Muscle Electromyographic Activity Research Articles

Safety of mapping the motor networks in the spinal cord using penetrating microelectrodes in Yucatan minipigs.

The goal of this study was to assess the safety of mapping spinal cord locomotor networks using penetrating stimulation microelectrodes in Yucatan minipigs (YMPs) as a clinically translational animal model. Eleven YMPs were trained to walk up and down a straight line. Motion capture was performed, and electromyographic (EMG) activity of hindlimb muscles was recorded during overground walking. The YMPs underwent a laminectomy and durotomy to expose the lumbar spinal cord. Using an ultrasound-guided stereotaxic frame, microelectrodes were inserted into the spinal cord in 8 animals. Pial cuts were made to prevent tissue dimpling before microelectrode insertion. Different locations within the lumbar enlargement were electrically stimulated to map the locomotor networks. The remaining 3 YMPs served as sham controls, receiving the laminectomy, durotomy, and pial cuts but not microelectrode insertion. The Porcine Thoracic Injury Behavioral Scale (PTIBS) and hindlimb reflex assessment results were recorded for 4 weeks postoperatively. Overground gait kinematics and hindlimb EMG activity were recorded again at weeks 3 and 4 postoperatively and compared with preoperative measures. The animals were euthanized at the end of week 4, and the lumbar spinal cords were extracted and preserved for immunohistochemical analysis. All YMPs showed transient deficits in hindlimb function postoperatively. Except for 1 YMP in the experimental group, all animals regained normal ambulation and balance (PTIBS score 10) at the end of weeks 3 and 4. One animal in the experimental group showed gait and balance deficits by week 4 (PTIBS score 4). This animal was excluded from the kinematics and EMG analyses. Overground gait kinematic measures and EMG activity showed no significant (p > 0.05) differences between preoperative and postoperative values, and between the experimental and sham groups. Less than 5% of electrode tracks were visible in the tissue analysis of the animals in the experimental group. There was no statistically significant difference in damage caused by pial cuts between the experimental and sham groups. Tissue damage due to the pial cuts was more frequently observed in immunohistochemical analyses than microelectrode tracks. These findings suggest that mapping spinal locomotor networks in porcine models can be performed safely, without lasting damage to the spinal cord.

EMG ACTIVITY OF MUSCLES OF THE CRANIOMANDIBULAR SYSTEM IN SUBJECTS WITH NARROWING UPPER JAW AND POSTERIOR CROSSBITE

Posterior crossbite in children and adolescents has been linked to asymmetrical function and performance of the masticatory muscles. Electromyography (EMG) serves as an objective and widely applicable evidence-based method for diagnosing muscle function. The aim of our study was to analyze electromyographic (EMG) activity of muscles of the craniomandibular system in subjects with a narrowing upper jaw and unilateral posterior crossbite. Material and methods. The first (study) group consisted of 18 subjects with narrow maxilla and unilateral posterior crossbite. 20 age-matched children with normal occlusion were included in the control group. The average age of subjects in the study group was 8.4±1.4 years, in the control group – 8.8±1.6 years. The exclusion criteria of the study were as follows: previous or active orthodontic treatment, clefts, traumas in the maxillofacial region, and general diseases. EMG activity of the anterior temporal, masseter, sternocleidomastoid (SCM), orbicularis oris, and mentalis muscles on both sides (left and right) was recorded during two 30-second tests: maximum voluntary clenching and swallowing a sip of water. Maximum voluntary clenching was performed in the intercuspal position. EMG data were processed using Neurotech's Synapsis software. EMG activity for each muscle was estimated by the maximum amplitude of the muscle contractions (μV). Results. EMG activity in children with narrowing upper jaw and unilateral posterior crossbite of anterior temporal, masseter, and sternocleidomastoid muscles was asymmetrical and differed between the left and right sides. Higher bioelectrical muscle activity was found on the crossbite side for the masseter and anterior temporalis muscle, and on the opposite side – for sternocleidomastoid muscles. Values of maximum amplitude of sternocleidomastoid muscles were higher in the study group than in the control group without significant difference. There was a statistically significant difference in EMG activity of mentalis and orbicularis oris muscles between the two groups of children (p<0.05). Values of EMG activity of mentalis and orbicularis oris were higher in the study group.

