sEMG Activity Research Articles

Older adults show higher increases in lower-limb muscle activity during whole-body vibration exercise

The purpose of this study was to compare lower limb muscle activity during whole-body vibration (WBV) exercise between a young and an older study population. Thirty young (25.9±4.3yrs) and thirty older (64.2±5.3yrs) individuals stood on a side-alternating WBV platform while surface electromyography (sEMG) was measured for the tibialis anterior (TA), gastrocnemius medialis (GM), soleus (SOL), vastus lateralis (VL), vastus medialis (VM), and biceps femoris (BF). The WBV protocol included nine vibration settings consisting of three frequencies (6, 11, 16Hz) x three amplitudes (0.9, 2.5, 4.0mm), and three control trials without vibration (narrow, medium, wide stance). The vertical platform acceleration (peak values of maximal displacement from equilibrium) was quantified during each vibration exercise using an accelerometer. The outcomes of this study showed that WBV significantly increased muscle activity in both groups for most vibration conditions in the TA (averaged absolute increase: young: +3.9%, older: +18.4%), GM (young: +4.1%, older: +9.5%), VL (young: +6.3%, older: +12.6%) and VM (young: +5.4%, older: +8.0%), and for the high frequency-amplitude combinations in the SOL (young: +7.5%, older: +12.6%) and BF (young: +1.9%, older: +7.5%). The increases in sEMG activity were significantly higher in the older than the young adults for all muscles, i.e., TA (absolute difference: 13.8%, P<0.001), GM (4.6%, P=0.034), VL (7.6%, P=0.001), VM (6.7%, P=0.042), BF (6.4%, P<0.001), except for the SOL (0.3%, P=0.248). Finally, the vertical platform acceleration was a significant predictor of the averaged lower limb muscle activity in the young (r=0.917, P<0.001) and older adults (r=0.931, P<0.001). In conclusion, the older population showed greater increases in lower limb muscle activity during WBV exercise than their young counterparts, meaning that they might benefit more from WBV exercises. Additionally, training intensity can be increased by increasing the vertical acceleration load.

The Change of Pennation Angle of Medial Gastrocnemius on Different Heights of Heels

Objectives This study aims to investigate the effect of pennation angle and surface Electromyography (sEMG) activity of medial gastrocnemius on different heights of high heels by using ultrasonography and sEMG. Methods/Statistical Analysis: Twenty eight healthy young females participate in this study. In order to measure the pennation angle and sEMG activity of medial gastrocnemius, we instructed subjects to stand barefoot and wearing two high heels (5 cm and 10 cm). We measured ultrasonography and sEMG activities for three times on three conditions (barefoot, 5 cm, 10 cm) repeatedly and used the mean of measurement values. One-way repeated ANOVA was used to see the difference of individual intervention and Bonferroni’s correction for post-hoc was used to that. Findings: Pennation angle and sEMG activities in medial gastrocnemius showed significant differences on three conditions (barefoot, 5 cm, 10 cm). Improvements/Applications: Furthermore, measurement of muscle activity using ultrasonography is considered useful way because pennation angle and sEMG activity in medial gastrocnemius increased in accordance with the increasing height of heels identically.

ADDUCTOR LONGUS ACTIVATION DURING TWO COMMON HIP ADDUCTION EXERCISES

Various exercises are prescribed in the management of adductor-related groin pain. Isometric adductor ball squeeze exercises are commonly incorporated into both prevention and rehabilitation training, as is the Copenhagen Adduction...

An investigation into the bilateral functional differences of the lower limb muscles in standing and walking.

