Decrease In Electromyographic Activity Research Articles

Effect of bodyweight support and incline running on electromyographic activity of triceps surae

During rehabilitation, body weight support (BWS) system is often used. It can be useful for optimizing time to return to practice by unloading joints and muscles. The present study aimed to explore the effects of Body Weight Support (BWS) and Incline Running (IR) on electromyographic activity (EMG) of triceps surae. We hypothesized that running with a slope of 7% and 30% of BWS could result in EMG comparable to level running. Eighteen healthy individuals participated in four randomized experimental sessions of ten minutes run at 10 km/h: 1) level running and 0% of BWS (LR), 2) incline running at 7% and 0% of BWS, 3) incline running at 7% and 15% of BWS, 4) incline running at 7% and 30% of BWS. EMG activity of Vastus Lateralis (VL), Gastrocnemius Lateralis (GL), Gastrocnemius Medialis (GM), and Soleus (SOL) was recorded during each 10 minutes running conditions and before two times during 30 seconds level running to normalize EMG activity (baseline). In addition, gait spatiotemporal parameters were taken at 1’, 5’ and 9 minutes and Rating of Perceived Exertion RPE was asked at 5’, 7’, and 10 minutes. Tests were conducted before and two minutes after running conditions. They included Counter Movement Jump (CMJ), and quadriceps low-frequency fatigue test.The results of the present study revealed a significant decrease in electromyographic activity of SOL at IR at 30% of BWS condition compared to IR without BWS (P < 0.002). Moreover, a significant decrease in electromyographic activity was observed of VL at IR at 30% of BWS condition compared to level running and IR conditions without BWS (P < 0.002 and P < 0.001). No changes were found in jump test (P = 0.246) and gait spatiotemporal parameters (P > 0.05) except in flight time (decrease with IR, increase with BWS, P < 0.006). Rate of Perceived Exertion was decreased with 30% of BWS (P < 0.002) and was no different to level running (P = 0.079). 15% of BWS (vs. uphill without BWS) did not significantly decrease the difficulty perception (P = 0.570). Also, low-frequency fatigue of the quadriceps was induced without BWS (P = 0.011) but not with 15% and 30% BWS (P > 0.05)Our results show that EMG activity of the triceps surae can be similar between running on a flat surface and running on a slope and 30% BWS. Furthermore, muscle fatigue, perceived exertion rate and spatio-temporal running parameters were similar between running on a flat surface and 30% BWS at 7% IR. Therefore, it can be useful to optimize the return time to practice and it is recommending for monitoring loads in Achilles Tendon and triceps surae. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Intra-operative Urodynamics: Is the Test an Accurate Representation of the Lower Urinary Tract in Children?

To compare intraoperative UDS results with UDS in the postoperative care unit (PACU) to assess the accuracy and efficacy of intraoperative UDS in children who cannot tolerate ambulatory urodynamic evaluation. Pediatric patients undergoing intraoperative UDS at a single institution were enrolled over a 5-year time period (1/2013-8/2018). Urodynamics were performed in the operating room under general anesthesia, then in the PACU after recovery from anesthesia. Electromyographic (EMG) activity during filling, bladder compliance, cystometric bladder capacity (CBC), detrusor overactivity, presence of urinary leak, leak point pressure (LPP), and pressure specific volumes (PSV) at 10, 20, 30, and 40 cm water were compared between studies. Nineteen patients underwent urodynamic evaluation under general anesthesia and met inclusion criteria. Ten patients (52.6%) underwent 2 filling cycles while awake in PACU, resulting in a total of 48 urodynamic studies available for subsequent analysis. Intraoperative urodynamic studies were more likely to have decreased EMG activity during filling (P=<.01), normal compliance (P <.01), and a lower detrusor LPP (P = .03) compared to UDS performed after recovery from anesthesia. Detrusor overactivity was less frequently observed intraoperatively (P <.001) and involuntary detrusor contractions were lower in magnitude than those observed in the PACU. Twelve of the 19 (63%) children had detrusor overactivity that was present only on the UDS in PACU and not intra-operatively. The results of urodynamic testing performed under general anesthesia should be interpreted with caution, as pediatric patients appear to have improved bladder compliance, lower detrusor LPP and decreased detrusor overactivity when under anesthesia. For this reason, it is preferable to utilize ambulatory urodynamic evaluation to guide patient management and treatment.

