Neurophysiological patterns of acute and post-acute foodborne botulism.

INTRODUCTION/AIMS: Neurophysiological patterns in patients with foodborne botulism are rarely described after the acute phase. We report data from a large Italian outbreak of botulism, with patients evaluated at different timepoints after poisoning. METHODS: Eighteen male patients (mean age 47 ± 8.4 y) underwent 22 clinical and neurophysiological evaluations (4 patients were re-evaluated). The resting compound muscle action potential (CMAP) amplitude, postexercise CMAP amplitude, CMAP change after high-frequency (50 Hz) repetitive nerve stimulation (HFRNS), and motor unit action potentials (MUAPs) were assessed in the acute (4-8 days after poisoning; 5 patients), early post-acute (32-39 days after poisoning; 5 patients), and late post-acute (66-80 days after poisoning; 12 patients) phases. RESULTS: In the acute, early post-acute, and late post-acute phases, respectively, reduced CMAP amplitudes were found in 100%, 20%, and 17% of patients; abnormal postexercise CMAP facilitation was observed in 100%, 40%, and 0% of patients; and pathological incremental responses to HFRNS were found in 80%, 50%, and 8% of patients. Baseline CMAP amplitudes, postexercise CMAP facilitation, and CMAP increases in response to HFRNS differed significantly between the acute and post-acute phases. Small MUAPs were found in 100% of patients in the acute and early post-acute phases and in 50% of patients in the late post-acute phase. DISCUSSION: The neurophysiological findings of foodborne botulism vary considerably according to the evaluation time point. In the post-acute phase, different neurophysiological techniques must be applied to support a diagnosis of botulism.

Myopathic changes in patients with long-term fatigue after COVID-19.

OBJECTIVE: To investigate the peripheral nerve and muscle function electrophysiologically in patients with persistent neuromuscular symptoms following Coronavirus disease 2019 (COVID-19). METHODS: Twenty consecutive patients from a Long-term COVID-19 Clinic referred to electrophysiological examination with the suspicion of mono- or polyneuropathy were included. Examinations were performed from 77 to 255 (median: 216) days after acute COVID-19. None of the patients had received treatment at the intensive care unit. Of these, 10 patients were not even hospitalized. Conventional nerve conduction studies (NCS) and quantitative electromyography (qEMG) findings from three muscles were compared with 20 age- and sex-matched healthy controls. RESULTS: qEMG showed myopathic changes in one or more muscles in 11 patients (55%). Motor unit potential duration was shorter in patients compared to healthy controls in biceps brachii (10.02 ± 0.28 vs 11.75 ± 0.21), vastus medialis (10.86 ± 0.37 vs 12.52 ± 0.19) and anterior tibial (11.76 ± 0.31 vs 13.26 ± 0.21) muscles. All patients with myopathic qEMG reported about physical fatigue and 8 patients about myalgia while 3 patients without myopathic changes complained about physical fatigue. CONCLUSIONS: Long-term COVID-19 does not cause large fibre neuropathy, but myopathic changes are seen. SIGNIFICANCE: Myopathy may be an important cause of physical fatigue in long-term COVID-19 even in non-hospitalized patients.

Adaptive changes in muscle activity after cryotherapy treatment: Potential mechanism for improvement the functional state in patients with multiple sclerosis.

BACKGROUND: The available literature lacks data about the influence of whole body cryotherapy (WBC) on muscle activity in patients with sclerosis multiplex (MS). OBJECTIVE: Assessment of the influence of the 20 WBC series on the surface electromyography (sEMG) signal and the relationship between it and the functional state in patients with MS. METHODS: The study group was 114 of MS patients (aged 45.24±11.88yr.,) which 74 of them received 20 of WBC. An assessment was made of: the hand grip (HGS), Timed 25-Foot Walk, Fatigue Severity Scale, sEMG signal from the dominant limb. RESULTS: After a series of 20 WBC: in the rest electromyograms, an increase of extensor carpi radialis (ECR) and a decrease of flexor carpi radialis (FCR) amplitude were demonstrated (non-normalized signal ECR p = 0.0001); significant differences in sEMG rest signals between ECR and FCR have decreased; for voluntary contraction in both assessed antagonistic muscle amplitude was significantly decreased (p = 0.0005; p = 0.0316, p = 0.0185); an increase of HGS (p < 0.001); gait improvement (p = 0.001); decrease fatigue (p = 0.024). No significant changes were observed in the control group. CONCLUSIONS: Series of 20 WBC improves the functional state and reduces fatigue in patients with MS, which may be due to adaptive changes in bioelectrical muscle activity.

