Anterior Electromyography Research Articles

Effects of Stroboscopic Vision on Depth Jump Motor Control: A Biomechanical Analysis.

Researchers commonly use the 'free-fall' paradigm to investigate motor control during landing impacts, particularly in drop landings and depth jumps (DJ). While recent studies have focused on the impact of vision on landing motor control, previous research fully removed continuous visual input, limiting ecological validity. The aim of this investigation was to evaluate the effects of stroboscopic vision on depth jump (DJ) motor control. Ground reaction forces (GRF) and lower-extremity surface electromyography (EMG) were collected for 20 young adults (11 male; 9 female) performing six depth jumps (0.51 m drop height) in each of two visual conditions (full vision vs. 3 Hz stroboscopic vision). Muscle activation magnitude was estimated from EMG signals using root-mean-square amplitudes (RMS) over specific time intervals (150 ms pre-impact; 30-60 ms, 60-85 ms, and 85-120 ms post-impact). The main effects of and interactions between vision and trial number were assessed using two-way within-subjects repeated measures analyses of variance. Peak GRF was 6.4% greater, on average, for DJs performed with stroboscopic vision compared to full vision (p = 0.042). Tibialis anterior RMS EMG during the 60-85 ms post-impact time interval was 14.1% lower for DJs performed with stroboscopic vision (p = 0.020). Vastus lateralis RMS EMG during the 85-120 ms post-impact time interval was 11.8% lower for DJs performed with stroboscopic vision (p = 0.017). Stroboscopic vision altered DJ landing mechanics and lower-extremity muscle activation. The observed increase in peak GRF and reduction in RMS EMG of the tibialis anterior and vastus lateralis post-landing may signify a higher magnitude of lower-extremity musculotendinous stiffness developed pre-landing. The results indicate measurable sensorimotor disruption for DJs performed with stroboscopic vision, warranting further research and supporting the potential use of stroboscopic vision as a sensorimotor training aid in exercise and rehabilitation. Stroboscopic vision could induce beneficial adaptations in multisensory integration, applicable to restoring sensorimotor function after injury and preventing injuries in populations experiencing landing impacts at night (e.g., military personnel).

Rehabilitation strategies and magnetic resonance imaging techniques for shoulder injuries in sports

ObjectiveShoulder sleeve injuries are high-risk in men's tennis, with rehabilitation focusing on activating shoulder muscle groups to regain strength. Specific plans use electromyography and isokinetic instruments to compare muscle activity and torque pre- and post-rehabilitation. The goal is to explore training effects on rotator cuff injuries and assess routine MRI and MRI shoulder arthrography for diagnostic value in shoulder injuries. This aims to provide a reference for restoring shoulder function in male tennis players. MethodsTwenty college students (n = 20) with rotator cuff injuries from a university tennis program were selected as experimental subjects, matched based on gender and injury severity, and divided into experimental (n = 10) and control (n = 10) groups. A paired sample T-test assessed the impact of rehabilitation training on muscle recruitment and strength around the shoulder joint in the experimental group before and after training. This evaluated the influence of rehabilitation plans on shoulder muscle mobilization and strength. Another paired sample T-test compared indicators before and after the experiment, examining mechanisms underlying the effects of functional rehabilitation training on shoulder sleeve injuries in male tennis players. Results(1) Surface electromyography (EMG) results for internal/external rotation showed a significant increase in anterior, middle, and posterior deltoid EMG values (P < 0.05). Supraspinatus and infraspinatus muscles exhibited substantial increases (P < 0.01), while no significant change occurred in the teres minor muscle. (2) Adduction/abduction EMG tests at 60°/s, 90°/s, and 120°/s revealed significant increases (P < 0.01) in deltoid bundles and supraspinatus/infraspinatus muscles for both experimental and control groups. Teres minor muscle showed no significant change. (3) Isokinetic muscle strength tests indicated a significant peak torque increase (P < 0.01) during inward/outward rotation at 60°/s, 90°/s, and 120°/s for the experimental group compared to the control group. ConclusionA 10-week functional shoulder rehabilitation training program can enhance the strength, endurance, and neuromuscular recruitment of shoulder-related muscles in male tennis players with rotator cuff injuries. This approach, combined with the diagnostic capabilities of routine MRI and MRI shoulder arthrography, enables modifications in the body's ongoing adaptation to injuries. This, in turn, contributes to improved shoulder joint stability and effectively facilitates the functional recovery of the rotator cuff muscle group.