Knee extensor electromyographic activity during different depths of squat exercise in strength training experienced adults: A Systematic Review

B ACKGROUND: Changes in range of motion during partial and deep squats can affect the electrical activity of the knee extensor muscles. There are results’ divergences between studies that evaluated the effects of deep and partial squats on the electrical activity of the knee extensor muscles. AIM: To systematically review the literature on the electromyographic activity of the knee extensor muscles during partial and deep squat exercises in subjects with strength training experience. METHOD: The search included MEDLINE (via Pubmed), Scielo, EMBASE, in addition to a manual search, until June 2023. Cross-sectional observational studies comparing partial squats (up to 90º of knee flexion) and deep squats (maximum knee flexion) that evaluated the electrical activation through surface electromyography in men and women with strength training experience were included. Methodological quality assessment was performed using the adapted Downs and Black tool, as suggested by the Cochrane Collaboration.  RESULTS: Of the 636 articles identified, four studies were included. The included studies presented electromyographic values of the two squat variations. No difference was found in the activation of the rectus femoris, vastus medialis and vastus lateralis muscles between partial and deep squats. Regarding methodological quality, one study was classified as having moderate and the other three studies showing high methodological quality. CONCLUSION: The similarity in the knee extensors’ electromyographic activation between partial and deep squat exercises in men and women with strength training experience suggests that both exercises can be used for recruiting these muscles during physical fitness activities.   

Predicting hand grip force based on muscle electromyographic activity using artificial intelligence and neural networks

The research aims to find predictive values for hand grip strength based on electromyographic activity, in addition to identifying differences between measured grip strength and the predicted grip strength. The research sample included 12 advanced handball players, with their medical records verified. Researchers measured grip strength using a device designed to read Newton force, recording data in real-time with a sampling window of 0.1 seconds. This measurement was synchronized with the recording of muscle electromyographic activity (sEMG) using the Noraxon myoMOTION technique, with a frequency and number of channels set at 400Hz and 8 channels, respectively. The recommended methodology and conditions were strictly adhered to, with the process repeated for each player with complete rest intervals. The following research variables were adopted: peak electromyographic activity, root mean square, time to peak, time ratio between peak and minimum values, average peaks, area under the curve, peak sustain time, peak changes, and voluntary maximum contraction. Grip strength measurements using the designed device were conducted at three stages (50%, 75%, 100%), maintaining the specified intensity for 3 seconds. After data collection, preliminary processing involved isolation and purification to identify the most influential factors. IBM Statistical was the chosen technique for implementing neural networks and using artificial intelligence techniques to process data with a database synchronized using Python. The results generally supported some of the proposed ideas, with interesting findings revealing statistically insignificant and slight differences between recorded and expected grip strength

Comparison of the Electromyography Activity during Exercises with Stable and Unstable Surfaces: A Systematic Review and Meta-Analysis.

The effect of electromyographic (EMG) activity on agonist muscles during exercises performed on stable and unstable surfaces remains uncertain. We aimed to review the literature regarding the comparison of the EMG activity of the agonist muscles of exercises performed on stable and unstable surfaces. Eighty-six studies that evaluated the EMG activity of 1783 individuals during exercises for the lower limbs, upper limbs, and core were included. The EMG activities of the pectoralis major (SMD = 0.28 [95% CI 0.09, 0.47]) and triceps brachii muscles (SMD = 0.45 [95% CI 0.25, 0.66]) were significantly increased when the unstable device was added to the exercise. Likewise, the EMG activity of all core muscles showed a significant increase with the unstable surface during the exercises, such as the rectus abdominis (SMD = 0.51 [95% CI 0.37, 0.66]), external oblique (SMD = 0.44 [95% CI 0.28, 0.61]), internal oblique (SMD = 1.04 [95% CI 0.02, 2.07]), erector spinae (SMD = 0.37 [95% CI 0.04, 0.71]), and lumbar multifidus (SMD = 0.35 [95% CI 0.08, 0.61]). However, the lower limb muscles did not show greater EMG activity during the exercise with unstable surfaces compared to the stable surface. In conclusion, unstable conditions increase the EMG activity of some upper limb and core muscles compared to a stable surface.