High-density surface electromyography to assess motor unit firing rate in Charcot-Marie-Tooth disease type 1A patients.

OBJECTIVE: The aim of this study was to elucidate the characteristics of the motor unit (MU) firing rate in Charcot-Marie-Tooth disease type 1A (CMT1A) patients and its longitudinal change using high-density surface-electromyography (surface-EMG) and MU decomposition analysis. METHODS: Nineteen patients with CMT1A and 21 force-matched healthy controls prospectively underwent surface-EMG recording of the vastus lateralis muscle during ramp-up and sustained contractions on performing isometric knee extension. After decomposition analysis, instantaneous firing rates (IFRs) of individually identified MUs were calculated. In CMT1A patients, follow-up measurements were performed one year after the baseline. Comparison of IFRs and clinical variables between CMT1A patients and controls at the baseline and between the baseline and after one year in CMT1A patients was performed. RESULTS: Mean IFRs of MUs were lower in CMT1A patients than in controls. This was true at various force levels in ramp-up contractions (p < 0.01. e.g., 10.3 (CMT1A patients) vs. 12.2 (controls) pulses-per-second (pps) at 22.5-27.5% of maximal voluntary contraction (MVC) in MUs recruited at <7.5% of MVC) and at any time-point during sustained contractions (p < 0.001. e.g., 8.0 vs. 9.3 pps, respectively, at 10-20 seconds). In CMT1A patients, mean IFRs at 0-10 seconds of sustained contraction were significantly decreased over one year (from 8.06 to 7.52 pps; p = 0.027), whereas the disease severity score and MVC of knee extension did not change over time. CONCLUSION: CMT1A patients had a lower individual MU firing rate. SIGNIFICANCE: The MU firing rate is a potential short-term biomarker of axonal damage in CMT1A patients.

A novel passive neck orthosis for patients with degenerative muscle diseases: Development & evaluation.

The current study evaluated the effect of a passive neck orthosis, developed for patients suffering from progressive muscular diseases, on neck muscle activity in 10 adult healthy participants. The participants performed discrete head movements involving pure neck flexion (-10 to 30°), pure neck rotation (up to 30° left and right) and combined neck flexion-rotation (-10 to 30°) in steps of 10° by moving a cursor on a screen to reach predefined targets and staying on target for 10 s. Surface electromyography (EMG) was recorded from upper trapezius and sternocleidomastoid muscles and amplitudes were averaged over the static phases in trials with and without the orthosis. Moreover, the variability in head position and time required to perform the tasks were compared between conditions. Wearing the orthosis caused significant reductions (p = 0.027) in upper trapezius activity (a change of 0.2-1.5% EMGmax) while working against gravity. The activity level of the sternocleidomastoid muscle increased (p ≤ 0.025) by 0.3-1.0% EMGmax during pure and combined rotations without any pain reported. The orthosis showed potential to reduce the activity level of the upper trapezius muscle, the main load bearing muscle of the neck. Further study will be carried out to evaluate the effect in different patient groups.

Changes in Low Back Muscle Activity and Spine Kinematics in Response to Smartphone Use During Walking.