Using Wavelet Analysis and Deep Learning for EMG-Based Hand Movement Signal Classification

In this study; time series electromyography (EMG) data have been classified according to hand movements using wavelet analysis and deep learning. A pre-trained deep CNN (Convolitonal Neural Network-GoogLeNet) has been used in the classification process performed with signal processing, by this way the results can be obtained by continuous wavelet transform and classification methods. The dataset used has been taken from the Machine Learning Repository at the University of California. In the data set; EMG data of 5 healthy individuals, 2 males and 3 females, of the same age (~20-22 years) are available. Data; It consists of grasping spherical objects (Spher), grasping small objects with fingertips (Tip), grasping objects with palms (Palm), grasping thin/flat objects (Lat), grasping cylindrical objects (Cyl) and holding heavy objects (Hook). It is desired to perform 6 hand movements at the same time. While these movements are necessary, speed and power depend on one's will. People perform each movement for 6 seconds and repeat each movement (action) 30 times. The CWT (Continuous Wavelet Transform) method was used to transform the signal into an image. The scalogram image of the signal was created using the CWT method and the generated images were collected in a data set folder. The collected scalogram images have been classified using GoogLeNet, a deep learning network model. With GoogLeNet, results with 97.22% and 88.89% accuracy rates were obtained by classifying the scalogram images of the signals received separately from channel 1 and channel 2 in the data set. The applied model can be used to classify EMG signals in EMG data with high success rate. In this study, 80% of data was used for educational purposes and 20% for validation purposes. In the study, the results of the classification processes have been evaluated separately for first and second channel data.

Higher Leg and Trunk Muscle Activation during Balance Control in Copers versus People with Chronic Ankle Instability and Healthy Female Athletes.

HighlightsAthletes with a history of ankle sprain that do not suffer from ankle instability (copers) exhibit similar balance and neuromuscular control compared to healthy athletes.Athletes with chronic ankle instability show a deficit in neuromuscular control and balance, which may increase the risk of subsequent injuries.Athletes with chronic ankle instability are advised to use neuromuscular training in their rehabilitation program to improve balance and neuromuscular performance to reduce the risk of injury.More than 70% of people with ankle sprain experience chronic ankle instability. However, some people are well adapted to this damage (copers) and do not suffer from chronic ankle instability (CAI). This cross-sectional study involved 34 female athletes, who were classified into three groups (athletes with CAI, copers, and healthy athletes) and tested on a Biodex Balance System. Surface electromyography (EMG) and balance scores were monitored. The coper and healthy group exhibited higher medial gastrocnemius (MG) EMG activity during unstable balance conditions. The rectus abdominus (RA) in the coper group and rectus femoris (RF) in the healthy group showed greater EMG activity compared to CAI during unstable conditions. During stable conditions, the coper group showed greater RA EMG activity compared to CAI, as well as higher tibialis anterior (TA) EMG activity compared to the healthy group. Additionally, balance error scores were higher in the CAI group than those in the healthy group under unstable conditions. In conclusion, decreased EMG activity of the MG, RF, and RA in CAI athletes may contribute to impaired balance in these individuals. The increased EMG activity of the MG, TA, and RA in copers might result in more trunk and ankle stability.

