Search

Functional independence of the transversus abdominis (TrA) from other trunk muscles for postural control is still unclear. This study aimed to clarify the specific function of the TrA to control standing posture by vibratory stimulation of the triceps surae. Fifteen men participated in this study. Muscle activity of the TrA, internal oblique, lumbar multifidus, gluteus maximus, rectus femoris, biceps femoris, gastrocnemius, and tibialis anterior was measured using fine-wire and surface electrodes. Participants were asked to maintain a quiet standing posture with and without vibration of the triceps surae, which induced a kinesthetic illusion and the concomitant backward sway of the body. The muscle activity of each muscle for 10 s was extracted with and without vibration. The muscle activity levels were compared between the conditions by a paired t-test or Wilcoxon signed-rank test. The activity of the TrA and rectus femoris was increased, whereas the internal oblique showed no change as a result of the induced kinesthetic illusion. In addition, the activity of the multifidus and biceps femoris was decreased. The TrA and rectus femoris could contribute to control the backward sway of the body. Furthermore, the TrA may have functional independence from the internal oblique during standing postural control. These results warrant further study in patients with low back pain. [ABSTRACT FROM AUTHOR]

Whole-body vestibular-evoked balance responses decrease following ~ 55 min of normobaric hypoxia. It is unclear how longer durations of hypoxia affect the vestibular control of balance at the muscle and whole-body levels. This study examined how four hours of normobaric hypoxia influenced the vestibular control of balance. Fifteen participants (4 females; 11 males) stood on a force plate with vision occluded and head rotated rightward while subjected to three blocks of binaural, bipolar stochastic electrical vestibular stimulation (EVS; 0–25 Hz, root mean square amplitude = 1.1 mA) consisting of two, 90-s trials. The relationship between EVS and anteroposterior (AP) forces or medial gastrocnemius (MG) electromyography (EMG) was estimated in the time and frequency domains at baseline (BL; 0.21 fraction of inspired oxygen—FIO2) and following two (H2) and four (H4) hours of normobaric hypoxia (0.11 FIO2). The EVS-MG EMG short-latency peak and peak-to-peak amplitudes were smaller than BL at H2 and H4, but the medium-latency peak amplitude was only lower at H4. The EVS-AP force medium-latency peak amplitude was lower than BL at H4, but the short-latency peak and peak-to-amplitudes were unchanged. The EVS-MG EMG coherence and gain were reduced compared to BL at H2 and H4 across multiple frequencies ≥ 7 Hz, whereas EVS-AP force coherence was blunted at H4 (≤ 4 Hz), but gain was unaffected. Overall, the central nervous system's response to vestibular-driven signals during quiet standing was decreased for up to four hours of normobaric hypoxia, and vestibular-evoked responses recorded within postural muscles may be more sensitive than the whole-body response. [ABSTRACT FROM AUTHOR]

Microgravity (µG) experienced during space flights promotes adaptation in several astronauts' organs and tissues, with skeletal muscles being the most affected. In response to reduced gravitational loading, muscles (especially, lower limb and antigravity muscles) undergo progressive mass loss and alteration in metabolism, myofiber size, and composition. Skeletal muscle precursor cells (MPCs), also known as satellite cells, are responsible for the growth and maintenance of muscle mass in adult life as well as for muscle regeneration following damage and may have a major role in µG-induced muscle wasting. Despite the great relevance for astronaut health, very few data are available about the effects of real µG on human muscles. Based on the MyoGravity project, this study aimed to analyze: (i) the cellular and transcriptional alterations induced by real µG in human MPCs (huMPCs) and (ii) the response of human skeletal muscle to normal gravitational loading after prolonged exposure to µG. We evaluated the transcriptomic changes induced by µG on board the International Space Station (ISS) in differentiating huMPCs isolated from Vastus lateralis muscle biopsies of a pre-flight astronaut and an age- and sex-matched volunteer, in comparison with the same cells cultured on the ground in standard gravity (1×g) conditions. We found that huMPCs differentiated under real µG conditions showed: (i) upregulation of genes related to cell adhesion, plasma membrane components, and ion transport; (ii) strong downregulation of genes related to the muscle contraction machinery and sarcomere organization; and (iii) downregulation of muscle-specific microRNAs (myomiRs). Moreover, we had the unique opportunity to analyze huMPCs and skeletal muscle tissue of the same astronaut before and 30 h after a long-duration space flight on board the ISS. Prolonged exposure to real µG strongly affected the biology and functionality of the astronaut's satellite cells, which showed a dramatic reduction of responsiveness to activating stimuli and proliferation rate, morphological changes, and almost inability to fuse into myotubes. RNA-Seq analysis of post- vs. pre-flight muscle tissue showed that genes involved in muscle structure and remodeling are promptly activated after landing following a long-duration space mission. Conversely, genes involved in the myelination process or synapse and neuromuscular junction organization appeared downregulated. Although we have investigated only one astronaut, these results point to a prompt readaptation of the skeletal muscle mechanical components to the normal gravitational loading, but the inability to rapidly recover the physiological muscle myelination/innervation pattern after landing from a long-duration space flight. Together with the persistent functional deficit observed in the astronaut's satellite cells after prolonged exposure to real µG, these results lead us to hypothesize that a condition of inefficient regeneration is likely to occur in the muscles of post-flight astronauts following damage. [ABSTRACT FROM AUTHOR]

This document discusses the importance of developing engineering technologies to prevent musculoskeletal injuries and improve treatment and rehabilitation strategies. It highlights recent advancements in implant design, surgical techniques, rehabilitation protocols, and injury prevention technologies. The document also introduces a special issue of Bioengineering dedicated to advanced engineering technologies in orthopedic research, featuring eight papers on topics such as posture control in the elderly, artificial intelligence preoperative planning, shape memory implants for osteoporotic fractures, in vitro joint testing systems, pedicle screw performance, knee arthroplasty designs, gait analysis for fracture healing, and shoulder arthrometry. The papers aim to improve the prevention of injuries, enhance implant compatibility, optimize post-operative function, and provide innovative diagnostic and therapeutic technologies for musculoskeletal diseases. [Extracted from the article]

This single-blind randomized controlled trial investigated the effectiveness of surface electromyography (sEMG)-triggered constraint-induced movement cycling therapy (CIMCT) in improving balance, lower extremity strength, and activities of daily living in patients with chronic stroke. The participants included patients with chronic stroke-induced hemiplegia who had been diagnosed for more than 6 months, with a minimum score of 24 points on the Mini-Mental State Examination and above level 3 on the Brunnstrom stages. The trial lasted 4 weeks and participants were divided into a CIMCT group and a general cycling training (GCT) group. The CIMCT group (n = 20) used an sEMG-triggered constrained-induced movement therapy device, whereas the GCT group (n = 19) used a standard stationary bicycle. The primary outcome measures showed a significant increase in muscle strength on the affected side in the CIMCT group, as assessed by a manual muscle tester (p < 0.05), with a large effect size (d = 1.86), while no meaningful improvement was observed in the GCT group. Both groups demonstrated significant improvements in dynamic balance, as measured by the Timed Up and Go (TUG) test (p < 0.05), with the CIMCT group showing superior results compared to the GCT group, reflected by a large effect size (d = 0.96). Additionally, both groups showed significant improvements in balance as assessed by the Berg Balance Scale (BBS) and the Functional Reach Test (FRT). The CIMCT group exhibited more pronounced improvements than the GCT group, with large effect sizes of 0.83 for the BBS and 1.25 for the FRT. The secondary outcome measures revealed significant improvements in activities of daily living in both groups, as assessed by the modified Barthel index (MBI), with the CIMCT group achieving a substantial improvement (p < 0.05), accompanied by a large effect size (d = 0.87). This study concludes that sEMG-triggered CIMCT effectively improved muscle strength, postural balance, and activities of daily living in patients with chronic stroke. [ABSTRACT FROM AUTHOR]

Neuromuscular fatigue (NMF) induces temporary reductions in muscle force production capacity, affecting various aspects of motor function. Although studies have extensively explored NMF's impact on muscle activation patterns and postural stability, its influence on motor adaptation processes remains less understood. This article investigates the effects of localized NMF on motor adaptation during upright stance, focusing on reaching tasks. Using a force-field perturbation paradigm, participants performed reaching movements while standing upright before and after inducing NMF in the ankle dorsiflexor muscles. Results revealed that despite maintained postural stability, participants in the NMF group exhibited larger movement errors during reaching tasks, suggesting impaired motor adaptation. This was evident in both initial and terminal phases of adaptation, indicating a disruption in learning processes rather than a decreased adaptation rate. Analysis of electromyography activation patterns highlighted distinct strategies between groups, with the NMF group showing altered activation of both fatigued and nonfatigued muscles. In addition, differences in coactivation patterns suggested compensatory mechanisms to prioritize postural stability despite NMF-induced disruptions. These findings underscore the complex interplay between NMF, motor adaptation, and postural control, suggesting a potential role for central nervous system mechanisms in mediating adaptation processes. Understanding these mechanisms has implications for sports performance, rehabilitation, and motor skill acquisition, where NMF may impact the learning and retention of motor tasks. Further research is warranted to elucidate the transient or long-term effects of NMF on motor adaptation and its implications for motor rehabilitation interventions. NEW & NOTEWORTHY: We assessed motor adaptation during force-field reaching following exercise-induced neuromuscular fatigue (NMF) on postural muscles. NMF impaired adaptation in performance. Similarly, diverging activation strategies were observed in the muscles. No effects were seen on measures of postural control. These results suggest the remodulation of motor commands to the muscles in the presence of NMF, which may be relevant in settings where participants could be exposed to NMF while learning, such as sports and rehabilitation. [ABSTRACT FROM AUTHOR]