“When you're down, stay down”: A lesson for all competitive alpine skiers supported by an ACL rupture measured in vivo

BackgroundDuring an experiment, a ski racer equipped with various measurement devices suffered an anterior cruciate ligament (ACL) rupture in his right knee. The aim of this study was to describe the underlying injury mechanism from a functional perspective. MethodsEight giant slalom turns (i.e., 4 left turns), followed by 1 left turn at which the ACL injury occurred, were recorded by 2 video cameras, electromyography of 4 relevant muscle groups, inertial measurement units to measure knee and hip angles, and pressure insoles to determine ground reaction forces. ResultsDue to a loss of balance, the ski racer began to slide sideways at the apex of a left turn. During sliding, his right (outside) leg was actively abducted upward without touching the ground. The ski racer then attempted to stand up again by dropping his leg back towards the snow surface. The end of this dropping was accompanied by a decrease in electromyographic activity in the knee stabilizing muscles. Once the inside edge of the outer ski caught the snow surface, a rapidly increasing peak force, knee flexion, and an aggressive sudden activation of the vastus medialis muscle were observed, while biceps femoris and rectus femoris further decreased their activation levels. This likely resulted in excessive anterior translation of the tibia relative to the femur, causing damage to the ACL. ConclusionOur example emphasizes that ski racers should not get up until they stop sliding. Remember: “When you're down, stay down.”

Transcranial direct-current stimulation (tDCS) in the primary motor cortex and its effects on sensorimotor function: a quasi-experimental single-blind sham-controlled trial

The main aim was to assess the short-term effects of active-tDCS (a-tDCS) in the primary motor cortex (anodal stimulation-M1) on sensorimotor variables. These variables included discriminative sensation through the two-point discrimination (2-PD) test, tactile acuity threshold and pressure pain threshold (PPT), and electromyographic (EMG) activity compared with a sham-tDCS (s-tDCS) in healthy individuals. A total of 100 participants were included. Fifty of the participants received the a-tDCS application of 2 mA for 20 min, whereas the remaining fifty received the s-tDCS. The 2-PD and tactile acuity threshold in thenar eminence of the hand and in the dorsal part of the foot and also, PPT and EMG activity during maximal voluntary contraction in the biceps brachii and rectus femoris were assessed before and after the tDCS application. The a-tDCS intervention was not significantly superior to the s-tDCS in any variable. However, significant within-group pre- and post-intervention differences were found in the a-tDCS, such as the tactile acuity threshold in thenar eminence of the hand, with a small effect size (p = .012, d = 0.20) and in the PPT of the rectus femoris, also with a small effect size (p = .001, d = − 0.17). Regarding EMG activity, a trend towards greater activity was observed in participants with a-tDCS compared with s-tDCS, which showed a trend towards decreased EMG activity. In fact, although no differences were found between the groups, within-group differences were statistically significant in the biceps brachii pre- and postintervention (p = .023, d = − 0.16, and p = .002, d = 0.18, respectively), and also in the rectus femoris, only in the a-tDCS, with a small effect size (p = .011, d = − 0.14). This study showed no significant between-group differences in sensorimotor outcomes. A single session of tDCS in isolation appears to produce immediate effects in healthy participants on sensorimotor function; however, these effects were very small.