To date, most studies use surface electromyographic (sEMG) signals as the control source on active rehabilitation robots, and unilateral data are collected based on the gait symmetry hypothesis, which has caused much controversy. The purpose of this study is to quantitatively evaluate the sEMG activity asymmetry of bilateral muscles in lower extremities during functional tasks. Nine participants were instructed to perform static and dynamic steady state tests. sEMG signals from the tibialis anterior, soleus, medial gastrocnemius and lateral gastrocnemius muscles of bilateral lower extremities were recorded in the experiments. Muscle activities are quantified in terms of sEMG amplitude. We investigated whether characteristics of left limb and the one of the right limb have the same statistical characteristics during functional tasks using The Wilcoxon rank-sum test, and studied dynamic signal irregularity degree for sEMG activities via sample entropy. The total of muscle activities showed significant differences between left limb and right limb during the static steady state (p = 0.000). For dynamic steady states, there were significant differences for most muscle activities between left limb and right limb at different speeds (p = 0.000). Nevertheless, there was no difference between the lateral gastrocnemius for bilateral limb at 2.0 kilometers per hour (p = 0.060). For medial gastrocnemius, differences were not found between left limb and right limb at 1.0 and 3.0 kilometers per hours (p = 0.390 and p = 0.085, respectively). Similarly, there was no difference for soleus at 3.0 kilometers per hour (p = 0.115). The importance of the differences in muscle activities between left limb and right limb were found. These results can potentially be used for evaluating lower limb extremity function of special populations (elderly people or stroke patients) in an objective and simple method.

SEMG ACTIVITIES OF THE THREE HEADS OF THE TRICEPS BRACHII MUSCLE DURING CRICKET BOWLING

The aim of the present study was to analyze the surface electromyography (sEMG) activities generated by the three heads of the triceps brachii (TB) muscle among the different phases during fast and spin bowling. sEMG signals from the lateral, long and medial heads of the TB from 20 bowlers were measured individually during bowling. To analyze the sEMG activities, the root mean square (RMS) value in each bowling phase for every trial per bowler was calculated from the sEMG signals from the three heads of the TB. Higher sEMG activities at the three heads of the TB were found during the fifth phase followed by the sixth, seventh, third, fourth, second and first phases in both types of bowling. sEMG activities were significantly different among the three heads of the TB and among the seven bowling phases for both bowling types at an alpha level of [Formula: see text]. These findings will be of particular importance for assessing different physical therapies for the three headed TB muscle which can improve the performance in ball delivery of cricket bowlers.

Extraction of the brachialis muscle activity using HD-sEMG technique and canonical correlation analysis.

The Brachialis (BR) is placed under the Biceps Brachii (BB) deep in the upper arm. Therefore, the detection of the corresponding surface Electromyogram (sEMG) is a complex task. The BR is an important elbow flexor, but it is usually not considered in the sEMG based force estimation process. The aim of this study was to attempt to separate the two sEMG activities of the BR and the BB by using a High Density sEMG (HD-sEMG) grid placed at the upper arm and Canonical Component Analysis (CCA) technique. For this purpose, we recorded sEMG signals from seven subjects with two 8 × 4 electrode grids placed over BB and BR. Four isometric voluntary contraction levels were recorded (5, 10, 30 and 50 %MVC) for 90° elbow angle. Then using CCA and image processing tools the sources of each muscle activity were separated. Finally, the corresponding sEMG signals were reconstructed using the remaining canonical components in order to retrieve the activity of the BB and the BR muscles.

Predicting 3D lip movement using facial sEMG: a first step towards estimating functional and aesthetic outcome of oral cancer surgery

In oral cancer, loss of function due to surgery can be unacceptable, designating the tumour as functionally inoperable. Other curative treatments can then be considered. Currently, predictions of these functional consequences are subjective and unreliable. We want to create patient-specific models to improve and objectify these predictions. A first step was taken by controlling a 3D lip model with volunteer-specific sEMG activities. We focus on the lips first, because they are essential for speech, oral food transport, and facial mimicry. Besides, they are more accessible to measurements than intraoral organs. 3D lip movement and corresponding sEMG activities are measured in five healthy volunteers, who performed 19 instructions repeatedly, to create a quantitative lip model by establishing the relationship between sEMG activities of eight facial muscles bilaterally on the input side and the corresponding 3D lip displacements on the output side. The relationship between 3D lip movement and sEMG activities was accommodated in a state-space model. A good relationship between sEMG activities and 3D lip movement was established with an average root mean square error of 2.43 mm for the first-order system and 2.46 mm for the second-order system. This information can be incorporated into biomechanical models to further personalise functional outcome assessment after treatment.