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We investigated the shuttling of Homer protein isoforms identified in soluble (cytosolic) vs. insoluble (membrane–cytoskeletal) fraction and Homer protein–protein interaction/activation in the deep postural calf soleus (SOL) and non-postural gastrocnemius (GAS) muscles of het−/− mice, i.e., mice with an autosomal recessive variant responsible for a vestibular disorder, in order to further elucidate a) the underlying mechanisms of disrupted vestibular system-derived modulation on skeletal muscle, and b) molecular signaling at respective neuromuscular synapses. Heterozygote mice muscles served as the control (CTR). An increase in Homer cross-linking capacity was present in the SOL muscle of het−/− mice as a compensatory mechanism for the altered vestibule system function. Indeed, in both fractions, different Homer immunoreactive bands were detectable, as were Homer monomers (~43–48 kDa), Homer dimers (~100 kDa), and several other Homer multimer bands (>150 kDA). The het−/− GAS particulate fraction showed no Homer dimers vs. SOL. The het−/− SOL soluble fraction showed a twofold increase (+117%, p ≤ 0.0004) in Homer dimers and multimers. Homer monomers were completely absent from the SOL independent of the animals studied, suggesting muscle-specific changes in Homer monomer vs. dimer expression in the postural SOL vs. the non-postural GAS muscles. A morphological assessment showed an increase (+14%, p ≤ 0.0001) in slow/type-I myofiber cross-sectional area in the SOL of het−/− vs. CTR mice. Homer subcellular immuno-localization at the neuromuscular junction (NMJ) showed an altered expression in the SOL of het−/−mice, whereas only not-significant changes were found for all Homer isoforms, as judged by RT-qPCR analysis. Thus, muscle-specific changes, myofiber properties, and neuromuscular signaling mechanisms share causal relationships, as highlighted by the variable subcellular Homer isoform expression at the instable NMJs of vestibular lesioned het−/− mice. [ABSTRACT FROM AUTHOR]

This paper introduces the foot-slip turning motion by combining a slider-like mechanism with the double-support parallel spring-loaded inverted pendulum model, in which the musculoskeletal robot uses the model to simplify the slip-turning motion with its compliant structure and utilizes the foot muscle to improve its postural stability. The slip-turning motion, characterized by slight movements for swift turning via foot slippage, is advantageous for musculoskeletal robots due to their limited range of movement. The challenge lies in the reduced support area during the motion, which impacts stability. In our previous study, the robot 'PneuTurn-T' successfully executed said motion, whereas the details of the turning mechanism were lacking. This study investigated the utilization of leg compliance in the motion and its static postural stability in the landing stance. Experimental results exhibited a leg compression rate derived from the collected data in the early phase of the motion and validated intrinsic toe joint stabilization with foot muscle for passive postural control. The ground reaction force proves the capability to maintain the posture for 130% longer in the foot with plantar intrinsic muscle. Despite structural challenges, this approach shows promise for musculoskeletal robots, highlighting their ability to handle a turning task with simple control. [ABSTRACT FROM AUTHOR]

While the simultaneous degradation of muscle composition and postural stability in aging are independently highly investigated due to their association with fall risk, the interplay between the two has received little attention. Thus, the purpose of this study is to explore how age-related changes in muscle composition relate to postural stability. To that aim, we collected posturography measures and ultrasound images of the dominant Vastus Lateralis and Biceps Brachii from 32 young (18–35 year old) and 34 older (65–85 year old) participants. Muscle properties were quantified with echo-intensity and texture-based metrics derived from gray-level co-occurrence matrix analysis, and postural stability with the variability of the center of pressure during bipedal stance tasks. Ultrasound parameters revealed that young muscle possessed lower echo-intensity and higher homogeneity compared to the elderly. Echo-intensity and muscle thickness, and several texture-based parameters possessed outstanding young versus older classification performance. A canonical correlation analysis demonstrated a significant relationship between ultrasound and postural measures only within the young group (r = 0.53, p < 0.002), where those with 'better' muscle composition displayed larger postural sways. Our results indicate that, in older individuals, postural stability and muscle composition, two common fall risk factors, are unrelated. In view of this decoupling, both may contribute independently to fall risk. Furthermore, our data support the view that texture-based parameters provide a robust alternative to echo-intensity in providing markers of muscle composition. [ABSTRACT FROM AUTHOR]

Muscle synergies are defined as coordinated recruitment of groups of muscles with specific activation balances and time profiles aimed at generating task-specific motor commands. While muscle synergies in postural control have been investigated primarily in reactive balance conditions, the neuromechanical contribution of muscle synergies during voluntary control of upright standing is still unclear. In this study, muscle synergies were investigated during the generation of isometric force at the trunk during the maintenance of standing posture. Participants were asked to maintain the steady-state upright standing posture while pulling forces of different magnitudes were applied at the level at the waist in eight horizontal directions. Muscle synergies were extracted by nonnegative matrix factorization from sixteen lower limb and trunk muscles. An average of 5-6 muscle synergies were sufficient to account for a wide variety of EMG waveforms associated with changes in the magnitude and direction of pulling forces. A cluster analysis partitioned the muscle synergies of the participants into a large group of clusters according to their similarity, indicating the use of a subjective combination of muscles to generate a multidirectional force vector in standing. Furthermore, we found a participant-specific distribution in the values of cosine directional tuning parameters of synergy amplitude coefficients, suggesting the existence of individual neuromechanical strategies to stabilize the whole-body posture. Our findings provide a starting point for the development of novel diagnostic tools to assess muscle coordination in postural control and lay the foundation for potential applications of muscle synergies in rehabilitation. [ABSTRACT FROM AUTHOR]

Background/Objectives: This study determined the effects of 60 min or 30 min Pilates program on cervicothoracic alignment, muscular strength, and endurance in university students with upper-crossed syndrome (UCS). Methods: Twenty-six university students with UCS were randomly allocated into 60 min Pilates (60 PG, n = 9), 30 min Pilates (30 PG, n = 9), and control (CG, n = 8) groups. The 60 and 30 PG students participated in the Pilates program, focusing on relaxation, stability, mobility, and strengthening of the cervical, thoracic, and scapular muscles for 60 or 30 min per session, twice a week, for 12 weeks. Cervicothoracic alignment was measured using BodyStyle to determine craniovertebral angle (CVA), forward shoulder angle (FSA), head position angle (HPA), head tilt angle (HTA), and kyphosis angle (KA). We measured the muscular strength and endurance of the shoulder on the dominant side. Results: After the intervention, CVA, HPA, HTA, and KA significantly improved in the 60 and 30 PG (all p < 0.01) but not in the CG (p > 0.05). There were no significant differences between the 60 and 30 PG at 4, 8, and 12 weeks. Shoulder strength differed between shoulder flexion and horizontal abduction (p < 0.01). Shoulder endurance differed between extension, flexion, and horizontal abduction (p < 0.05, p < 0.01, and p < 0.001, respectively). Conclusions: This study confirmed the effectiveness of the Pilates program in improving cervicothoracic sagittal alignment and shoulder muscular function in university students with UCS. Additionally, the effects of participating in 60 and 30 min Pilates programs were found to be equivalent. Therefore, encouraging busy university students to participate in at least 30 min of the Pilates program is important. [ABSTRACT FROM AUTHOR]

The elimination of ground reaction force (support withdrawal) vastly affects slow postural muscles in terms of their regulation and structure. One of the effects of support withdrawal in this study was an immediate postural muscle inactivation, followed by the daily gradual development of spontaneous activity of the slow postural soleus muscle in response to rat hindlimb suspension to mimic space flight. The origin of this activity is somewhat akin to muscle spasticity after spinal cord injuries and is the result of KCC2 content decline in the spinal cord's motor neurons. However, the physiological consequences of unloading-induced spontaneous activity remain unexplored. We have conducted an experiment with the administration of a highly specific KCC2 activator during 7-day unloading. For this experiment, 32 male Wistar rats were divided into 4 groups: C+placebo, C+CLP-290 (100 mg/kg b w), 7HS+placebo, and 7HS+CLP—hindlimb-suspended group with CLP-290 administration (100 mg/kg b w). The soleus muscles of the animals were dissected and analyzed for several proteostasis- and metabolism-related parameters. CLP-290 administration to the unloaded animals led to the upregulation of AMPK downstream (p-ACC) and mTOR targets (p-p70S6k and p-4E-BP) and an enhanced PGC1alpha decrease vs. the 7HS group, but neither prevented nor enhanced atrophy of the soleus muscle or myofiber CSA. [ABSTRACT FROM AUTHOR]

Introduction: Patients with chronic non-specific low back pain (CNLBP) often experience impaired postural control, contributing to pain recurrence. Although repetitive peripheral magnetic stimulation (rPMS) combined with core muscle training (CMT) could improve postural control, its neural mechanism remains unclear. This study aims to investigate the postural control-related cortical mechanism of the effect of rPMS on patients with CNLBP. Methods: This unicentric, prospective, randomized, double-blind, controlled trial was conducted in a public hospital from May to December 2023. A total of 40 patients (27 females and 13 males, mean age 29.38 ± 7.72) with CNLBP were randomly assigned to either the rPMS group (real rPMS with CMT) or the sham-rPMS group (sham-rPMS with CMT) for 12 sessions over 4 weeks. The rPMS was applied to the lumbar paravertebral multifidus muscle on the painful side. Pain and disability were quantified using the visual analog scale (VAS) and Oswestry dysfunction index (ODI) pre- and post-intervention. Furthermore, the sway area and velocity of the center of pressure (COP) were measured using a force platform. The cortical activities in 6 regions of interest during 4 tasks (standing with eyes open/closed on a stable/unstable plane) were recorded by functional near-infrared spectroscopy (fNIRS) pre- and post-intervention. The repeated measure ANOVA was applied for statistical analysis. Spearman's correlation was used to determine the relationships between variables. Results: After the intervention, the rPMS group showed decreased pain intensity (p = 0.001) and sway area (unstable eyes-closed task) (p = 0.046) compared to the sham-rPMS group. Additionally, the rPMS group exhibited increased activation in left primary motor cortex (M1) (p = 0.042) and reduced in left supplementary motor area (SMA) (p = 0.045), whereas the sham-rPMS group showed no significant changes. The increased activation of left M1 was negatively correlated to the reduction of pain intensity (r = − 0.537, p = 0.018) and sway area (r = − 0.500, p = 0.029) under the static balancing task. Furthermore, there was a positive correlation between sway velocity and VAS (r = 0.451, p = 0.046) post-rPMS intervention. Conclusion: Repetitive peripheral magnetic stimulation combined with core muscle training demonstrated better analgesic effects and postural control improvements, compared to sham-stimulation. This may be attributed to the increased activation of the left primary motor cortex. Clinical Trial Registration: The trial was registered on ClinicalTrials.gov (ChiCTR2300070943). [ABSTRACT FROM AUTHOR]