Effect of botulinum toxin treatment in patients with bruxism and orofacial pain - randomized double-blind clinical trial

Introduction: Bruxism is defined as a parafunctional chewing activity characterized by the clenching and / or grinding of teeth that occurs both during sleep and during the surveillance period. Methods: Thirty female patients between 18 and 40 years old who had bruxism and orofacial pain were selected and randomized into two groups: control group (n = 15), where individuals received 0.05 ml of sterile saline solution that was applied to the bundle anterior temporal muscles and 0.2 ml for each masseter muscle, and an experimental group (n = 15), individuals received 20 units of A-botulinum toxin (Botox®) applied to each masseter muscle and 5 units of A-botulinum toxin applied to the anterior bundle of each temporal muscle. Patients were called back for reevaluation every thirty days. At these moments, they underwent an evaluation of the load force and electromyography. Results: At 30, 60, 90 and 120 days, a decrease in electromyographic activity was observed in the A-botulinum toxin group (p &lt;0.001). In the experimental group, the left masseter muscle showed no significant difference between the variable load cell and time (p = 0.968), nor between electromyography versus load (p = 0.072), with a statistically significant difference between time and electromyography. (coef = 0.322; p &lt;0.001). Conclusion: The intramuscular application of botulinum toxin type A in patients with bruxism has proved to be an effective method for hyperactivity of the masseter muscle in patients with bruxism, improving and decreasing the levels of muscle contraction.

Severity of Sleep Bruxism and its Implications for the Stomatognathic System in Healthy Subjects

BACKGROUND: Sleep bruxism (SB) changes the functionality patterns of the stomatognathic system. However, its severity can be an aggravating factor in the function of this complex system.&#x0D; AIM: The purpose of the study was to investigate the stomatognathic system of healthy subjects with different severity of SB, as determined by BiteStrip.&#x0D; METHODS: Thirty-four subjects were divided into two groups: Mild SB (n = 15) and severe SB (n = 19). Electromyograph was used to evaluate the electromyographic activity of the right masseter (RM), left masseter (LM), right temporal (RT), and left temporal (LT) muscles at mandibular rest, right and left laterality, protrusion, and maximum voluntary contraction. Molar bite force was measured by the dynamometer. The data were tabulated and submitted for statistical analysis (p &lt; 0.05).&#x0D; RESULTS: Molar bite force was significantly lower in the severe SB group. There was a significant increase in electromyographic activity in the severe SB group for the mandibular rest tasks (RM, RT, and LT), protrusion (RM, LM, RT, and LT), and right and left laterality in the temporalis muscles. There was a significant decrease in electromyographic activity in the severe SB group in maximum voluntary contraction for the masseter and temporalis muscles.&#x0D; CONCLUSION: Subjects with severe SB demonstrated greater functional impairment of the stomatognathic system, mainly affecting the electromyographic activity and molar bite force.

Effects of intrathecal transient receptor potential vanilloid 1 blocker on cervical distension induced visceral pain response

Objective: With the aid of an acute visceral pain model of uterine cervical distension (UCD), the present study aimed to observe the effects of intrathecal administration of transient receptor potential vanilloid 1 (TRPV1) antagonist SB-366791 on UCD induced-visceral nociception as well as its involved molecular mechanisms. Methods: A total of 30 Sprague-Dawley-derived adult virgin female rats were used. UCD model was established under isoflurane inhalation anesthesia. Briefly, a lower abdominal incision at midline was made to expose the uteral cervix, two metal rods were inserted through both sides of the cervix separately, one rod was fixed and the other one was connected to a pulley system with application of manual weighted traction (0, 25, 50, 75 or 100 g) for simulating 1 h of cervical distension. In addition, 12 Sprague-Dawley-derived adult virgin female rats were subjected to intrathecal catheter implantation, and UCD was established 7 days later. The rats were divided randomly into two groups; one group was administrated with intrathecal SB-366791 while the other was administrated with the same volume of saline as control. The 75 g distension force was then applied for an hour and the electromyographic (EMG) of musculus rectus abdominis, heart rate as well as respiratory frequency were measured continuously during the surgery. The spinal cord (T(12)-L(2)) was collected 30 minutes after UCD for the detection of changes of c-FOS and TRPV1 expression. Results: UCD increased EMG activity (P<0.05) and c-FOS expression (P<0.05) in the deep dorsal horn region and central canal of the spinal cord (T(12)-L(2)) in a stimuli-dependent manner, the expression of TRPV1 in the T(12)-L(2) spinal cord also increased in response to UCD stimulation (P<0.05). Compared with the saline group, intrathecal SB-366791 significantly decreased EMG activity (P<0.05) as well as spinal c-FOS (P<0.05) expression induced by UCD. Conclusions: UCD in rats increases EMG activity of musculus rectus abdominis as well as spinal c-FOS and TRPV1 expression. Intrathecal administration of TRPV1 antagonist SB-366791 significantly decreases the visceral nociception induced by UCD.