Gender variability in electromyographic activity, in vivo behaviour of the human gastrocnemius and mechanical capacity during the take‐off phase of a countermovement jump

The purpose of this study was to analyse gender differences in neuromuscular behaviour of the gastrocnemius and vastus lateralis during the take-off phase of a countermovement jump (CMJ), using direct measures (ground reaction forces, muscle activity and dynamic ultrasound). Sixty-four young adults (aged 18-25years) participated voluntarily in this study, 35 men and 29 women. The firing of the trigger allowed obtainment of data collection vertical ground reaction forces (GRF), surface electromyography activity (sEMG) and dynamic ultrasound gastrocnemius of both legs. Statistically significant gender differences were observed in the jump performance, which appear to be based on differences in muscle architecture and the electrical activation of the gastrocnemius muscles and vastus lateralis. So while men developed greater peak power, velocity take-offs and jump heights, jump kinetics compared to women, women also required a higher electrical activity to develop lower power values. Additionally, the men had higher values pennation angles and muscle thickness than women. Men show higher performance of the jump test than women, due to significant statistical differences in the values of muscle architecture (pennation angle and thickness muscle), lower Neural Efficiency Index and a higher amount of sEMG activity per second during the take-off phase of a CMJ.

The Effect of Radial Extracorporeal Shock Wave Stimulation on Upper Limb Spasticity in Chronic Stroke Patients: A Single–Blind, Randomized, Placebo-Controlled Study

The main purpose of this study was to determine the clinical, electrophysiological and thermal effects of radial extracorporeal shock wave (rESW) stimulation on upper limb muscles affected by spasticity in patients with chronic stroke. Patients included in the study were randomly assigned into the following two groups: 30 patients stimulated with active rESW (A); and 30 patients stimulated with placebo rESW (B). All patients were analyzed using the Modified Ashworth Scale (MAS) to test the spasticity levels of the elbow (E), radio carpal (RC) and fingers (FF) joints; surface electromyography (sEMG) was performed for the resting bioelectrical activity registration of the flexor carpi radialis (FCR) and flexor carpi ulnaris (FCU) muscles; and infrared thermal imaging (IRT) was used to assess the temperature distributions of the carpal flexor muscles (CFM). All assessments were performed at baseline (t0), immediately after rESW (t1) as well as 1 and 24 h following its finalization (t2 and t3). Patients treated with active rESW showed a statistically significant reduction in the MAS score for the RC joint at t1 and for the FF joints at t1, t2 and t3 (p < 0.05). A significant decrease in sEMG activity was observed in the FCR and FCU muscles at t1, t2 and t3 (p < 0.05); significant increases in the mean and maximum values of the IRT detection was observed using inter-group comparisons in t2 and t3 (p < 0.05). No significant alterations were observed in patients after placebo rESW stimulation (p > 0.05). Applications of rESW demonstrating positive effects at reducing the level of spastic hypertonia of the upper limb muscles in patients with chronic stroke. ESW treatments should be considered as a potential anti-spastic effect to regulate vasculature.

The Coordination of Cough and Swallow Behaviors in Humans

It is not currently known if the coordinated motor control of cough and swallow behaviors described in animal models is preserved in humans. We hypothesized that similar relationships exist, namely the increased muscle activation and decreased swallow duration during combined cough and swallow behaviors. Young healthy individuals were recruited, and during the experiments voluntary cough was elicited by asking subjects to cough “like there was something stuck in their throat” and continue until instructed to stop. Swallow was initiated by infusing 3 ml of water into the subject's mouth and instructing them to “swallow whenever you need to.” Cough and swallow were elicited individually as well as together to mimic an “aspiration” response. Cough excitability was measured by recording the airflow taken from the mouth and surface electromyographic (sEMG) activity from the 6th intercostal, rectus abdominus, abdominal obliques, and submental muscles. Swallow excitability was measured by submental sEMG. All subjects produced multiple cough epochs and swallows to the stimuli. In the combined condition swallows occurred during the inter‐bout interval, with increased intercostal and abdominal drive during cough; and an increased submental drive during swallow. These results confirm the theory of a highly cooperative airway protection system in the human. Furthermore, this model could be used as a novel diagnostic tool for dysphagia/dystussia, eliminating the ceiling effect of a single cough trial. Supported by HL 111215, HL 103750, and P30‐GM103507.Support or Funding InformationSupported by HL 111215, HL 103750, and P30‐GM103507.

