EMG Analysis of Dominant and Non-Dominant Arm of Latissimus Dorsi Muscles in Bowlers of Karad, Maharashtra, India

BACKGROUND Latissimus dorsi plays an important role in bowlers. Different bowling techniques recruit latissimus dorsi at different phases of bowling. This causes the muscle to undergo excessive contraction than its limit. Despite widespread knowledge about the recruitment of latissimus dorsi in bowling, there is limited electromyographic (EMG) studies about latissimus dorsi. It is necessary to evaluate and document the recruitment of latissimus dorsi in dominant and non-dominant arm in bowlers, which is focused in this study. This study was done to analyse the surface EMG activity of latissimus dorsi muscle in dominant and non-dominant arm during bowling. METHODS A cross-sectional analytical study was carried out among 96 professional cricket bowlers from deluxe cricket club and Yashwanthrao Chavan’s cricket club in Karad. EMG electrodes were applied over the latissimus dorsi muscle and the bowlers were asked to perform the action of bowling. The root mean square (RMS) and mean peak amplitude of the dominant and non-dominant arm were recorded. RESULTS The RMS (12.45 ± 2.84) values and mean peak amplitude (131.77 ± 44.11) of the dominant latissimus dorsi varied significantly from non-dominant muscle (P = 0.0015). Wilcoxon test was utilized for analysis of within group parameters. CONCLUSIONS The result of the present study showed strong evidence to support high recruitment of dominant latissimus dorsi in professional bowlers suggests the changes occurred in the physiological as well as biomechanical muscular structure. KEY WORDS EMG, Dominant, Non-Dominant, Latissimus Dorsi, Fast Bowlers

Affordable Embroidered EMG Electrodes for Myoelectric Control of Prostheses: A Pilot Study

Commercial myoelectric prostheses are costly to purchase and maintain, making their provision challenging for developing countries. Recent research indicates that embroidered EMG electrodes may provide a more affordable alternative to the sensors used in current prostheses. This pilot study investigates the usability of such electrodes for myoelectric control by comparing online and offline performance against conventional gel electrodes. Offline performance is evaluated through the classification of nine different hand and wrist gestures. Online performance is assessed with a crossover two-degree-of-freedom real-time experiment using Fitts’ Law. Two performance metrics (Throughput and Completion Rate) are used to quantify usability. The mean classification accuracy of the nine gestures is approximately 98% for subject-specific models trained on both gel and embroidered electrode offline data from individual subjects, and 97% and 96% for general models trained on gel and embroidered offline data, respectively, from all subjects. Throughput (0.3 bits/s) and completion rate (95–97%) are similar in the online test. Results indicate that embroidered electrodes can achieve similar performance to gel electrodes paving the way for low-cost myoelectric prostheses.

Fixed Functional Appliances

Considering the large number of fixed functional appliances, choosing the best device for your patient is not an easy task. To describe the development of fixed functional appliances as well as our 20-year experience working with them. Fixed functional appliances are grouped into flexible, rigid and hybrid. They are different appliances, whose action is described here. Four clinical cases will be reported with a view in illustrating the different appliances. Rigid fixed functional appliances provide better skeletal results than flexible and hybrid ones. Flexible and hybrid appliances have similar effects to those produced by class II elastics. They ultimately correct class II with dentoalveolar changes. From a biomechanical standpoint, fixed functional appliances are more recommended to treat class II in dolichofacial patients, in comparison to class II elastics. The electromyographic (EMG) activity of masticatory muscles was monitored longitudinally with chronically implanted EMG electrodes to determine whether functional appliances produce a change in postural EMG activity of the muscles. Pre-appliance and post-appliance EMG levels in four experiments that had been fitted with functional appliances were compared against the background of EMG levels in controls without appliances. The insertion of two types of functional appliance to induce mandibular protrusion was associated with a decrease in postural EMG activity of the superior and inferior heads of the lateral pterygoid, superficial masseter, and anterior digastric muscles; the decrease in the first three muscles was statistically significant. This decreased postural EMG activity persisted for approximately 6 weeks, with a gradual return towards pre-appliance levels during a subsequent 6-week period of observation. Progressive mandibular advancement of 1.5 to 2 mm every 10 to 15 days did not prevent the decrease in postural EMG activity. KEY WORDS Orthodontics, Class II Malocclusion, Fixed Functional Appliance.

