Myoelectric Activity Research Articles

Neuromuscular characteristics of agonists and antagonists during maximal eccentric knee flexion in soccer players with a history of hamstring muscle injuries.

Muscle strain injuries (MSIs) in the hamstrings are among the most prevalent injuries in elite soccer. We aimed to examine the relation between biomechanical maladaptation in eccentric strength and neuromuscular factors separated by their time and frequency domains. 20 elite soccer players with a previous history of unilateral MSI in the M. biceps femoris (BF) long head and 20 without MSI participated. Knee flexion torques, rate of torque development (RTD) and electromyographic signals (EMG) of the BF, the M. semitendinosus (SMT) and knee extensors were obtained during unilateral maximal eccentric knee flexions performed at slow (30°/s) and fast (120°/s) angular speeds. Root mean squares and mean power frequency (MF) was calculated. In the group with a history of MSI, reduced maximal eccentric flexion torque (slow eccentrics -8±11, p<0.05; fast eccentrics -18±13 N*m, p<0.05) and RTD (-33±28 N*m/s, p<0.05; -95±47 N*m/s, p<0.05) concomitantly occurred with diminished agonistic myoelectrical activities (-4±5% of MVC, p<0.05; -10±7% of MVC, p<0.05) and MFs (-24±13 Hz, p<0.05; -24±18 Hz, p<0.05) in the BF. Simultaneously, antagonistic myoelectric activity was elevated (+4±3% of MVC, p<0.05; +3±3% of MVC, p<0.05) in MSI affected legs as compared to unaffected legs for both eccentric contractions. Deficits in myoelectrical activity (r2 = 0.715, p<0.05; r2 = 0.601, p<0.05) and MF (r2 = 0.484, p<0.05; r2 = 0.622, p<0.05) correlated with deficits in maximal torque in the affected leg in the MSI group. Analysis of SMT demonstrated no significant differences. Positive relationships between neuromuscular deficits and the reduced eccentric strength profile underpin neuronal inhibition after MSI. This persistent involvement of dysfunctional synergist and antagonist neural hamstring function in strength weakness is of clinical relevance in sports medicine for prevention and rehabilitation.

Does exertional heat stress impact gastrointestinal function and symptoms?

Exertional-heat stress generates a thermoregulatory strain that exacerbates splanchnic hypoperfusion and sympathetic drive, but the effects on gastrointestinal function are poorly defined. The study aimed to determine the effects of exertional-heat stress on gastric myoelectrical activity, orocecal transit time (OCTT), and gastrointestinal symptoms (GIS). Randomised cross-over study. Endurance runners (n = 16) completed 2 h of running at 60 % V̇O2max in 35 °C (HOT) and 22 °C (TEMP) ambient conditions. Surface electrogastrography (cEGG) was recorded pre- and post-exercise to determine gastric myoelectrical activity, a lactulose challenge was used to determine OCTT, and GIS were recorded using a modified visual analogue scale tool. Post-exercise Tre [HOT:38.8(38.5 to 39.0)°C and TEMP:38.1(37.8 to 38.4)°C] and Δ Tre [HOT:2.2(2.0 to 2.4)°C and TEMP:1.5(1.2 to 1.8)°C] was higher on HOT compared to TEMP (p < 0.001). Normal gastric myoelectrical cycle frequency reduced (p = 0.010) on HOT [-11.7(-20.8 to -2.6)%], but this decrease did not differ (p = 0.058) from TEMP [-2.7(-8.3 to 3.0)%]. Bradygastria increased post-exercise on both trials (HOT:11.3(2.3 to 20.4)%, p = 0.030; and TEMP:7.4(2.1 to 12.6)%, p = 0.009). OCTT did not differ between trials (p = 0.864) with transit response classified as very slow on both HOT (99(68 to 131)min) and TEMP (98(74 to 121)min). GIS incidence was higher on HOT (88 %) compared to TEMP (81 %), in accordance with greater total-GIS and upper-GIS severity (p = 0.005 and p = 0.033, respectively). Running for 2 h at 60 % V̇O2max in either hot or temperate ambient conditions instigates perturbations in myoelectrical activity and OCTT, with GIS incidence and severity greater in hot conditions.