STUDY DESIGN: Within-subject design of an experimental study. OBJECTIVE: The aim of this study was to determine the effects of smartphone use on the activity level of the lumbar erector spinae muscles and spine kinematics during walking. SUMMARY OF BACKGROUND DATA: Using a smartphone while walking makes the user hold the phone steady and look downward to interact with the phone. Walking with this non-natural posture of the head and the arms may alter the spine kinematics and increase the muscular load on the low back extensor muscles. METHODS: Twenty healthy young individuals participated in the laboratory experiment. Each participant walked on a treadmill in five different conditions: normal walking without using a phone, conducting one-handed browsing while walking, two-handed texting while walking, walking with one arm bound, and walking with both arms bound. Spine kinematics variables and the myoelectric activity levels of the lumbar erector spinae muscles were quantified and compared between the five walking conditions. RESULTS: Participants walked with significantly (P < 0.05) more thoracic kyphosis and lumbar lordosis when using a phone compared to when walking without using the phone. The median level of muscle activity was also 16.5% (browsing) to 31.8% (texting) greater for the two smartphone use conditions than for the normal walking condition, and the differences were significant (P < .05). Between the normal walking and the two bound arm walking conditions, no significant difference in the muscle activity was found. CONCLUSION: Study results show that the concurrent use of a smartphone while walking could pose a larger muscular load to the lumbar erector spinae muscles than that of normal walking. Habitual use of a smartphone while walking could be a risk factor for low back musculoskeletal problems.Level of Evidence: N/A.

XXXIV Reunión Anual de la Sociedad Andaluza de Neurofisiología Clínica / No disponible

No disponible

Probing the neuromodulatory gain control system in sports and exercise sciences.

The monoaminergic bulbospinal pathways from the brainstem are central to motor functions by regulating the gains of spinal motoneurons and represent, in that respect, probably the primary control system for motoneuron excitability. Yet, the efficiency of this system is few, if not never, assessed in the fields of sports and exercise sciences. In this review paper, we propose a methodological approach intended to assess how this neuromodulatory system affects motoneuron excitability. This approach is based on the use of tendon vibration which can, in certain circumstances, induce the generation of the so-called tonic vibration reflex through the stimulation of muscle spindles. Force and EMG responses to tendon vibration are indeed indicative of how this descending system modulates the gain of the ionotropic inputs from Ia afferents and thus of the strength of the monoaminergic drive. After a brief presentation of the neuromodulatory system and of the mechanisms involved in the generation of the tonic vibration reflex, we address some important methodological considerations regarding the use of the TVR to probe this neuromodulatory gain control system. Hopefully, this paper will encourage sports and exercise scientists to investigate this system.

Fasciculations demonstrate daytime consistency in amyotrophic lateral sclerosis.

INTRODUCTION: Fasciculations represent early neuronal hyperexcitability in amyotrophic lateral sclerosis (ALS). To aid calibration as a disease biomarker, we set out to characterize the daytime variability of fasciculation firing. METHODS: Fasciculation awareness scores were compiled from 19 ALS patients. In addition, 10 ALS patients prospectively underwent high-density surface electromyographic (HDSEMG) recordings from biceps and gastrocnemius at three time-points during a single day. RESULTS: Daytime fasciculation awareness scores were low (mean: 0.28 muscle groups), demonstrating significant variability (coefficient of variation: 303%). Biceps HDSEMG recordings were highly consistent for fasciculation potential frequency (intraclass correlation coefficient [ICC] = 95%, n = 19) and the interquartile range of fasciculation potential amplitude (ICC = 95%, n = 19). These parameters exhibited robustness to observed fluctuations in data quality parameters. Gastrocnemius demonstrated more modest levels of consistency overall (44% to 62%, n = 20). DISCUSSION: There was remarkable daytime consistency of fasciculation firing in the biceps of ALS patients, despite sparse and intermittent awareness among patients' accounts.

Current Trends and Confounding Factors in Myoelectric Control: Limb Position and Contraction Intensity.

