Electromyographic Variables Research Articles

Effects of simulated hypo-gravity on lower limb kinematic and electromyographic variables during anti-gravitational treadmill walking.

Introduction: This study investigated kinematic and EMG changes in gait across simulated gravitational unloading levels between 100% and 20% of normal body weight. This study sought to identify if each level of unloading elicited consistent changes-particular to that percentage of normal body weight-or if the changes seen with unloading could be influenced by the previous level(s) of unloading. Methods: 15 healthy adult participants (26.3 2.5years; 53% female) walked in an Alter-G anti-gravity treadmill unloading system (mean speed: 1.49 mph) for 1min each at 100%, 80%, 60%, 40% and 20% of normal body weight, before loading back to 100% in reverse order. Lower-body kinematic data were captured by inertial measurement units, and EMG data were collected from the rectus femoris, biceps femoris, medial gastrocnemius, and anterior tibialis. Data were compared across like levels of load using repeated measures ANOVA and statistical parametric mapping. Difference waveforms for adjacent levels were created to examine the rate of change between different unloading levels. Results: This study found hip, knee, and ankle kinematics as well as activity in the rectus femoris, and medial gastrocnemius were significantly different at the same level of unloading, having arrived from a higher, or lower level of unloading. There were no significant changes in the kinematic difference waveforms, however the waveform representing the change in EMG between 100% and 80% load was significantly different from all other levels. Discussion: This study found that body weight unloading from 100% to 20% elicited distinct responses in the medial gastrocnemius, as well as partly in the rectus femoris. Hip, knee, and ankle kinematics were also affected differentially by loading and unloading, especially at 40% of normal body weight. These findings suggest the previous level of gravitational load is an important factor to consider in determining kinematic and EMG responses to the current level during loading and unloading below standard g. Similarly, the rate of change in kinematics from 100% to 20% appears to be linear, while the rate of change in EMG was non-linear. This is of particular interest, as it suggests that kinematic and EMG measures decouple with unloading and may react to unloading uniquely.

The effects of the Posterior X Taping versus augmented feedback on lower-extremity kinematic and muscle activity pattern during unilateral weight-bearing activities in men with tibiofemoral varus malalignment

PurposeTibiofemoral Varus Malalignment (TFRV) contributes to overuse injuries by altering lower limb biomechanics. Both Posterior X Taping (PXT) and Real Time Feedback (RTF), have each been recommended for subjects with TFRV as they are thought to enhance control of excessive tibiofemoral rotations. This paper evaluates this claim.MethodsA total of recreational male 24 athletes with TFRV participated in the current study. Kinematic and electromyography variables of lower extremity were synchronously ​recorded on five consecutive repetitions of the single-legged-squat (SLS) and forward-step-down) FSD) tasks before and after applications of PXT and RTF.ResultsThe subjects at post-intervention in RTF group exhibited decreased hip adduction during FSD, and decreased hip adduction and internal rotation during eccentric and concentric phases of the SLS; Additionally, we observed increased gluteus medius activity during eccentric phase of the SLS and FSD tasks. In contrast, subjects at the post-intervention in PXT group exhibited decreased tibiofemoral external rotation and increased ankle external rotation during all the phases of both SLS and FSD tasks.ConclusionThese results suggest that the PXT and RTF interventions are recommended to immediately improve the functional defects of the subjects with TFRV during SLS and FSD tasks.

Hip Abductor Muscle Fatigue Induces Different Strategies During Disrupted Postural Control.