Heavy animals incur large forces on their limb bones, due to the transmission of body weight and ground reaction forces, and the contractions of the various muscles of the limbs. This is particularly true for rhinoceroses, the heaviest extant animals capable of galloping. Several studies have examined their musculoskeletal system and the forces their bones incur, but no detailed quantification has ever been attempted. Such quantification could help understand better the link between form and function in giant land animals. Here we constructed three‐dimensional musculoskeletal models of the forelimb and hindlimb of Ceratotherium simum, the heaviest extant rhino species, and used static optimisation (inverse) simulations to estimate the forces applied on the bones when standing at rest, including magnitudes and directions. Overall, unsurprisingly, the most active muscles were antigravity muscles, which generate moments opposing body weight (thereby incurring the ground reaction force), and thus keep the joints extended, avoiding joint collapse via flexion. Some muscles have an antigravity action around several joints, and thus were found to be highly active, likely specialised in body weight support (ulnaris lateralis; digital flexors). The humerus was subjected to the greatest amount of forces in terms of total magnitude; forces on the humerus furthermore came from a great variety of directions. The radius was mainly subject to high‐magnitude compressive joint reaction forces, but to little muscular tension, whereas the opposite pattern was observed for the ulna. The femur had a pattern similar to that of the humerus, and the tibia's pattern was intermediate, being subject to great compression in its caudal side but to great tension in its cranial side (i.e. bending). The fibula was subject to by far the lowest force magnitude. Overall, the forces estimated were consistent with the documented morphofunctional adaptations of C. simum's long bones, which have larger insertion areas for several muscles and a greater robusticity overall than those of lighter rhinos, likely reflecting the intense forces we estimated here. Our estimates of muscle and bone (joint) loading regimes for this giant tetrapod improve the understanding of the links between form and function in supportive tissues and could be extended to other aspects of bone morphology, such as microanatomy. [ABSTRACT FROM AUTHOR]

Balance control is essential for postural adjustment in physical activities. This study investigates the behavior of human postural control and the coordination and adaptation strategy of hip, knee, and ankle when standing on an unstable surface. Twenty participants were recruited. Four different conditions were investigated: a quiet bipedal stance with eyes open and eyes closed, and standing on an unstable surface with eyes open and eyes closed. Other than the joint angle, the standard body sway measures, such as sway area and sway velocity. were computed. A nonlinear time series measure, that is, sample entropy, was used to determine the regularity of the time series and body adaptability to change and perturbation. The results show that the body sway increases as the difficulty increases. This study also confirms the coordination of the hip. knee, and ankle to maintain body balance on the unstable surface by decreasing the joint angle and adopting a lower posture. Even though the individual joint has lower sample entropy value and is deemed to be rigid and less adaptive to perturbation, the postural control exhibits higher sample entropy value, particularly in the anteriorposterior direction, and has the ability to stabilize the body by manipulating the joints simultaneously. These outcomes suggest that an unstable surface not only challenges the human postural control. but also reduces the hip. knee, and ankle adaptability to perturbation, thus making it a great tool to train body balance. [ABSTRACT FROM AUTHOR]

White matter hyperintensities (WMH) are markers of subcortical ischemic vascular cognitive impairment (SIVCI) associated with impaired postural balance. Physical reserve (PR) is a recently established construct that reflects one's capacity to maintain physical function despite brain pathology. This cross-sectional study aims to map functional networks associated with PR, and examining the relationship between PR, WMH, and postural balance. PR was defined in 22 community-dwelling older adults with SIVCI. Functional networks of PR were computed using general linear model. Subsequent analyses examined whether PR and relevant networks moderated the relationship between WMH and postural balance under two conditions—eyes open while standing on foam (EOF) or on floor (EONF). We found that PR and the relevant networks—frontoparietal network (FPN) and default mode network (DMN)—significantly moderated the association between WMH and postural balance. For individuals with high PR, postural balance remained stable regardless of the extent of WMH load; whereas for those with low PR, postural balance worsened as WMH load increased. These results suggest the attenuated effects of WMH on postural stability due to PR may be underpinned by functional neural network reorganization in the FPN and DMN as a part of compensatory processes. [ABSTRACT FROM AUTHOR]

• Prism adaptation induces transfer after-effects of non-adapted tasks. • Cerebellar stimulation accelerated the error correction during prism exposure. • All stimulation groups had equal pointing displacements after prism exposure. • Posterior parietal cortex stimulation induced a transfer after-effect on standing. • Prism adaptation did not change the perception of the longitudinal body axis. Prism adaptation (PA) induces the after-effects of adapted tasks and transfers after-effects of non-adapted tasks, in which PA with pointing movements transfers to postural displacement during eyes-closed standing. However, the neural mechanisms underlying the transfer of PA after-effects on standing postural displacement remain unclear. The present study investigated the region-specific effects of transcranial direct current stimulation (tDCS) over the posterior parietal cortex (PPC) and cerebellum during prism exposure (PE) on standing postural displacement in healthy adults. Forty-two healthy young adults were grouped into pointing during PE with cathodal tDCS over the right PPC, anodal tDCS over the right cerebellum, and sham tDCS groups. They received 20 min of tDCS, during which they pointed to the visual targets while wearing prism lenses with a leftward visual shift (30 diopters) for 15 min. During the early PE, the pointing errors in the cerebellum group were significantly displaced more accurately toward the targets than those in the PPC group. However, after leftward PE, all groups had similar rightward displacements of the straight-ahead pointing with eyes closed. The PPC group only exhibited significant rightward center-of-pressure displacement during eyes-closed standing with feet-closed after leftward PE. The perception of longitudinal body axis rotation, as an indicator of the subjective body vertical axis, did not differ significantly between the pre- and post-evaluations in all groups. These results show that the PPC during PE could make an important neural contribution to inducing transfer of PA after-effect on standing postural displacement. [ABSTRACT FROM AUTHOR]

Both the primary motor cortex (M1) and the cerebellum are crucial for postural stability and deemed as potential targets for non‐invasive brain stimulation (NIBS) to enhance balance performance. However, the optimal target remains unknown. The purpose of this study was to compare the role of M1 and the cerebellum in modulating balance performance in young healthy adults using facilitatory 5 Hz repetitive transcranial magnetic stimulation (rTMS). Twenty‐one healthy young adults (mean age = 27.95 ± 1.15 years) received a single session of 5 Hz rTMS on M1 and the cerebellum in a cross‐over order with a 7‐day washout period between the two sessions. Three balance assessments were performed on the Biodex Balance system SD: Limits of Stability (LOS), modified Clinical Test of Sensory Interaction on Balance (mCTSIB), and Balance Error Scoring System (BESS). No significant effect of rTMS was found on the LOS. The effect of rTMS on the mCTSIB was mediated by stimulation target, proprioception, and vision (p =.003, ηp2 = 0.37). Cerebellar rTMS improved the mCTSIB sway index under eyes closed‐foam surface condition (p =.02), whereas M1 rTMS did not result in improvement on the mCTSIB. The effect of rTMS on the BESS was mediated by stimulation target, posture, and proprioception (p =.049, ηp2 = 0.14). Cerebellar rTMS enhanced reactive balance performance during most sensory deprived conditions. [ABSTRACT FROM AUTHOR]

Objective: This study explored the impact of one session of low-pressure leg blood flow restriction (BFR) during treadmill walking on dual-task performance in older adults using the neurovisceral integration model framework. Methods: Twenty-seven older adults participated in 20-min treadmill sessions, either with BFR (100 mmHg cuff pressure on both thighs) or without it (NBFR). Dual-task performance, measured through light-pod tapping while standing on foam, and heart rate variability during treadmill walking were compared. Results: Following BFR treadmill walking, the reaction time (p = 0.002) and sway area (p = 0.012) of the posture dual-task were significantly reduced. Participants exhibited a lower mean heart rate (p < 0.001) and higher heart rate variability (p = 0.038) during BFR treadmill walking. Notably, BFR also led to band-specific reductions in regional brain activities (theta, alpha, and beta bands, p < 0.05). The topology of the EEG network in the theta and alpha bands became more star-like in the post-test after BFR treadmill walking (p < 0.005). Conclusion: BFR treadmill walking improves dual-task performance in older adults via vagally-mediated network integration with superior neural economy. This approach has the potential to prevent age-related falls by promoting cognitive reserves. [ABSTRACT FROM AUTHOR]