Frequency-specific electrogastrography as a non-invasive tool to measure gastrointestinal maturity in preterm infants

Enteral feeding is challenging in preterm infants because of gastrointestinal (GI) immaturity. Electrogastrography (EGG) is a non-invasive technology that measures gastric myoelectrical activity and can be utilized to measure changes that occur with maturation at different gestational ages (GA). Three gastric rhythms (GR) exist between 0.5–9 cycles per minute (cpm), namely, bradygastria (0.5 ≤ GR < 2 cpm), normogastria (2 ≤ GR < 4 cpm), and tachygastria (4 ≤ GR < 9 cpm). We aimed to characterize EGG-derived parameters for different GA by quantifying (1) power spectral density (PSD) and its spectral means at three GR bands (i.e., mPSDGR) and (2) the percent (%) time spent in each band. Data analyzed was from a longitudinal cohort of preterm infants (n = 51) born at early, mid, and term GA of < 29, 29–33, and ≥ 37 weeks, respectively. Weekly EGG monitoring was performed until 40 weeks’ postmenstrual age or discharge. Pre-, during, and post-feed data were analyzed for mPSDGR at each GR band. Also, % bradygastria, % normogastria, and % tachygastria were calculated by continuous wavelet transform analysis. Results showed (1) mPSD values in normogastria and tachygastria during feeding increased with advancing GA, and (2) % normogastria increased with advancing GA regardless of GR ranges, suggesting EGG may measure GI maturity in preterm infants.

Myoelectric Activity of Selected Trunk Muscles Following the Use of Various Insole Wedges During Running

Myoelectric Activity of Selected Trunk Muscles Following the Use of Various Insole Wedges During Running

Gastric sensorimotor function and its clinical measurement.

Gastroduodenal symptoms are highly prevalent, with underlying sensorimotor dysfunction contributing in many patients. Common symptoms include early satiation, postprandial fullness, epigastric bloating, pain or burning, nausea and vomiting, which collectively affect over 7% of adults. However, the clinical evaluation of these symptoms remains challenging, with current tests of gastric function remaining limited in their ability or availability to separate specific patient subgroups or guide-targeted care. In the current edition of Neurogastroenterology & Motility, Silver et al. present new data showing correlations between patterns of intragastric meal distribution and symptom profiles in a large series of patients undergoing gastric emptying scintigraphy. Studies of this type are important, as they motivate understanding beyond existing disease labels, and orient focus toward deeper mechanistic profiling. This brief review provides an overview of gastric sensorimotor function and profiles several current and emerging methods of clinical evaluation. Perspectives are provided on accommodation testing, gastric emptying, measuring gastric myoelectrical activity including new approaches, and antroduodenal manometry. Although gastric physiology is complex, recent progress has been encouraging, with the heterogenous pathophysiology of gastric symptoms continuing to be unraveled, and new techniques for evaluating gastric function and symptoms emerging. Ongoing progress will now depend on continuing to accurately profile the underlying mechanisms of gastroduodenal disorders to identify specific disease phenotypes that inform care.

Alteration of muscle activity during voluntary rehabilitation training with single-joint Hybrid Assistive Limb (HAL) in patients with shoulder elevation dysfunction from cervical origin.

Shoulder elevation, defined here as arm raising, being essential for activities of daily living, dysfunctions represent a substantial burden in patients' lives. Owing to the complexity of the shoulder joint, the tightly coordinated muscular activity is a fundamental component, and neuromuscular impairments have devastating effects. A single-joint shoulder type version of the Hybrid Assistive Limb (HAL) allowing motion assistance based on the intention of the user via myoelectric activation has recently been developed, and its safety was demonstrated for shoulder rehabilitation. Yet, little is known about the physiological effects of the device. This study aims to monitor the changes in muscle activity and motion during shoulder HAL rehabilitation in several patients suffering from shoulder elevation dysfunction from cervical radicular origin. 8 patients (6 males, 2 females, mean age 62.4 ± 9.3 years old) with weakness of the deltoid muscle resulting from a damage to the C5 nerve root underwent HAL-assisted rehabilitation. We combined surface electromyography and three-dimensional motion capture to record muscular activity and kinematics. All participants showed functional recovery, with improvements in their Manual Muscle Testing (MMT) scores and range of motion (ROM). During training, HAL decreased the activity of deltoid and trapezius, significantly more for the latter, as well as the coactivation of both muscles. We also report a reduction of the characteristic shrugging compensatory motion which is an obstacle to functional recovery. This reduction was notably demonstrated by a stronger reliance on the deltoid rather than the trapezius, indicating a muscle coordination tending toward a pattern similar to healthy individuals. Altogether, the results of the evaluation of motion and muscular changes hint toward a functional recovery in acute, and chronic shoulder impairments from cervical radicular origin following shoulder HAL rehabilitation training and provide information on the physiological effect of the device.