BackgroundAnkle sprain is one of the most common injuries in sport, and hip abductor muscle weakness has recently been reported as a predisposing factor. Currently, the influence of hip abductor muscle fatigue on ankle joint control has not been elucidated during an ankle disturbed balance exercise. This study aimed to determine the influence of hip abductor muscle fatigue on ankle joint control during a disturbed balance task, and to consider inter-individual variability in the kinematic and neuromuscular reorganizations implemented.MethodsTwenty-six healthy subjects (13 males; 13 females) performed a unipedal postural balance task with eyes closed before and after a fatiguing exercise (up to a 50% decrease in strength) of the hip abductor muscles. Subjects completed balance task while equipped with an ankle destabilization device that allows inversion/eversion movements. Electromyographic (EMG) activity of the gastrocnemius lateralis (GastL), peroneus longus (PL) and brevis, tibialis anterior, and gluteus medius were recorded during task. Kinematics (e.g., frontal foot angulation) of the ankle complex were determined using inertial measurement units.ResultsIn the overall group, no significant time, sex or interaction effect was observed for kinematic and EMG variables. However, when considering individual responses to hip fatigue, 14 subjects decreased the standard deviation of frontal angulation (−30%) suggesting enhancement of ankle joint control, while 12 subjects increased it (+46%). Normalized EMG for PL and GastL muscles changed with fatigue for both these groups. However, variations were significantly different between groups (p = 0.027 for PL and p = 0.006 for GastL). Indeed, the contribution of ankle muscles increased for the enhanced-stability group while no change for the impaired-stability group.ConclusionThese results highlight that subject adopt different neuromuscular and kinematic ankle strategies to control ankle destabilization in response to hip abductor muscle fatigue. Frontal foot angulation variability seemed to be a valuable marker to detect the type of strategy employed. The strategy adopted by the impaired-stability group might have important implications when analyzing risk factors for ankle sprains. Further studies should consider individual responses to fatigue, to understand which factor could predispose athletes to use of one or other strategy.

Inference of Upcoming Human Grasp Using EMG During Reach-to-Grasp Movement.

Electromyography (EMG) data has been extensively adopted as an intuitive interface for instructing human-robot collaboration. A major challenge to the real-time detection of human grasp intent is the identification of dynamic EMG from hand movements. Previous studies predominantly implemented the steady-state EMG classification with a small number of grasp patterns in dynamic situations, which are insufficient to generate differentiated control regarding the variation of muscular activity in practice. In order to better detect dynamic movements, more EMG variability could be integrated into the model. However, only limited research was conducted on such detection of dynamic grasp motions, and most existing assessments on non-static EMG classification either require supervised ground-truth timestamps of the movement status or only contain limited kinematic variations. In this study, we propose a framework for classifying dynamic EMG signals into gestures and examine the impact of different movement phases, using an unsupervised method to segment and label the action transitions. We collected and utilized data from large gesture vocabularies with multiple dynamic actions to encode the transitions from one grasp intent to another based on natural sequences of human grasp movements. The classifier for identifying the gesture label was constructed afterward based on the dynamic EMG signal, with no supervised annotation of kinematic movements required. Finally, we evaluated the performances of several training strategies using EMG data from different movement phases and explored the information revealed from each phase. All experiments were evaluated in a real-time style with the performance transitions presented over time.

Kinematic and Kinetic Characteristics of Repetitive Countermovement Jumps with Accentuated Eccentric Loading.

Two methods for challenging the musculoskeletal and nervous systems to better exploit the stretch-shortening cycle (SSC) mechanism during plyometric training are reactive strength exercises and accentuated eccentric loading (AEL). Combining repetitive, reactive jumping with AEL poses a novel approach, in which the effects of both methods may be combined to elicit a unique stimulus. This study compared kinematic, kinetic, and electromyographic variables between a control (CON1) and two AEL conditions (AEL2 and AEL3). Additionally, non-reactive and reactive jumps performed within these sets were compared. Participants performed two sets of six countermovement jumps (CMJ) under each loading condition. AEL3 had moderate to large positive effects (es) on peak and mean eccentric force (es = 1.1, 0.8, respectively; both p < 0.01), and eccentric loading rate (es = 0.8, p < 0.01), but no effect on concentric variables or muscle activation intensity. The effects of AEL2 were similar but smaller. With or without AEL, there were moderate to large positive effects associated with reactive CMJ (second jump in a set, compared to the first) on peak and mean eccentric velocity (es = 1.7, 0.8, respectively; both p < 0.01), peak and mean eccentric force (es = 1.3, 1.2, p < 0.01), eccentric loading rate (es = 1.3, p < 0.01) and muscle activity (es = 1.8–1.9, p < 0.01). Concentric variables did not differ. Thus, the flight phase and act of landing during reactive jumps elicited greater increases in eccentric forces, loading rates, and muscle activity than AEL. Nonetheless, kinetic variables were greatest when AEL was combined with reactive jumping. Considering the limitations or complexity associated with most AEL protocols, sets of repetitive (reactive) CMJ may be more pragmatic for augmenting eccentric kinetic variables and neuromuscular stimuli during training.