This manuscript presents a hybrid study of a comprehensive review and a systematic(research) analysis. Myoelectric control is the cornerstone ofmany assistive technologies used in clinicalpractice, such as prosthetics and orthoses, and human-computer interaction, such as virtual reality control.Although the classification accuracy of such devices exceeds 90% in a controlled laboratory setting,myoelectric devices still face challenges in robustness to variability of daily living conditions.The intrinsic physiological mechanisms limiting practical implementations of myoelectric deviceswere explored: the limb position effect and the contraction intensity effect. The degradationof electromyography (EMG) pattern recognition in the presence of these factors was demonstratedon six datasets, where classification performance was 13% and 20% lower than the controlledsetting for the limb position and contraction intensity effect, respectively. The experimental designsof limb position and contraction intensity literature were surveyed. Current state-of-the-art trainingstrategies and robust algorithms for both effects were compiled and presented. Recommendationsfor future limb position effect studies include: the collection protocol providing exemplars of at least 6positions (four limb positions and three forearm orientations), three-dimensional space experimentaldesigns, transfer learning approaches, and multi-modal sensor configurations. Recommendationsfor future contraction intensity effect studies include: the collection of dynamic contractions, nonlinearcomplexity features, and proportional control.

Slow Orthostatic Tremor: Review of the Current Evidence.

Background: Orthostatic tremor (OT) is defined as tremor in the legs and trunk evoked during standing. While the classical description is tremor of ≥13 Hz, slower frequencies are recognized. There is disagreement as to whether the latter represents a slow variant of classical OT, or different tremor disorder(s) given frequent coexistent neurological disease. Methods: A systematic literature search of PubMed was performed in February 2019 for "slow orthostatic tremor" and related terms which generated 573 abstracts, of which 61 were included. Results: Between 1970 and 2019, there were 70 cases of electrophysiologically confirmed slow OT. Two-thirds were female, of mean age 60 years (range 26-86), and mean disease duration 6 years (range 0-32). One-third of cases were isolated, and two-thirds had a coexistent disorder(s), including parkinsonism (30%), ataxia (12%), and dystonia (10%). Postural arm tremor was present in 34%. Median tremor frequency was 6-7 Hz (range 3-12). Tremor bursts ranged from 50 to 150 ms duration, and were alternating or synchronous in antagonistic and/or analogous muscles. Low and high coherences were reported. Five cases (7%) had coexistent classical OT. Clonazepam was the most effective medication across all frequencies, and levodopa was effective for 4-7 Hz OT with coexistent parkinsonism. Two cases resolved with the treatment of Graves' disease. Electrophysiology and imaging predominantly support a central tremor generator. Discussion: While multiple lines of evidence separate slow OT from classical OT, clinical and electrophysiological overlap may occur. Primary and secondary causes are identified, similar to classical OT. Further exploration to clarify these slow OT subtypes, clinically and neurophysiologically, is proposed.

Invalidation of Parkinson's disease diagnosis after years of follow-up based on clinical, radiological and neurophysiological examination.

INTRODUCTION: Diagnosis of Parkinson's disease (PD) is mainly based on clinical features. Accurate neurological examination is required but dopamine transporter (DaT) single photon emission computed tomography (SPECT) could be perfomed to support the diagnosis in ambiguous cases. The aim of this work is to describe the characteristics of patients with a prolonged PD misdiagnosis. METHODS: We collected data from 24 patients initially diagnosed with PD who had an atypical long-term evolution. We analyzed demographic and clinical characteristics and antiparkinsonian drugs medication. Brain MRI, DaT-SPECT and/or accelerometry/electromyography (EMG) recording were performed in a subgroup of patients. We analyzed the causes of erroneous PD diagnosis as well as the final diagnoses. RESULTS: Mean age at PD diagnosis was 60.4 ±â€¯14.8 years. Symptoms at onset were rest tremor (n = 19), gait instability (n = 7) and micrographia (n = 4). Mean duration before diagnosis correction was 8.4 ±â€¯5.3 years. All patients were treated by antiparkinsonian drugs with a mean daily levodopa equivalent dose (LED) of 508.1 ±â€¯528.4 mg. All 18 patients who underwent DaT-SPECT had a normal result. The most frequent final diagnoses were essential tremor (n = 11) and functional movement disorders (n = 9). CONCLUSION: Cases that have been initially diagnosed as PD and then progress in an atypical long-duration fashion may have been misdiagnosed. Absence of genuine bradykinesia, non-sustained response to antiparkinsonian drugs, or absence of levodopa-related side effects should prompt the clinician to reappraise the diagnosis and to consider performing a DaT-SPECT.

