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Abstract Background Gait initiation (GI) can be divided into three sections according to the center of pressure (COP) trace (S1, S2, and S3). Almost all studies do not separate each phase of the GI profile in postural control assessment and muscular investigation, whereas differences in the COP and muscles are found in each phase of the GI profile in people with gait problems. Methods Twenty individuals with CAI and twenty healthy controls were included in the present study. A force plate synchronized with Qualisys motion analysis, MEGAWIN electromyography, and a pair of auditory cues were used for data capture. The participants carried out five trials of GI with the affected leg (dominant leg). The peak and mean COP excursions; the mean and maximum velocities of COP excursion during S1, S2,, S3, and the total phases in the mediolateral (ML) and anterior‒posterior (AP) directions; the root mean square (RMS); and the onset activity of the Tibialis Anterior (TA) and Soleus (SOL) muscles for both legs were used for statistical analysis. Independent t tests and Mann‒Whitney U tests were used for statistical analysis on the basis of a significance level of ≤ 0.05. Results Compared with those of healthy controls, independent t tests revealed a significant decrease in the peak COP excursion in the AP direction during S2 (P = 0.021) and in the mean velocity of COP excursion in the AP direction during S1 (P = 0.044) in the CAI group. Additionally, there was a significant increase in the duration of S1 in the GI profile (P = 0.045) in the CAI group compared with the healthy control group. There was no significant difference in the other COP variables, TA or SOL RMS or onset activity for either leg during S1, S2, or S3 between the two groups (P > 0.065). Conclusion Individuals with CAI exhibit increased stiffness in the AP direction in the injured ankle. This leads to a reduction in the velocity and peak of COP excursion, as well as an increase in the time required for postural control adjustment. These findings highlight the challenges individuals with CAI may face in meeting postural demands when trying to unload the affected foot. Ethical code IR.SBMU.RETECH.REC.1402.095, 2023–5-28.

Background: Gait initiation (GI) can be divided into three sections according to the center of pressure (COP) trace (S1, S2, and S3). Almost all studies do not separate each phase of the GI profile in postural control assessment and muscular investigation, whereas differences in the COP and muscles are found in each phase of the GI profile in people with gait problems. Methods: Twenty individuals with CAI and twenty healthy controls were included in the present study. A force plate synchronized with Qualisys motion analysis, MEGAWIN electromyography, and a pair of auditory cues were used for data capture. The participants carried out five trials of GI with the affected leg (dominant leg). The peak and mean COP excursions; the mean and maximum velocities of COP excursion during S1, S2,, S3, and the total phases in the mediolateral (ML) and anterior‒posterior (AP) directions; the root mean square (RMS); and the onset activity of the Tibialis Anterior (TA) and Soleus (SOL) muscles for both legs were used for statistical analysis. Independent t tests and Mann‒Whitney U tests were used for statistical analysis on the basis of a significance level of ≤ 0.05. Results: Compared with those of healthy controls, independent t tests revealed a significant decrease in the peak COP excursion in the AP direction during S2 (P = 0.021) and in the mean velocity of COP excursion in the AP direction during S1 (P = 0.044) in the CAI group. Additionally, there was a significant increase in the duration of S1 in the GI profile (P = 0.045) in the CAI group compared with the healthy control group. There was no significant difference in the other COP variables, TA or SOL RMS or onset activity for either leg during S1, S2, or S3 between the two groups (P > 0.065). Conclusion: Individuals with CAI exhibit increased stiffness in the AP direction in the injured ankle. This leads to a reduction in the velocity and peak of COP excursion, as well as an increase in the time required for postural control adjustment. These findings highlight the challenges individuals with CAI may face in meeting postural demands when trying to unload the affected foot. Ethical code: IR.SBMU.RETECH.REC.1402.095, 2023–5-28. [ABSTRACT FROM AUTHOR]

Featured Application: The reverse lunge is a commonly used exercise in strength training and rehabilitation. This study seeks to describe the EMG activation of key lower extremity muscles during the bodyweight reverse lunge and compare between limbs and phases of the lunge. Limited studies exist examining the reverse lunge. The purpose of this study was to describe the activation of the rectus femoris (RF), biceps femoris (BF), gluteus medius (GMed), and gluteus maximus (GMax) of both limbs during a bodyweight reverse lunge movement. A secondary purpose was to describe the phases of the stationary (non-moving) and lead (moving) limbs during the reverse lunge. Surface electromyography (EMG) was used to record the activity of the target muscles in 20 healthy adults (10 male, 10 female; aged 22–25). Root mean squared values for mean maximum and average percent activation normalized to maximum voluntary isometric contraction (MVIC) activation were calculated. Descriptive terminology was created to describe the phases of the lunge for both limbs. The mean maximum percentage of muscle activation for the RF and BF was greater in the lead limb, while GMed and GMax activations were greater in the stationary limb. Only the lead limb RF and stationary limb GMed reached a strengthening stimulus in mean maximum percentage measurements. Clinically, it may be important to consider when each muscle is maximally active and at what percentage of its MVIC to properly prescribe the reverse lunge in a safe manner. [ABSTRACT FROM AUTHOR]