Quantitative analysis for grading uterine electromyography activities during labor

The strength of uterine contraction is one of the decisive factors for labor progression and parturition. Clinicians usually encounter difficulties in early identification of inadequate contractions and in oxytocin treatment. Electromyography-an emerging technology for uterine contraction monitoring-can quantify the intensity of myoelectric activity of uterine contraction. Therefore, grading patients with different uterine contraction intensities by electromyography is of great significance to the clinical intensive management of uterine contraction and labor process. This study aimed to quantify and grade electromyography activity during the latent phase of the first stage of labor and explore its relationship with oxytocin treatment and length of labor. We performed a retrospective cohort study to identify electromyography parameters as a predictor for oxytocin treatment and length of labor among a cohort of term singleton primipara (n=508) during the latent phase who delivered in Guangzhou between August 2018 and December 2021. The electromyography parameters were graded according to the quartile method, and the significance of grading and delivery outcome was explored. Univariateandmultivariate logistic regression were used to determine the predictors of oxytocin treatment. Maternal gestational age (adjusted risk ratio, 1.2; 95% confidence interval, 1.0-1.5), root mean square (adjusted risk ratio, 0.01; 95% confidence interval, 0.004-0.03), and power (adjusted risk ratio, 0.02; 95% confidence interval, 0.01-0.05) were significant predictors of oxytocin argumentation. The low electromyography activity group had a longer first stage labor and total labor time and were more likely to use oxytocin. Electromyography parameters root mean square and power had high predictive values for later oxytocin treatment among patients with spontaneous labor. Patients with low-grade electromyography were more likely need oxytocin treatment. Electromyography grading is very important for its clinical promotion and use, and it could lead to more reliable analyses of oxytocin treatments and eventually to more effective interventions to prevent prolonged labor.

AI-Derived Threshold Score of Intraabdominal Myoelectrical Activity Predicts Presence and Stage of Endometriosis with 100% Accuracy

Study Objective 1) Demonstrate non-invasive cutaneous Electroviscerography (EVG)-detected abnormal gastrointestinal myoelectrical activity (GMA) has 100% accuracy diagnosing endometriosis. 2) Demonstrate GMA-based artificial intelligence (AI)-derived formulae detects endometriosis regardless of hormonal suppression, surgical stage or symptoms. Design Prospective open-labeled study. Setting Clinical center for women's healthcare. Patients or Participants 50 women ages 17-45 with chronic abdominal pain, negative CT or MRI, and gastrointestinal endoscopy, scheduled for laparoscopy. Interventions Baseline EVG w/water load satiety test(WLST) and pain scores, followed by diagnostic laparoscopic surgery w/biopsy. Measurements and Main Results Response to EVG WLST identified specifically elevated GMA frequencies of 15-20(9.5 vs 2.2, p<0.001), 30-40(3.1 vs 0.8, p<0.001) and 50-60(1.1 vs 0.5,p<0.05) compared to known population normals and disease free subjects with abdominal pain. GMA-derived 2 stage Ai-determined threshold (AIET) was calculated to be >0.5, using linear regression of area under curve on first pass and age and pain scores in the second pass, demonstrated 100% selectivity and 100% specificity, respectively. All subjects exceeded AIET and had ASRM stages 1-4 at laparoscopy. AIET scores ranged 0.52 to 8.9, and escalated according to advancing surgical grade. Hormonal suppression did not affect diagnosis. Conclusion Endometriosis-specific abnormalities of GMA post-WLST predicts surgically detected endometriosis w/100% accuracy. AI GMA-derived threshold detects endometriosis with 100% sensitivity and specificity. Hormonal suppression, symptoms and surgical grade of endometriosis did not affect test accuracy. Variations in Ai-derived threshold scores may predict surgical stage of endometriosis. EVG represents an ideal test for the detection and screening of endometriosis. 1) Demonstrate non-invasive cutaneous Electroviscerography (EVG)-detected abnormal gastrointestinal myoelectrical activity (GMA) has 100% accuracy diagnosing endometriosis. 2) Demonstrate GMA-based artificial intelligence (AI)-derived formulae detects endometriosis regardless of hormonal suppression, surgical stage or symptoms. Prospective open-labeled study. Clinical center for women's healthcare. 50 women ages 17-45 with chronic abdominal pain, negative CT or MRI, and gastrointestinal endoscopy, scheduled for laparoscopy. Baseline EVG w/water load satiety test(WLST) and pain scores, followed by diagnostic laparoscopic surgery w/biopsy. Response to EVG WLST identified specifically elevated GMA frequencies of 15-20(9.5 vs 2.2, p<0.001), 30-40(3.1 vs 0.8, p<0.001) and 50-60(1.1 vs 0.5,p<0.05) compared to known population normals and disease free subjects with abdominal pain. GMA-derived 2 stage Ai-determined threshold (AIET) was calculated to be >0.5, using linear regression of area under curve on first pass and age and pain scores in the second pass, demonstrated 100% selectivity and 100% specificity, respectively. All subjects exceeded AIET and had ASRM stages 1-4 at laparoscopy. AIET scores ranged 0.52 to 8.9, and escalated according to advancing surgical grade. Hormonal suppression did not affect diagnosis. Endometriosis-specific abnormalities of GMA post-WLST predicts surgically detected endometriosis w/100% accuracy. AI GMA-derived threshold detects endometriosis with 100% sensitivity and specificity. Hormonal suppression, symptoms and surgical grade of endometriosis did not affect test accuracy. Variations in Ai-derived threshold scores may predict surgical stage of endometriosis. EVG represents an ideal test for the detection and screening of endometriosis.