A review of acute responses, after-effects and chronic complications related to microneurography.

Microneurography, a technique used to detect postganglionic sympathetic nerve traffic in humans, is increasingly used to further the understanding of autonomic regulation in health and disease. The technique involves the transcutaneous insertion of a microelectrode into a peripheral nerve, following which, a variety of adverse acute responses; after-effect and chronic complications have been documented. Here, we comprehensively review the potential adverse outcomes of microneurography and provide updated quantifiable incidence rates of their occurrence within a general population. We also present recommendations for risk assessment and management of such outcomes, as well as recommendations to improve future reporting. This review aims to use objective evidence to improve the understanding of the rare, but present, adverse outcomes of microneurography.

Effects of resistance training on impulse above end-test torque and muscle fatigue.

NEW FINDINGS: What is the central question of this study? What role do neuromuscular fatigue mechanisms play in resistance training-induced adaptations of the impulse above end-test torque (IET) after the training period? What is the main finding and its importance? IET and global and peripheral fatigue were increased after a short period of resistance training. Thus, resistance training-induced adaptations in neuromuscular fatigue seem to contribute to enhanced IET after the training period. ABSTRACT: Short-term resistance training has a positive influence on the curvature constant of the power-duration relationship (W'). The physiological mechanism of W' enhancement after resistance training is unclear. This study aimed to determine whether one-leg maximal isometric resistance training influences (1) impulse above end-test torque (IET; an analogue of W') during a 5 min all-out isometric test; and (2) exercise tolerance (limit of tolerance, Tlim) and neuromuscular fatigue during severe exercise (i.e. above end-test torque; ET). Sixteen healthy active males participated in a 3-week unilateral knee extensor resistance-training programme, and 10 matched subjects participated as controls. The subjects were instructed to ramp up to 100% of maximal voluntary contraction (MVC) over 1 s, hold it for 3 s, and relax. Each repetition had a 2 s interval (10) and each set, a 2 min interval (3). MVC (18.6%) and muscle thickness (12.8%) were significantly improved after training. Significantly greater global (i.e. reduced MVC, 43.2 ± 13.5% vs. 58.9 ± 6.9%) and peripheral (51.7 ± 13.6% vs. 57.3 ± 15.3%) fatigue, IET (26%) and Tlim (92%) were obtained after resistance training. Moreover, both global (r = 0.57, P < 0.05) and peripheral fatigue (r = 0.55, P < 0.05) accrued during severe exercise were associated with IET. However, echo intensity, which reflects muscle quality, ET and central fatigue remained unchanged throughout the training period. No significant changes in the control group for any variable were observed. Resistance training-induced adaptations in muscle size and neuromuscular fatigue seem to contribute to enhanced IET and Tlim after the training period.

Functional plasticity of the ipsilateral primary sensorimotor cortex in an elite long jumper with below-knee amputation.