Introduction: previous studies show that adequate levels of calcidiol are associated with greater muscle strength, maintenance of daily activities and less progression of aortic calcification. The objective of this study was to assess the effect of vitamin D deficiency on muscular activity and vascular health in an experimental model. Material and methods: 18-month-old FVB/N mice were used. One group received a diet without vitamin D (deficient group, n = 20) and another group received a normal diet (control group, n = 17) for 8 weeks. To measure muscular activity, a wooden rod fixed to a table with a mark 10 cm from the supported end was used to indicate the finish line. Mice were placed on the "open" end of the rod with their backs to the target. After a previous training process, the animals were evaluated three times measuring two parameters: orientation time (time necessary to turn 180° from the initial position and look towards the supported end) and transition time (time necessary to reach the goal). At sacrifice, blood and tissues were removed. Results: calcidiol levels were higher in the control group (23.3 ± 3.9 vs 12.7 ± 3.1 ng/mL, p < 0.001). Orientation times (43 ± 46 vs 15 ± 21 seconds, p = 0.020) and transition times (62 ± 51 vs 31 ± 37 seconds, p = 0.041) were much higher in the deficient group compared to the control group. At the aortic level, the gene expression of α-actin and miR-145 were highly compromised in the deficient group. Runx2 expression was not altered. Conclusions: these experimental results confirm previous clinical results where maintaining adequate levels of vitamin D prevents the loss of muscular functionality and vascular damage. [ABSTRACT FROM AUTHOR]

Researchers have attempted to control robotic hands and prostheses through biosignals but could not match the human hand. Surface electromyography records electrical muscle activity using non-invasive electrodes and has been the primary method in most studies. While surface electromyography-based hand motion decoding shows promise, it has not yet met the requirements for reliable use. Combining different sensing modalities has been shown to improve hand gesture classification accuracy. This work introduces a multimodal bracelet that integrates a 24-channel force myography system with six commercial surface electromyography sensors, each containing a six-axis inertial measurement unit. The device's functionality was tested by acquiring muscular activity with the proposed device from five participants performing five different gestures in a random order. A random forest model was then used to classify the performed gestures from the acquired signal. The results confirmed the device's functionality, making it suitable to study sensor fusion for intent detection in future studies. The results showed that combining all modalities yielded the highest classification accuracies across all participants, reaching 92.3 ± 2.6 % on average, effectively reducing misclassifications by 37% and 22% compared to using surface electromyography and force myography individually as input signals, respectively. This demonstrates the potential benefits of sensor fusion for more robust and accurate hand gesture classification and paves the way for advanced control of robotic and prosthetic hands. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the correlation between electromyography (EMG) activity and vehicle motion during double lane change driving. This study measured five vehicle motions: the steering wheel angle, steering wheel torque, lateral acceleration, roll angle, and yaw velocity. The EMG activity for 19 muscles and vehicle motions was applied for envelope detection. There was a significantly high positive correlation between muscles (mean correlation coefficient) for sternocleidomastoid (0.62) and biceps brachii (0.71) and vehicle motions for steering wheel angle, steering wheel torque, lateral acceleration, and yaw velocity, but a negative correlation between the muscles for middle deltoid (−0.75) and triceps brachii long head (−0.78) and these vehicle motions. The ANOVA test was used to analyze statistically significant differences in the main and interaction effects of muscle and vehicle speed. The mean absolute correlation coefficient exhibited an increasing trend with the increasing vehicle speed for the muscles (increasing rate%): upper trapezius (30.5%), pectoralis major sternal (38.7%), serratus anterior (13.3%), and biceps brachii (11.0%). The mean absolute correlation coefficient showed a decreasing trend with increasing vehicle speed for the masseter (−9.6%), sternocleidomastoid (−12.9%), middle deltoid (−5.5%), posterior deltoid (−20.0%), pectoralis major clavicular (−13.4%), and triceps brachii long head (−6.3%). The sternocleidomastoid muscle may decrease with increasing vehicle speed as the neck rotation decreases. As shoulder stabilizers, the upper trapezius, pectoralis major sternal, and serratus anterior muscles are considered to play a primary role in maintaining body balance. This study suggests that the primary muscles reflecting vehicle motions include the sternocleidomastoid, deltoid, upper trapezius, pectoralis major sternal, serratus anterior, biceps, and triceps muscles under real driving conditions. [ABSTRACT FROM AUTHOR]

