyzed. Results: EES stimulation with 40 Hz at the L3 and L6 spinal cord segments specifically activated TA and MG, respectively. High stimulation intensity (>2 x motor threshold) activated non-target muscles, while low stimulation frequency (<20 Hz) produced intermittent contraction. Compared to electrical stimulation alone (0.577 ± 0.081 mV), the combined stimulation strategy could induce stronger EMG amplitude of MG (1.426 ± 0.365 mV) after spinal cord injury (p < 0.01). The combined application of nINS effectively decreased the EESinduced motor threshold of MG (from 0.237 ± 0.001 mA to 0.166 ± 0.028 mA, p < 0.001). Additionally, the pulse width (PW) of nINS had a slight impact on the regulation of muscle activity. The EMG amplitude of MG only increased by ~70% (from 3.978 ± 0.240 mV to 6.753 ± 0.263 mV) when the PW increased by 10-fold (from 1 to 10 ms). Conclusion: The study demonstrates the feasibility of epidural combined electrical and optical stimulation for highly specific regulation of muscle activity after SCI, and provides a new strategy for improving motor dysfunction caused by SCI. [ABSTRACT FROM AUTHOR]

Quantitative sensory testing (QST) is useful when analysing musculoskeletal pain disorders. A handheld algometer is most commonly used for pressure pain threshold (PPT) tests. However, reference intervals for PPTs are not elucidated. We assessed reference intervals of PPTs for QST in 158 healthy adult Japanese with no history of musculoskeletal or neurological problems. A handheld algometer was used to record PPT at five different assessment sites on the body: lumbar paravertebral muscle, musculus gluteus maximus, quadriceps, tibialis anterior muscle, and anterior talofibular ligament. Multiple regression analysis was performed to explore sources of variation of PPT according to sex, age, body mass index, UCLA Activity Level Rating, and Tegner Activity Score. Reference intervals were determined parametrically by Gaussian transformation of PPT values using the two-parameter Box-Cox formula. Results of multiple regression analysis revealed that age was significantly associated with PPT of lumbar paravertebral muscle and musculus gluteus maximus. In females, body mass index showed significant positive correlation with PPT of anterior talofibular ligament, and UCLA Activity Level Rating also showed significant positive association with tibialis anterior muscle and anterior talofibular ligament. Site-specific reference intervals of PPTs for Japanese are of practical relevance in fields of pain research using a handheld algometer. [ABSTRACT FROM AUTHOR]

The use of body weight support (BWS) can reveal important insights into the relationship between lower-limb muscle activities and the ventilatory response during sinusoidal walking. Here, healthy participants (n = 15) walked on a treadmill while 0%, 30%, and 50% of their body weight was supported with BWS. The walking speed was varied sinusoidally between 3 and 6 km h−1, and three different frequencies, and periods ranging from 2 to 10 min were used. Breath-by-breath ventilation ( V ˙ E ) and CO2 output ( V ˙ CO 2 ) were measured. The tibialis anterior (TA) muscle activity was measured by electromyography throughout the walking. The amplitude (Amp), normalized Amp [Amp ratio (%)], and phase shift (PS) of the sinusoidal variations in measurement variables were calculated using a Fourier analysis. The results revealed that the Amp ratio in V ˙ E increased with the increase in BWS. A steeper slope of the V ˙ E – V ˙ CO 2 relationship and greater V ˙ E / V ˙ CO 2 values were observed under reduced body weight conditions. The Amp ratio in TA muscle was significantly positively associated with the Amp ratio in the V ˙ E (p < 0.001). These findings indicate that the greater amplitude in the TA muscle under BWS may have been a potent stimulus for the greater response of ventilation during sinusoidal walking. [ABSTRACT FROM AUTHOR]

Skeletal muscle stem cells (MuSC) are crucial for tissue homoeostasis and repair after injury. Following activation, they proliferate to generate differentiating myoblasts. A proportion of cells self-renew, re-enter the MuSC niche under the basal lamina outside the myofiber and become quiescent. Quiescent MuSC have a primary cilium, which is disassembled upon cell cycle entry. Ex vivo experiments suggest cilia are important for MuSC self-renewal, however, their requirement for muscle regeneration in vivo remains poorly understood. Talpid3 (TA3) is essential for primary cilia formation and Hedgehog (Hh) signalling. Here we use tamoxifen-inducible conditional deletion of TA3 in MuSC (iSC-KO) and show that regeneration is impaired in response to cytotoxic injury. Depletion of MuSC after regeneration suggests impaired self-renewal, also consistent with an exacerbated phenotype in TA3iSC-KO mice after repeat injury. Single cell transcriptomics of MuSC progeny isolated from myofibers identifies components of several signalling pathways, which are deregulated in absence of TA3, including Hh and Wnt. Pharmacological activation of Wnt restores muscle regeneration, while purmorphamine, an activator of the Smoothened (Smo) co-receptor in the Hh pathway, has no effect. Together, our data show that TA3 and primary cilia are important for MuSC self-renewal and pharmacological treatment can efficiently restore muscle regeneration. The Talpid3 gene, essential for primary cilia formation, is required for skeletal muscle stem cell (MuSC) self-renewal and loss of Talpid3 in MuSCs deregulates hedgehog and Wnt signalling pathways. [ABSTRACT FROM AUTHOR]