Electrophysiological evaluation of alterations in penile sensation due to penile prosthesis implantation in patients with erectile dysfunction

ObjectiveThe present study was aimed to determine the effect of penile prosthesis implantation (PPI) surgery on penile sensation by evaluating the penile electromyography (EMG) variables. MethodsThe research was designed as a prospective study. Thirty patients who were diagnosed with organic erectile dysfunction and had underwent PPI surgery between January 2017 and January 2018 in the Urology Clinic of Antalya Training and Research Hospital were included in this study. Penile sensory EMG was performed on each patient 1 day prior to the surgery by the Physical Therapy and Rehabilitation clinic. Additionally, the control EMG study was also performed in the 3rd and 6th postoperative months. ResultsWe included 27 patients in this study who attended regular follow-ups and had complete EMG results. Out of the 27 patients, 23 (85.2%) patients had received malleable (ProMedon) penile prosthesis, one (3.7%) patient had received a two-piece inflatable (Ambicor) penile prosthesis, and three (11.1%) patients had received a three-piece inflatable (AMS 700 CXR) penile prosthesis. The mean nerve conduction value (NCV) of the patients was 29.85 (standard derivation: 22.54; range: 0–78.4) m/s during the preoperative period, whereas it was 27.64 (standard derivation: 24.72; range: 0–83.3) m/s in the 3rd postoperative month and 24.80 (standard derivation: 22.31; range: 0–88.4) m/s in the 6th postoperative month. There was no significant difference between preoperative NCV and 3rd postoperative month NCV (p=0.607). Similarly, no significant difference was observed between preoperative NCV and 6th postoperative month NCV (p=0.276). Additionally, the change between NCV values at postoperative 3rd and 6th months was not statistically significant (p=0.553). ConclusionSignificant loss of penile sensation does not occur in patients who undergo PPI surgery.

Comparison of the Effectiveness of Traditional and Post-activation Potentiation Warm-up Methods on EMG Variables of Selected Lower Limb Muscles During Squat Jump

Purpose: A proper warm-up method can be used as a strategy to improve the performance of athletes in various sports fields. The present study aimed to compare the effect of two traditional and post-activation potentiation (PAP) warm-up methods on electromyographic variables of lower limb muscles during squat jumps. Methods: Fourteen trained male athletes randomly performed three different protocols: traditional warm-up method, dynamic post-activation potentiation (PD) by implementing two dynamic half-squat repetitions with 90% 1RM (one rep maximum), and static post-activation potentiation (PS) warm-up by implementing two static half-squat repetitions with 90% 1RM. Vertical jump tests were performed five minutes after implementing each protocol (recovery time). EMG activity of the rectus femoris, vastus lateralis, vastus medialis, biceps femoris, semi-tendinous, medial gastrocnemius, and tibialis anterior was recorded. Also, the co-contraction index and median frequencies were calculated. Repeated measures analysis of variance (ANOVA) was used for data analysis (P&lt;0.05). Results: The results of this study showed that the activity level of all muscles in the concentric and flight phases, the co-contraction index of the ankle and knee joints, and also median frequencies of rectus femoris, vastus lateralis, semi-tendinous, biceps femoris, and medial gastrocnemius significantly changed in the PD and PS warm-up methods compared to the traditional warm-up method (P≥0.05). Also, the activity level of rectus femoris, vastus medialis, and biceps femoris muscles had a significant difference between the PD and PS compared to the traditional warm-up method in the eccentric phases (P≥0.05). Conclusion: According to the study results, the PAP warm-up method can improve the performance of athletes in training and competition conditions.