Our understanding of the nervous tissues that affect the wing flapping of insects mainly focuses on the brain, but wing flapping is a rhythmic movement related to the central pattern generator in the ventral nerve cord. To verify whether the neural activity of the abdominal ganglion of the honeybee (Apis mellifera) affects the flapping‐wing flight, we profiled the response characteristics of indirect flight muscles to abdominal ganglion excitation. Strikingly, a change in the neural activity of ganglion 3 or ganglion 4 has a stronger effect on the electrophysiological activity of indirect flight muscles than that of ganglion 5. The electrophysiological activity of vertical indirect flight muscles is affected more by the change in neural activity of the abdominal ganglion than that of lateral indirect flight muscles. Moreover, the change in neural activity of the abdominal ganglion mainly causes the change in the muscular activity of indirect wing muscles, but the activity patterns change relatively little and there is little change in the complicated details. This work improves our understanding of the neuroregulatory mechanisms associated with the flapping‐wing flight of honeybees. [ABSTRACT FROM AUTHOR]

Background: Therapeutic exercise has been considered a useful tool to rehabilitate shoulder pain, namely through its influence on scapular dynamics. Accordingly, the effectiveness of scapular therapeutic exercise needs to be explored. The present study aims to evaluate the effectiveness of scapular therapeutic exercises in shoulder pain and to identify the most effective exercise type (focal or multijoint) and ways of delivering them (as dose and progression). Methods: Search was conducted at EMBASE, Cochrane Library, MEDLINE via PubMed, Web of Science, PEDro (Physiotherapy Evidence Database), and trial registration databases. The meta-analysis considered randomized controlled/crossover trials that compared the effect of scapular exercises against other types of intervention in the shoulder pain, shoulder function, scapular motion, and/or muscular activity. The risk of bias was assessed through the PEDro scale. Results: From the 8318 records identified, 8 (high to low risk of bias– scoring from 4 to 8 on the PEDro scale) were included. The overall data, before sensitivity analysis, indicated that the scapular therapeutic exercises are: a) more effective than comparators in improving shoulder function (standardized mean difference [SMD] = 0.52 [95% Cl: 0.05, 0.99], P = .03, I2 = 76%); and b) as effective as comparators in reducing shoulder pain (SMD = 0.32 [95% Cl: −0.09, 0.73], P = .13, I2 = 70%). Subgroup analysis revealed that scapular exercises are more effective in improving shoulder function when the program duration is equal to or higher than 6 weeks (SMD = 0.43 [95% Cl: 0.09, 0.76] P = .01, I2 = 21%) and/or when the maximum number of exercise repetitions per session is lower than 30 (SMD = 0.79 [95% Cl: 0.15, 1.42], P = .01, I2 = 77%). Only 1 study considered scapular motion as an outcome measure, revealing therapeutic exercise effectiveness to improve scapular range of motion. Conclusions: Intervention programs involving scapular therapeutic exercises are effective in improving shoulder function, presenting benefits when performed for 6 or more weeks and/or when used up to a maximum of 30 repetitions per exercise, per session.

Landing is a frequently executed motion in athletic activities, and injuries have been reported to occur often during landing, suggesting that legs are subjected to large loads during landing. Many studies, based on posture and floor reaction, have been conducted on this subject; however, few have been conducted from the muscular-activity perspective. Moreover, we found no studies investigating the functions of biarticular muscles (muscles that cross two joints). Therefore, we studied landing motion in which feet make ground contact after falling from a suspended position. Our objective was to clarify activity patterns of biarticular thigh muscles in two different trunk postures. Our results showed that the activity patterns of the antagonistic biarticular muscle pair at the thigh anterior and posterior were affected by trunk posture. [ABSTRACT FROM AUTHOR]

Introduction: A recent study showed that cadence modulation during short eccentric cycling exercise affects oxygen consumption (...O2), muscular activity (EMG), and perception of effort (PE). This study examined the effect of cadence on ...O2, EMG, and PE during prolonged eccentric cycling and exercise-induced neuromuscular alterations. Methods: Twenty-two participants completed three sessions 2-3 wk apart: 1) determination of the maximal concentric peak power output, familiarization with eccentric cycling at two cadences (30 and 60 rpm at 60% peak power output), and neuromuscular testing procedure; 2) and 3) 30 min of eccentric cycling exercise at a cadence of 30 or 60 rpm. PE, cardiorespiratory parameters, and vastus lateralis and rectus femoris EMG were collected during exercise. The knee extensors' maximal voluntary contraction torque, the torque evoked by double stimulations at 100 Hz (Dt100) and 10 Hz (Dt10), and the voluntary activation level were evaluated before and after exercise. Results: ...O2, EMG, and PE were greater at 30 than 60 rpm (all P <0.05). Maximal voluntary contraction torque, evoked torque, and Dt10/Dt100 ratio decreased (all P < 0.01) without cadence effect (all P > 0.28). Voluntary activation level remained constant after both eccentric cycling exercises (P = 0.87). Conclusions: When performed at the same power output, eccentric cycling exercise at 30 rpm elicited a greater PE, EMG, and cardiorespiratory demands than pedaling at 60 rpm. Exercise-induced fatigability was similar in both eccentric cycling conditions without neural impairments, suggesting that eccentric cycling seemed to alter more specifically muscular function, such as the excitation-contraction coupling process. In a rehabilitation context, eccentric cycling at 60 rpm seems more appropriate because it will induce lower PE for similar strength loss compared with 30 rpm. [ABSTRACT FROM AUTHOR]