AbstractPurposeMethodResultsConclusionsRCT registration numberRegistration date\nIMPLICATIONS FOR REHABILITATIONTo investigate the effects of concurrent sensorimotor training (SMT) and transcranial direct current stimulation (tDCS) on the anticipatory and compensatory postural adjustments (APAs and CPAs) in patients with chronic low back pain (CLBP).The interventions included (1) SMT plus tDCS and (2) SMT plus sham tDCS. Outcome measures were the normalized integrals of electromyography activity (NIEMG) during the phases of anticipatory and compensatory, and muscle onset latency. The investigated muscles were ipsilateral and contralateral multifidus (MF), transversus abdominus/internal oblique (TrA/IO), and gluteus medius (GM).Between-group comparisons demonstrated that ipsilateral TrA/IO NIEMG during CPA1 (p = 0.010) and ipsilateral GM NIEMG during CPA1 (p = 0.002) and CPA2 (p = 0.025) were significantly lower in the SMT combined with tDCS than in the control group. Furthermore, this group had greater NIEMG for contralateral GM during APA1 than the control group (p = 0.032). Moreover, the onset latency of contralateral TrA/IO was significantly earlier after SMT combined with tDCS (p = 0.011).Both groups that received SMT showed positive effects, but anodal tDCS had an added value over sham stimulation for improving postural control strategies in patients with CLBP. Indeed, SMT combined with tDCS leads to stronger APA and less demand for CPA.IRCT20220228054149N12022-04-04Evidence suggests that reduced excitability in the sensory and motor cortex is linked to chronic and recurring lower back pain.Increasing the excitability of these two areas using anodal transcranial direct current stimulation (tDCS), in conjunction with sensorimotor training (SMT), may improve anticipatory and compensatory postural control strategies.This study showed that the combination of SMT with tDCS targeting the sensory and motor cortex notably enhances motor preparation and refines postural control strategies in patients with chronic unilateral lumbar radiculopathy.Rehabilitation professionals are encouraged to integrate SMT with tDCS into treatment protocols to enhance the ability of individuals with back pain to handle postural disturbances in daily life, thereby potentially alleviating the persistence of their symptoms.Incorporating brain stimulation enhances the effectiveness of SMT for patients with chronic unilateral lumbar radiculopathy.Evidence suggests that reduced excitability in the sensory and motor cortex is linked to chronic and recurring lower back pain.Increasing the excitability of these two areas using anodal transcranial direct current stimulation (tDCS), in conjunction with sensorimotor training (SMT), may improve anticipatory and compensatory postural control strategies.This study showed that the combination of SMT with tDCS targeting the sensory and motor cortex notably enhances motor preparation and refines postural control strategies in patients with chronic unilateral lumbar radiculopathy.Rehabilitation professionals are encouraged to integrate SMT with tDCS into treatment protocols to enhance the ability of individuals with back pain to handle postural disturbances in daily life, thereby potentially alleviating the persistence of their symptoms.Incorporating brain stimulation enhances the effectiveness of SMT for patients with chronic unilateral lumbar radiculopathy. [ABSTRACT FROM AUTHOR]

Purpose: The short external rotator muscles (SERMs) of the hip are composed of six postural muscles that constitute a single functional unit that is aligned to coapt the articular surfaces of the hip joint, providing dynamic stability. This study aims to provide a morphometric evaluation of this unit that could benefice clinical practice. In particular, the implication of the morphology and direction of the hip triceps tendon when performing a posterolateral approach for total hip arthroplasty. Methods: A total of 18 cadaveric hips were dissected rigorously. Variations of the origin, course and insertion of all SERMs were recorded and quantified. Measurements were conducted for the following parameters: total muscle lengths, intra-muscular and extra-muscular tendon lengths, muscle sagittal and frontal angles, and femoral neck length. Correlation was searched for between total muscle length and femoral neck length. Results: Results were as follows: (a) the obturator internus and externus muscles insert quasi perpendicularly on the proximal femur, (b) both gemelli take distal insertion onto the tendon of the obturator internus to form the hip triceps tendon, (c) morphometric data of the studied parameters was reported, and (d) moderate to high correlation with femoral neck length was found for all muscles but the quadratus femoris. Conclusion: Our results showed that the direction of the hip triceps tendon is always orthogonal to the proximal femur in the frontal plane. Such anatomical reference could be used when performing total hip arthroplasty with the posterolateral approach. Future research is needed to assess whether the easy identification and re-insertion of the hip triceps could reduce leg length discrepancy and offset. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Virtual reality (VR) holds promise for stroke rehabilitation. However, many existing VR systems requires users to stand while playing, posing a potential falling risk for stroke patients. This study investigated the effects of a custom-developed VR system that focus on trunk rehabilitation in stable sitting position on muscle activities, postural control, and physiological cost compared to conventional trunk exercises in stroke patients. MATERIALS AND METHODS: A cross-sectional observational pilot study was conducted involving 12 paretic stroke subjects performing four exercises: two Conventional Trunk Exercises (CTE) and two VR-based Trunk Exercises (VRTE) using customized Tilt-The-Maze (self-paced) or Catch-The-Mole (game-paced) games. Muscle activity was measured using electromyography (EMG). Postural control data in the Anterior-Posterior (AP) and Medio-Lateral (ML) axes was recorded using a force plate, while the physiological cost was measured via a heart rate sensor during the exercises. RESULTS: The results indicated low muscle activity and light -intensity cardiovascular responses in all CTE and VRTE exercises. Game-paced VRTE recorded slightly higher Center of Pressure (CoP) velocity in the AP and ML axes versus CTE (AP:4.40±1.80 vs. 4.02±1.20 cm/s; ML:6.40±2.54 vs. 5.42±2.21 cm/s). In contrast, the self-paced VRTE showed an insignificant impact on postural control than both CTE and game-paced VRTE. CONCLUSION: The game-paced VRTE induced comparable effects on muscular activation, postural control, and physiological cost to that of CTE in stroke patients. The findings suggest the stable-sitting VR system as a supplementary approach to the existing trunk rehabilitation protocols for stroke patients. [ABSTRACT FROM AUTHOR]

Many children with physical disabilities need additional postural support when sitting and supplementary padding is used on standards approved child restraints to achieve this when traveling in a motor vehicle. However, the effect of this padding on crash protection for a child is unknown. This study aimed to investigate the effect of additional padding for postural support on crash protection for child occupants in forward facing child restraints. Forty frontal sled tests at 49 km/h were conducted to compare Q1 anthropometric test device (ATD) responses in a forward-facing restraint, with and without additional padding in locations to increase recline of the restraint, and/or support the head, trunk and pelvis. Three padding materials were tested: cloth toweling, soft foam, and expanded polystyrene (EPS). The influence of padding on head excursion, peak 3 ms head acceleration, HIC15, peak 3 ms chest acceleration and chest deflection were analyzed. The influence of padding varied depending on the location of use. Padding used under the restraint to increase the recline angle increased head injury metrics. Toweling in multiple locations which included behind the head increased head excursion and chest injury metrics. There was minimal effect on injury risk measures with additional padding to support the sides of the head or the pelvis position. Rigid EPS foam, as recommended in Australian standards and guidelines, had minimal effect on injury metrics when used inside the restraint, as did tightly rolled or folded toweling secured to the restraint at single locations around the body of the child. This study does not support the use of postural support padding to increase recline of a forward-facing restraint or padding behind the head. Recommendations in published standards and guidelines to not use foam that is spongy, soft or easily compressed, with preference for secured firm foam or short-term use of tightly rolled or folded toweling under the child restraint cover is supported. This study also highlights the importance of considering the whole context of child occupant protection when using additional padding, particularly the change in the child's seated position when adding padding in relation to the standard safety features of the restraint. [ABSTRACT FROM AUTHOR]

Introduction: Although sloped surfaces are common in daily living, most studies of body balance are carried out on flat surfaces, and few data are available for sloping angles below 14°. Objectives: The purpose of this study was to explore the effect of forward and backward sloping surfaces at 7° and 15° on postural equilibrium and the activity of flexor/extensor ankle muscles. Methods: Fifteen healthy subjects (8 males and 7 females) (27.67 ± 3.9 years) underwent a posturographic examination associated with a surface electromyogram (EMG) of tibialis anterior (TA), soleus (Sol) and gastrocnemius medialis (GasM) under five conditions of support inclination: 0° (H0), backward inclination at 7° and 15° (DF7 and DF15), forward inclination at 7° and 15° (PF7 and PF15). Results: Results showed that the center of pressure (CP) was shifted according to the surface slope, with a forward move in PF7 (p <0.001) and PF15 (p <0.001) and a backward move in DF7 (p <0.01) and in DF15 (p <0.001). The mean displacement of the CP along the anterior-posterior axis (Xm) was increased in DF15 (p <0.01) relative to the H0 condition but reduced in PF7 (p <0.01). The normalized EMG revealed higher values when the muscles were in a shortened position (PF7 for Sol, p <0.05; PF15 for GasM, p <0.01; DF15 for TA, p<0.01) and lower values of GasM and Sol when lengthened (DF15, p <0.05). Conclusion: Our findings indicate that standing on a backward sloped surface impairs body balance, while low-angle forward sloped surfaces might improve postural stability. Muscular activity variations of the ankle flexors/extensors, which are stretched or shortened, also seem to be related to the length-tension relationship of skeletal muscles. [ABSTRACT FROM AUTHOR]

Background: Maintaining static balance is relevant and common in everyday life and it depends on a correct intersegmental coordination. A change or reduction in postural capacity has been linked to increased risk of falls. People with Parkinson's disease (pwPD) experience motor symptoms affecting the maintenance of a stable posture. The aim of the study is to understand the intersegmental changes in postural sway and to apply a trend change analysis to uncover different movement strategies between pwPD and healthy adults. Methods: In total, 61 healthy participants, 40 young (YO), 21 old participants (OP), and 29 pwPD (13 during medication off, PDoff; 23 during medication on, PDon) were included. Participants stood quietly for 10 s as part of the Short Physical Performance Battery. Inertial measurement units (IMU) at the head, sternum, and lumbar region were used to extract postural parameters and a trend change analysis (TCA) was performed to compare between groups. Objective: This study aims to explore the potential application of TCA for the assessment of postural stability using IMUs, and secondly, to employ this analysis within the context of neurological diseases, specifically Parkinson's disease. Results: Comparison of sensors locations revealed significant differences between head, sternum and pelvis for almost all parameters and cohorts. When comparing PDon and PDoff, the TCA revealed differences that were not seen by any other parameter. Conclusions: While all parameters could differentiate between sensor locations, no group differences could be uncovered except for the TCA that allowed to distinguish between the PD on/off. The potential of the TCA to assess disease progression, response to treatment or even the prodromal PD phase should be explored in future studies. Trial registration: The research procedure was approved by the ethical committee of the Medical Faculty of Kiel University (D438/18). The study is registered in the German Clinical Trials Register (DRKS00022998). [ABSTRACT FROM AUTHOR]