Resilience of visually guided weight shifting to a proprioceptive perturbation depends on the complexity of the guidance stimulus

BackgroundWhole-body tracking of visual motion cues is used in balance training to improve weight shifting ability in old age and sports. Research questionHow tracking of a complex (pink noise) and a periodic visual target motion during anteroposterior weight shifting affects postural and muscle responses to unilateral hip vibration. MethodsTwenty-six participants performed 160 anteroposterior weight shifting cycles while tracking the vertical motion of a visual target, concurrently receiving Center of Pressure (CoP) feedback. They were randomly divided to groups; (a) the Constant group tracked a visual target motion constructed by 3 sinusoids of different amplitude, and (b) the Pink group tracked a complex visual target motion constructed by a pink noise generation process. Between the 60th and the 120th cycle, vibration was applied to the right gluteus medius, introducing a sideways CoP deviation. CoP displacement and electromyographic (EMG) responses of soleus, tibialis anterior and peroneus longus were recorded and summarized in blocks of 3 cycles. ResultsSideways CoP deviation induced at the onset/offset of unilateral hip vibration was smaller for the Pink than the Constant group. The Pink group demonstrated greater tibialis anterior and peroneus longus EMG activity around the most anterior sway peak while soleus EMG was similar for the two groups. Both groups successfully coupled weight shifting amplitude to the target motion, but the Pink group tracked the target motion with a greater delay compared to the Constant group. SignificanceWhole body tracking of complex visual motions evokes perception-based action and increases ankle muscle co-activation making sway more resilient to a proprioceptive perturbation induced by unilateral hip vibration. Complex visual guidance motions should be considered when designing balance rehabilitation regimes, aiming at improving weight shifting ability and dynamic balance control.

Electromyographic responses to unexpected Achilles tendon vibration-induced perturbations during standing in young and older people.

This study aimed to investigate age-related differences in electromyographic (EMG) responses to unexpected Achilles tendon vibration (ATV) perturbations while standing blindfold. ATV with variable and random duration (12-15s) and rest periods (20-24s) was applied on 18 young and 16 older volunteers. The anterior/posterior center of pressure (CoP) and the soleus (SOL) and tibialis anterior (TA) EMG were analyzed for 1s before and 8s after the ATV onset and offset. ATV induced a posterior shift of CoP in both groups, with more pronounced shift in the older group. During ATV onset, the older group demonstrated less SOL and more TA EMG increase compared to the young group. During the first 0.5s of ATV offset, SOL EMG was decreased in both age groups, while TA showed a burst of EMG activity that was greater in the older group. No difference in the latencies of EMG peaks or valleys was observed between the groups. It is concluded that ATV induces greater posterior CoP shift in older adults, and they adopt a recovery strategy, characterized by a decreased SOL activation and an increased TA activation. These differences are possibly attributed to the increased fear of falling, decreased limits of stability and reduced capacity of older people to reweight their sensory inflow when proprioception is distorted.

Electromyography-based fatigue assessment of an upper body exoskeleton during automotive assembly.

The purpose of this study was to assess an upper body exoskeleton during automotive assembly processes that involve elevated arm postures. Sixteen team members at Toyota Motor Manufacturing Canada were fitted with a Levitate Airframe, and each team member performed between one and three processes with and without the exoskeleton. A total of 16 assembly processes were studied. Electromyography (EMG) data were collected on the anterior deltoid, biceps brachii, upper trapezius, and erector spinae. Team members also completed a usability survey. The exoskeleton significantly reduced anterior deltoid mean active EMG amplitude (p=.01, Δ=-3.2 %MVC, d=0.56 medium effect) and fatigue risk value (p<.01, Δ=-5.1 %MVC, d=0.62 medium effect) across the assembly processes, with no significant changes for the other muscles tested. A subset of nine assembly processes with a greater amount of time spent in arm elevations at or above 90° (30 vs. 24%) and at or above 135° (18 vs. 9%) appeared to benefit more from exoskeleton usage. For these processes, the exoskeleton significantly reduced anterior deltoid mean active EMG amplitude (p<.01, Δ=-5.1 %MVC, d=0.95 large effect) and fatigue risk value (p<.01, Δ=-7.4 %MVC, d=0.96 large effect). Team members responded positively about comfort and fatigue benefits, although there were concerns about the exoskeleton hindering certain job duties. The results support quantitative testing to match exoskeleton usage with specific job tasks and surveying team members for perceived benefits/drawbacks.

Adaptive Stimulation Profiles Modulation for Foot Drop Correction Using Functional Electrical Stimulation: A Proof of Concept Study.