The main objective of the research was to determine neuromuscular control for different external loads, from 75% to 100% 1 RM (One Rep Max), during the flat bench press (BP) exercise performed with free weights and pneumatic loading. Despite extensive research on the internal structure of the BP exercise, few studies have examined the differences between muscular activity during the flat bench press movement between Free Weights and Pneumatic Loading. For this purpose, 10 male, trained subjects performed the BP exercise under two conditions with three different external loads (70%, 85%, and 100% 1RM), alternately with free weights and pneumatic loading. Pneumatic loading was performed on the Keiser Power Rack, where the pneumatic load was transferred as the resistance of the cables attached to the ground. EMG activity was recorded during the lifts for the following muscles: PM (Pectoralis Major), AD (Anterior Deltoid), Tblat, and TBlong (Triceps Brachii). The EMG signals were sampled at a rate of 1000 Hz. Signals were band-pass filtered with a cutoff frequency of 8 Hz and 450 Hz, after which the root-mean-square (RMS) was calculated. After completion of all the tests in a single day, 2–3 s evaluations of Maximal Voluntary Isometric Contraction (MVIC) of the prime movers in the bench press movement (AD, PM, and TBlong) were performed according to SENIAM procedures. The results of the present study indicate that pneumatic loading provides a significantly different muscle activation pattern compared to a standard bar during a heavy-loaded BP exercise. The pneumatic load was superior in activating the AD and TB muscles compared to the standard bar during the BP exercise. [ABSTRACT FROM AUTHOR]

Limited studies exist examining the reverse lunge. The purpose of this study was to describe the activation of the rectus femoris (RF), biceps femoris (BF), gluteus medius (GMed), and gluteus maximus (GMax) of both limbs during a bodyweight reverse lunge movement. A secondary purpose was to describe the phases of the stationary (non-moving) and lead (moving) limbs during the reverse lunge. Surface electromyography (EMG) was used to record the activity of the target muscles in 20 healthy adults (10 male, 10 female; aged 22–25). Root mean squared values for mean maximum and average percent activation normalized to maximum voluntary isometric contraction (MVIC) activation were calculated. Descriptive terminology was created to describe the phases of the lunge for both limbs. The mean maximum percentage of muscle activation for the RF and BF was greater in the lead limb, while GMed and GMax activations were greater in the stationary limb. Only the lead limb RF and stationary limb GMed reached a strengthening stimulus in mean maximum percentage measurements. Clinically, it may be important to consider when each muscle is maximally active and at what percentage of its MVIC to properly prescribe the reverse lunge in a safe manner.

Copyright of International Journal of Medicine & Science of Physical Activity & Sport / Revista Internacional de Medicina y Ciencias de la Actividad Física y del Deporte is the property of Revista Internacional de Medicina y Ciencias de la Actividad Fisica y del Deporte and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: Agricultural fields like weed management and horticultural operations are the most common and labor-intensive. Most of these tasks are completed with the help of push-pull-type agricultural machinery. The push-pull tasks are mainly done using agricultural machinery (push-pull weeders, manually operated rice transplanters or seeders, long-handled agricultural tools, etc.) by farm workers. Since these are manually operated machinery, long working hours in awkward positions are expected, which causes physical stress and musculoskeletal disorders in the operators. An electromyography study for agricultural workers during push and pull operations was conducted in this study. Methods: To evaluate muscle activity, a laboratory test setup was developed based on the ergonomic criteria of the uniform force application. Four loads (50, 100, 150, and 200 N) and the four most used upper body muscles (middle deltoid MD, triceps brachii TR, brachioradialis BR, and biceps brachii BI) during push-pull operations were selected for an electromyographic study on twelve medically fit agricultural workers as subjects. This study attempted to minimize muscle activity, thereby reducing overexertion injuries. Results: The most activated muscles during the pushing and pulling operations were TR and BR, respectively. The muscle activity of the TR during the pushing task was found to be 109 µV, 135 µV, 178 µV and 195 µV at loads of 50 N, 100 N, 150 N, and 200 N, respectively. During the pulling task, the muscle activity of the BR was 51 µV, 66 µV, 80 µV, and 126 µV at loads of 50 N, 100 N, 150 N, and 200 N, respectively. Conclusion: For all subjects, a load of 200 N was found difficult to operate compared to other selected loads during push and pull operations. Muscle activation was found to increase with increasing load for each of the selected muscles.