Introduction: Upper Cross Syndrome is a pattern of muscle imbalance and postural dysfunction that can cause discomfort and pain. This study's objective was to compare the effects of Pilates exercises, corrective exercises, and Alexander's technique on upper cross syndrome in adolescent girls aged 13–16 years: a six-week intervention study. Methods: The present study was Quasi-experimental, and its statistical population consisted of 13 to 16-year-old female students. Forty-five students who were diagnosed with upper cross syndrome were purposefully selected as samples and randomly assigned to three groups: Pilates exercises (N = 15), corrective exercises (N = 15), and Alexander's technique (N = 15). The participants performed exercises for 60 min per session, three sessions per week, and six weeks. This study's objective was to compare the effects of Pilates exercises, corrective exercises, and Alexander's technique on upper cross syndrome in adolescent girls aged 13–16 years: a six-week intervention study. This study was retrospectively registered in the Iranian Registry of Clinical Trials (IRCT) on 2023-09-19 to comply with the journal's policies. The assigned trial registration number is IRCT20230810059106N1. Results: The results of the dependent t-test showed significant decreases in forward head angle (p = 0.0001), rounded shoulder (p = 0.001), and kyphosis (p = 0.0001) as a result of corrective exercises. There were also significant decreases in forward head angle (p = 0.0001), rounded shoulder (p = 0.002), and kyphosis (p = 0.001) after six weeks of practising Alexander's technique. However, in the case of Pilates exercises, a significant decrease in forward head angle (p = 0.110), rounded shoulder (p = 0.598), and kyphosis (p = 0.371) was not observed. The one-way analysis of variance revealed a significant difference in the forward head angle (p = 0.012), rounded shoulders (p = 0.013), and kyphosis (p = 0.009). Conclusions: The effect of Alexander's technique and corrective exercises on forward head angle, rounded shoulder, and kyphosis abnormalities was almost similar and more effective than pilates exercises. [ABSTRACT FROM AUTHOR]

Background: Sensory information obtained from the visual, somatosensory, and vestibular systems is responsible for regulating postural control, and if damage occurs in one or more of these sensory systems, postural control may be altered. Objective: To evaluate and compare the postural sway velocity between children with normal hearing and with sensorineural hearing loss (SNHL), matched by sex and age group, and to compare the postural sway velocity between children with normal hearing and with SNHL, with and without vestibular dysfunction. Methods: Cross-sectional study that evaluated 130 children (65 with normal hearing and 65 with SNHL), of both sexes and aged between 7 and 11 years, from public schools of the city of Caruaru, Pernambuco state, Brazil. The postural sway velocity of the center of pressure (COP) was assessed by a force platform, in two directions, anteroposterior (AP) and mediolateral (ML)), in three positions, namely bipedal support with feet together and parallel (parallel feet (PF)), bipedal support with one foot in front of the other (tandem foot (TF)), and single-leg support (one foot (OF)), evaluated with the eyes open and closed. Results: Children with SNHL demonstrated greater postural sway velocity compared to children with normal hearing in all the positions evaluated, with significant differences in the AP direction, with the eyes open (PF: p = 0.001; TF: p = 0.000; OF: p = 0.003) and closed (PF: p = 0.050; TF: p = 0.005). The same occurred in the ML direction, with the eyes open (PF: p = 0.001; TF: p = 0.000; OF: p = 0.001) and closed (PF: p = 0.002; TF: p = 0.000). The same occurred in relation to vestibular function, where the children with SNHL with an associated vestibular dysfunction demonstrated greater postural sway velocity compared to children with normal hearing in all the positions evaluated, demonstrating significant differences in the AP direction, with the eyes open (TF: p = 0.001; OF: p = 0.029) and eyes closed (PF: p = 0.036; TF: p = 0.033). The same occurred in the ML direction, with the eyes open (TF: p = 0.000) and with the eyes closed (PF: p = 0.008; TF: p = 0.009). Conclusions: Children with SNHL demonstrated greater instability of postural control than children with normal hearing in all the directions assessed. Children with SNHL and an associated vestibular dysfunction demonstrated the greatest instability of postural control in this study. [ABSTRACT FROM AUTHOR]

During skeletal muscle development, the intricate mitochondrial network formation relies on continuous fission and fusion. This process in larger mammals differs from rodents, the most used animal models. However, the expression pattern of proteins regulating mitochondrial dynamics in developing skeletal muscle remains unexplored in larger mammals. Therefore, we characterized the cellular expression and tissue‐level distribution of these proteins during development taking goat as a model. We have performed histological and immunohistochemical analyses to study metabolic features in various muscles. Neonatal muscles display uniform distribution of mitochondrial activity. In contrast, adult muscles exhibit clear distinctions based on their function, whether dedicated for posture maintenance or facilitating locomotion. Mitochondrial fission proteins like DRP‐1, MFF, and fusion proteins like MFN‐1 and 2 are abundantly expressed in neonatal muscles. Fission proteins exhibit drastic downregulation with limited peripheral expression, whereas fusion proteins continue to express in a fiber‐specific manner during adulthood. Locomotory muscles exhibit different fibers based on mitochondrial activity and peripheralization with high SDH activity. The proximity ligation assay between MFN1 and MFN2 demonstrates that their interaction is restricted to subsarcolemmal mitochondria in adult fibers while distributed evenly in neonatal fibers. These differences between postural and locomotory muscles suggest their physiological and metabolic properties are different. [ABSTRACT FROM AUTHOR]

Although recent studies in nonhuman primates have provided evidence that transcranial magnetic stimulation (TMS) activates cells within the reticular formation, it remains unclear whether descending brain stem projections contribute to the generation of TMS-induced motor evoked potentials (MEPs) in skeletal muscles. We compared MEPs in muscles with extensive direct corticomotoneuronal input (first dorsal interosseous) versus a prominent role in postural control (gastrocnemius) to determine whether the amplitudes of early and late MEPs were differentially modulated by cortical suppression. Suprathreshold TMS was applied with and without a preceding suprathreshold TMS pulse at two interstimulus intervals (50 and 80 ms). H reflexes in target muscles were also tested with and without TMS conditioning. Early and late gastrocnemius MEPs were differentially modulated by cortical inhibition, the amplitude of the early MEP being significantly reduced by cortical suppression and the late MEP facilitated. The amplitude of H reflexes in the gastrocnemius was reduced within the cortical silent period. Early MEPs in the first dorsal interosseous were also reduced during the silent period, but late MEPs were unaffected. Independent modulation of early and late MEPs in the gastrocnemius muscle supports the idea that the MEP is generated by multiple descending pathways. Suppression of the early MEP is consistent with transmission along the fast-conducting corticospinal tract, whereas facilitation of the late MEP suggests transmission along a corticofugal, potentially cortico-reticulospinal, pathway. Accordingly, differences in late MEP modulation between the first dorsal interosseous and gastrocnemius reflect an increased role of corticofugal pathways in the control of postural muscles. NEW & NOTEWORTHY: Early and late portions of the response to transcranial magnetic stimulation (TMS) in a lower limb postural muscle are modulated independently by cortical suppression, late motor evoked potentials (MEPs) being facilitated during cortical inhibition. These results suggest a cortico-brain stem transmission pathway for late portions of the TMS-induced MEP. [ABSTRACT FROM AUTHOR]

Acute exposure to hypoxia increases postural sway, but the underlying neurophysiological factors are unclear. Golgi tendon organs (GTOs), located within the musculotendinous junction (MTJ), provide inhibitory signals to plantar flexor muscles that are important for balance control; however, it is uncertain if GTO function is influenced by hypoxia. The aim of this study was to determine how normobaric hypoxia influences lower limb tendon-evoked inhibitory reflexes during upright stance. We hypothesized that tendon-evoked reflex area and duration would decrease during hypoxia, indicating less inhibition of postural muscles compared with normoxia. At baseline (BL; 0.21 fraction of inspired oxygen, FIO2) and at ∼2 (H2) and 4 (H4) h of normobaric hypoxia (0.11 FIO2) in a normobaric hypoxic chamber, 16 healthy participants received electrical musculotendinous stimulation (MTstim) to the MTJ of the left Achilles tendon. The MTstim was delivered as two sets of 50 stimuli while the participant stood on a force plate with their feet together. Tendon-evoked inhibitory reflexes were recorded from the surface electromyogram of the ipsilateral medial gastrocnemius, and center of pressure (CoP) variables were recorded from the force plate. Normobaric hypoxia increased CoP velocity (P ≤ 0.002) but not CoP standard deviation (P ≥ 0.12). Compared with BL, normobaric hypoxia reduced tendon-evoked inhibitory reflex area by 45% at H2 and 53% at H4 (P ≤ 0.002). In contrast, reflex duration was unchanged during hypoxia. The reduced inhibitory feedback from the GTO pathway could likely play a role in the increased postural sway observed during acute exposure to hypoxia. NEW & NOTEWORTHY: The Ib pathway arising from the Golgi tendon organ provides inhibitory signals onto motor neuron pools that modifies force and, hence, postural control. Although hypoxia influences standing balance (increases sway), the underlying mechanisms have yet to be unraveled. Our study identified that tendon-evoked inhibition onto a plantar flexor motoneuron pool is reduced by acute exposure to normobaric hypoxia. This reduction of inhibition may contribute to the hypoxia-related increase in postural sway. [ABSTRACT FROM AUTHOR]