Comparing exercises with and without electromyographic biofeedback in subacromial pain syndrome: A randomized controlled trial

BackgroundDeficits in movement and muscle activation of scapulohumeral joint are related to Subacromial Pain Syndrome. Electromyography biofeedback during exercise may enhance muscle activation and coordination, and consequently improve pain and shoulder function. MethodsThis study compared the effects of an exercise protocol with and without using electromyographic biofeedback on pain, function and movement of the shoulder complex in subjects with Subacromial Pain Syndrome. A total of 24 patients with subacromial pain (mean age = 46.2 + 8.1;18 women) were randomized to either therapeutic exercise or exercise plus biofeedback to the trapezius and serratus muscles. Pain and shoulder function were evaluated as the primary outcome and range of motion, muscle strength, electromyographic activity and scapulohumeral kinematics as secondary outcomes. The subjects underwent eight weeks of intervention and comparisons were made between groups in baseline, at 4 weeks, 8 weeks, and at 4 weeks post intervention. FindingsThere were differences between groups for pain [mean difference = 1.5 (CI 0.3, 3.2) p = 0.01] at 8 weeks in the Exercise group and scapular upward rotation at 60° of arm elevation [mean difference = 13.9 (CI 0.9, 9.3), p = 0.006] in the Biofeedback group. There was no difference for the other variables of scapular kinematics as well as for shoulder function (DASH), muscle strength, range of motion and electromyographic variables. InterpretationThe addition of Biofeedback to the exercise protocol increased upward rotation of the scapula. However, the volunteers who performed only the Exercises had a better response in reducing pain.

Differences in strength and landing biomechanics between female jumpers and swimmers

BACKGROUND: It remains unclear if plyometric training as a single component could improve landing mechanics that are potentially associated with lower risk of ACL injury in the long term OBJECTIVE: The purpose of this study was to investigate the influence of experience undertaking plyometrics on landing biomechanics in female athletes. METHODS: Non-jumpers with little experience in plyometric training (12 female college swimmers) and jumpers with five years of experience in plyometric training (12 female college long jumpers and high jumpers) were recruited to participate in two testing sessions: an isokinetic muscle force test for the dominant leg at 120∘/s and a 40-cm drop landing test. An independent t test was applied to detect any significant effects between cohorts for selected muscle force, kinematic, kinetic, and electromyography variables. RESULTS: While female jumpers exhibited greater quadriceps eccentric strength (P= 0.013) and hamstring concentric strength (P= 0.023) during isokinetic testing than female swimmers, no significant differences were observed in kinematics, kinetics, and muscle activities during both drop landing and drop jumping. CONCLUSIONS: The results suggest that the female jumpers did not present any training-induced modification in landing mechanics regarding reducing injury risks compared with the swimmers. The current study revealed that plyometric training as a single component may not guarantee the development of low-risk landing mechanics for young female athletes.

EFEITO DOS EXERCÍCIOS DE PILATES NA ATIVAÇÃO ELÉTRICA MUSCULAR EM ADULTOS COM LOMBALGIA CRÓNICA: REVISÃO SISTEMÁTICA

ABSTRACT Low back pain is one of the most prevalent orthopedic conditions, affecting around 70% to 80% of the world’s population at least once during their life times. Surface electromyography is an important tool for assessing the muscle function of the lumbar stabilizers. One of the best treatment options for patients with chronic low back pain (CLBP) is physical exercise, particular lyaerobic exercise and Pilates, as these can reduce short-term pain and disability, and improve balance. This review aims to identify the state of art regarding the benefits of pilates on the population with CLBP, evaluating changes in the muscular activation of the muscles of the lumbar region. Searches were conducted on the following databases: PubMed (Medline), Science Direct, Scopus, Web of Science, Cochrane, Ebsco and Scielo; including gray literature: Google Scholar, Grey Literature, Pro Quest Dissertations &amp; Theses. The inclusion criteria were adults with low back pain for three months or more, with or without referred pain in the lower limbs; studies that used electromyographic variables; studies with a pain assessment measure at two different times; studies with physical exercise performed only using the Pilates method. Applying these criteria, the searches retrieved 439 abstracts. Of these, 44 articles were evaluated for eligibility, and three fulfilled the qualitative and quantitative synthesis criteria. The average methodological quality score on the Downs and Black checklist was 15 out of 28. It was therefore concluded that Pilates is an excellent option for the treatment of non-specific low back pain, promoting health and helping prevent low back pain among asymptomatic individuals. Level of evidence II; Systematic Review of Level II or Level I Studies with Discrepant Results.