The main objective of the research was to determine neuromuscular control for different external loads, from 75% to 100% 1 RM (One Rep Max), during the flat bench press (BP) exercise performed with free weights and pneumatic loading. Despite extensive research on the internal structure of the BP exercise, few studies have examined the differences between muscular activity during the flat bench press movement between Free Weights and Pneumatic Loading. For this purpose, 10 male, trained subjects performed the BP exercise under two conditions with three different external loads (70%, 85%, and 100% 1RM), alternately with free weights and pneumatic loading. Pneumatic loading was performed on the Keiser Power Rack, where the pneumatic load was transferred as the resistance of the cables attached to the ground. EMG activity was recorded during the lifts for the following muscles: PM (Pectoralis Major), AD (Anterior Deltoid), Tblat, and TBlong (Triceps Brachii). The EMG signals were sampled at a rate of 1000 Hz. Signals were band-pass filtered with a cutoff frequency of 8 Hz and 450 Hz, after which the root-mean-square (RMS) was calculated. After completion of all the tests in a single day, 2–3 s evaluations of Maximal Voluntary Isometric Contraction (MVIC) of the prime movers in the bench press movement (AD, PM, and TBlong) were performed according to SENIAM procedures. The results of the present study indicate that pneumatic loading provides a significantly different muscle activation pattern compared to a standard bar during a heavy-loaded BP exercise. The pneumatic load was superior in activating the AD and TB muscles compared to the standard bar during the BP exercise.

BACKGROUND: Gluteus medius (GM) is a segmented muscle involving three muscular subdivisions. Rehabilitation exercises has been suggested to strengthen specific subdivisions. OBJECTIVE: This study aimed to evaluate muscular activation of the anterior, middle, and posterior subdivisions of the GM during two different exercises. METHODS: A total of 28 healthy active subjects participated in this study. Muscle activity using surface electromyography was recorded for the three GM subdivisions during figure-of-four position (FFP) and wall press (WP). Non-parametric Kruskal-Wallis test was used to detect differences between GM subdivisions on each exercise and the Mann-Whitney U test was used to compare muscular activation across exercises. RESULTS: There were statistically significant differences (P < 0.001) in all GM subdivision during FFP and WP exercises. Both exercises showed greater activation of the posterior subdivision than the middle and anterior subdivisions, with the WP causing highest activation of the posterior subdivision. CONCLUSION: In line with the WP exercise, the FFP produces sufficient activity to provide potential strength gains on the posterior subdivision and could be a viable option to include in the early stages of the rehabilitation process. Clinicians may use this information to make more informed decisions about exercise selection for strengthening specific GM subdivision. [ABSTRACT FROM AUTHOR]

Surface electromyography (sEMG) is the acquisition, from the skin, of the electrical signal produced by muscle activation. Usually, sEMG is measured through electrodes with electrolytic gel, which often causes skin irritation. Capacitive contactless electrodes have been developed to overcome this limitation. However, contactless EMG devices are still sensitive to motion artifacts and often not comfortable for long monitoring. In this study, a non-invasive contactless method to estimate parameters indicative of muscular activity and fatigue, as they are assessed by EMG, through infrared thermal imaging (IRI) and cross-validated machine learning (ML) approaches is described. Particularly, 10 healthy participants underwent five series of bodyweight squats until exhaustion interspersed by 1 min of rest. During exercising, the vastus medialis activity and its temperature were measured through sEMG and IRI, respectively. The EMG average rectified value (ARV) and the median frequency of the power spectral density (MDF) of each series were estimated through several ML approaches applied to IRI features, obtaining good estimation performances (r = 0.886, p < 0.001 for ARV, and r = 0.661, p < 0.001 for MDF). Although EMG and IRI measure physiological processes of a different nature and are not interchangeable, these results suggest a potential link between skin temperature and muscle activity and fatigue, fostering the employment of contactless methods to deliver metrics of muscular activity in a non-invasive and comfortable manner in sports and clinical applications. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative and fatal disease, characterized by the loss of motor neurons and progressive musculoskeletal deterioration. The clinical onset is mainly bulbar or spinal. Considering that there is no effective medical treatment, there is a need to understand the muscle activation patterns to design better physical exercise routines. The objective of this study was to determine muscle strength and fatigue in patients with ALS performing a unilateral exercise, and according to sex and type of ALS. A cross-sectional, analytical study was conducted with 23 patients. Five maximal unilateral isometric contractions were performed with the right and left biceps brachii. Muscle activation was calculated by surface electromyography bilaterally in the biceps brachii, triceps brachii, rectus femoris anterior, and tibialis anterior. The results showed more accentuated fatigue in men than in women, between the first and last contractions performed and especially on the dominant side (p = 0.016). In addition, there was evidence of a coactivation effect on the muscles around the work joint, which reflects a growing activation of synergists, regardless of sex or type of ALS. These findings support the use of systematic and extensive resistance exercise as a non-invasive option for maintaining the functional capacity of patients with ALS. [ABSTRACT FROM AUTHOR]