Surface Electromyography for Identification of Pre-Phonatory Activity

Surface electrode EMG is an established method for studying biomechanical activity. It has not been well studied in detecting laryngeal biomechanical activity of pre-phonatory onset. Our aims were to compare the sensitivity of surface EMG in identifying pre-phonatory laryngeal activity to needle electrode laryngeal EMG and to compare the pre-phonatory period in patients with adductor laryngeal dystonia (ADLD) with that in controls. ADLD patients (n = 10) undergoing needle LEMG prior to Botox injection and participants with normal voices (n = 6) were recruited. Surface EMG electrodes were placed over the cricoid ring and thyrohyoid membrane. Needle EMG electrodes were inserted into the thyroarytenoid muscle. EMG and auditory output samples were collected during phonation onset. Tracings were de-identified and evaluated. Measurements of time from onset in change of the amplitude and motor unit frequency on the interference pattern to onset of phonation were calculated by two blinded raters. 42 of 71 patient and 40 of 50 control tracings were available for analysis. Correlation for pre-phonatory time between electrode configuration was 0.70 for patients, 0.64 for controls and 0.79 for all the data combined. Inter-rater correlation was 0.97 for needle and 0.96 for surface electrodes. ADLD patients had a longer pre-phonatory time than control subjects by 169.48ms with surface electrode and 140.23ms with needle electrode (p < 0.001). Surface EMG demonstrates equal reliability as Needle EMG in detecting pre-phonatory activity in controls and subjects. Patients with ADLD have a significantly prolonged pre-phonatory period when compared with controls.

109 Chemogenetic silencing of corticotropin releasing factor neurons in the paraventricular nucleus: the effect on post-stress sleep

Introduction We have previously shown that pharmacological elevation of corticotropin releasing factor (CRF) signaling in the brain results in exacerbation of sleep disturbances evoked by the exposure of rats to an acute stressor, the dirty cage of a male rat. In the present study we (1) assessed wake-sleep behavior of mice after the exposure to the dirty cage stress paradigm, and (2) examined the effect of chemogenetic silencing of CRF neurons in the hypothalamic paraventricular nucleus (PVN) on sleep occurring following the exposure to this stressor. Methods First, a group of mice (n=12) was implanted with EEG/EMG electrodes. In two weeks, post-surgery, six mice were transferred to dirty cages of male rats and recorded for 24 hours. Control mice were transferred to clean cages. In the second study, a group of CRF-ires-cre mice (n=8) received bilateral injections of AAV-hSyn-DIO-hM4Di-mCherry targeting the PVN. The other group of CRF-ires-cre mice (n=8) was injected AAV-hSyn-DIO-mCherry (control vector). All mice were implanted with EEG/EMG electrodes. Dirty cage experiments were started following a 4-week postsurgical period to allow gene recombination and expression. Mice were subjected to intraperitoneal (IP) administration of clozapine-n-oxide (CNO; 3 mg/kg) at ZT1, placed into dirty cages, and recorded for post-stress sleep. Results: Results In mice expressing hM4Di inhibitory DREADDs (designer receptors activated by designer drugs) versus mice injected with control AAV, IP CNO (3 mg/kg) resulted in a significant decrease of post-stress sleep onset latency, decrease of time spent in wakefulness (first hour, 74±5.3 vs. 89±11.0, second hour, 37.2±10.3% vs. 81.3±9.3%; third hour, 40.1±3.3% vs. 47.1±14.3%; fourth hour, 44.4±6.0 vs. 55.5±9.9), and increase in non-rapid eye movement (NREM) sleep time (26.0±5.4% vs. 11.0±11.1%; 62.8%±9.8 vs. 18.7 ± 9.6%; 59.9±3.2% vs. 52.9±14.5%; 55.6±6.2 vs. 44.5±10.0). The hM4Di expressing mice exhibited longer episodes of NREM sleep, compared to mice injected with control AAV (first hour, 133.3±80.1sec vs. 21±1.7sec; second hour, 43256±83.4sec vs. 73.5±44.1sec; third hour, 459.2±139.8sec vs. 139±80.6sec; fourth hour, 233.1±82.6sec vs. 190±72.3sec). Conclusion Chemogenetic silencing of CRF neurons in the PVN attenuates acute stress-induced sleep disturbance in mice. Support (if any) Supported by Department of Veterans Affairs Merit Review Grant # BX00155605 and SRNSF (Georgia) grant FR-18-12533