Introduction: The risk of falls among the elderly significantly increases, which has become a serious public health concern. Falls can not only lead to serious complications such as fractures and brain injuries but also limit their mobility function, reducing quality of life. Foot intrinsic muscles (FIMs) are an essential part of foot core stability even overall postural stability. This study aimed to investigate the effects of aging on the function of FIMs and to explore the influence of FIMs on postural control in the elderly. Materials and Methods: 56 healthy old participants (60– 75 years) and 57 healthy young participants (18– 29 years) joined this study. An ergoFet dynamometer was used to determine foot muscle strength (Doming, T1, T23 and T2345), and ankle muscle strength (plantarflexion and dorsiflexion). The morphology of FIMs and extrinsic foot muscle was determined using a Doppler ultrasound system, whereas the postural stability was assessed through Limits of Stability test. Independent samples t-test was used to determine the differences in strength and morphological parameters and Spearman correlation analysis was used to determine whether an association existed between muscle strength and postural stability parameters in the elderly. Results: Compared with young adults, foot muscle strength and ankle muscle strength (Doming, T1, T23, T2345, dorsiflexion, and plantarflexion, all p < 0.05) and the morphology of foot muscles (all p < 0.05) were significantly reduced in the elderly. The strength of FIMs and the limit of stability (r = 0.302– 0.424, all p < 0.05) were significantly correlated in the elderly. Conclusion: Compared with young adults, the weakness of strength as well as the morphological decline of the intrinsic and extrinsic foot muscles were found in the elderly. In addition, a correlation was observed between FIM's strength and postural stability in the elderly, suggesting their potential role in posture stability. [ABSTRACT FROM AUTHOR]

Background: Abnormal gait is prevalent among the elderly population, leading to reduced physical activity, increased risk of falls, and the potential development of dementia and disabilities, thus degrading the quality of life in later years. Numerous studies have highlighted the crucial roles of lower limb muscle strength asymmetry and static postural control in gait, and the reciprocal influence of lower limb muscle strength asymmetry on static postural control. However, research exploring the interrelationship between lower limb muscle strength asymmetry, static postural control, and gait performance has been limited. Methods: A total of 55 elderly participants aged 60 to 75 years were recruited. Isokinetic muscle strength testing was used to assess bilateral knee extension strength, and asymmetry values were calculated. Participants with asymmetry greater than 15% were categorized as the Asymmetry Group (AG), while those with asymmetry less than 15% were classified in the Symmetry Group (SG). Gait parameters were measured using a plantar pressure gait analysis system to evaluate gait performance, and static postural control was assessed through comfortable and narrow stance tests. Results: First, participants in the AG demonstrated inferior gait performance, characterized by slower gait speed, longer stance time and percentage of stance time in gait, and smaller swing time and percentage of swing time in gait. Spatial-temporal gait parameters of the weaker limb tended to be abnormal. Second, static postural control indices were higher in AG compared to SG in all aspects except for the area of ellipse during the comfortable stance with eyes open test. Third, abnormal gait parameters were associated with static postural control. Conclusion: Firstly, elderly individuals with lower limb muscle strength asymmetry are prone to abnormal gait, with the weaker limb exhibiting poorer gait performance. Secondly, lower limb muscle strength asymmetry contributes to diminished static postural control in the elderly. Thirdly, the mechanism underlying abnormal gait in the elderly due to lower limb muscle strength asymmetry may be linked to a decline in static postural control. [ABSTRACT FROM AUTHOR]

Background: Running economy, commonly defined as the metabolic energy demand for a given submaximal running speed, is strongly associated with distance running performance. It is commonly believed among running coaches and runners that running with increased forward postural lean either from the ankle or waist improves running economy. However, recent biomechanical research suggests using a large forward postural lean during running may impair running economy due to increased demand on the leg muscles. Purpose: This study tests the effect of altering forward postural lean and lean strategy on running economy, kinematics, and muscle activity. Methods: 16 healthy young adult runners (23±5 years, 8M/8F) ran on a motorized treadmill at 3.58m/s using three postural lean angles [upright, moderate lean (50% of maximal lean angle), and maximal lean] and two strategies (lean from ankle and lean from waist [trunk lean]). Metabolic energy consumption, leg kinematics, and muscle activation data were recorded for all trials. Results: Regardless of lean strategy, running with an increased forward postural lean (up to 8±2 degrees) increased metabolic cost (worsened economy) by 8% (p <.001), increased hip flexion (p <.001), and increased gluteus maximus (p =.016) and biceps femoris (p =.02) muscle activation during the stance phase. This relation between running economy and postural lean angle was similar between the ankle and trunk lean strategies (p =.743). Conclusion: Running with a large forward postural lean reduced running economy and increased reliance on less efficient extensor leg muscles. In contrast, running with a more upright or moderate forward postural lean may be more energetically optimal, and lead to improved running performance. [ABSTRACT FROM AUTHOR]

Background: Stand-to-sit (StandTS) is an important daily activity widely used in rehabilitation settings to improve strength, postural stability, and mobility. Modifications in movement smoothness and speed significantly influence the kinematics, kinetics, and muscle activation patterns of the movement. Understanding the impact of StandTS speed and smoothness on movement control can provide valuable insights for designing effective and personalized rehabilitation training programs. Research question: How do the smoothness and speed of StandTS movement affect joint kinematics, kinetics, muscle activation patterns, and postural stability during StandTS? Methods: Twelve healthy younger adults participated in this study. There were two StandTS conditions. In the reference condition, participants stood in an upright position with their feet positioned shoulder-width apart on the force plate. Upon receiving a visual cue, participants performed StandTS at their preferred speed. In the smooth condition, participants were instructed to perform StandTS as smoothly as possible, aiming to minimize contact pressure on the seat. Lower leg kinetics, kinematics, and coordination patterns of muscle activation during StandTS were measured: (1) angular displacement of the trunk, knee, and hip flexion; (2) knee and hip extensor eccentric work; (3) muscle synergy pattern derived from electromyography (EMG) activity of the leg muscles; and (4) postural sway in the anterior--posterior (A-P), medio-lateral (M-L), and vertical directions. Results: Compared to the reference condition, the smooth condition demonstrated greater eccentric knee extensor flexion and increased joint work in both the knee and hip joints. Analysis of specific muscle synergy from EMG activity revealed a significant increase in the relative contribution of hip joint muscles during the smooth condition. Additionally, a negative correlation was observed between knee extensor and vertical postural sway, as well as hip extensor work and M-L postural sway. Conclusion: Smooth StandTS facilitates enhanced knee eccentric control and increased joint work at both the hip and knee joints, along with increased involvement of hip joint muscles to effectively manage falling momentum during StandTS. Furthermore, the increased contributions of knee and hip joint work reduced postural sway in the vertical and M-L directions, respectively. These findings provide valuable insights for the development of targeted StandTS rehabilitation training. [ABSTRACT FROM AUTHOR]

Human postural control system is inherently complex with nonlinear interaction among multiple subsystems. Accordingly, such postural control system has the flexibility in adaptation to complex environments. Previous studies applied complexity-based methods to analyze center of pressure (COP) to explore nonlinear dynamics of postural sway under changing environments, but direct evidence from central nervous system or muscular system is limited in the existing literature. Therefore, we assessed the fractal dimension of COP, surface electromyographic (sEMG) and electroencephalogram (EEG) signals under visual-vestibular habituation balance practice. We combined a rotating platform and a virtual reality headset to present visual-vestibular congruent or incongruent conditions. We asked participants to undergo repeated exposure to either congruent (n = 14) or incongruent condition (n = 13) five times while maintaining balance. We found repeated practice under both congruent and incongruent conditions increased the complexity of high-frequency (0.5--20 Hz) component of COP data and the complexity of sEMG data from tibialis anterior muscle. In contrast, repeated practice under conflicts decreased the complexity of low-frequency (<0.5 Hz) component of COP data and the complexity of EEG data of parietal and occipital lobes, while repeated practice under congruent environment decreased the complexity of EEG data of parietal and temporal lobes. These results suggested nonlinear dynamics of cortical activity differed after balance practice under congruent and incongruent environments. Also, we found a positive correlation (1) between the complexity of high-frequency component of COP and the complexity of sEMG signals from calf muscles, and (2) between the complexity of low-frequency component of COP and the complexity of EEG signals. These results suggested the low- or high-component of COP might be related to central or muscular adjustment of postural control, respectively. [ABSTRACT FROM AUTHOR]

To evaluate the effects of a 12-week injury prevention program on the isokinetic performance of knee extensor and flexor muscles and postural control in young indoor soccer athletes. Twelve athletes (23.14 ± 4.37 years) were included and assessed before and after the intervention. Muscle strength was assessed using the isokinetic dynamometer (Biodex System Pro 4), and postural control was assessed using posturography dynamics (EquiTest® System) and sensory organization tests (TOS). This parameter was divided into six conditions that analyzed systems responsible for maintaining balance (visual, vestibular, and somatosensory). The isokinetic performance improved after the intervention, especially in peak torque and thallus flexors power, as well as postural control (TOS) in conditions III and VI. Thus, the improvement observed in these parameters after intervention may reduce the risk of lesions in indoor soccer athletes. [ABSTRACT FROM AUTHOR]

Fatigue and balance disorders are common challenges experienced by Multiple Sclerosis (MS) individuals. The purpose of this study was to compare the concurrent effects of cerebellar and prefrontal anodal trans-cranial direct current stimulation (a-tDCS) with postural training on balance and fatigue in MS patients. 51 patients were evaluated to randomly allocation to a-tDCS over cerebellum, a-tDCS over dorsolateral prefrontal cortex (DLPFC) and sham group. 46 individuals (n = 16 in experimental groups and n = 14 in control group) followed treatment. All the groups received 10 sessions of postural training. The experimental groups underwent a-tDCS with a current of 1.5 mA for a period of 20 min. While, in the sham group, tDCS was only activated for 30 s and then turned off. The treatment included 10 sessions for four weeks. Before and after intervention, fatigue and balance were assessed using Fatigue Severity Scale (FSS), Timed Up and Go (TUG) test and Berg Balance Score (BBS), respectively. There was found a significant reduction in fatigue in the group receiving a-tDCS over the prefrontal cortex with postural training compared to the other two groups (P < 0.001). Additionally, a significant improvement was found in balance in the group receiving a-tDCS over the cerebellum concurrent with postural training in comparison to the other two groups (P < 0.001). Besides, in the sham group, the significant results were not reported in the variables. (P > 0.001). The results demonstrated that a-tDCS enhances the effects of postural training on balance and fatigue in MS patients. [ABSTRACT FROM AUTHOR]