A Comprehensive Analysis of Trapezius Muscle EMG Activity in Relation to Stress and Meditation

Introduction: This study analyzes the efficacy of trapezius muscle electromyography (EMG) in discerning mental states, namely stress and meditation. Methods: Fifteen healthy participants were monitored to assess their physiological responses to mental stressors and meditation. Sensors were affixed to both the right and left trapezius muscles to capture EMG signals, while simultaneous electroencephalography (EEG) was conducted to validate cognitive states. Results: Our analysis of various EMG features, considering frequency ranges and sensor positioning, revealed significant changes in trapezius muscle activity during stress and meditation. Notably, low-frequency EMG features facilitated enhanced stress detection. For accurate stress identification, sensor configurations can be limited to the right trapezius muscle. Furthermore, the introduction of a novel method for determining asymmetry in EMG features suggests that applying sensors on bilateral trapezius muscles can improve the detection of mental states. Conclusion: This research presents a promising avenue for efficient cognitive state monitoring through compact and convenient sensing.

Electromyographic Assessment of Muscle Activity in Children Undergoing Orthodontic Treatment-A Systematic Review.

Background: Surface electromyography (sEMG) can provide an objective and quantitative image of the functional state of neuromuscular balance in the stomatognathic system. The objective of this systematic review is to examine current scientific evidence regarding the effects of orthodontic treatment on muscle electromyographic (EMG) activity in children. Methods: The search strategy included the PubMed, PubMed Central, Web of Science, Scopus, and Embase databases. The inclusion criteria were studies assessing EMG muscle activity in children undergoing orthodontic treatment compared with untreated children. The Cochrane risk-of-bias tool (RoB2) and the Newcastle-Ottawa Scale (NOS) were used to evaluate the quality of the studies. The quality of evidence assessment was performed using GRADE analysis. The PRISMA diagram visually represented the search strategy, as well as screening and inclusion process. Results: The search strategy identified 540 potential articles. Fourteen papers met the inclusion criteria. Six studies were judged at a low risk of bias. The certainty of evidence was rated as moderate to low, according to the GRADE criteria. Studies showed alterations in EMG muscle activity in children undergoing orthodontic treatment. Conclusions: Orthodontic treatment appears to affect muscle activity in children undergoing orthodontic treatment. However, the quality of evidence is low and, therefore, it is not possible to definitively state this effect. Further long-term studies are needed to confirm the findings of this review. Study protocol number in PROSPERO database: CRD42023491005.

Effects of scapular treatment on chronic neck pain: a systematic review and meta-analysis of randomized controlled trials

BackgroundChronic neck pain (CNP) is a common public health problem that affects daily living activities and quality of life. There is biomechanical interdependence between the neck and scapula. Studies have shown that shoulder blade function might be related to chronic neck pain. We therefore evaluated the effects of scapular targeted therapy on neck pain and function in patients with CNP.MethodsDatabases, including MEDLINE (via PubMed), EMBASE (via Ovid), Ovid, Web of Science, and Scopus, were systematically searched for randomized controlled trials published in English investigating treatment of the scapula for CNP before July 16, 2023.ResultsA total of 313 participants were included from 8 RCTs. Compared with those in the control group, the intervention in the scapular treatment group exhibited greater improvement in pain intensity (standardized mean difference (SMD) = 2.55; 95% CI = 0.97 to 4.13; P = 0.002), with moderate evidence. Subgroup analysis for pain intensity revealed a significant difference between the sexes, with only the female population (SMD = 6.23, 95% CI = 4.80 to 7.65) showing better outcomes than those with both sexes (SMD = 1.07, 95% CI = 0.57 to 1.56) (p < 0.00001). However, moderate evidence demonstrated no improvement in neck disability after scapular treatment (SMD of 0.24[-0.14, 0.62] of Neck Disability Index or Northwick Park Neck Pain Questionnaire). No effect of scapular treatment was shown on the pressure pain threshold (PPT). The cervical range of motion (CROM) and electromyographic activity of neck muscles could not be conclusively evaluated due to limited support in the articles, and further study was needed. However, the patient’s head forward posture appeared to be corrected after scapular treatment.ConclusionScapular therapy was beneficial for relieving pain intensity in patients with CNP, especially in women. Head forward posture might also be corrected with scapular therapy. However, scapular therapy may have no effect on the PPT or neck disability. However, whether scapular therapy could improve CROM and cervical muscle activation in patients with CNPs had not been determined and needed further study.