Effects of ankle destabilization devices and rehabilitation on gait biomechanics in chronic ankle instability patients: A randomized controlled trial

Patients with chronic ankle instability (CAI) have altered gait patterns, which are characterized by increased inversion positioning during gait. Ankle destabilization devices increase peroneus longus muscle activation during gait, which may increase eversion. ObjectiveTo determine whether incorporating destabilization devices into a 4-week impairment-based rehabilitation program has beneficial effects on gait biomechanics and surface electromyography (sEMG) compared to impairment-based rehabilitation without destabilization devices in CAI patients. DesignRandomized controlled trial. SettingLaboratory. ParticipantsTwenty-six CAI patients. Outcome measuresPatients completed baseline gait trials and were randomized into no device or device groups. Groups completed 4-weeks of rehabilitation with or without devices, and then completed post-intervention gait trials. Lower extremity sagittal and frontal plane kinematics and kinetics and sEMG activity were measured. ResultsThe device group increased dorsiflexion during mid-late stance and had lower normalized sEMG amplitude for the peroneus longus during early stance and mid-swing after rehabilitation. The no device group had less peroneus brevis sEMG activity during early stance after rehabilitation. ConclusionIncorporating destabilization devices in a 4-week rehabilitation program was an effective method of improving dorsiflexion during the stance phase of gait. However, impairment-based rehabilitation, regardless of instability tool, was not effective at improving frontal plane motion.

Flexion–relaxation ratio in computer workers with and without chronic neck pain

This study evaluated the flexion–relaxation phenomenon (FRP) and flexion–relaxation ratios (FR-ratios) using surface electromyography (sEMG) of the cervical extensor muscles of computer workers with and without chronic neck pain, as well as of healthy subjects who were not computer users. This study comprised 60 subjects 20–45years of age, of which 20 were computer workers with chronic neck pain (CPG), 20 were computer workers without neck pain (NPG), and 20 were control individuals who do not use computers for work and use them less than 4h/day for other purposes (CG). FRP and FR-ratios were analyzed using sEMG of the cervical extensors. Analysis of FR-ratios showed smaller values in the semispinalis capitis muscles of the two groups of workers compared to the control group. The reference FR-ratio (flexion relaxation ratio [FRR], defined as the maximum activity in 1s of the re-extension/full flexion sEMG activity) was significantly higher in the computer workers with neck pain compared to the CG (CPG: 3.10, 95% confidence interval [CI95%] 2.50–3.70; NPG: 2.33, CI95% 1.93–2.74; CG: 1.99, CI95% 1.81–2.17; p<0.001). The FR-ratios and FRR of sEMG in this study suggested that computer use could increase recruitment of the semispinalis capitis during neck extension (concentric and eccentric phases), which could explain our results. These results also suggest that the FR-ratios of the semispinalis may be a potential functional predictive neuromuscular marker of asymptomatic neck musculoskeletal disorders since even asymptomatic computer workers showed altered values. On the other hand, the FRR values of the semispinalis capitis demonstrated a good discriminative ability to detect neck pain, and such results suggested that each FR-ratio could have a different application.

Acute effects of Expiratory Positive Airway Pressure (EPAP) on different levels in ventilation and electrical activity of sternocleidomastoid and parasternal muscles in Chronic Obstructive Pulmonary Disease (COPD) patients: a randomized controlled trial