Regional differences of tachykinin effects on smooth muscle and pacemaker potentials of the stomach, duodenum, ileum and colon of an emetic model, the house musk shrews

Background and aimsThe contractile effects of tachykinins on the gastrointestinal tract are well-known, but how they modulate slow-waves, particularly in species capable of emesis, remains largely unknown. We aimed to elucidate the effects of tachykinins on myoelectric and contractile activity of isolated gastrointestinal tissues of the Suncus murinus. MethodsThe effects of substance P (SP), neurokinin (NK)A, NKB and selective NK1 (CP122,721, CP99,994), NK2 (SR48,968, GR159,897) and NK3 (SB218,795, SB222,200) receptor antagonists on isolated stomach, duodenum, ileum and colon segments were studied. Mechanical contractile activity was recorded using isometric force displacement transducers. Electrical pacemaker activity was recorded using a microelectrode array. ResultsCompared with NKA, SP induced larger contractions in stomach tissue and smaller contractions in intestinal segments, where oscillation magnitudes increased in intestinal segments, but not the stomach. CP122,721 and GR159,897 inhibited electrical field stimulation-induced contractions of the stomach, ileum and colon. NKB and NK3 had minor effects on contractile activity. The inhibitory potencies of SP and NKA on the peristaltic frequency of the colon and ileum, respectively, were correlated with those on electrical pacemaker frequency. SP, NKA and NKB inhibited pacemaker activity of the duodenum and ileum, but increased that of the stomach and colon. SP elicited a dose-dependent contradictive pacemaker frequency response in the colon. ConclusionThis study revealed distinct effects of tachykinins on the mechanical and electrical properties of the stomach and colon vs. the proximal intestine, providing a unique aspect on neuromuscular correlation in terms of the effects of tachykinin on peristaltic and pacemaker activity in gastrointestinal-related symptoms.

Gastric myoelectrical activity based AI-derived threshold predicts resolution of gastroparesis post-pyloric balloon dilation.

A patient subset with gastroparesis (GP) has normal gastric myoelectrical activity (GMA) and pyloric dysfunction. (1) To determine pyloric balloon dilation (BD) effect on symptoms and gastric emptying in GP patients with normal 3 cycles per minute (cpm) GMA. (2) To demonstrate GMA-based artificial intelligence (AI)-derived formulae predict BD success at 10-12-month follow-up. Cohort subjects completed baseline electrogastrogram w/water load satiety test (WLST), solid-phase nuclear gastric emptying, Gastrointestinal Cardinal Symptom Index (ANMS GCSI-DD) and Leeds questionnaires. Subjects were divided into two groups based on response to the WLST. Group 1 (n = 26) with hypernormal/normal 3cpm GMA and Group 2 (n = 4) hyponormal/normal range 3cpm GMA, compared to healthy normals. All subjects underwent endoscopic pyloric BD. After 10-12months, gastric emptying and dyspepsia questionnaires were repeated to evaluate outcomes. Group 1 ANMS GCSI-DD scores improved from 2 points at baseline (BL) to 0 at follow-up (f/u) (p < 0.001); Group 2 ANMS GSCI-DD scores were 2 at BL and 1.6 at f/u (p = 0.25). Leeds scores improved (p < 0.001) only for Group 1. Group 1 gastric emptying improved (54.5% retained at 2h at BL vs. 12.2% at f/u, p < 0.001) in contrast to Group 2 patients (51.25% at BL vs. 56.25% at f/u, p = 0.252). Percentage 3cpm GMA decreased (41.1% at BL vs. 24.9% at f/u, p ≤ 0.005) in Group 1 versus Group 2 (15.3% at BL vs. 23.4% at f/u, p = 0.114). AI-derived GMA threshold (GMAT) of 0.59 predicted positive pyloric BD outcomes at 10-12months with sensitivity 96%, specificity 75%, and 93% correct classification. Pyloric BD improved symptoms and gastric emptying long term in patients with GP and hypernormal/normal 3cpm GMA. AI-derived GMAT predicted pyloric BD success. GMA post-WLST and GMAT are objective measures for improved selection and outcomes for endoscopic pyloric BD.