Functional plasticity of the sensorimotor cortex occurs following motor practice, as well as after limb amputation. However, the joint effect of limb amputation and intensive, long-term motor practice on cortical plasticity remains unclear. Here, we recorded brain activity during unilateral contraction of the hip, knee, and ankle joint muscles from a long jump Paralympic gold medalist with a unilateral below-knee amputation (Amputee Long Jumper, ALJ). He used the amputated leg with a prosthesis for take-off. Under similar conditions to the ALJ, we also recorded brain activity from healthy long jumpers (HLJ) and non-athletes with a below-knee amputation. During a rhythmic isometric contraction of knee extensor muscles with the take-off/prosthetic leg, the ALJ activated not only the contralateral primary sensorimotor cortex (M1/S1), but also the ipsilateral M1/S1. In addition, this ipsilateral M1/S1 activation was significantly greater than that seen in the HLJ. However, we did not find any significant differences between the ALJ and HLJ in M1/S1 activation during knee muscle contraction in the non-take-off/intact leg, nor during hip muscle contraction on either side. Region of interest analysis revealed that the ALJ exhibited a greater difference in M1/S1 activity and activated areas ipsilateral to the movement side between the take-off/prosthetic and non-take-off/intact legs during knee muscle contraction compared with the other two groups. However, difference in activity in M1/S1 contralateral to the movement side did not differ across groups. These results suggest that a combination of below-knee amputation and intensive, prolonged long jump training using a prosthesis (i.e. fine knee joint control) induced an expansion of the functional representation of the take-off/prosthetic leg in the ipsilateral M1/S1 in a muscle-specific manner. These results provide novel insights into the potential for substantial cortical plasticity with an extensive motor rehabilitation program.

Open Database for Accurate Upper-Limb Intent Detection Using Electromyography and Reliable Extreme Learning Machines.

Surface Electromyography (sEMG) signal processing has a disruptive technology potential to enable a natural human interface with artificial limbs and assistive devices. However, this biosignal real-time control interface still presents several restrictions such as control limitations due to a lack of reliable signal prediction and standards for signal processing among research groups. Our paper aims to present and validate our sEMG database through the signal classification performed by the reliable forms of our Extreme Learning Machines (ELM) classifiers, used to maintain a more consistent signal classification. To perform the signal processing, we explore the use of a stochastic filter based on the Antonyan Vardan Transform (AVT) in combination with two variations of our Reliable classifiers (denoted R-ELM and R-Regularized ELM (RELM), respectively), to derive a reliability metric from the system, which autonomously selects the most reliable samples for the signal classification. To validate and compare our database and classifiers with related papers, we performed the classification of the whole of Databases 1, 2, and 6 (DB1, DB2, and DB6) of the NINAProdatabase. Our database presented consistent results, while the reliable forms of ELM classifiers matched or outperformed related papers, reaching average accuracies higher than 99 % for the IEEdatabase, while average accuracies of 75 . 1 % , 79 . 77 % , and 69 . 83 % were achieved for NINAPro DB1, DB2, and DB6, respectively.

Electrical Impedance Methods in Neuromuscular Assessment: An Overview.

Electrical impedance methods have been used as evaluation tools in biological and medical science for well over 100 years. However, only recently have these techniques been applied specifically to the evaluation of conditions affecting nerve and muscle. This specific application, termed electrical impedance myography (EIM), is finding wide application as it can provide a quantitative index of muscle condition that can assist with diagnosis, track disease progression, and assess the beneficial impact of therapy. Using noninvasive surface methods, EIM has been studied in a number of conditions ranging from amyotrophic lateral sclerosis to muscular dystrophy to disuse atrophy. Data support that the technique is sensitive to disease status and can offer the possibility of performing clinical trials with fewer subjects than would otherwise be possible. Recent advances in the field include improved approaches for using EIM as a "virtual biopsy" and the development of combined needle impedance-electromyography technology.

A Spinal Mechanism Related to Left-Right Symmetry Reduces Cutaneous Reflex Modulation Independently of Speed During Split-Belt Locomotion.