Electromyographic Activity of Gluteus Maximus Muscle in Nonspecific Chronic Low Back Pain

AbstractBackground: Nonspecific chronic low back pain is a common problem that can cause economic and social problems for an individual. Although there were alot of studies have reported the changes in the gluteus maximus activity in nonspecific chronic low back pain patients but it still debated.Aim of Study: This study was conducted to investigate electromyographic activity of gluteus maximus muscle in nonspecific chronic low back pain male patients.Subjects and Methods: Thirty nonspecific chronic low back pain male patients and 30 healthy male subjects with age from 20 to 40 years old with body mass index less than 30kg/m2 were recruited and assigned into 2 groups. Assessment was conducted by surface electromyography to assess gluteus maximus activity. Normalized root mean square of gluteus maximus muscle was collected and analyzed by SPSS version (24).Results: There were significance decrease in electromy-ographic activity of right and left gluteus maximus in the study group when compared to control with p-values >0.005.Conclusion: There was a decrease in the activity of the gluteus maximus in nonspecific chronic low back pain male patients when compared to the control group.

Effects of mouth rehabilitation with removable complete dentures on stimulus perception and the electromyographic activity of the orbicularis oris muscle

Statement of problemMany elderly individuals are rehabilitated with removable complete dentures, which require an initial adaptation period for both oral perception and the perioral muscles. Studies assessing the changes in stimulus perception and the electromyographic (EMG) activity of the orbicularis oris muscle shortly after conventional complete denture insertion are lacking. PurposeThe purpose of this clinical study was to evaluate the effect of mouth rehabilitation with removable complete dentures on stimulus perception and the EMG activity of the orbicularis oris muscle. Material and methodsThis study was approved by the Human Research Ethics Committee of the Araçatuba Dental School (São Paulo State University). Fifteen participants who had worn their removable complete dentures for at least 5 years and needed rehabilitation with new prostheses were enrolled in the study. A perception questionnaire was applied, and surface EMG examinations of the orbicularis oris muscle during rest, suction of water with a straw, and pronunciation of the syllables /bah/, /mah/, /pah/, and the word ‘Mississippi’ were performed before (T0) and 30 (T1) and 100 (T2) days after insertion of the new prostheses. The data were analyzed with the Cochran Q test, McNemar test, 2-way repeated measures ANOVA, and honestly significant difference (HSD) Tukey test (α=.05). ResultsSignificant improvement was reported in the perception questionnaire in terms of the oral discomfort sensation in the T2 period. EMG activity decreased during rest and suction after insertion of the new prostheses. A statistical difference between the upper and lower fascicles of the orbicularis oris muscle was detected, with a decrease of EMG activity between the T0 and T1 periods on the lower fascicle, except for when pronouncing the /pah/ syllable. ConclusionsMouth rehabilitation with removable complete dentures decreased oral discomfort and, depending on the oral function, decreased or increased EMG activity of the orbicularis oris muscle. In addition, the lower fascicle was more active than the upper fascicle during rest and most functional activities.