Effects of hanger reflex on the cervical muscular activation and function: A surface electromyography assessment.

Introduction: Cervical muscular dysfunction is closely associated with disorders and neuromuscular diseases of the cervical spine, and the hanger reflex (HR) has the potential to become a rehabilitation method. The muscular electrophysiology mechanism of HR is unclear. This study aims to identify the impacts of HR on cervical rotators’ myoelectrical activity and function. Methods: We designed a self-control clinical trial, and asymptomatic volunteers were continuously included from 1 September 2021 to 30 April 2022 in our department. Rotation tasks were performed on both sides under each of the situations: no HR, unilateral HR, and bilateral HR. Surface electromyography (SEMG) was used to detect the myoelectrical activity of agonistic splenius capitis (SPL), upper trapezius (UTr), and sternocleidomastoid (SCM). The co-contraction ratio (CCR) during rotation tasks was calculated. Correlation analyses and multiple linear regression were performed. Results: Finally, 90 subjects were enrolled (power >90%). The adjusted EMG value (aEMG) of SPL UTr, SCM, and rotating CCR under the unilateral HR and bilateral HR were higher than no HR; the aEMG of SPL and rotating CCR under the bilateral HR were higher than the unilateral HR. Multiple linear regression showed that HR pattern and age were the independent affecting factors for the aEMG of SPL (p < 0.001, p < 0.001), UTr (p < 0.001, p < 0.001), and SCM (p < 0.001, p < 0.001); BMI was an independent affecting factor for the aEMG of SPL (p < 0.001) and SCM (p < 0.001); HR pattern was the only affecting factor for CCR (p < 0.001). Conclusion: HR can increase the cervical rotators’ myoelectrical activities and rotating CCR, and the effects of bilateral HR are greater than unilateral HR, suggesting that bilateral HR has a greater clinical potential to become a rehabilitation method for treating cervical neuromuscular disorders.

Risk factors for various clinical variants of irritable bowel syndrome

Introduction . Irritable bowel syndrome (IBS) affects a significant portion of the population worldwide. The disease is characterized by a multifactorial pathogenesis and a variable clinical picture, in the center of which is abdominal pain and violations of the act of defecation. Our work shows the relationship between the functional polymorphism of the serotonin reuptake transporter (5-HTTLPR of the SLC6A4 gene) and the features of myoelectric activity (MEA) of the small intestine in various clinical variants of IBS. Purpose — to study clinical, functional and genetic features in patients with IBS and on their basis to determine significant risk factors for the formation of various IBS variants. Materials and methods . 148 patients were examined: 79 patients with IBS (group 1), including 45 patients with IBS with a predominance of diarrhea (group 1a) and 34 patients with IBS with a predominance of diseases (group 1b), 10 healthy volunteers (group 2), 59 patients of therapeutic profile without IBS (group 3). The diagnosis of “IBS” was established according to the Rome criteria III revision. All of them thoroughly studied peripheral electrogastroenterography (PEGEG) and groups of patients 1 and 3 — genetic analysis of the 5-HTTLPR polymorphism of the SLC6A4 gene. Results . In the diarrheal variant of IBS, the 5-HTTLPR promoter more often contains the S allele associated with a decrease in the function of the serotonin reuptake transporter. The risk factors for the formation of clinical variants of IBS include: gender, polymorphic variants of the 5-HTTLPR gene SLC6A4 and the values of the postprandial coefficient of myoelectric activity (MEA) at the frequencies of “ileum” and “jejunum”. Conclusions . The revealed relationships between the motor-evacuation function (MEF) of the gastrointestinal tract and polymorphism of the serotonin transporter gene demonstrate the pathophysiological significance of these associations in the development of IBS and its clinical variability. Features of the functioning and genetic features of the serotonergic system deserve further study, which is promising for improving the diagnostic and therapeutic approach to patients with IBS.