The Impacts of Age and Sex in a Mouse Model of Childhood Narcolepsy

Narcolepsy is a sleep disorder caused by selective death of the orexin neurons that often begins in childhood. Orexin neuron loss disinhibits REM sleep during the active period and produces cataplexy, episodes of paralysis during wakefulness. Cataplexy is often worse when narcolepsy develops in children compared to adults, but the reason for this difference remains unknown. We used orexin-tTA; TetO DTA mice to model narcolepsy at different ages. When doxycycline is removed from the diet, the orexin neurons of these mice express diphtheria toxin A and die within 2–3 weeks. We removed doxycycline at 4 weeks (young-onset) or 14 weeks (adult-onset) of age in male and female mice. We implanted electroencephalography (EEG) and electromyography (EMG) electrodes for sleep recordings two weeks later and then recorded EEG/EMG/video for 24 h at 3 and 13 weeks after removal of doxycycline. Age-matched controls had access to doxycycline diet for the entire experiment. Three weeks after doxycycline removal, both young-onset and adult-onset mice developed severe cataplexy and the sleep-wake fragmentation characteristic of narcolepsy. Cataplexy and maintenance of wake were no worse in young-onset compared to adult-onset mice, but female mice had more bouts of cataplexy than males. Orexin neuron loss was similarly rapid in both young- and adult-onset mice. As age of orexin neuron loss does not impact the severity of narcolepsy symptoms in mice, the worse symptoms in children with narcolepsy may be due to more rapid orexin neuron loss than in adults.

Analysis of EMG Electrode Locations Using 3D Body Scanning for Digital Pattern Construction of a Smart EMG Suit

According to recent trends, smart clothing products that can receive electromyography (EMG) signals during the wearer’s muscle activity are being developed and commercialized. On the other hand, there is a lack of knowledge on the way to specify the electrode locations on the clothing pattern. Accurately located EMG electrodes in the clothing support the reliability and usefulness of the products. Moreover, a systematic process to construct anatomically validated smart clothing digitally should be performed to facilitate the application of a mass-customized manufacturing system. The current study explored the EMG measurement locations of nine muscles and analyzed them in association with various anthropometric points and even postures based on the 3D body scan data. The results suggest that several line segments of the patterns can be substituted by size-dependent equations for the electrodes in place. As a final step, a customized pattern of a smart EMG suit was developed virtually. The current study proposes a methodology to develop body-size dependent equations and patterns of a smart EMG suit with well-located electrodes using 3D scan data. These results suggest ways to produce smart EMG suits in response to impending automation and mass customization of the clothing manufacturing system.

Could Relative Movement Between the Adductor Muscles and the Skin Invalidate Surface Electromyography Measurement?

The superficial hip adductor muscles are situated in close proximity to each other. Therefore, relative movement between the overlying skin and the muscle belly could lead to a shift in the position of surface electromyography (EMG) electrodes and contamination of EMG signals with activity from neighboring muscles. The aim of this study was to explore whether hip movements or isometric contraction could lead to relative movement between the overlying skin and 3 adductor muscles: adductor magnus, adductor longus, and adductor gracilis. The authors also sought to investigate isometric torque–EMG relationships for the 3 adductor muscles. Ultrasound measurement showed that EMG electrodes maintained a position which was at least 5 mm within the muscle boundary across a range of hip flexion–extension angles and across different contraction levels. The authors also observed a linear relationship between torque and EMG amplitude. This is the first study to use ultrasound to track the relative motion between skin and muscle and provides new insight into electrode positioning. The findings provide confidence that ultrasound-based positioning of EMG electrodes can be used to derive meaningful information on output from the adductor muscles and constitute a step toward recognized guidelines for surface EMG measurement of the adductors.

Development of Soft sEMG Sensing Structures Using 3D-Printing Technologies

3D printing of soft EMG sensing structures enables the creation of personalized sensing structures that can be potentially integrated in prosthetic, assistive and other devices. We developed and characterized flexible carbon-black doped TPU-based sEMG sensing structures. The structures are directly 3D-printed without the need for an additional post-processing step using a low-cost, consumer grade multi-material FDM printer. A comparison between the gold standard Ag/AgCl gel electrodes and the 3D-printed EMG electrodes with a comparable contact area shows that there is no significant difference in the EMG signals’ amplitude. The sensors are capable of distinguishing a variable level of muscle activity of the biceps brachii. Furthermore, as a proof of principle, sEMG data of a 3D-printed 8-electrode band are analyzed using a patten recognition algorithm to recognize hand gestures. This work shows that 3D-printed sEMG electrodes have great potential in practical applications.