Functional electrical stimulation (FES) provides an effective way for foot drop (FD) correction. To overcome the redundant and blind stimulation problems in the state-of-the-art methods, this study proposes a closed-loop scheme for an adaptive electromyography (EMG)-modulated stimulation profile. The developed method detects real-time angular velocity during walking. It provides feedbacks to a long short-term memory (LSTM) neural network for predicting synchronous tibialis anterior (TA) EMG. Based on the prediction, it modulates the stimulation intensity, taking into account of the subject-specific dead zone and saturation of the electrically evoked activation. The proposed method is tested on ten able-bodied participants and six FD subjects as proof of concept. The experimental results show that the proposed method can successfully induce the dorsiflexion of the ankle joint, and generate an activation pattern similar to a natural gait, with the mean Correlation Coefficient of 0.9021. Thus, the proposed method has the potential to help patients to retrieve normal gait.

The Effects of Verbal Instructions on Lower Limb Muscles’ Excitation in Back-Squat

ABSTRACT The present study investigated whether or not verbal instruction affects the electromyographic (EMG) amplitude of back-squat prime movers. Fifteen resistance-trained men performed back-squat at 50%1-RM and 80%1-RM and received external (EF) or internal focus (IF) on lower-limb posterior muscles. EMG amplitude of gluteus maximus, biceps femoris, gastrocnemius medialis, vastus lateralis, and tibialis anterior was recorded during both concentric and eccentric phases. During the concentric phase, the gluteus maximus and biceps femoris EMG amplitude was greater in IF vs EF at 50% [effect size (ES): 0.63 (95%CI 0.09/1.17) and 0.49 (0.10/0.78), respectively] and 80% [ES: 1.30 (0.29/2.21) and 0.59 (0.08/1.10)]. The gastrocnemius medialis EMG amplitude was greater in IF vs EF during the eccentric phase at 50% [ES: 0.73 (0.13/1.33)] and at 80% [ES: 0.72 (0.10/1.34)]. Concomitantly, vastus lateralis EMG amplitude was lower at 50% [ES: −0.71 (−1.38/-0.04)] and 80% [ES: −0.68 (−1.33/-0.03)]. During the eccentric phase, the tibialis anterior EMG amplitude was greater in IF vs EF at 50% [ES: 0.90 (0.12 to 1.68)] and 80% [ES: 0.74 (0.13/1.45)]. Irrespective of the load, in the thigh muscles the internal focus promoted a different motor pattern, increasing the hip extensors and reducing the knee extensor excitation during the concentric phase. Concomitantly, both ankle muscles were more excited during the eccentric phase, possibly to increase the anterior–posterior balance control. The internal focus in back-squat seems to have phase-dependent effects, and it is visible at both moderate and high loads.

Electromyographic Assessment of a Shoulder Support Exoskeleton During on-Site Job Tasks

OCCUPATIONAL APPLICATIONSWe performed an ergonomic assessment of a passive upper body exoskeleton at on-site job tasks, using surface electromyography (EMG) to quantify muscular demands at the shoulder. Six workers were assessed during cab assembly, hydraulic assembly, parts painting, parts hanging, and frame welding tasks, both with and without an exoskeleton. Workers were evaluated during consecutive job tasks, at beginning and at end of a shift. EMG amplitudes were measured and compared to recommended threshold limit values (TLVs) to determine fatigue risk values. Wearing the exoskeleton significantly reduced anterior deltoid EMG amplitudes and fatigue risk values during the consecutive job cycles, with no significant effects on the biceps brachii, superior trapezius, or lumbar erector spinae. Reduced EMG amplitudes were found at five of the six job tasks, and in three of the tasks fatigue risk values were reduced from above the TLV without the exoskeleton to below the TLV with the exoskeleton. Workers indicated that they would recommend the exoskeleton to others who perform overhead job tasks, but expressed concern that it might interfere with tasks that involve tight spaces, sitting, and bending over. We suggest evaluating specific job tasks when making decisions about exoskeleton usage.