Uterine and Abdominal Muscle Electromyographic Activities in Control and PCEA-Treated Nulliparous Women During the Second Stage of Labor.

Patient-controlled epidural analgesia (PCEA), used to relieve pain during delivery, delays labor but the mechanism is unknown. The aim was to investigate the effects of PCEA on uterine and abdominal muscles electromyographic (EMG) activity during the second stage of labor. This study included 45 nulliparous pregnant women without PCEA, 42 women with standard PCEA treatment given during the first stage of labor and stopped near the end of the first stage, and 22 women with standard PCEA treatment with continued use throughout the first and second stages of labor. The EMG signals were recorded from the abdominal surface using PowerLab hardware and LabChart software (ADInstruments, New South Wales, Australia) and filtered to separate uterine and abdominal EMG. Various EMG burst parameters were obtained. There are no differences ( P > .05) in the age, body mass index, fetal weight, and Apgar scores between the patients from the various groups. PCEA (both stopped and continued) inhibits ( P < .05) duration, number of bursts, and root mean square of uterine EMG. PCEA also produces statistically significant ( P < .001) reductions in abdominal EMG. The decrease in EMG activity is accompanied by a significant ( P < .001) prolongation of the second stage duration (PCEA continued = 95.08 ± 8.60 minutes, PCEA stopped = 79.39 ± 6.25 minutes, no PCEA = 61.00 ± 7.23 minutes). PCEA suppresses uterine and abdominal muscle EMG during the second stage of labor but inhibition depends upon the treatment schedule. PCEA prolongs the duration of labor by inhibition of uterine and abdominal muscle and neural activity.

Acute changes in neuromuscular activity in vertical jump and flexibility after exposure to whole body vibration.

This study was aimed to investigate the neuromuscular activity after 10 minutes of exposure to a whole body vibration (WBV) session.Twenty male young adults (24.8 ± 2.5 year olds) were randomized and divided into 2 groups: the vibration group (VG) was exposed to 10 minutes of WBV at 35 Hz; performed 10 minutes of WBV at 35 Hz (displacement = 5 mm; magnitude = 5 g); the nonvibrated group (NVG) was the placebo group that maintained the same position on the plate but without exposure to any type of vibration. Subjects were evaluated with counter movement jump (CMJ) and muscular flexibility by means of electromyographic (EMG) analysis recorded on the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and gastrocnemius lateralis (LG).The 10 minutes of WBV showed an increase in muscular flexibility, associated with a decrease of EMG activity in BF (P < .01) and jump height. The latter was associated with a reduction of EMGs activity in BF (P < .01). The control group did not show any significant difference in all considered parameters.These results support the hypothesis that 10 minutes of WBV had effects on flexibility and explosive strength performance influencing neuromuscular behavior through inhibitor effects on antagonist muscles more than the stretch reflex activity on agonist muscles.

The clinical and EMG assessment of the effects of stabilization exercise on nonspecific chronic neck pain: A randomized controlled trial.

Neck pain is an important cause of disability. In spite of its high prevalence rate, treatment of the disorder is a challenging topic. Stabilization exercise has been the topic of many studies. To compare the effects of stabilization and routine exercises on chronic neck pain. Forty patients were randomly assigned into either stabilization or routine exercise groups and undertook a 10-week training program. Electromyographic (EMG) activity was recorded from Sternocleidomastoid (SCM), Anterior Scalene (AS) and Splenius Capitis (SC) muscles bilaterally. Endurance time of deep flexor muscles was measured by chronometer.Pain and disability were measured using Visual Analogue Scale (VAS) and neck disability index (NDI) questionnaire, respectively before and after training period. Findings revealed significant decreased pain and disability in both groups after intervention (P< 0/001). Flexor muscles endurance of stabilization group was significantly increased compared with that of routine (P< 0/001). Also EMG activity of SCM, AS and SC muscles were significantly decreased in stabilization group compared with routine (P< 0/001). Increased deep flexor endurance and decreased EMG activity of SCM, AS and SC muscles suggest an important role for stabilizing exercises on reducing the activity of superficial muscles in chronic neck pain.