Introduction: Anthropometric assessments, muscle strength, range of motion, and postural stability are integral part of pre-competition medical assessments (PCMA). However, there is limited understanding of the association of this assessment with regard to postural stability. Postural stability performance is crucial, not only for injury prevention, but also athlete’s performance. Thus, the aim is to examine the association of anthropometric, lower limb strength, and lower limb range of motion with single leg stability test. Methods: A prospective cross-sectional study examining 83 Malaysian footballers who came for PCMA at Sports Medicine clinic, University Malaya Medical Centre, underwent extensive musculoskeletal examinations, including anthropometric assessments using body impedance analysis, isometric muscle strength testing using handheld dynamometer, lower limb range of motion assessments using goniometer, and single leg stability test using Biodex. Results: Dominant leg demonstrated a higher mean knee flexor (216 ± 43.6 newton), ankle extensor (179.6 ± 54.4 newton) and lower limb strength index (1219.1 ± 241.9 newton), and has lower overall stability index (1.36 ± 0.45) compared to non-dominant leg (1.26 ± 0.37). Body mass index (BMI) and skeletal muscle mass showed a significant correlation with overall stability index, both in dominant and non-dominant legs. There is no significant correlation seen between muscle strength, and lower limb joint range motion with postural stability. Conclusion: This study demonstrated that anthropometric, lower limb strength, range of motion of lower limb and lower limb postural stability are independent of each other. [ABSTRACT FROM AUTHOR]

In everyday life, we recurrently perform two tasks simultaneously, which is called dual-tasking. A common dual task is smartphone use while standing or walking. According to previous studies, this task can compromise postural stability. However, few studies have analyzed lower limb muscle activity during dual-tasking using smartphones. This study aimed to assess the postural sway and muscle activity during dual-tasking in young adults. Thirty-six healthy young adults (23.08 ± 3.92 years) participated in this study. They performed a single task (ST: keeping a quiet standing posture) and a dual task (DT: keeping the ST while simultaneously performing a cognitive task on their smartphone). Postural sway was assessed through the center of pressure (CoP) analysis using a force platform: total CoP displacement, CoP displacement in the anterior–posterior and medial–lateral directions, mean total velocity of the CoP, mean velocity of the CoP in the anterior–posterior and medial–lateral directions, and 95% confidence ellipse sway area. A surface electromyography system recorded the muscle activity of the lumbar spinal erector and five muscles of the lower limb (bilaterally). The results showed an increase in postural sway from the ST to the DT in all CoP variables (p < 0.05), and muscle activity in most muscles analyzed decreased from the ST to the DT (p < 0.05). In conclusion, our results reflect a decentralization of attention from motor performance once postural sway increased and muscle activity decreased in dual-task conditions. [ABSTRACT FROM AUTHOR]

Spinal cord epidural stimulation can promote the recovery of motor function in individuals with severe spinal cord injury (SCI) by enabling the spinal circuitry to interpret sensory information and generate related neuromuscular responses. This approach enables the spinal cord to generate lower limb extension patterns during weight bearing, allowing individuals with SCI to achieve upright standing. We have shown that the human spinal cord can generate some standing postural responses during self-initiated body weight shifting. In this study, we investigated the ability of individuals with motor complete SCI receiving epidural stimulation to generate standing reactive postural responses after external perturbations were applied at the trunk. A cable-driven robotic device was used to provide constant assistance for pelvic control and to deliver precise trunk perturbations while participants used their hands to grasp onto handlebars for self-balance support (hands-on) as well as when participants were without support (free-hands). Five individuals with motor complete SCI receiving lumbosacral spinal cord epidural stimulation parameters specific for standing (Stand-scES) participated in this study. Trunk perturbations (average magnitude: 17 ± 3% body weight) were delivered randomly in the four cardinal directions. Participants attempted to control each perturbation such that upright standing was maintained and no additional external assistance was needed. Lower limb postural responses were generally more frequent, larger in magnitude, and appropriately modulated during the free-hands condition. This was associated with trunk displacement and lower limb loading modulation that were larger in the free-hands condition. Further, we observed discernible lower limb muscle synergies that were similar between the two perturbed standing conditions. These findings suggest that the human spinal circuitry involved in postural control retains the ability to generate meaningful lower limb postural responses after SCI when its excitability is properly modulated. Moreover, lower limb postural responses appear enhanced by a standing environment without upper limb stabilization that promotes afferent inputs associated with a larger modulation of ground reaction forces and trunk kinematics. These findings should be considered when developing future experimental frameworks aimed at studying upright postural control and activity-based recovery training protocols aimed at promoting neural plasticity and sensory-motor recovery. [ABSTRACT FROM AUTHOR]

Simple Summary: Laminitis is a significant cause of horse mortality and it profoundly impacts the distal locomotor apparatus, causing intense pain primarily in the thoracic limbs. Affected horses exhibit a characteristic arched back and flexed thoracolumbar spinal posture. To the authors' knowledge, there are no studies investigating the relationship between chronic laminitis and thoracolumbar spine injuries. The aim of this study was to investigate the occurrence and severity of injuries in the thoracolumbar spine of horses and the association with (n = 30) or without (n = 30) chronic laminitis. We developed a clinical-assessment method for the equine thoracolumbar spine, along with the equine Grimace Scale for pain assessment and ultrasound scans. The results indicated a significant association between chronic laminitis and thoracolumbar spinal injuries, with affected horses showing higher pain manifestations and increased injury rates based on clinical examination and ultrasound assessments. Horses with laminitis displayed a 14-times higher prevalence of relevant ultrasound injuries in the thoracolumbar spine. These findings emphasize the urgent need for further research to characterize and address these injuries, and an identification of targeted preventive and therapeutic measures to enhance the well-being of horses with chronic laminitis. Postural adaptation is a prominent feature in horses affected by laminitis. Laminitis induces intense pain, especially in the forelimbs, prompting affected horses to assume a caudally displaced trunk posture, resulting in the hyperflexion of the thoracolumbar spine. This study assessed the nature and prevalence of thoracolumbar injuries in horses with chronic laminitis compared to horses without it. Sixty horses were used (thirty laminitic and thirty non-laminitic) of different athletic purposes and ages (2–20 years). The experimental protocol entailed a single assessment of horses' thoracolumbar spines, utilizing physical examination by MACCTORE, a scoring system developed specifically for this study. Additional evaluations included the Grimace Equine Pain Scale (HGS) and ultrasound exams. Statistical tests were used to compare values (Mann–Whitney or t-test) and lesions prevalences (Fisher) between groups (p < 0.05). The results showed a higher pain manifestation (HGS and heart rate, p < 0.0001) and thoracolumbar-spine-injury levels in chronic laminitis horses, both in MACCTORE clinical examinations (11.7 ± 4.8 vs. 4.2 ± 3.3, p < 0.0001) and general ultrasonographic indices (39.6 ± 12.0 vs. 20.7 ± 7.1, p < 0.0001), including specific examination approaches for various spinal elements. Horses with laminitis presented with a 14-fold higher prevalence of ultrasound-relevant lesions in the thoracolumbar spine (CI: 4.4 to 50.6, p < 0.0001) compared to controls. These findings constitute new evidence of an association between chronic laminitis and the presence of thoracolumbar spine injuries in horses, which may be confirmed by more sophisticated study designs. [ABSTRACT FROM AUTHOR]

Due to Achilles tendon compliance, passive ankle stiffness is insufficient to stabilise the body when standing. This results in 'paradoxical' muscle movement, whereby calf muscles tend to shorten during forward body sway. Natural variation in stiffness may affect this movement. This may have consequences for postural control, with compliant ankles placing greater reliance upon active neural control rather than stretch reflexes. Previous research also suggests ageing reduces ankle stiffness, possibly contributing to reduced postural stability. Here we determine the relationship between ankle stiffness and calf muscle movement during standing, and whether this is associated with postural stability or age. Passive ankle stiffness was measured during quiet stance in 40 healthy volunteers ranging from 18 to 88 years of age. Medial gastrocnemius muscle length was also recorded using ultrasound. We found a significant inverse relationship between ankle stiffness and paradoxical muscle movement, that is, more compliant ankles were associated with greater muscle shortening during forward sway (r ≥ 0.33). This was seen during both quiet stance as well as voluntary sway. However, we found no significant effects of age upon stiffness, paradoxical motion or postural sway. Furthermore, neither paradoxical muscle motion nor ankle stiffness was associated with postural sway. These results show that natural variation in ankle stiffness alters the extent of paradoxical calf muscle movement during stance. However, the absence of a clear relationship to postural sway suggests that neural control mechanisms are more than capable of compensating for a lack of inherent joint stiffness. What is the central question of this study?Do individual variations in standing ankle stiffness affect calf muscle movement, and is this related to postural sway or age?What is the main finding and its importance?Less stiff ankles are associated with a greater tendency for 'paradoxical' calf muscle movement during standing, whereby the muscle shortens during forward sway. However, this tendency was not related to postural sway or age. This suggests that neural control mechanisms are more than capable of compensating for a lack of inherent joint stiffness. [ABSTRACT FROM AUTHOR]

To describe the role of body posture and skeletal class in the symmetrical activity of chewing muscles. Descriptive study with association. Skeletal class measured by the Steiner method. Postural analysis through APECS mobile application for forward head posture and shoulder discrepancy, and surface electromyography with Biopac® device. The skeletal class, forward head posture, and shoulder discrepancy presented statistical association with the symmetrical electromyographic response of digastric muscles and masseter muscles during swallowing. This study exhibited a positive relationship between digastric muscle symmetry and skeletal class during swallowing. The compensation of the hyoid system explains these results, showing that skeletal Class III has better electromyographic balance. In contrast, masseter muscle symmetry during swallowing presented a negative relationship with skeletal class. The stabilization role that this muscle plays during swallowing explains these findings, caused by the different lengths and direction of this muscle in skeletal Class III. [ABSTRACT FROM AUTHOR]