NEUROMUSCULAR ADAPTIONS FOLLOWING A DAILY STRENGTHENING EXERCISE IN INDIVIDUALS WITH ROTATOR CUFF RELATED SHOULDER PAIN: A PILOT CASE-CONTROL STUDY

The goal of therapeutic exercise is to facilitate a neuromuscular response by increasing or decreasing muscular activity in order to reduce pain and improve function. It is not clear what dosage of exercise will create a neuromuscular response. The purpose of this study was to assess the effects following a three-week home program of a daily single exercise, the prone horizontal abduction exercise (PHA), on neuromuscular impairments of motor control as measured by scapular muscle EMG amplitudes, strength, and secondarily outcomes of self-reported pain and function between individuals with and without subacromial pain syndrome. Prospective Case-Control, Pilot Study. Twenty-five individuals participated; eleven with shoulder pain during active and resistive motions (Penn Shoulder Score: 77 ± 11) and 14 matched healthy controls (Penn Shoulder Score: 99 ± 27) (p < 0.001). Participants underwent baseline and follow up testing at three weeks including surface electromyography (EMG) of the serratus anterior, upper, and lower trapezius of the involved (painful group) or matched shoulder (control group) during an elevation task and maximal isometric shoulder strength testing. All participants were instructed in a PHA exercise to be performed daily (3 sets; 10 reps). Subjects logged daily exercise adherence. Neuromuscular adaptations were defined by changes in EMG amplitudes (normalized to MVIC) of serratus anterior, upper trapezius, and lower trapezius and strength. Secondary outcomes of self-reported pain and function were also compared between groups following the three-week intervention. After three weeks of a daily PHA exercise, the painful group demonstrated a greater decrease in baseline-elevated EMG amplitudes in the lower trapezius by 7% (95%CI 2.6-11%) during the concentric phase of the overhead lifting task (p 0.006). EMG amplitudes of the healthy control group did not change at three-week follow-up. Additionally, the change in serratus anterior mean EMG amplitude in the painful group -1.6% (IQR -22.9 to 0.8%) was significantly greater (p 0.033) than the healthy group change score, 2.5% (IQR -2.3 to 5.7%) during the eccentric phase (p 0.034). While the painful group was weaker in abduction and flexion at baseline and at follow up, both groups had a significant increase in all strength measures (p≤0.014). Concurrent with increased strength and normalizing EMG amplitudes, the painful group significantly improved on the Penn Shoulder Score with a mean change 9.8 points (95%CI 7.0, 12.6) (p < 0.001). In this pilot case-control study, a single home exercise performed daily for three weeks demonstrated neuromuscular adaptations with improvements in muscle activity and strength. These were concurrent with modest, yet significant improvements pain and function in individuals with mild rotator cuff related shoulder pain. 3.

The mechanical loading and muscle activation of four common exercises used in osteoporosis prevention for early postmenopausal women

High impact exercise can reduce postmenopausal bone loss, however stimulus frequency (loading cycles per second) can affect osteogenesis. We aimed to examine the effect of stimulus frequency on the mechanical loading of four common osteoporosis prevention exercises, measuring body acceleration and muscle activation with accelerometry and electromyography (EMG), respectively. Fourteen early postmenopausal women completed randomised countermovement jumps (CMJ), box-drops (BD), heel-drops (HD) and stamp (STP) exercises for continuous and intermittent stimulus frequencies. Sacrum accelerometry and surface electromyography (EMG) of four muscles were recorded. CMJ (mean ± SD: 10.7 ± 4.8 g & 10.0 ± 5.0 g), BD (9.6 ± 4.1 g & 9.5 ± 4.0 g) and HD (7.3 ± 3.8 g & 8.6 ± 4.4 g) conditions generated greater peak acceleration than STP (3.5 ± 1.4 g & 3.6 ± 1.7 g) across continuous and intermittent trials. CMJ and BD generated greater acceleration gradients than STP across continuous and intermittent trials. CMJ generated greater rectus femoris EMG than all other exercises, CMJ and BD generated greater semitendinosus and tibialis anterior EMG than HD across continuous and intermittent trials. CMJ and BD provide greater peak acceleration than STP and remain similar during different stimulus frequencies. CMJ, BD and HD may exceed STP in maintaining postmenopausal bone health.