In vivo potency of different ligands on voltage-gated sodium channels

The Ranvier nodes of thick myelinated nerve fibers contain almost exclusively voltage-gated sodium channels (Navs), while the unmyelinated fibers have several receptors (e.g., cannabinoid, transient receptor potential vanilloid receptor 1), too. Therefore, a nerve which contains only motor fibers can be an appropriate in vivo model for selective influence of Navs. The goals were to evaluate the potency of local anesthetic drugs on such a nerve in vivo; furthermore, to investigate the effects of ligands with different structures (arachidonic acid, anandamide, capsaicin and nisoxetine) that were proved to inhibit Navs in vitro with antinociceptive properties.The marginal mandibular branch of the facial nerve was explored in anesthetized Wistar rats; after its stimulation, the electrical activity of the vibrissae muscles was registered following the perineural injection of different drugs.Lidocaine, bupivacaine and ropivacaine evoked dose-dependent decrease in electromyographic activity, i.e., lidocaine had lower potency than bupivacaine or ropivacaine. QX-314 did not cause any effect by itself, but its co-application with lidocaine produced a prolonged inhibition. Nisoxetine had a very low potency. While anandamide and capsaicin in high doses caused about 50% decrease in the amplitude of action potential, arachidonic acid did not influence the responses.We proved that the classical local anesthetics have high potency on motor nerves, suggesting that this method might be a reliable model for selective targeting of Navs in vivo circumstances. It is proposed that the effects of these endogenous lipids and capsaicin on sensory fibers are not primarily mediated by Navs.

Evaluation of the Immediate Effect of Auricular Acupuncture on Pain and Electromyographic Activity of the Upper Trapezius Muscle in Patients with Nonspecific Neck Pain: A Randomized, Single-Blinded, Sham-Controlled, Crossover Study.

Background. The aim of the present study was to assess the immediate effects of auricular acupuncture (AA) on the electromyographic (EMG) activity of the upper trapezius muscle and pain in nonspecific neck pain (NS-NP) patients. Twelve patients with NS-NP (NS-NP group) and 12 healthy subjects (HS Group) were enrolled in a randomized, single-blinded, crossover study. Each subject received a single session of AA and sham AA (SAA). Surface EMG activity was measured in the upper trapezius muscle at different “step contractions” of isometric shoulder elevation (15%, 20%, 25%, and 30% MVC). The outcome measure in patients with NS-NP was based on the numerical pain rating scale (NRS). AA treatment led to a significant decrease in EMG activity in both groups (NS-NP group: p = 0.0001; HS group: p < 0.0001—ANOVA test). This was not the case for the SAA treatment (NS-NP group: p = 0.71; HS group: p < 0.54). Significant decreases (p < 0.001) in the NRS were found for both treatments (AA and SAA). This study demonstrated the immediate effect of auricular acupuncture on the electromyographic activity of the upper trapezius muscle but the effect of this intervention on pain symptoms in patients with nonspecific neck pain was inconclusive.

Effect of experimental jaw muscle pain on dynamic bite force during mastication

Knowledge about how Temporomandibular Disorder (TMD) pain patients regulate masticatory function is still unclear. To investigate the effect of experimental jaw muscle pain as well as texture and size of food on mastication, twelve healthy participants (30.6±7.5 years old) participated in this study. Experimental pain was induced by an infusion of 0.5M monosodium glutamate (MSG) with isotonic saline (IS) serving as a control. After the infusions, the Jaw Functional Limitation Scale (JFLS) and Pain Catastrophizing Scale (PCS) were filled out. Electromyographic (EMG) activity in the masseter and temporalis muscles, jaw movements and bite force, which was measured by a customized intra-oral device, were recorded simultaneously during mastication of three different types of food. Pain was scored continuously on a visual analog scale. The results demonstrated a trend towards a decrease in the impulse of the bite force, as well as a significant decrease in EMG activity of the masseter muscle during the first five masticatory cycles, in the MSG session. Also, MSG induced increased JFLS and PCS scores compared with IS. On the other hand, the results suggested that the applied levels of pain may not change habitual masticatory movements. This study has revealed that a clinically relevant level of pain in the masseter muscle has only minor impact on the performance of mastication, probably due to a lack of exacerbation of pain during function. In future studies of jaw muscle function during painful conditions, it is important to include patient-based reports of functional limitation and emotional distress.