ABSTRACTObjectiveTo investigate the acute effects of EPAP on the activity of sternocleidomastoid (SCM), parasternal muscles and ventilatory parameters in COPD patients. MethodTwenty-four patients with COPD were studied using surface electromyography (sEMG) and a ventilometer. Patients were randomly assigned to EPAP 10 cmH2O-EPAP10 or 15 cmH2O-EPAP15 for 20 minutes. ResultsThe parasternal muscle sEMG activity increased during EPAP10 and EPAP15; however, a greater and significant increase was observed with EPAP10 (mean between-group difference: 12.5% RMS, 95% CI: 9.5 to 15.4, p<0.001). In relation to the baseline, at 10 and 20 minutes and upon recovery, respectively parasternal activity increased by 23.9%, 28.9% and 19.1% during EPAP10 and by 10.7% at 10 and 20 minutes and upon recovery, respectively, 11.4% and 6.9% during EPAP15 at 10 and 20 minutes and upon recovery, respectively. The sEMG activity of SCM muscle showed an opposite pattern, increasing with EPAP15 and decreasing with EPAP10 (mean between-group difference: 15.5% RMS, 95% CI: 12.6 to 18.4, p<0.001). SCM muscle activity during EPAP15, increased by 4.8% and 6.1% at 10 and 20 minutes and decreased by -4.0% upon recovery compared to decreases of –5.6%, –20.6% and –21.3% during EPAP10 at 10, 20 minutes, and recovery. Ventilation at both EPAP intensities promoted significant reductions in respiratory rate (RR) and dyspnea, more pronounced in EPAP15: RR (mean between-group difference: –3,8bpm, 95%CI: –7,5 to –0,2, p=0,015) and dyspnea (mean between-group difference: –1.01, 95%CI: –1.4 to –0.53, p=0.028) . ConclusionIn COPD patients, the use of EPAP10 was more effective in reducing accessory inspiratory activity and increasing parasternal activity, which was accompanied by an improvement in ventilation and a reduction in dyspnea.

Radiographic and masticatory physiologic evaluation after conservative treatment of condylar fractures in children and adolescents

To evaluate the developmental and functional outcome of condylar fractures in children and adolescents after conservative treatment. Eight children and adolescents with unilateral condylar fracture, aged 5-13 were included. A removable occlusal splint, the thickness of which was determined according to the age, the developmental stage of the dentition, the level of the fracture and the degree of dislocation, worn for 1-3 months, and the patients were asked to perform functional exercises. The patients were followed up by clinical observation, panoramic radiograph, temporomandibular joint(TMJ ) cone beam computed tomography(CBCT), and surface electromyography(sEMG) of masticatory muscles (superficial masseter, anterior temporalis, and anterior digastric muscles). Ramus height and body length of mandible were measured on panoramic radiograph. The patients were asked to return for follow-up visits at 1, 3, and 6 months after treatment, and then once a year. The patients underwent clinical examination at each follow-up visit, and radiological examinations at 6 months and then annually. All the patients showed clinically satisfactory results. CBCT showed smooth and continuous cortex. Panoramic X-ray revealed that the ramus height was shorter in the fractured side than in the contralateral side, while body length was longer. The mean asymmetry index(AI,x±s) for ramus height and body length were (3.29±2.68)% and (4.01 ± 2.54)%. sEMG showed either hypertension or hypotension in the masticatory muscles of the fractured side and asymmetries were obvious. The mean AI for sEMG activity of the anterior temporalis, masseter, and anterior digastric muscle were masseter: (15.0 ± 16.9)%; anterior temporalis: (21.5 ± 15.9)%; anterior digastric muscles: (11.9 ± 10.7)%. Conservative treatment of condylar fracture in children and adolescents had clinically satisfactory results, while mandibular development was slightly interrupted. Asymmetries of EMG activities of masticatory muscles were obvious. EMG could objectively reveal the functional recovery of condylar fracture in children.

EMG Activity of Masseter Muscles in the Elderly According to Rheological Properties of Solid Food.