Assessment of Waveform Similarity in Electromyographical Clinical Gait Data: The Linear Fit Method

The assessment of waveform similarity is a crucial issue in gait analysis for the comparison of electromyography (EMG) and kinematic patterns with reference data. A typical scenario is in fact the comparison of a patient’s EMG pattern with a relevant physiological pattern. Many methods have been proposed for a quantitative comparison of the two patterns, suggesting the absence of a gold standard. A recently proposed method for comparing kinematic patterns is the linear fit method (LFM). This study aims at testing the applicability of this method on data of EMG. The validity of LFM was tested in terms of appropriateness, sensitivity, specificity, and reliability, by comparing 20 EMG pathological gait patterns (obtained by a group of patients with Parkinson’s Disease) and 20 EMG physiological gait patterns (obtained by healthy subjects). When gastrocnemious and tibialis anterior EMG activity was analyzed, the appropriateness of LFM in discriminating pathological patterns resulted of 97.5%, with a sensitivity of 95% and a specificity of 100%. The reliability was good for 2 out of 3 parameters in each group of subjects. The LFM resulted a simple method suitable for analysing the waveform similarity in gait EMG clinical analysis.

Altered pain sensitivity and axioscapular muscle activity in neck pain patients compared with healthy controls.

Previous studies have indicated that neck pain patients feel increased symptoms following upper limb activities, and altered axioscapular muscle function has been proposed as a contributing factor. Pain sensitivity and muscle activity, during arm movements, were assessed in neck pain patients and controls. Patients with ongoing insidious-onset neck pain (IONP, N=16) and whiplash-associated disorders (WAD, N=9) were included along with sex- and age-matched controls (N=25). Six series of repeated arm abductions were performed during electromyographic (EMG) recordings from eight bilateral muscles. The first and last three series were separated by 8 min and 42 s, respectively. Each series consisted of three slow and three fast movements. Pressure pain thresholds (PPTs) were recorded bilaterally from neck, head and arm at baseline, after the third and sixth movement series. Pain intensity was recorded on an electronic visual analogue scale (VAS). Larger pain areas and higher VAS scores were found in patients compared with controls (p<0.001), and in patients, the VAS scores increased in the course of movements (p<0.02). PPTs were lower in patients compared with controls at all sites (p<0.03), and these decreased during arm movements in the IONP group (p<0.03), while increasing at head and neck sites in controls (p<0.04). During the slow movements, increasing serratus anterior EMG activity was found in the series with short breaks in-between for the WAD group compared with IONP and controls (p<0.001). Axioscapular movement caused different responses in pain sensitivity and muscle activity between neck pain patient groups compared with controls. Neck pain patients report increased symptoms following upper limb activities. This study shows that repeated arm movements caused differentiated responses in pain sensitivity and muscle activity between subgroups of neck pain patient and asymptomatic controls. Such findings may be of great clinical significance when planning rehabilitation for this patient population.

Effect of Glenohumeral Joint Rotation on Serratus Anterior, Pectoralis Major and Upper Trapezius EMG Activity during Push-up Plus Exercise

Purpose: The aim of this study is to determine the effect of glenohumeral (GH) rotation position in modified knee push-up plus exercise (MKPUP) by examining the surface electromyography (EMG) amplitude in serratus anterior (SA), pectoralis major (PM), and upper trapezius (UTz) and the activity ratio of each muscle. Methods: A total of 22 healthy subjects volunteered for the study. Each subject performed the MKPUP at 0°, 45°, and 90° of GH joint internal rotation. EMG of the SA and PM, UTz was compared between GH rotation positions and each muscle activity ratio. EMG was used to measure the muscle activity in terms of ratios to maximal voluntary isometric contraction (MVIC). Results: The difference in EMG activity during the exercise in three GH joint internal rotation positions was observed with the SA and the PM. The greater the GH joint internal rotation angle was, the lower the activity of the PM. In contrast, the SA showed higher activity. However, the activity of UT was similar under all conditions. The ratio of the SA and the PM was considerably greater at 90° GH joint internal rotation than at 0° and 45°. Conclusion: When excessive activation of the PM or imbalanced activation between the PM and the SA occurs, the MKPUP exercise is most effective at 90° of GH joint internal rotation. Use of this position would be a beneficial strategy for selective strengthening of the SA and minimizing PM activation.