Kinematic, Electromyographic Activity and Muscular Architecture Description in Patients Operated with Pars-Dresden Technique

Category: Sports; Ankle; Basic Sciences/Biologics Introduction/Purpose: Kinematic, muscular architecture and myoelectric activity are altered during the healing process after Achilles tendon surgery. Currently, there are minimally invasive surgical techniques (PARS-Dresden) which have accelerated rehabilitation processes. However, evidence that compares kinematic, architecture and myoelectric activity between operated vs. non-operated leg is limited. The aim of this study is to describe the kinematic changes, muscular architecture and electromyographic (EMG) activity of the lower limb between operated vs. non-operated legs after Achilles tendon surgery. Methods: After obtaining IRB approval, patients undergoing the PARS-Dresden technique for acute Achilles tendon ruptures were invited to participate. We excluded patients with previous injuries or surgery in lower limbs that affect gait, muscular activity, or architecture. Eleven patients met the inclusion/exclusion criteria. Patients were evaluated at three time-frames: 8, 12, and 24 weeks. Evaluations were performed walking on a treadmill at self-selected speed, while kinematic and surface EMG activity was measured in stance and swing phases of the gait. Kinematic variables were captured using a 3D motion analysis system with eight infrared cameras and twenty reflective markers over the lower limbs. Muscle architecture was evaluated using ultrasonography. A descriptive analysis was performed comparing operated versus non-operated legs. Results: Median age 36 years, 3 females. Kinematic evaluation shows sagittal plane asymmetry between operated versus non- operated legs at 8 and 12w. However, the 24w evaluation shows symmetry between both lower limbs. The EMG shows lower activity in the stance phase for the medial gastrocnemius, lateral gastrocnemius, and soleus for operated legs at 8w and 12w, but at the 24w evaluation the activity was symmetric for these muscles evaluated in both legs. The muscular architecture shows less thickness in gastrocnemius muscles in the operated leg at 8w (median 11.2% operated vs 35.4% no-operated), reaching a symmetric thickness at 24w (median 34.2% operated vs 35.7% no-operated). Achilles tendon present asymmetric transversal area between both legs at three time-frames (median 1.88 cm2 versus 0.59 cm2). The pennation angles showed no difference between both legs in the three evaluation periods (median 22.0° versus 24.3° for MG, and 15.0° versus 13.5° for LG). Conclusion: We described kinematic, electromyographic and architectonic asymmetries between operated versus non-operated legs at 8 and 12 weeks postoperative of patients who underwent PARS-Dresden surgery for acute Achilles tendon ruptures. All patients achieved symmetric results at 24 weeks evaluation.

S3674 Successful Endoscopic Pyloric Therapy in a Patient With Gastroparesis and Normal 3 Cpm Gastric Myoelectrical Activity After Failed Surgeries for Superior Mesentery Artery Syndrome and Median Arcuate Ligament Syndrome

S3674 Successful Endoscopic Pyloric Therapy in a Patient With Gastroparesis and Normal 3 Cpm Gastric Myoelectrical Activity After Failed Surgeries for Superior Mesentery Artery Syndrome and Median Arcuate Ligament Syndrome

Association of Gastric Myoelectric Activity with Dietary Intakes, Substrate Utilization, and Energy Expenditure in Adults with Obesity.

Obesity can modulate gastric myoelectric activity (GMA); however, the relationship of GMA with nutrient intakes and substrate utilization in adults with obesity is lacking. We examined the association of dietary intakes, energy expenditure, and substrate utilization with the GMA. Participants (n = 115, 18–60 y) were divided into healthy weight (HW, n = 24), overweight (OW, n = 29), obese (OB, n = 41) and morbidly obese (MO, n = 21). Two-day multi-pass 24 h recalls were conducted. The GMA was measured by multichannel electrogastrography (EGG) with water-load (WL) testing. Resting metabolic rate (RMR) and percentages of substrate utilization were measured by indirect calorimetry. In the HW, protein intake was directly correlated with average dominant frequency (ADF) and with WL volume, while in obese participants and the MO subgroup, WL volume correlated with carbohydrate intake. In participants with obesity, ADF was positively correlated with fiber intake. In participants with obesity and the OB subgroup, RMR was positively correlated with water-load volume (r = 0.39 and 0.37, p < 0.05). The ADF showed negative correlations with percent of fat utilization and positive correlations with percent of CHO utilization in non-obese groups. However, protein utilization showed inverse correlation in all obese groups. In conclusion, these distinctive associations suggest that certain dietary compositions and dieting regimens impact GMA patterns.