Introduction: Sensory systems provide the necessary information for a motor response to be provided. In this sense, the objective of this study is to evaluate the effectiveness of a sensorimotor exercise program on proprioceptive acuity, balance, muscle strength, functional mobility and risk of falls in institutionalized elderly. Methodology: 56 participants (84.6 ± 8.4 years) were randomly distributed between the control (CG, n = 28) and intervention groups (IG, n = 28). The CG performed a protocol based on warm-up, muscle strengthening and warm down and the IG performed the same intervention, with the addition of sensorimotor exercises. Joint Position Sensation (JPS) was evaluated in both limbs at angles of 20° and 45°, balance, functional mobility, fear of falling in the elderly and muscle strength of quadriceps, hamstrings, adductors and abductors in both limbs, before and after the 12 weeks of intervention. Results: Both groups showed gains in muscle strength. When analyzing functionality through Timed Up and Go (TUG), before and after for each group separately, both showed a significant difference (CG p = 0.002; IG p < 0.001). For the Short Physical Performance Battery (SPPB) variable, there were significant differences in IG in balance (p < 0.001), gait speed time (s) (p = 0.004) and sit-to-stand (p = 0.002). In JPS, significant differences were recorded for Absolute Error 45° Non-Dominant (p = 0.045) and Relative Error 45° Non-Dominant (p = 0.045) in the CG and Relative Error 45° Non-Dominant for IG (p = 0.018). In the Falls Efficacy Scale International (FES-I) variable there were significant improvements in the CG (p = 0.006) and in the GI (p = 0.002). However, only IG showed significant improvements (p = 0.013) for Activities-Specific Balance Confident (ABC) in a comparison between before and after the 12-week research period. When comparing the differences verified with the intervention between CG and IG, only balance SPPB (p < 0.001) and sit-tostand SPPB (p = 0.022) showed significant values. Conclusion: He effectiveness of sensorimotor exercises provides balance gain in the elderly (p < 0.001) and positively impacts their confidence (p = 0.013) when performing their duties. It is concluded that the protocol presented in its different levels of difficulty is effective and important for the quality of life of the institutionalized sedentary elderly. [ABSTRACT FROM AUTHOR]

Emotion affects postural control during quiet standing. Emotional states can be defined as two-dimensional models comprising valence (pleasant/unpleasant) and arousal (aroused/calm). Most previous studies have investigated the effects of valence on postural control without considering arousal. In addition, studies have focused on the center of pressure (COP) trajectory to examine emotional effects on the quiet standing control; however, the relationship between neuromuscular mechanisms and the emotionally affected quiet standing control is largely unknown. This study aimed to investigate the effects of arousal and valence on the COP trajectory and ankle muscle activity during quiet standing. Twenty-two participants were instructed to stand on a force platform and look at affective pictures for 72 seconds. The tasks were repeated six times, according to the picture conditions composed of arousal (High and Low) and valence (Pleasant, Neutral, and Unpleasant). During the task, the COP, electromyogram (EMG) of the tibialis anterior and soleus muscles, and electrocardiogram (ECG) were recorded. The heart rate calculated from the ECG was significantly affected by valence; the value was lower in Unpleasant than that in Neutral and Pleasant. The 95% confidence ellipse area and standard deviation of COP in the anterior-posterior direction were lower, and the mean power frequency of COP in the anterior-posterior direction was higher in Unpleasant than in Pleasant. Although the mean velocity of the COP in the medio-lateral direction was significantly lower in Unpleasant than in Pleasant, the effect was observed only when arousal was low. Although the EMG variables were not significantly affected by emotional conditions, some EMG variables were significantly correlated with the COP variables that were affected by emotional conditions. Therefore, ankle muscle activity may be partially associated with postural changes triggered by emotional intervention. In conclusion, both valence and arousal affect the COP variables, and ankle muscle activity may be partially associated with these COP changes. [ABSTRACT FROM AUTHOR]

Background: Little evidence has been provided regarding the effects of carrying standardized load equipment and foot parameters during quiet standing. Therefore, the main purpose of the study was to examine whether a load carriage might impact static foot parameters in police recruits. Methods: Eight hundred and forty-five police recruits (27.9% women) were tested in 'no load' vs. standardized '3.5 kg load' conditions. Foot characteristics during standing were assessed with the Zebris FDM pedobarographic pressure platform. Results: Carrying a 3.5 kg load significantly increased the 95% confidence ellipse area (∆ = 15.0%, p = 0.009), the center of pressure path length (∆ = 3.3%, p = 0.023) and average velocity (∆ = 11.1%, p = 0.014), the length of the minor axis (∆ = 8.2%, p < 0.009) and the deviation in the X (∆ = 12.4%, p = 0.005) and Y (∆ = 50.0%, p < 0.001) axes. For relative ground reaction forces, a significant increase in the left forefoot (∆ = 2.0%, p = 0.002) and a decrease in the left hindfoot (∆ = −2.0%, p = 0.002) were shown. No significant changes in relative ground reaction forces beneath the forefoot and hindfoot regions for the right foot were observed (p > 0.05). Conclusions: The findings suggest that spatial and temporal foot parameters may be more prone to change while carrying heavy loads, especially the center of pressure characteristics. [ABSTRACT FROM AUTHOR]

Interaction with the environment appears necessary for the maturation of sensorimotor and cognitive functions in early life. In rats, a model of sensorimotor restriction (SMR) from postnatal day 1 (P1) to P28 has shown that low and atypical sensorimotor activities induced the perturbation of motor behavior due to muscle weakness and the functional disorganization of the primary somatosensory and motor cortices. In the present study, our objective was to understand how SMR affects the muscle–brain dialogue. We focused on irisin, a myokine secreted by skeletal muscles in response to exercise. FNDC5/irisin expression was determined in hindlimb muscles and brain structures by Western blotting, and irisin expression in blood and cerebrospinal fluid was determined using an ELISA assay at P8, P15, P21 and P28. Since irisin is known to regulate its expression, Brain-Derived Neurotrophic Factor (BDNF) levels were also measured in the same brain structures. We demonstrated that SMR increases FNDC5/irisin levels specifically in the soleus muscle (from P21) and also affects this protein expression in several brain structures (as early as P15). The BDNF level was increased in the hippocampus at P8. To conclude, SMR affects FNDC5/irisin levels in a postural muscle and in several brain regions and has limited effects on BDNF expression in the brain. [ABSTRACT FROM AUTHOR]

Key Clinical Message: This case report aims to raise a physiotherapy intervention for subjects with SMS. The basis is an active work, based on postural control and balance training. Physiotherapists can play an important role in the management of these subjects. Smith–Magenis syndrome (SMS) is a genetic alteration that encompasses a series of psychophysical repercussions that interferes with postural control and the autonomous functionality of the subjects who suffer from it. In this study, a clinical case of an 18‐year‐old adolescent with a genetic diagnosis of an SMS mutation is presented. This work proposes a physiotherapy intervention, adapted to the individual conditions and agreed upon with his family. The goal would be to analyze the effectiveness of postural control and balance training in a subject with SMS. A physiotherapy intervention based on postural control and balance was proposed. This approach is combined with the strengthening and readaptation of the antigravity muscles, through strength training, mobilization exercises, gait and transfers reeducation. An initial assessment was carried out. The interventions were developed at the home of the clinical case. The main variables were balance and postural control. For this, the following measurement scales and tests were used: Face Scale, Gross Motor Function Scale, Berg Balance Scale, Romberg Test, Barthel Index, and Functional Assessment of Sitting (SATco scale). After the intervention, the case presented under observation greater postural control in the transfers, less imbalances, and introduced new positions during their development, which allow more functional and autonomous movement. This was also extrapolated to gait, which was optimized in its development. This observation was not reflexed in test scores, which remained the same than the initial assessment. The intervention had a positive effect on the development of trunk control, transfers, and gait. [ABSTRACT FROM AUTHOR]

Bistability in spinal motoneurons supports tonic spike activity in the absence of excitatory drive. Earlier work in adult preparations suggested that smaller motoneurons innervating slow antigravity muscle fibers are more likely to generate bistability for postural maintenance. However, whether large motoneurons innervating fast-fatigable muscle fibers display bistability is still controversial. To address this, we examined the relationship between soma size and bistability in lumbar (L4–L5) ventrolateral α-motoneurons of choline acetyltransferase (ChAT)-green fluorescent protein (GFP) and Hb9-GFP mice during the first 4 wk of life. We found that as neuron size increases, the prevalence of bistability rises. Smaller α-motoneurons lack bistability, whereas larger fast α-motoneurons [matrix metalloproteinase-9 (MMP-9)+/Hb9+] with a soma area ≥ 400 µm2 exhibit significantly higher bistability. Ionic currents associated with bistability, including the persistent Nav1.6 current, the thermosensitive Trpm5 Ca2+-activated Na+ current, and the slowly inactivating Kv1.2 current, also scale with cell size. Serotonin evokes full bistability in large motoneurons with partial bistable properties but not in small motoneurons. Our study provides important insights into the neural mechanisms underlying bistability and how motoneuron size correlates with bistability in mice. NEW & NOTEWORTHY: Bistability is not a common feature of all mouse spinal motoneurons. It is absent in small, slow motoneurons but present in most large, fast motoneurons. This difference results from differential expression of ionic currents that enable bistability, which are highly expressed in large motoneurons but small or absent in small motoneurons. These results support a possible role for fast motoneurons in maintenance of tonic posture in addition to their known roles in fast movements. [ABSTRACT FROM AUTHOR]