Effects of Attentional Focus on Muscular Endurance: A Meta-Analysis

Several studies explored the effects of attentional focus on resistance exercise, but their analysed outcomes most commonly involved surface electromyography variables. Therefore, the effects of attentional focus on resistance exercise performance remain unclear. The aim of this review was to perform a meta-analysis examining the acute effects of external focus vs. internal focus vs. control on muscular endurance. Five databases were searched to find relevant studies. The data were pooled in a random-effects meta-analysis. In the analysis for external vs. internal focus of attention, there were seven comparisons with 14 study groups. In the analyses for external focus vs. control and internal focus vs. control, there were six comparisons with 12 study groups. An external focus of attention enhanced muscular endurance when compared with an internal focus (Cohen’s d: 0.58; 95% confidence interval (CI): 0.34 and 0.82) and control (Cohen’s d: 0.42; 95% CI: 0.08 and 0.76). In the analysis for internal focus vs. control, there was no significant difference between the conditions (Cohen’s d: –0.19; 95% CI: –0.45 and 0.07). Generally, these results remained consistent in the subgroup analyses for upper-body vs. lower-body exercises. From a practical perspective, the results presented in this review suggest that individuals should use an external focus of attention for acute enhancement of muscular endurance.

Impact of Lockdown during COVID-19 Pandemic on Central Activation, Muscle Activity, Contractile Function, and Spasticity in People with Multiple Sclerosis.

Background People with multiple sclerosis (MS) suffer from symptoms related to neural control, such as reduced central activation, lower muscle activity, and accentuated spasticity. A forced 9-week home confinement related to COVID-19 in Spain may have worsened these symptoms. However, no study has demonstrated the impact of home confinement on neuromuscular mechanisms in the MS population. This study was aimed at analyzing the effects of a 9-week home confinement on central activation, muscle activity, contractile function, and spasticity in MS patients. Methods Eighteen participants were enrolled in the study. Left and right knee extensor maximum voluntary isometric contraction (MVIC), maximal neural drive via peak surface electromyography (EMG) of the vastus lateralis, central activation ratio (CAR), and muscle contractile function via electrical stimulation of the knee extensor muscles, as well as spasticity using the pendulum test, were measured immediately before and after home confinement. Results Seventeen participants completed the study. CAR significantly decreased after lockdown (ES = 1.271, p < 0.001). Regarding spasticity, there was a trend to decrease in the number of oscillations (ES = 0.511, p = 0.059) and a significant decrease in the duration of oscillations (ES = 0.568, p = 0.038). Furthermore, in the left leg, there was a significant decrease in the first swing excursion (ES = 0.612, p = 0.027) and in the relaxation index (ES = 0.992, p = 0.001). Muscle contractile properties, MVIC, and EMG variables were not modified after confinement. Conclusions The results suggest that a home confinement period of 9 weeks may lead to an increase in lower limb spasticity and a greater deficit in voluntary activation of the knee extensors.

Air pistol shooting: upper limb muscle activation between training and simulated competition

ABSTRACT Heightened stress during air pistol competitions may impair shooters’ abilities to maintain gun stability, resulting in inferior performance. This study aimed to compare the pre-trigger muscle activation levels of upper muscles in 10-m air pistol shooters between training and simulated competition conditions. Seven sub-elite shooters from the Singapore National Youth Air Pistol Team shot 30 shots in a training versus simulated competition condition in randomised orders on separate days. Muscle activation for the forearm and shoulder muscles, namely extensor carpi radialis, flexor carpi ulnaris, anterior deltoid, and posterior deltoid, were recorded using electromyography (EMG). Shooting performance was evaluated by total shot scores. Stress level was monitored via heart rate and the Mental Readiness Form-3. No statistically significant differences were found in EMG, performance, or stress-related variables between conditions, although moderate-to-large effect sizes were observed in some muscle activation and self-reported stress indicators. Analysis of individual performances using smallest worthwhile change showed that two participants improved under the simulated competition condition, while two declined, and three remained unaffected. In conclusion, sub-elite youth air pistol shooters were able to exhibit good neuromuscular control under high anxiety situations and thus their performance was largely unaffected.