Effects of Differing Foam Rolling Periods on Training Volume and Myoelectric Responses of Lower-Body Muscles.

Santana, HG, Paz, GA, Willardson, JM, de Araújo Farias, D, and Miranda, H. Effects of differing foam rolling periods on training volume and myoelectric responses of lower-body muscles. J Strength Cond Res 36(12): 3311-3318, 2022-Foam rolling (FR) is a practice that has increased in popularity before and after resistance training. The purpose of this study was to compare the acute effects of different foam rolling periods for the lower body muscles on subsequent performance, myoelectric activity and rating of perceived exertion in trained men. Fourteen men (26.2 ± 3.2 years, 178 ± 0.04 cm, 82.2 ± 10 kg and body mass index 25.9 ± 3.3kg/m -2 ) volunteered for this study. Four repetition maximum (4-RM) loads were determined for hexagonal bar deadlift and 45°-angled leg press during test and retest sessions over two nonconsecutive days. The experimental conditions included a traditional protocol (TP) with no prior foam rolling, and four other conditions that involved FR applied to the quadriceps, hamstrings and triceps surae for one set of 30 sec (P1), two sets of 30 sec (P2), three sets of 30 sec (P3), or four sets of 30 sec (P4).The resistance training consisted of five sets with 4-RM loads. The number of repetitions completed, the myoelectric activity of lower limbs were recorded, as well as the rating of perceived exertion for each protocol. There were no differences between the protocols in the total repetitions for the hexagonal bar deadlift and 45° angled leg press exercises. Similar results between protocols were also noted for muscle activity and rated perceived exertion (RPE). Therefore, the results of the present study indicated that the FR didn't provide effects on performance, myoelectric activity and rating of perceived exertion responses during high intensity resistance performance for lower limb exercises.

Plasma atropine concentrations associated with decreased intestinal motility in horses.

IntroductionAtropine is an essential part of the treatment protocol for equine uveitis. Topical atropine administration has been associated with decreased intestinal motility and abdominal pain in horses. Experimental studies have indicated that frequent dosing is associated with a higher risk than dosing every 6 h. Unfortunately, no quantitative pharmacodynamic data for inhibition of the equine gut are published.Materials and methodsEight standardbred horses were assigned to receive either atropine or saline (control) to be infused over 30 min in a two-treatment cross-over design. Atropine concentrations in plasma were measured using ultra-high-performance liquid chromatography–tandem mass spectrometry. Intestinal motility was measured using borborygmi frequency and electrointestinography (EIG). Experimental data were analyzed using a non-linear mixed effects model. The model was then used to simulate different dosing regimens.ResultsAtropine significantly decreased borborygmi response and EIG response. Six horses developed clinical signs of abdominal pain. The pharmacokinetic typical values were 0.31, 1.38, 0.69, and 1.95 L/kg·h for the volumes of the central, the highly perfused, the scarcely perfused compartments, and the total body clearance, respectively. The pharmacodynamic typical values were 0.31 μg/L and 0.6 and 207 nV27 cpm for the plasma concentration at 50% of the maximum response and the maximum response and the baseline of cecal EIG response, respectively. Six different dosing regimens of topical atropine sulfate to the eye (0.4 and 1 mg every hour, every 3 h, and every 6 h) were simulated.ConclusionThe IV PK/PD data coupled with simulations predict that administration of 1 mg of topical atropine sulfate administered to the eye every hour or every 3 h will lead to atropine accumulation in plasma and decreased intestinal myoelectric activity. Administration every 6 h predicted a safe dosing regimen in full-sized horses. Clinical studies would be valuable to confirm the conclusions. For smaller equids and horses put at risk for colic due to othercauses, droplet bottles that deliver 40 μl of 1% atropine sulfate per drop or less may be used to lower the risk further.