Purpose: To investigate progressive tunnel widening and its correlation with postoperative outcomes after anterior cruciate ligament (ACL) reconstruction using allografts. Methods: Sixty-five patients who underwent ACL reconstruction using a tibialis anterior allograft between 2015 and 2017 were enrolled. Femoral and tibial tunnel widths were measured on anteroposterior (AP) and lateral radiographs immediately and at 3, 6, 12, and 24 months postoperatively. Average femoral and tibial tunnel widths in AP and lateral views were calculated at three different measurement points. Tunnel widening was calculated as the difference in tunnel width immediately and 2 years postoperatively. The correlation between tunnel widening and the postoperative results was analysed. Results: Tunnel width changes between immediate and 2 years postoperatively were as follows, in AP and lateral views, respectively: femur, 3.0 mm ± 1.5 mm and 2.4 mm ± 1.4 mm; and tibia, 2.8 mm ± 1.4 mm and 2.9 mm ± 1.5 mm. Femoral tunnel widths significantly increased until 1 year, but not from 1 to 2 years postoperatively. Tibial tunnel width significantly increased until 2 years postoperatively. In all tunnels, the increments in tunnel widening decreased over time. Increased knee laxity significantly correlated with greater femoral tunnel widening in AP (r = 0.346, P = 0.006) and lateral views (r = 0.261, P = 0.049). Conclusion: Femoral tunnel widths gradually increased until 1 year postoperatively, and tibial tunnel widths increased until 2 years after ACL reconstruction with allografts. The tunnel widening rate gradually decreased over time. Femoral tunnel widening of 3.7 mm and 3.2 mm on AP and lateral views, respectively, were the cut-off values for postoperative knee laxity. Level of evidence: Level III. [ABSTRACT FROM AUTHOR]

Introduction: Overcorrection is a possible complication of clubfoot treatment, whose prevalence varies from 5 to 67%. Overcorrected clubfoot usually presented as a complex flatfoot with different degrees of hindfoot valgus, flat top talus, dorsal bunion, and dorsal navicular subluxation. The management of clubfoot overcorrection is challenging, and both conservative and surgical treatments are available. This study aims to present our experience in the surgical management of overcorrected clubfoot and to provide an overview of actual treatment options for each specific sub-deformity. Materials and methods: A retrospective cohort study of patients surgically treated for an overcorrected clubfoot from 2000 to 2015 at our Institution was conducted. Surgical procedures were tailored to the type and symptomatology of the deformity. A medializing calcaneal osteotomy or subtalar arthrodesis was performed for hindfoot valgus. Subtalar and/or midtarsal arthrodesis were considered in cases of dorsal navicular subluxation. The first metatarsus elevatus was addressed through a proximal plantarflexing osteotomy, sometimes associated with a tibialis anterior tendon transfer. Clinical scores and radiographic parameters were obtained pre-operatively and at the last follow-up. Results: Fifteen consecutive patients were enrolled. The series included 4 females and 11 males, with a mean age at surgery of 33,1 (18–56) years, and a mean follow-up of 4,46 (2–10) years. Seven medializing calcaneal osteotomies, 5 subtalar arthrodesis, 11 first metatarsal plantarflexing osteotomies, and 7 anterior tibialis tendon transfers were performed. A statistically significant improvement in both clinical and radiographic scores was observed. Conclusions: Management of overcorrected clubfoot involves many surgical techniques because of the high interpersonal variability of the deformities. The surgical approach showed positive results, as long as the indication is based on clinical symptoms and functional impairment rather than morphological alterations and radiographic findings. [ABSTRACT FROM AUTHOR]

This study aimed to determine effects of cooling on contraction‐induced peroxisome proliferator‐activated receptor γ coactivator‐1α (PGC‐1α) and vascular endothelial growth factor (VEGF) gene expression, phosphorylations of its related protein kinases, and metabolic responses. Male rats were separated into two groups; room temperature (RT) or ice‐treated (COLD) on the right tibialis anterior (TA). The TA was contracted isometrically using nerve electrical stimulation (1‐s stimulation × 30 contractions, with 1‐s intervals, for 10 sets with 1‐min intervals). The TA was treated before the contraction and during 1‐min intervals with an ice pack for the COLD group and a water pack at RT for the RT group. The muscle temperature of the COLD group decreased to 19.42 ± 0.44°C (p < 0.0001, −36.4%) compared with the RT group after the experimental protocol. An increase in mRNA expression level of PGC‐1α, not VEGF, after muscle contractions was significantly lower in the COLD group than in the RT group (p < 0.0001, −63.0%). An increase in phosphorylated AMP‐activated kinase (AMPK) (p = 0.0037, −28.8%) and a decrease in glycogen concentration (p = 0.0231, +106.3%) after muscle contraction were also significantly inhibited by cooling. Collectively, muscle cooling attenuated the post‐contraction increases in PGC‐1α mRNA expression coinciding with decreases in AMPK phosphorylation and glycogen degradation. [ABSTRACT FROM AUTHOR]