Copyright of Dilemas Contemporáneos: Educación, Política y Valores is the property of Dilemas Contemporaneos: Educacion, Politica y Valores and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study aims to investigate the modifications in the temporalis and the masseter activity in adult patients before and after SARPE (Surgically Assisted Rapid Palatal Expansion) by measuring electromyographic and electrokinesographic activity. 24 adult patients with unilateral posterior crossbite on the right side were selected from the Orthodontic Department of the University of Milan. Three electromyographic and electrokinesographic surface readings were taken respectively before surgery (T0) and 8 months after surgery (T1). The electromyographic data of both right and left masseter and anterior temporalis muscles were recorded during multiple tests: standardized maximum voluntary contraction (MVC)s, after transcutaneous electrical nerve stimulation (TENS) and at rest. T0 and T1 values were compared with paired Student's t-test (p < 0.05). Results: Significant differences were found in the activity of right masseter (p = 0.03) and right temporalis (p = 0.02) during clench, in the evaluation of right masseter at rest (p = 0.03), also the muscular activity of masseters at rest after TENS from T0 to T1 (pr = 0.04, pl = 0.04). No significant differences were found in the activity of left masseter (p = 0.41) and left temporalis (p = 0.39) during clench and MVC, in the evaluation of left masseter at rest (p = 0.57) and in the activity during MVC of right masseter (p = 0.41), left masseter (p = 0.34), right temporalis (p = 0.51) and left temporalis (p = 0.77). Results showed that the activity of the masseter and temporalis muscles increased significantly after SARPE during rest and clenching on the side where the cross-bite was treated. [ABSTRACT FROM AUTHOR]

Health of the population of the Russian Federation is an indicator of national safety. Therefore, one of the priority directions of state policy organization of events, providing preservation and increase in level of somatic health of citizens of the Russian Federation is considered. In this context, one of powerful methods of management of activity of the person is muscular work, long-term adaptation to which causes formation of a number of the effects having improving and preventive orientation. In this connection in recent years, the attention of experts and patients to the various systems of improving trainings increases, and the need for them in all of age groups of the population stimulates active development of their various forms and the fitness services industry. At the same time, achievement of necessary result demands understanding of both regularities of formation of adaptation reactions of an organism when using of the existing arsenal of physical activities, exercises, and the basic principles of their realization taking into account conclusions and recommendations of evidential medicine. These are organizational and methodical features of planning of training programs and styles of concrete occupations, the choice and dispensing both classical forms of physical activity, and options of technologies of fitness taking into account exercises potentially dangerous to the musculoskeletal device especially at children. Within the above-stated positions, the real material in a format of lecture statement is made and presented.

One of the most effective methods in the system of medical rehabilitation is the use of physical exercises to restore patients after diseases and injuries. Muscle loads are an integral part of physical therapy, various health programs, and, finally, sports. All these types of motor activity, depending on the goal pursued, are based on certain principles of choice, purpose and dosage of physical exercises, taking into account their physiological substantiation of the effect on the body under various nosological forms So, any violation in a different link of the neuroreflex pathway of the motor stimulus leads to a change in the process of realization of the body's response to physical exercises. In this connection, it is important and necessary to have a clear understanding of the mechanism of the action of muscle activity, the variability of the formation of locomotion and their effects, the classification of exercises, the approaches used in the construction and conduct of both individual procedures and the course of physical rehabilitation, a qualitative realization of the tactics of managing patients with private methods of their recovery. Besides, it is always necessary to take into account currently allocated physical exercises, so-called potentially dangerous for the body and, therefore, requiring careful correlation with the nosological form of the disease in which they are used.