Prevalence of sleep disorders among ESRD patients

Sleep disorders are common among the patients undergoing dialysis in end stage renal disease (ESRD). Although variable, their prevalence has been reported to be higher when compared to the general population. The most frequently reported complaints are insomnia, restless leg syndrome (RLS), sleep-disordered breathing and excessive daytime sleepiness (EDS). The aim of this study was to assess the prevalence of sleep disorders in end stage renal disease patients on regular hemodialysis (group I with 30 patients) and CKD patients (group II with 30 patients) in comparison to 30 normal population (control group). In addition to laboratory investigations which included creatinine clearance using Cockroft and Gault formula, hemoglobin level (Hb), blood urea, serum creatinine, serum albumin, serum calcium and phosphorus and lipid profile, all subjects underwent one night of laboratory-based polysomnography (PSG) consisting of a standard montage of electroencephalography (EEG) (C3/A1 and O2/C3 or O1/C4), monopolar left and right electrooculography (EOG) referenced to the opposite mastoid, surface mentalis electromyography (EMG), respiratory airflow (measured by thermistor) and effort (piezoelectric sensors), electrocardiography (ECG), anterior tibialis EMG and pulse oximetry. For hemodialysis subjects, this study was performed on a night immediately following hemodialysis treatment. The results showed that patients on hemodialysis have sleep disorders, and that sleep disorders are common in group I and II than control group. The percentage of sleep disorders in hemodialysis patients were as follows: insomnia (69%), followed by obstructive sleep apnea syndrome OSAS (24%), RLS and periodic limb movement PLM (18%), nightmares (13%), EDS (12%), sleepwalking (2%), possible rapid eye movement behavior disorders RED (2%), possible narcolepsy (1.4%). While the percentage of sleep disorders in CKD patients were as follows: insomnia (54%), followed by RLS (19%), PLM (12%), OSAS (16%), nightmares (15%), EDS (15%), sleepwalking (4%), possible RBD (3%), possible narcolepsy (1%). There was inverse correlation between sleep disorders and Hb, albumin and creatinine clearance; also there was positive correlation between sleep disorder and phosphorus. We concluded that the sleep disorders are common in CKD patients either on conservative management or on regular hemodialysis. Treatment of anemia, hyperphosphatemia and hypoalbuminemia may improve sleep disorders among those patients.

Presynaptic inhibition of soleus Ia afferents does not vary with center of pressure displacements during upright standing

The present work was designed to investigate the presynaptic modulation of soleus Ia afferents with the position and the direction of the displacement of the center of pressure (CoP) during unperturbed upright standing and exaggerated CoP displacements in young adults. Hoffmann (H) reflex was evoked in the soleus by stimulating the tibial nerve at the knee level. Modulation of Ia presynaptic inhibition was assessed by conditioning the H reflex with fibular nerve (D1 inhibition) and femoral nerve (heteronymous facilitation) stimulation. Leg muscle activity was assessed by electromyography (EMG). The results indicate that in unperturbed standing and exaggerated CoP displacements, the H-reflex amplitude was greater during forward than backward CoP direction (p<0.05). However, the amplitude of the conditioned H reflex (expressed relative to unconditioned H reflex) did not vary with CoP displacement, regardless of the experimental condition. The soleus EMG was greater during forward than backward CoP direction and during anterior than posterior position in both experimental conditions (p<0.05). The modulation of the unconditioned H reflex with CoP direction was positively associated with the corresponding changes in soleus EMG (r2>0.34). The tibialis anterior EMG did not change during unperturbed standing, but was greater for backward than forward CoP direction during exaggerated CoP displacements. In this experimental condition, soleus EMG was negatively associated with tibialis anterior EMG (r2=0.81). These results indicate that Ia presynaptic inhibition is not modulated with CoP direction and position, but rather suggest that CoP displacements induced changes in excitability of the soleus motor neuron pool.