Effects of Quadriceps Muscle Fatigue on Stiff-Knee Gait in Patients with Hemiparesis

The relationship between neuromuscular fatigue and locomotion has never been investigated in hemiparetic patients despite the fact that, in the clinical context, patients report to be more spastic or stiffer after walking a long distance or after a rehabilitation session. The aim of this study was to evaluate the effects of quadriceps muscle fatigue on the biomechanical gait parameters of patients with a stiff-knee gait (SKG). Thirteen patients and eleven healthy controls performed one gait analysis before a protocol of isokinetic quadriceps fatigue and two after (immediately after and after 10 minutes of rest). Spatiotemporal parameters, sagittal knee and hip kinematics, rectus femoris (RF) and vastus lateralis (VL) kinematics and electromyographic (EMG) activity were analyzed. The results showed that quadriceps muscle weakness, produced by repetitive concentric contractions of the knee extensors, induced an improvement of spatiotemporal parameters for patients and healthy subjects. For the patient group, the increase in gait velocity and step length was associated with i) an increase of sagittal hip and knee flexion during the swing phase, ii) an increase of the maximal normalized length of the RF and VL and of the maximal VL lengthening velocity during the pre-swing and swing phases, and iii) a decrease in EMG activity of the RF muscle during the initial pre-swing phase and during the latter 2/3 of the initial swing phase. These results suggest that quadriceps fatigue did not alter the gait of patients with hemiparesis walking with a SKG and that neuromuscular fatigue may play the same functional role as an anti-spastic treatment such as botulinum toxin-A injection. Strength training of knee extensors, although commonly performed in rehabilitation, does not seem to be a priority to improve gait of these patients.

Muscle activity during lifting: Examining the effect of core conditioning of multifidus and transversus abdominis

It is well accepted that both multifidus and transversus abdominis muscles have a vital role in maintaining spinal stability. To determine if multifidus and transversus abdominis could be strengthened by a six-week conditioning program and to establish if the amount of electromyographic (EMG) activity in external oblique differed in a lifting and holding task after the conditioning program. EMG activity of external oblique during a lifting and holding task was obtained. Multifidus cross-sectional area and transversus abdominis width were measured using real time ultrasound in six males and five females, with no back pain (mean age of 26.3 (± 5.4) years). The participants then performed a six-week muscle-conditioning program for multifidus and transversus abdominis, after which the EMG activity of external oblique and dimensions of multifidus and transversus abdominis were re-measured. Both multifidus and transversus abdominis significantly increased in size. There was significantly less activity in external oblique during a lifting task after the conditioning program, with no change in external oblique activity during a holding task. this study may indicate a link between the dimensional increase of multifidus and transversus abdominis, and the decrease in EMG activity in external oblique during lifting.