Ergonomic considerations when slotting piece-pick operations in distribution centers

Many warehouse slotting algorithms have overlooked worker ergonomics. This research aimed to develop ergonomics slotting guidelines based upon the back and shoulder postures and electromyographic (EMG) responses of the deltoid and erector spinae muscles when individual items are picked from, or full cases replenished to, different shelf heights In the first study of two studies, participants lifted small items representative of piece-pick tasks from seven shelf heights. In the second study, participants performed a simulated full case replenishment task in which they lifted boxes weighing between 2.7 and 10.9 kg from a cart into a flow rack. Shelf height significantly affected all postural and EMG variables and there was a trade-off between back and shoulder muscle activity across the varying shelf heights. Together, these studies were used to develop some general ergonomic slotting guidelines that could be implemented to reduce biomechanical load exposures experienced by distribution center workers.

Effects of Postoperative Rehabilitation on Gait Parameters and Electromyography Variables in Acute and Chronic Anterior Cruciate Ligament Reconstruction Surgery in Football Players.

Results The results of the a-ACLR, c-ACLR, and control groups were compared. At 8 weeks following postoperative rehabilitation, the a-ACLR group shows more significant changes than the c-ACLR group (p < 0.001). At 6 and 12 months, there are normal values of kinematic and kinetic values in a-ACLR compared with the results of the control group (p < 0.001). Conclusion The study showed that postoperative rehabilitation provides significant effects in the kinematic, kinetic, and EMG gait parameters in acute ACLR than chronic ACLR subjects. Early surgical intervention and postrehabilitation are mandatory to get the significant effects in the clinical parameters in acute and chronic ACL injury.

Electromyographical and Physiological Correlation in Patient with Heart Disease

Abstract Background: Walking is an economic activity, the more efficient the mechanical contribution, the less metabolic energy is necessary to keep walking. Patients with chronic heart failure and heart transplant present peripheral musculoskeletal disorders, dyspnea, and fatigue in their activities. Objective: In this scenario, the present study sought to verify the correlations between metabolic and electromyographic variables in chronic heart failure, heart transplant patients, and healthy controls. Methods: Regression and correlation between cost of transport and electromyographic cost, as well [...]

Oral behaviours and wake-time masseter activity in patients with masticatory muscle pain.

Little is known about wake-time masseter activity of patients with masticatory muscle pain in real-life settings. The aims of this study were (1) to assess wake-time masseter activity of women with masticatory muscle pain (MMP) and compare it with that of pain-free women; and (2) to investigate the association between objectively measured masseter contractions and self-reported oral behaviours. Adult women (N=27) diagnosed with MMP were age-matched with pain-free women (N=26). The electromyographic (EMG) activity of the masseter muscle when awake was recorded unilaterally for two consecutive days. The number of contraction episodes and relative contraction time (%) were calculated using cut-off thresholds of 3%, 5% and 10% of maximum voluntary contraction (MVC). Self-reported daytime oral activity was assessed using the Oral Behaviours Checklist (OBC, items 3-21). Data were analysed using univariate tests and mixed-model analyses. The number of contraction episodes was similar between groups for all detection thresholds, but the relative contraction time at the lower detection thresholds (i.e. 3% MVC and 5% MVC) was significantly longer (1.5-fold) in the MMP than in the pain-free group. The OBC scores were significantly higher in the women with MMP than in controls, but no positive association could be found between EMG variables and OBC scores. Women with MMP engage in low-level masseter muscle contractions, which last longer than those of pain-free controls. There was no relationship between self-reported oral behaviours and masseter activity when awake. These findings support the notion that prolonged low-level clenching when awake may play a role in the pathophysiology of MMP.