The effect of walking while typing on neck/shoulder patterns.

This project aimed to quantify the effects of modifying computer work posture on neck/shoulder patterns during a prolonged typing task. Twenty healthy participants completed a 90-min typing task while sitting or walking on a treadmill. Electromyography (EMG) was recorded from eight upper body muscles and laser Doppler flowmetry (LDF) from two upper body sites. Effects of Time and Posture were assessed for EMG amplitude (RMS), variability (CoV), normalized mutual information (NMI), LDF and upper limb discomfort. Upper limb discomfort was higher during sitting and increased with time, from 0.86 ± 1.3 to 3.7 ± 3.1 out of 10. Interaction effects showed that EMG amplitude decreased over time for the lumbar erector spinae (LES) (from 6.3 ± 2.9 to 5.6 ± 3.2 % MIVC) and wrist extensor (from 12.4 ± 2.7 to 11.3 ± 3.5 % MIVC) during walking, but increased during sitting. Anterior Deltoid EMG amplitude was 64 % lower during walking while External Oblique EMG amplitude (43 %) and Lower Trapezius EMG variability (65 %) were higher during walking. Interaction effects showed higher LES CoV during walking compared to sitting (p = 0.019) in the beginning but not at the end of the task, and higher neck/shoulder NMI (p = 0.050) towards the end of the task during sitting compared to walking. Results suggest that walking while performing computer work may be effective in inducing healthier muscular patterns, possibly explaining the lower level of discomfort compared to sitting.

Reduced plantar sole sensitivity induces balance control modifications to compensate ankle tendon vibration and vision deprivation

The aim of this study was to investigate if sensory reweighting occurred to control balance when the sensitivity of the plantar sole is reduced using cooling. To address this question, visual information was manipulated and/or ankle proprioception was altered by Achilles tendon vibration. It was expected that Achilles tendon vibration and vision deprivation would induce greater center of pressure (CoP) excursions and/or increase of electromyographic (EMG) activity of the ankle muscles (triceps surea and tibialis anterior) with than without cooling of the plantar sole. To verify these hypotheses, the CoP and EMG activity of the ankle muscles were simultaneously recorded during quiet standing trials of 30s before and after feet cooling procedure. Results showed that plantar sole sensitivity alteration did not lead to larger CoP excursions even during Achilles tendon vibration in absence of vision. This could be explained by an increase in the EMG activity of the triceps surae after the cooling procedure without modification of tibialis anterior EMG activity. This study suggests that to compensate alteration in plantar sole sensitivity, the central nervous system increased the muscular activity of the triceps surae to limit CoP excursions.

Investigation of Neurologic Complications in Closed Wedge High Tibial Valgization Osteotomy Technique by Using Electrophysiological Methods

Objective: The aim of this study is to investigate neurologic complications of closed wedge valgization osteotomy technique using electrophysiological methods. Methods: Eleven extremities of 11 patients (mean age 52.75±5.39) with medial gonarthrosis and varus deformity were included. All patients underwent closed wedge valgization osteotomy in order to correct varus deformity. Results: The post-operative amplitude of nervus peroneus superficialis significantly decreased when compared to pre-operative amplitude. The mean pre-operative N. peroneus superficialis amplitude was 12.77, whereas it reduced to 5.44 postoperatively (p<0.05). Other nerve conduction velocity investigations showed no significant differences between preand post-operative values. A Needle Electromyography (EMG) study demonstrated neurogenic involvement in 4 patients after surgery. All of these 4 patients had denervation in the m.extensor hallucis longus needle EMG study. In 2 patients, the musculus tibialis anterior needle EMG study showed neurogenic involvement. One of these had denervation. One patient showed denervation in the m.extensor digitorum brevis needle EMG study. Conclusion: Although fibula osteotomy used in the closed wedge osteotomy technique was applied from the safe zone, electrophysiological investigations suggested that this zone may, in fact, not be safe. (JAREM 2014; 1: 12-7)