Electromyographic activity of pelvic floor muscles in different positions during the use an innovative vaginal educator: Cross-sectional study.

The pelvic floor requires an integrated anatomical structure owing to its multiple functions. Therefore, it is necessary to study methods for improving muscle recruitment during training. This study aimed to analyze the effect of using an innovative vaginal trainer on the bioelectrical activity of the pelvic floor muscles. Pelvic positioning and interference factors, such as age, childbirth, sexual activity, urinary incontinence, and menopause, were also analyzed. A cross-sectional study assessed 30 women using an evaluation form, International Consultation on Incontinence Questionnaire-Short Form, and surface electromyography. The root mean square of a 5-second contraction period, peak root mean square values, area values, % maximal voluntary contraction (root mean square normalized by peak signal), and median frequency were collected. These findings with and without the use of a vaginal educator were compared in the anteversion, neutral, and retroversion pelvic positions. The use of a vaginal educator was found to increase the electromyographic activity of the pelvic floor muscles in the neutral position. In this position, older women showed an increased peak contraction when using the educator. Multiparas also benefited from increased bioelectric activity (root mean square and area). Sexually active women increased their bioelectric activity in a neutral position when using the trainer, exerting less effort in retroversion (%-maximal voluntary contraction). Incontinent and menopausal women exhibited slower body-building activation (decreased frequency) with the device, which requires further investigation. Our innovative biofeedback device induced greater recruitment of muscle fibers, is more effective in the neutral pelvic position, and may be effective in training the pelvic floor muscles, even in women with a greater tendency toward pelvic floor dysfunction.

Electroneuromyography comparison between pre-elderly adult females with and without MS; the potential role of a mind-body therapy in improving neurophysiological profile of MS during pandemic

IntroductionImaginary exercises seem to be useful therapeutic approaches to modulate neuromuscular functions due to two main reasons: first, this training would not greatly increase body temperature, and secondly, it can positively affect brain-muscle pathways—which are both primary factors should be considered in rehabilitation programs for patients with multiple sclerosis (MS). Method32 pre-elderly adult females with relapsing-remitting MS (n = 16 - age M (SD): 56.75 (5.07)) and without MS (n = 16 - age M (SD): 56.56 (4.35)) voluntarily recruited. First, they were assigned into two groups: MS patients and healthy controls, to investigate baseline between-group comparison. Then, MS patients were randomly divided into two groups of eight each, designated as experimental and control groups. Recording the nerve conduction velocity (NCV) of tibial nerve and integrated electromyographic muscle activation (IEMG) of gastrocnemius muscle was conducted twice, before and after a six-week mind-body exercise therapy to evaluate its effectiveness on improving neuromuscular function. ResultsThe results showed significant difference in both tibial NCV (P < 0.001) and IEMG (P = 0.001) variables between non-MS group and MS group. Furthermore, there was a significant main effect of intervention (P = 0.05) and time (P < 0.001) on IEMG in the MS group, while there was no significant effect of intervention (P = 0.18) and time (P = 0.23) on NCV (p = 0.89). ConclusionNeuromuscular dysfunction were apparent in MS patients, and a mind-body therapy of imagery isometric training was found to be useful on improving the neurological deficit in women with MS. Trial registration numberUMIN000046935.

The Effect of Variations in Knee and Hip Angles on Electromyographic Activity of the Hamstrings and Related Muscles During the Nordic Hamstring Exercise.