Describing post-polio syndrome

IntroductionPatients presenting sequelae of poliomyelitis may present new symptoms, known as post-polio syndrome (PPS). ObjectiveTo identify the clinical and functional profile and epidemiological characteristics of patients presenting PPS. Patients and methodsWe performed a retrospective study of 400 patients with poliomyelitis attended at the Institut Guttmann outpatient clinic, of whom 310 were diagnosed with PPS. We describe patients’ epidemiological, clinical, and electromyographic variables and analyse the relationships between age of poliomyelitis onset and severity of the disease, and between sex, age of PPS onset, and the frequency of symptoms. ResultsPPS was more frequent in women (57.7%). The mean age at symptom onset was 52.4 years, and was earlier in women. Age at primary infection > 2 years was not related to greater poliomyelitis severity.The frequency of symptoms was: pain in 85% of patients, loss of strength in 40%, fatigue in 65.5%, tiredness in 57.8%, cold intolerance in 20.2%, dysphagia in 11.7%, cognitive complaints in 9%, and depressive symptoms in 31.5%. Fatigue, tiredness, depression, and cognitive complaints were significantly more frequent in women.Fifty-nine percent of patients presented electromyographic findings suggestive of PPS. ConclusionsWhile the symptoms observed in our sample are similar to those reported in the literature, the frequencies observed are not. We believe that patients’ clinical profile may be very diverse, giving more weight to such objective parameters as worsening of symptoms or appearance of weakness; analysis of biomarkers may bring us closer to an accurate diagnosis.

EFFECT OF AN ANNUAL TAEKWONDO TRAINING PROGRAM ON THE ELECTROMYOGRAPHIC CHARACTERISTICS OF FRONTAL KICK YOP CHAGI

Taekwondo is one of the most difcult and complex but one of the most complete and exciting Olympic sport. Fitness and conditioning are what you need to gain points with kicks that determine the level of competitive ability. The purpose of this study is to examine the results of an annual training program, in selected electromyographic variables of Yop chagi to maximize the performance of Taekwondo athletes. The sample consisted of 20 Taekwondo athletes, advanced holders of Black Belt, aged M = 19.11 years, sd = 3.45, height M = 1.73 cm, sd = 6.80 and weight M = 67.23 Kg, sd = 12.73 which were divided into 2 equal groups. The rst team (TT), Training Team followed a specic tness program, technique. The second group followed its own program, Control Group (CG). Surface electrodes (motion control co.) with preamplier, an electronic shield (approved by the WTF) were used for the measurements. Electromyographic characteristics of the test were measured with the APAS (Ariel Performance Analysis System), dynamic and evaluated with Bioanalysis program. Three measurements were performed in this study, an initial, an intermediate a nal measurement at the end of the program. The subject executes the technique of Yop Chagi kick, on the opponent's electronic chest, with simultaneously electromyographic activity of the Rectus Femoris (RF), the long head of Biceps Femoris (BF) and the lateral head of Gastrocnemius (GAS). The neuromuscular activity recorded during the execution of the technique in the experimental group for each muscle group is different from that of the control group. Athletes who followed the annual program improved their muscular pre-activation and activation, responded successfully enough to the execution of the kick, since a successful kick depends on both technical and physical condition

Reliability and sources of variability of 3D kinematics and electromyography measurements to assess newly-acquired gait in toddlers with typical development and unilateral cerebral palsy

The aim was to 1) determine intersession and intertrial reliability and 2) assess three sources of variability (intersubject, intersession and intertrial) of lower limb kinematic and electromyographic (EMG) variables during gait in toddlers with typical development (TD) and unilateral cerebral palsy (UCP) (age <3 years, independent walking experience ≤6 months). Gait kinematics and surface EMG were recorded in 30 toddlers (19 TD and 11 UCP), during two, 3D-motion capture sessions. Standard error of measurement (SEM) between trials (gait cycles) of the same session and between sessions was calculated to assess reliability. Standard deviations (SD) between subjects, sessions and trials were calculated to estimate sources of variability. Sixty-four percent of kinematic SEM-values were acceptable (2°-5°). Frontal plane measurements were most reliable (SEM 2°-4.6°). In toddlers with UCP, EMG variables were most reliable for affected side, distal muscles. Intrinsic (intertrial and intersubject) variability was high, reflecting both motor immaturity and the high variability of toddler gait patterns. In toddlers with UCP, variability was amplified by motor impairment and delayed motor development. 3D gait analysis and surface EMG are partially reliable tools to study individual gait patterns in toddlers in clinical practice and research, although some variables must be interpreted with caution.