Task- and phase-dependent reflex modulation during locomotion is well established, but we do not know the signals driving this modulation. To determine whether signals related to left-right symmetry of the locomotor pattern modulate cutaneous reflexes, we stimulated the superficial peroneal nerve in five intact female cats and in four spinal-transected cats (spinal cats, two males and two females) during split-belt locomotion at different left-right speeds. We compared cutaneous reflexes evoked in three ipsilateral and two contralateral hindlimb muscles during split-belt locomotion with those evoked during tied-belt (equal left-right speeds) locomotion at matched speeds of the slow and fast limbs. Our results showed similar phase-dependent modulation of cutaneous reflexes during tied-belt and split-belt locomotion in intact and spinal cats. During tied-belt locomotion in intact cats, an increase in speed significantly increased reflex modulation from minimum to maximum values, whereas in spinal cats, we observed a significant decrease. However, in all muscles of intact and spinal cats, split-belt locomotion significantly reduced reflex modulation compared with tied-belt locomotion independently of which limb was stepping on the slow or fast belt. Additionally, reflex modulation correlated more with spatial left-right symmetry, as opposed to a temporal one, in intact and spinal cats. Our results indicate that signals related to left-right symmetry reduce cutaneous reflex modulation independently of speed via a spinal mechanism. We propose that asymmetric sensory feedback from the left and right legs alters the state of the spinal network, thereby reducing cutaneous reflexes to prevent inputs from destabilizing a potentially unstable pattern.SIGNIFICANCE STATEMENT When we contact an obstacle during walking, receptors in the skin send signals to the CNS to alter the trajectory of the leg to maintain balance. This response, or reflex, is different when the leg is in the air and when it is contacting the ground. The reflex also differs when we walk at different speeds. Here, we investigated this reflex when the left and right legs were walking at different speeds on a split-belt treadmill in cats. We show that the reflex is smaller during split-belt locomotion compared with when both legs are walking at equal speeds. We propose that the spinal locomotor network controlling walking reduces the reflex response to optimize balance when gait is unstable.

Temporal dynamics of the transition period between nonrapid eye movement and rapid eye movement sleep in the rat.

Study Objectives: We studied the sequence of events that occur in electroencephalogram (EEG), electromyogram (EMG), and ocular activities along the transition period between nonrapid eye movement and rapid eye movement (REM) sleep and their temporal relationships. Methods: Twenty adult Wistar rats underwent polygraphic recordings of EEG, EMG, and eye movements during the transition periods. The studied EEG variables included the time of occurrence of the last sleep spindle and the evolution of the amplitudes of δ (1-5 Hz), θ (6-9 Hz), and high-frequency (110-160 Hz) oscillations (HFO). Motor variables included the development of atonia in the acromiotrapezius muscle and the occurrence of the first REM. The phase-amplitude coupling between θ and HFO was also analyzed. Results: The transition periods started with the onset of θ, followed by HFO onset and the decline of δ activities. From onset, HFO amplitude was coupled to the phase of θ. The first REM and the last sleep spindle coincided with the complete extinction of δ. At that point, the muscle tonus started to decrease, reaching its atonia when HFO achieved maximum amplitude. Conclusions: As the development of HFO delimited the duration of all transitional changes with precision, it can be considered a good delimiter for the transition period. Furthermore, as transitional changes occurred in a precise sequence, alterations in their temporal dynamics could be of interest in the study of sleep disorders and pathologies.

Muscle activation during fast walking with two types of foot orthoses in participants with cavus feet.

The aim of this study was to quantify the effects of foot orthoses (FOs) with and without a lateral bar on muscle activity of participants with cavus feet. Fifteen participants were recruited from the Université du Québec à Trois-Rivières students and podiatry clinic. The muscle activity of the tibialis anterior, fibularis longus, gastrocnemius lateralis and medialis, vastus medialis and lateralis, biceps femoris and gluteus medius were recorded during fast walking under two experimental conditions (FOs with and without a lateral bar) and a control condition (shoes). Experimentations were completed after a one-month adaptation period to each experimental condition. The root mean square of the electromyography (EMG) data was analyzed. To compare the effects between conditions, a curve analysis was performed using one-dimensional statistical parametric mapping. The main result of this study was an increased gastrocnemius lateralis muscle activity (maximum mean difference: +28%) during the propulsion phase of gait (44-46%) when participants wore FOs compared to the control condition. This result will help researchers and clinicians better understand the FOs' EMG effects of individuals with cavus feet. As FOs are mainly prescribed for symptomatic patients, future studies should assess their effects on individuals suffering of a pathology, such as Achilles tendinopathy.