The benefit of performing the Nordic Hamstring Exercise (NHE) on an inclined board has been described, however, isometric hamstring activation in different knee and hip angles has not yet been thoroughly explored. This study investigated the effect of variations in knee and hip angles during the isometric performance of the NHE on electromyographic activity of the hamstring muscles. Crossover study. Thirteen male volunteers performed isometric contractions during the NHE with the knee (30°, 50°, 60°) and the hip (0°, 30°, and 45°) in various angles of flexion on a leg support platform which was inclined at 30°. An electrical goniometer was used to monitor the knee and hip joint angles during 5-s isometric contractions. A multivariate analysis of variance with repeated measures was used to compare normalized electromyographic values of each muscle across different knee and hip angles, followed by pairwise comparisons. The electromyographic activity of the biceps femoris, semitendinosus, and semimembranosus at a knee angle of 30° and hip angle of 0° were significantly higher than those observed with a knee angle of 50° and hip angle of 0°, or a knee angle of 60° and hip angle of 0° (p<0.05). The electromyographic activity of the semimembranosus at a knee angle of 60° and hip angle of 45° was significantly higher than values obtained with knee and hip angles of 60° and 0°, respectively (p<0.05). The results indicate that using a knee flexion of 30° and a hip flexion of 0°, while isometrically performing the NHE on a platform inclined at 30°, may optimize electromyographic activity of the hamstrings. 3.

Clinical and electromyographic signals analysis about the effect of space-adjustment splint on overerupted maxillary molars

BackgroundOvererupted maxillary molars is common in adults, which can lead to insufficient intermaxillary vertical space ,great difficulty in prosthetic reconstruction ,and cause occlusal interference in movements.To reconstruct occlusal function, it is necessary to prepare enough space for prostheses. The aim of the present study was to evaluate the effect of space-adjustment occlusal splint on overerupted maxillary molars by clinical and electromyographic signals analysis.MethodsEighteen patients with overerupted maxillary molars were selected to wear space-adjustment occlusal splint suppressing overerupted maxillary molars for three months. Satisfaction was assessed by 5-point Likert; intermaxillary vertical space and the teeth transportation distance were measured in models; clinical periodontal status were evaluated by periodontal probing depth (PPT) and bleeding index (BI); electromyographic recordings of the masseter and anterior temporal muscles were monitored by Cranio-Mandibular K7 Evaluation System.ResultsAll the patients were satisfied with the treatment effect (Likert scale ≧ 4). The intermaxillary space in edentulous areas after treatment showed statistically significant increasing when compared with those before treatment. PPT and BI showed no significant difference. No statistically significant differences were found in electromyographic activity of anterior temporal muscles, while a reduction of muscle activity in masseter in the contralateral side were detected in post-treatment evaluations compared with pre-treatment at mandibular rest position.ConclusionsSpace-adjustment occlusal splint is an efficient treatment option on overerupted maxillary molars by intruding the maxillary molar to obtain adequate intermaxillary space for prostheses.

Impact of Ergonomics on Muscle Fatigue During Surgical Drilling Using Surface Electromyography.

To investigate the relationship between ergonomic positions and electromyographic muscle activity during otologic drilling. Cross-over experimental trial. Tertiary Academic Medical Center. Surgeon participants were tasked with delicate eggshell drilling in 3 different seated positions: "neutral,""slouched,"and "craned." Surface electromyography (sEMG) sensors recorded the amplitude and frequency of muscle activity. The joint analysis of spectrum and amplitude (JASA) method, which combines temporal trends in frequency and amplitude, was used to identify trials that exhibited patterns of fatigue. The sEMG amplitude and frequency responses demonstrated wide temporal changes. In a majority of experiments, amplitude increased over the course of the experiment, while frequency remained more stable. On analysis of variance testing, only the mean frequency of the deltoid differed significantly between postures (P = .02). Under the JASA framework, external carpi radialis and upper trapezius experienced fatigue in nearly half of the trials regardless of position (47% vs 49%). The upper trapezius demonstrated fatigue during 46% and 69% of the "craned" and "slouched" trials, respectively, compared to just 31% of the "neutral" trials. Fewer attendings demonstrated upper trapezius fatigue compared to trainees (33% vs 62%). Female surgeons experienced fatigue in more trials than male counterparts (73% vs 25%). This study highlights a first step in quantifying the relationship between operating postures and muscle fatigue. Results suggest that specific muscle groups are more susceptible to fatigue; gender and experience may also impact muscle activity.

Evaluating peripheral neuromuscular function with brief movement-evoked pain.