Effect of ketamine, an NMDA-receptor antagonist, on gastric myoelectric activity in experimental pigs

Summary: Introduction: Preclinical studies in experimental pigs are carried out mostly under general anaesthesia. Ketamine is commonly used for induction of anaesthesia. However, there are concerns that ketamine, an NMDA-receptor antagonist, may influence gastric motor function. The aim of this study was to investigate porcine gastric myoelectric activity by means of electrogastrography (EGG). Methods: Seventeen female animals (mean weight 36.2±3.8 kg) were enrolled. Drugs used for induction of anaesthesia were: Group A (n=5): medetomidine 0.1 mg/kg i. m.; butorphanol 0.3 mg/kg i. m.; midazolam 0.3 mg/kg i. m.; Group B (n=6): azaperon 2.2 mg/kg i. m.; Group C (n=6): ketamine 20 mg/kg i. m.; azaperon 2.2 mg/kg i. m., followed in all groups by i.v. 1% propofol (repeated one-mL boluses, 10–12 mL in total). EGG recording started 15 min. after the induction administration and lasted 30 min. Results were evaluated as the dominant frequency of gastric slow waves (DF) and EGG power (areas of amplitudes). Results: In total, 510 one-minute EGG intervals were assessed. DFs were (mean ± standard deviation): 1.4±0.4 (Group A), 1.3±0.3 (Group B) and 0.2±0.1 cycles per min. (Group C). The differences between group C and groups A and B were statistically significant (p&lt;0.001). Median power (IQR) was 0.13 (0.02–0.44; Group A), 0.13 (0.03–0.54; Group B) and 0.30 V2 (0.07–1.44; Group C). The difference between groups A and C was of borderline significance (p=0.066; type 2 error beta 0.295). Conclusions: Ketamine, administered even in a single intramuscular dose, affected myoelectric function of the porcine stomach. Therefore, it should be avoided in gastrointestinal motility studies in experimental pigs. Key words: ketamine – NMDA (N-methyl-D-aspartate) -receptor antagonist – electrogastrography – myoelectrical activity – experimental pigs

Role of cannabinoid receptor-2 in small intestinal fasted myoelectric activity of rats

Cannabinoid receptor-1 (CB1R) and cannabinoid receptor-2 (CB2R) have significant roles in the esophagus, small intestine, and colon motility in the postprandial period besides gastric emptying, secretion, and defecation in the gastrointestinal system. Furthermore, our previous study showed that activation of peripheral CB1R inhibited migrating myoelectric complex (MMC), forming the source of fasted small intestinal motility. However, the role of the central/peripheral CB2Rs on the MMC pattern is still unknown. The present study aimed to investigate the roles of peripheral and central CB2Rs in forming and regulating small intestine MMC patterns in rats. In this study, we used 42 adult male Sprague-Dawley rats (n:7). We implanted bipolar electrodes in three different jejunum sites of rats (J1, J2, J3) to record the MMC pattern. We placed a cannula in the right lateral ventricle to perform drug intracerebroventricularly (i.c.v.) and implanted a catheter in the right jugular vein to inject the drug intravenously (i.v). After the amelioration period, we conducted experiments following an 18-hour fasting period and later took at least a one-hour baseline recording of the MMC pattern. Then, we injected JWH 133, a CB2R agonist i.v. (1.25-10 mg/kg) or i.c.v. (2.5- 20 μg/rat) and also administered AM 630, a CB2R antagonist, i.v. (0.25-2 mg/kg) or i.c.v. (2.5-20 μg/rat). We compared the effects of JWH 133 or AM 630 on the MMC pattern to the vehicle group (10% dimethyl sulfoxide). Centrally or peripherally injected JWH 133 and AM 630 did not cause any change in the spike frequency and the number of the MMC cycle. The results of the present study propose that CB2Rs are involved in neither endogenous formation nor exogenous regulation of the fasting myoelectric activity in healthy fasted rats.

Looped Elastic Resistance during Squats: How Do Band Position and Stiffness Affect Hip Myoelectric Activity?

Looped elastic bands around the thigh are commonly used during squats and result in increased hip activation. Due to the closed kinetic chain nature of the squat exercise, one may expect that placing the elastic band on distal segments, close to the floor contact, may not result in the same increase in hip muscle activation as that achieved with a looped band around the thigh. We analyzed the effects of band position (thigh, lower leg, and forefoot) and band stiffness on the myoelectric activity of the tensor fascia latae, gluteus medius, gluteus maximus, biceps femoris, vastus medialis, and vastus lateralis during squats in 35 healthy subjects (18 men and 17 women). The greatest myoelectric activity of hip muscles was observed when the stiffest band was positioned around the forefeet with an increase in 24% for the tensor fascia latae, 83% for the gluteus medius, and 68% for the gluteus maximus compared to free (without resistance band) squatting. Contrary to previous thinking, the use of elastic bands around the forefeet during squats can elicit increased myoelectric activity of hip muscles, with a magnitude often greater than when the band is placed around the thigh segments.