ObjectiveTo assess the impact of aging on masticatory muscle function according to changes in hardness of solid food.MethodsEach of fifteen healthy elderly and young people were selected. Subjects were asked to consume cooked rice, which was processed using the guidelines of the Universal Design Foods concept for elderly people (Japan Care Food Conference 2012). The properties of each cooked rice were categorized as grade 1, 2, 3 and 4 (5×103, 2×104, 5×104, and 5×105 N/m2) respectively. Surface electromyography (sEMG) was used to measure masseter activity from food ingestion to swallowing of test foods. The raw data was normalized by the ratio of sEMG activity to maximal voluntary contraction and compared among subjects. The data was divided according to each sequence of mastication and then calculated within the parameters of EMG activities.ResultsIntraoral tongue pressure was significantly higher in the young than in the elderly (p<0.05). Maximal value of average amplitude of the sequence in whole mastication showed significant positive correlation with hardness of food in both young and elderly groups (p<0.05). In a comparisons between groups, the maximal value of average amplitude of the sequence in whole mastication and peak amplitude in whole mastication showed that mastication in the elderly requires a higher percentage of maximal muscle activity than in the young, even with soft foods (p<0.05).ConclusionsEMG data of the masseter can provide valuable information to aid in the selection of foods according to hardness for the elderly. The results also support the necessity of specialized food preparation or products for the elderly.

Effect of clinical parameters on the control of myoelectric robotic prosthetic hands.

Improving the functionality of prosthetic hands with noninvasive techniques is still a challenge. Surface electromyography (sEMG) currently gives limited control capabilities; however, the application of machine learning to the analysis of sEMG signals is promising and has recently been applied in practice, but many questions still remain. In this study, we recorded the sEMG activity of the forearm of 11 male subjects with transradial amputation who were mentally performing 40 hand and wrist movements. The classification performance and the number of independent movements (defined as the subset of movements that could be distinguished with >90% accuracy) were studied in relationship to clinical parameters related to the amputation. The analysis showed that classification accuracy and the number of independent movements increased significantly with phantom limb sensation intensity, remaining forearm percentage, and temporal distance to the amputation. The classification results suggest the possibility of naturally controlling up to 11 movements of a robotic prosthetic hand with almost no training. Knowledge of the relationship between classification accuracy and clinical parameters adds new information regarding the nature of phantom limb pain as well as other clinical parameters, and it can lay the foundations for future "functional amputation" procedures in surgery.

Quantification of muscle co-contraction using supersonic shear wave imaging

Muscle stiffness estimated using shear wave elastography can provide an index of individual muscle force during isometric contraction and may therefore be a promising method for quantifying co-contraction. We estimated the shear modulus of the lateral gastrocnemius (LG) muscle using supersonic shear wave imaging and measured its myoelectrical activity using surface electromyography (sEMG) during graded isometric contractions of plantar flexion and dorsiflexion (n=7). During dorsiflexion, the average shear modulus was 26±6kPa at peak sEMG amplitude, which was significantly less (P=0.02) than that measured at the same sEMG level during plantar flexion (42±10kPa). The passive tension during contraction was estimated using the passive LG muscle shear modulus during a passive ankle rotation measured at an equivalent ankle angle to that measured during contraction. The passive shear modulus increased significantly (P<0.01) from the plantar flexed position (16±5kPa) to the dorsiflexed position (26±9kPa). Once this change in passive tension from joint rotation was accounted for, the average LG muscle shear modulus due to active contraction was significantly greater (P<0.01) during plantar flexion (26±8kPa) than at sEMG-matched levels of dorsiflexion (0±4kPa). The negligible shear modulus estimated during isometric dorsiflexion indicates negligible active force contribution by the LG muscle, despite measured sEMG activity of 19% of maximal voluntary plantar flexion contraction. This strongly suggests that the sEMG activity recorded from the LG muscle during isometric dorsiflexion was primarily due to cross-talk. However, it is clear that passive muscle tension changes can contribute to joint torque during isometric dorsiflexion.

The surface electromyographic evaluation of the Functional Reach in elderly subjects