Movement-evoked pain is an understudied manifestation of musculoskeletal conditions that contributes to disability, yet little is known about how the neuromuscular system responds to movement-evoked pain. The present study examined whether movement-evoked pain impacts force production, electromyographic (EMG) muscle activity, and the rate of force development (RFD), during submaximal muscle contractions. Fifteen healthy adults (9 male, age = 30.3 ± 10.2; range = 22-59) performed submaximal isometric first finger abduction contractions without pain (baseline) and with movement-evoked pain induced by laser stimulation to the dorsum of the hand. Normalized force (% maximal voluntary contraction) and RFD decreased by 11% (p<0.001) and 15% (p=0.003), respectively, with movement-evoked pain, without any change in normalized peak EMG (p=0.77). Early contractile RFD, force impulse, and corresponding EMG amplitude computed within time segments of 50, 100, 150, 200ms relative to the onset of movement were also unaffected by movement-evoked pain (p>0.05). Our results demonstrate that movement-evoked pain impairs peak characteristics and not early measures of submaximal force production and RFD without affecting EMG activity (peak and early). Possible explanations for the stability in EMG with reduced force includes antagonist coactivation and a reorganization of motoneuronal activation strategy, which will be discussed herein.

Electromyographic activity of core muscles in isometric pole dance exercises with thigh locks

There is little technical and scientific research on Pole Dancing — an artistic, sensual and sporting activity based on friction and opposition between the body and a bar. The objective of this study is to analyze and compare the electromyographic (EMG) activity of the rectus abdominis (RA), obliquus externus abdominis (OE), and erector spinae (ES) muscles during the execution of different isometric Pole Dance exercises using the thigh lock to fix the body on the bar in the vertical, horizontal and inverted positions (basic seat, plank seat, and inverted seat). Experimental study consisting of a convenience sample of ten female Pole Dance practitioners with more than one year of experience and physically active. The EMG signal obtained during all exercises was quantified in the time domain by root mean square (RMS) and normalized by maximal voluntary isometric contraction (MVIC). Data were collected using simple differential surface electrodes and analyzed using repeated-measures analysis of variance. The results showed a significant difference only for the ES muscle, which was higher for the inverted position when compared to the vertical and horizontal ones. The three exercises produced low to moderate EMG activity in the muscles analyzed. Therefore, these exercises can be prescribed both for Pole Dance training programs — its variations present interesting intensity progression — and for low back pain prevention, as they can improve trunk neuromuscular control.

Electromyographic activity of periscapular muscles in symptomatic people: Does scapular dyskinesis have an impact on it?

BACKGROUND: Scapular dyskinesis (SD) is a modification of the positioning and movement of the scapula and is associated with shoulder pain. Exercises to strengthen the shoulder and scapular muscles have been proposed as a therapeutic strategy to reduce pain and improve function. OBJECTIVE: We aimed to investigate the electromyographic activity of the periscapular and trunk muscles in individuals with shoulder pain and SD in different multi-joint exercises. METHODS: Thirty-two subjects with subacromial pain, of both sexes, with the presence or absence of SD, participated in this study. Volunteers performed five repetitions in five exercises (Closed Row; Pronated Row; Push-up; Scapular Push-up; T-push-up). The activity of the upper trapezius, middle trapezius, lower trapezius, serratus anterior, external oblique, and rectus abdominis muscles was recorded using electromyography. RESULTS: Our results showed a decrease in the electromyographic activity of the serratus anterior and external oblique during the T-push-up exercise in individuals with shoulder pain and SD. No differences were observed between groups for the trapezius and the rectus abdominis. CONCLUSIONS: Rehabilitation programs may initially prioritize rowing and push-up exercises to strengthen periscapular muscles. More complex exercises with greater mechanical demand on the kinetic chain, such as the T-push-up, may have to be implemented in later phases.

Type of correlation between bite force and EMG activity of the temporalis and masseter muscles during maximal and submaximal clenching.

Maximal bite force is an important determinant of masticatory function and is essential for the estimation of dental status. Bite force is usually measured by gnathodynamometry.