Myofascia, deep fascia enveloping skeletal muscles, consists of abundant collagen and elastin fibres that play a key role in the transmission of muscular forces. However, understanding of biomechanical dynamics in myofascia remains very limited due to less quantitative and relevant approaches for in vivo examination. The purpose of this study was to evaluate the myofascial fibril structure by means of a quantitative approach using two‐photon microscopy (TPM) imaging in combination with intravital staining of Evans blue dye (EBD), a far‐red fluorescence dye, which potentially labels elastin. With focus on myofascia of the tibial anterior (TA) muscle, the fibril structure intravitally stained with EBD was observed at the depth level of collagen fibrous membrane above the muscle belly. The EBD‐labelled fibril structure and orientation in myofascia indicated biomechanical responses to muscle activity and ageing. The orientation histograms of EBD‐labelled fibrils were significantly modified depending upon the intensity of muscle activity and ageing. Moreover, the density of EBD‐labelled fibrils in myofascia decreased with habitual exercise but increased with muscle immobilization or ageing. In particular, the diameter of EBD‐labelled fibrils in aged mice was significantly higher. The orientation histograms of EBD‐labelled fibrils after habitual exercise, muscle immobilization and ageing showed significant differences compared to control. Indeed, the histograms in bilateral TA myofascia of exercise mice made simple waveforms without multiple sharp peaks, whilst muscular immobilization or ageing significantly shifted a histogram with sustaining multiple sharp peaks. Therefore, the dynamics of fibre network with EBD fluorescence in response to the biomechanical environment possibly indicate functional tissue adaptation in myofascia. Furthermore, on the basis of the knowledge that neutrophil recruitment occurs locally in working muscles, we suggested the unique reconstruction mechanism involving neutrophilic elastase in the myofascial fibril structure. In addition to the elastolytic susceptibility of EBD‐labelled fibrils, distinct immunoreactivities and activities of neutrophil elastase in the myofascia were observed after electric pulse stimulation‐induced muscle contraction for 15 min. Our findings of EBD‐labelled fibril dynamics in myofascia through quantitative approach using TPM imaging and intravital fluorescence labelling potentially brings new insights to examine muscle physiology and pathology. [ABSTRACT FROM AUTHOR]

Obesity is an emerging health problem and its incidence has been increasing throughout the workforce. In industrial workstations, vertical handling tasks (VHT), including lifting and lowering, are very common and can cause a significant muscular overload for the involved workers. During these tasks, muscular activity may be considerably affected by workers' body conditions. This study aims to analyze and compare the muscular activity in subjects with different obesity levels, using surface electromyography (EMG), during predefined VHT. Six different VHT (combining 5, 10 and 15-kg loads with two task styles) were performed. EMG data normalization was based on the percentage of maximum contraction during each task (MCT%). The results show that obesity influences the MCT%, which in turn increases the muscular effort during VHT. The current investigation demonstrates that obesity is a relevant musculoskeletal risk factor regarding VHT. The engineering analysis and design implications of this work can thus be perceived. [ABSTRACT FROM AUTHOR]

This study aimed to identify and to compare the difference the changes of one-leg drop landing pattern depending on chronic ankle instability (CAI) among basketball club members. For 30 basketball club members who are currently participating in recreational basketball games in Busan Metropolitan City, 21 CAI groups and 9 CON groups were classified according to the CAI standards provided by the International Ankle Consortium. The one-leg drop landing pattern was measured with the alignment of the lower extremity and joint movement at the initial contact (IC), and the point of peak knee flexion. In addition, the one-leg drop landing pattern was tested with the muscular activity of tibialis anterior, peroneus longus, medial gastrocnemius and gluteus medius at the initial contact (IC), heel contact (HC), and the point of peak knee flexion. The results of this study showed that there was no significant difference in lower limb alignment and lower limb muscular activity among single leg drop landing. These results showed no significant differences in the one leg drop landing pattern and muscular activity depending on CAI. The further studies should classify the types of chronic ankle instability and consider the physical demands and movement characteristics depending on their playing position for providing useful information on prevention of CAI in basketball club members. [ABSTRACT FROM AUTHOR]

A custom-designed, wearable, lightweight, and passive exoskeleton was proposed to provide gravity support for industrial workers to reduce prevalence of musculoskeletal disorders, joint injures, and arthritis caused by repeatedly or persistently squatting task. The designed exoskeleton can act as a wearable chair to allow workers to squat for an extended period when performing prolonged tasks. The exoskeleton employs torsion springs to store energy harvested from the squatting motion, and the stored energy is released to help the workers stand up. Dimensions optimization designs based on the finite element analysis program were implemented for a lightweight of the device. Besides, the exoskeleton effectiveness was investigated by performing an ergonomic assessment on muscular activity, plantar pressure, endurance time, and comfort. The plantar pressure and electromyography of rectus femoris, biceps femoris, vastus medialis, and vastus laterals were measured in a simulated assembly task with the knee bend for three different angles (60°, 90°, 120°) under two conditions of with and without the exoskeleton. The endurance time was recorded in three different static squatting tasks. The comfort with the exoskeleton was recorded. Under the condition of wearing the exoskeleton, the average reduction of muscle activity was 44.8–71.5%, and the plantar pressure was 58.5–64.2%. The exoskeleton contributed to an increase in endurance time from 2.76 to 13.58 min. Moreover, 70% of the subjects exhibited a comprehensive exoskeleton comfort score of higher than 70. The experimental results demonstrated that this exoskeleton has good potential to reduce physical workload and increase endurance time during industrial assembly tasks. [ABSTRACT FROM AUTHOR]