This study proposes a comprehensive assessment of myoelectric activity of the main muscles involved in the Functional Reach (FR) test, in 24 elderly subjects. A specific protocol for the surface electromyography (sEMG) signal acquisition during FR-test was developed. Results show that anterior muscles activate following a caudo-cranial order. Tibialis Anterior (TA) is the first to be activated (−18.0±16.3% of the FR-period), together with Rectus Femoris (−10.4±17.9%). Then, Rectus Abdominis (19.7±24.7%) and Sternocleidomastoideus (19.9±15.6%) activate after the FR-start. Hamstrings, Soleus, and L4-level Erectores Spinae (posterior muscles) activate after the FR-start in this order (11.4±16.8%, 17.7±16.6%, and 35.2±29.0%, respectively) and remain active until the movement end. The analysis of the kinematic strategies adopted by subjects revealed an association between TA-activation patterns and two kinematic strategies (hip/mixed strategy), quantified by an increase (p<0.05) of TA-activity duration in subjects adopting the hip strategy (89.9±34.5) vs. subjects adopting the mixed strategy (27.0±16.8). This suggests that TA sEMG activity could be able to discriminate among kinematic strategies, providing different information on balance control. Thus, the present analysis represents the first attempt to quantify the sEMG activity during FR-test in elderly subjects, providing an early contribution in building a reference frame for balance assessment in clinical context.

Effects of 2 Resistive Exercises on Electrophysiological Measures of Submandibular Muscle Activity

ObjectiveTo compare the electrophysiological activity in submandibular hyolaryngeal muscles during performance of 2 exercises that incorporate resistance against muscular contraction. DesignWithin-subject repeated-measures design. SettingAcademic research laboratory. ParticipantsHealthy, young adult women (N=26; mean age, 24.1y) without a history of dysphagia, cervical spine conditions, neurologic disease, or head/neck cancer. InterventionsParticipants performed 2 isometric exercises requiring contraction against resistance to the submandibular hyolaryngeal muscles: one requiring jaw opening against a semirigid brace (chin-to-chest [CtC] exercise) and one requiring a chin tuck against an air-inflated rubber ball (chin tuck against resistance [CTAR] exercise). Measures of electrophysiology using surface electromyography (sEMG) were obtained during exercise performance. Main Outcome MeasuresMicrovolts as measured from sEMG electrode sensors placed on the skin surface above the hyolaryngeal muscles (surface of skin above geniohyoid, mylohyoid, and anterior digastric). Dependent variables included peak contraction amplitude (in μV) and mean contraction amplitude (in μV) across 10 seconds of sustained contraction. ResultsSignificant effects of exercise on peak and mean contraction amplitudes were present when both exercises were compared with baseline sEMG activity. (P<.001 for both). Normalized values of peak contraction amplitude and mean contraction amplitude during performance of CtC were not significantly different compared with CTAR. ConclusionsThis study provides supporting evidence for the influence of 2 published exercises on motor unit recruitment in the submandibular hyolaryngeal muscles, both of which have been previously proposed as rehabilitative modalities. Theoretical and clinical implications are discussed.

Efeitos da manipulação cervical alta sobre a atividade eletromiográfica dos músculos mastigatórios e amplitude de movimento de abertura da boca em mulheres com disfunção temporomandibular: ensaio clínico randomizado e cego

We evaluated the effects of upper cervical manipulation on the surface electromyographic activity (sEMG) of masticatory muscles and range of motion of the opening movement of the mouth in women with temporomandibular disorders (TMD). We evaluated 10 women with myogenic a TMD diagnosis, according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and divided randomly into an experimental group (EG) n=5, which received upper cervical manipulation, and a placebo group (PG) n=5, which received maneuvers without therapeutic effects. Five interventions were performed in both groups, once a week, with performance of pre-intervention assessments, post-immediate assessments (after 1st intervention) and post-delayed assessments (48 hours after the 5th intervention). The sEMG activity was processed using the root mean square and normalized by the peak value (RMS EMGn). We used for comparison the Student's t-test and ANOVA two-way repeated measures, adopting as significance the amount of 5%, and the Cohen d for treatment effect size. We found a significant interaction of group vs time (p<0.05) in the RMS EMGn of the left and right temporal muscles at rest, as well as for all masticatory muscles during maximal isometric contraction during jaw-elevation and jaw-depression. Treatment effect size, high to moderate, was observed in the EG, especially in the post-delayed assessment. We also observed a significant increase (p<0.05) and a high treatment effect during mouth opening in the EG. The upper cervical manipulation demonstrated a balance of the RMS EMGn of the masticatory muscles and increase the opening range of motion of the mouth in women with myogenic TMD.