Quantifying the effectiveness of a passive trunk-support exosuit at reducing erector spinae muscle fatigue during a quasi-static posture maintenance task

The objective of this study was to explore the effectiveness of a passive back-support exosuit at reducing low back muscle fatigue during an 18-minute trunk posture maintenance task. On two separate days sixteen participants performed an 18-minute trunk posture profile that reflected trunk flexion postures observed during a challenging vascular surgery procedure. On one day they performed the procedure with the support of the exosuit, on the other day without. Test contractions were performed every three minutes to capture the time-dependent electromyographic activity of the bilateral erector spinae muscles. Time domain (amplitude) and frequency domain (median frequency) measures of erector spinae muscle fatigue were assessed. Results revealed that the exosuit significantly reduced the measures of erector spinae muscle fatigue in terms of both amplitude (6.1%) and median frequency (5.3%), demonstrating a fatigue reduction benefit of the exosuit in a realistic surgical posture maintenance task.

Electromyographic Activity of Lower Limb Muscles during Ankle Destabilizing Tests.

Ankle destabilizing devices were developed to improve the recruitment of the evertor muscles. Nevertheless, the activity of lower-leg muscles has never been compared to each other during functional tests performed with destabilization. The objectives were i) to compare the electromyographic activity between the lower-leg muscles during four functional tests performed with ankle destabilization, and ii) to determine sex-related differences in neuromuscular activation. Twenty-six healthy volunteers (13 males, 13 females) performed the modified Star Excursion Balance Test (mSEBT), unipedal balance and weight-bearing inversion and eversion tests with a destabilizing device, while recording electromyographic activity of the peroneus longus and brevis, tibialis anterior, gastrocnemius lateralis and gluteus medius. The activity of peroneal muscles was significantly greater than other muscles during all functional tests. Furthermore, the anterior direction of the mSEBT was the one implying the greatest activity of the peroneus longus muscle compared to the posteromedial (p=0.003) or posterolateral (p<0.001) directions. Finally, no significant sex-related differences in neuromuscular activity were reported. This study highlights the effectiveness of the destabilizing device to involve specifically the peroneal muscles when performing various functional tests. This device should be used by clinicians to be more specific to the stabilizers of the ankle joint during functional exercises.

Effects of Expertise on Muscle Activity during the Hang Power Clean and Hang Power Snatch Compared to Snatch and Clean Pulls - An Explorative Analysis.

The purpose was to compare the electromyographic (EMG) activity of the Hang Power Clean (HPC) and Hang Power Snatch (HPS) with the Hang Clean Pull (HCP) and Hang Snatch Pull (HSP). Additionally, the influence of weightlifting expertise (beginner, advanced and elite) on EMG activity was analyzed. Twenty-seven weightlifters (beginner: n = 11, age: 23.9 ± 3.2 years, bodyweight: 75.7 ± 10.5 kg; advanced: n = 10, age: 24.8 ± 4.5 years, bodyweight: 69.4 ± 13.9 kg; elite: n = 6, age: 25.5 ± 5.2 years, bodyweight: 75.5 ± 12.5 kg) participated in this study. Participants performed two repetitions of HPC, HPS, HCP, and HSP at 50%, 70%, and 90% 1RM, respectively. The EMG activity of vastus lateralis (VL), gluteus maximus (GM), erector spinae (ES), rectus abdominis (RA) and trapezius (TZ) was recorded and normalized to the maximum voluntary isometric contraction (MVIC) of each muscle. There were significant differences in RA and ES EMG activity at 70% and 90% 1RM during HPC compared to HCP in the beginner group (p < 0.05, Hedges g = 0.50-1.06). Significant greater ES activity was observed in the beginner, advanced, and elite groups (p < 0.05, g = 0.27-0.98) during the HPS when compared to the HSP at 50-90% 1RM. TZ muscle activity was significantly greater at 50% and 70% 1RM in the HCP compared to the HPC in the elite group (p < 0.05, g = 0.61-1.08), while the beginner group reached significance only at 50% 1RM favoring HPC (p < 0.05, g = 0.38). Moreover, the EMG activity of the TZ during the HSP and HPS was significantly different only at 50% 1RM in the elite group and favored HSP (p < 0.05, g = 0.27). No differences were observed between the levels of weightlifting expertise. Based upon the results of this study, the overall pattern of EMG activity of the predominant muscles involved in HPC/HPS and the corresponding weightlifting pulling derivatives, apart from the stabilizing muscle (RA and ES), is similar at higher intensities (>70% 1RM) and expertise does not influence muscle activity.