The Effect of Varying Implant Position in Immediately Loaded Implant-Supported Mandibular Overdentures

This study was carried out to evaluate the effect of varying implant position in immediately loaded implant-supported mandibular overdentures on peri-implant bone density, muscle activity, and patient satisfaction. Fourteen completely edentulous patients were selected for the study. After complete denture construction, patients were divided into 2 equal groups. Four dental implants were installed bilaterally in the interforaminal region in the first group, while in the second group, 4 dental implants were inserted bilaterally: 2 in the interforaminal region and 2 in the first molar area. Immediately after suturing, telescopic abutments were screwed to the implants, and the retaining caps were picked up into the fitting surface of the lower denture, which was delivered to the patient. Patients were recalled for radiographic bone density evaluation just after denture delivery and then at 3, 6, and 12 months thereafter. Muscle activities of masseter and temporalis muscles as well as patient satisfaction were also evaluated. The results of the study showed a high success rate approximating 98.2% of the immediately loaded implants. The electromyographic (EMG) records of both muscles in group 1 were significantly higher during chewing hard food after 3 months compared with group 2 (P < .05). Bone density changes were comparable in the 2 groups except at the end of the follow-up period, when group 2 showed a significant increase in peri-implant bone density values of the posteriorly placed implants compared with group 1 (P < .05). From the results of this study, it may be concluded that wide distribution of immediately loaded implants used for supporting mandibular overdentures through posterior placement beyond the interforaminal area results in a favorable response in terms of increased peri-implant bone density as well as decreased EMG activity of masseter and temporalis muscles.

Case report involving temporomandibular dysfunction, eagle’s syndrome and torus mandibularis —Multidisciplinary approaches

The prevalence of torus mandibularis, Eagle’s syndrome and parafunctional activity was reported to be higher in patients with temporomandibular joint dysfunction and might be useful as an indicator of increased risk of temporomandibular disorders. This study case report was to evaluate a 62-year-old female patient, with limited mandibular and cervical movements, articular and muscular pain, ear fullness, irritation of the lingual mucosa, discomfort associated with movement of her tongue, involving temporomandibular dysfunction, torus mandibularis and Eagle’s syndrome. The treatment comprehended the collection of data of Helkimo’s Clinical Dysfunction Index, electromyographic activity of the masseter and temporalis muscles in rest position and bite force, masticatory efficiency, speech evaluation and oclusal splint, after the excision of the stylohyoid process and mandibularis torus. The authors found a decrease in electromyographic activity of masticatory muscles, a reduction of painful symptoms throughout the region muscular and joint pains, an increase in the amplitude of mandibular movements, an improvement in masticatory efficiency and an increase in bite force.

Effect of experimental jaw muscle pain on bite force during mastication

Abstract Background/aims Muscular pain often impairs masticatory function in Temporomandibular disorder patients. The specific aim of this study was to investigate how the bite force during mastication is influenced by experimental muscle pain caused by infusion of glutamate into the masseter muscle. Methods 12 healthy adults participated, after providing informed consent. Customized metal frames of the intraoral bite force sensor were manufactured for all subjects, and placed on their preferred chewing side. To induce experimental pain, a sterile solution of glutamate (0.5 M) was infused into the posterior part of the masseter muscle. Isotonic saline (0.9%) was infused as a control (randomized, cross-over design). During chewing three different kinds of test food (two different size carrots and gummy), bite force, electromyographic (EMG) activity of bilateral masseter muscle and anterior temporalis muscle were recorded. The first and last five masticatory cycles were used for analyses. The outcome parameters were as follows; Visual Analog Scale (VAS) for pain, impulse and duration from the bite force signal, duration and amplitude of EMG. Three-way ANOVAs with food (3 levels), sessions (5 levels: baseline, during glutamate, baseline 2, during isotonic saline, follow-up), cycles (2 × 5 levels) were carried out. Results Glutamate caused moderate levels of pain (mean VAS: 2.4 ± 0.9) whereas isotonic saline only caused low levels of pain (Mean VAS: 0.7 ± 0.5). The ANOVA of impulse data, as well as most EMG data, demonstrated a significant effect of session. Post hoc tests showed significantly higher impulse values of both the first and last five cycles in the glutamate session compared to baseline whereas the EMG activity was significantly decreased (P &lt; 0.05). Conclusion Surprisingly, experimental pain induced by glutamate increased the bite force during mastication coupled with a decrease in EMG activity. This indicates a major reorganization of the motor control during painful mastication.