Purpose: Latissimus dorsi tendon transfer is a surgical option for the treatment of massive irreparable posterosuperior rotator cuff tear. Whether a favourable clinical outcome is due to the latissimus dorsi muscle contraction rather than the passive tenodesis effect remains to be confirmed. The purpose of the current case-control study was to evaluate the shoulder kinematics and latissimus dorsi activation after latissimus dorsi tendon transfer.Methods: Eighteen patients suffering from irreparable rotator cuff tear that underwent latissimus dorsi tendon transfer and 18 healthy individuals were examined using a 3D kinematic tracking system and electromyography. Active maximal flexion-extension and abduction-adduction of the humerus were measured for the operated and the contralateral shoulder of the patients and the shoulder of healthy individuals to evaluate the range of motion (ROM) and scapulohumeral rhythm. Electromyographic comparison of isometric contraction between the latissimus dorsi of the operated and contralateral shoulder was carried out.Results: After arthroscopic-assisted latissimus dorsi tendon transfer, patients showed comparable flexion and abduction ROM to their asymptomatic contralateral shoulders and to the shoulders of healthy individuals. Significantly higher scapular ROM values were found between the latissimus dorsi tendon transfer side and the shoulders of healthy individuals. While performing external rotation with 0° shoulder abduction, a greater percentage of the electromyographic peak value (p = 0.047) and a higher latissimus dorsi internal/external rotation ratio (p = 0.004) were noted for the transferred muscle in comparison to the contralateral shoulder.Conclusion: Although the arthroscopic-assisted latissimus dorsi tendon transfer failed to normalize scapulothoracic joint movements of patients, a functional latissimus flap and a shoulder ROM similar to the contralateral side or the shoulder of healthy individuals can be expected after this procedure in patients with massive irreparable posterosuperior rotator cuff tear.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

In volleyball matches, there are three minute intervals between sets. Therefore, the improvement of the muscle output ratio is one of the most import foundational physical elements for the players. The purpose of this study was to investigate the effects of plyometric training on the changes in electrical signals in the lower limb muscles of male college volleyball players during continuous blocking and to examine the benefits of plyometric training on blocking agility and maximum vertical jump height. In this study, twenty elite male college volleyball players were recruited and divided into a plyometric training group (PTG) and a control group (CG). The wireless electromyography was used for data acquisition, and the electrodes were applied to the left and right rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius. The median frequency was used as the measurement of the electromyographic signals during the jumping blocks. This study used covariate analysis methods, with previously measured results used as covariates to perform a two-way analysis of covariance for the independent samples. Based on the results of this study, after 6 weeks of training, the median frequency of the rectus femoris (2.13% to 4.75% improved) and that of the tibialis anterior muscles (4.14% to 7.71% improved) were significantly lower in the PTG than in the CG. Additionally, the blocking agility increased by 6.26% and the maximum vertical jump height increased by 3.33% in the PTG compared to the CG. The findings provide important insights on the neuromuscular status for volleyball players during continuous blocking jumps. Six weeks of appropriate plyometric training can facilitate the performance of volleyball players. [ABSTRACT FROM AUTHOR]

The pilot study on changes of selected muscles tension caused by vertical and horizontal whole-body vibration focused on employees belonging to two professional (occupational) groups. One of these groups consisted of men aged 50 years professionally exposed to vibration and the second were men not exposed to vibration at the workplace. Tests have been conducted in two series on special designed laboratory test bench for simulation of exposure to whole-body vibration. During the I series of tests, vertical vibration had acted on subjects and during II series horizontal lateral vibration had acted. The EMG signals were registered from muscles of the shoulder girdle and lower back, both sites of the body. Muscles tension values obtained during I and II series indicates that there are no statistical significant differences between reaction of subjects on vertical and horizontal vibration. However slightly lower EMG RMS values during II series were noticed. Exposure to whole-body vibration may cause changes in muscle tension both in employees (aged 50 years and older) occupationally exposed to vibration and not exposed to vibration. The observed changes vary in both groups of subjects. In occupationally exposed to vibration subjects the impact of exposure to vibration on muscle tension is less than in reference group. [ABSTRACT FROM AUTHOR]

Background: Rhythmic gymnastics performance is characterized by technical elements involving flexibility, aerobic capacity and strength. Increased core strength in rhythmic gymnastics could lead to improved sporting performance. Objective: The aim of this study was to analyze the effect of 12 weeks of core muscle training on core muscle performance in rhythmic gymnasts. Methods: A randomized controlled study involving 24 rhythmic gymnastics was conducted. Participants were randomly assigned to a control group (CG; n = 12; age 13.50 ± 3.17 years) or a training group (TG; n = 12; age 14.41 ± 2.35 years). Body composition, isometric strength of trunk, core endurance and core muscle electromyographic activity were measured (EMG) after 12 weeks of core training. Independent sample t-tests were carried out to compare baseline values between groups. A two-way repeated-measures analysis of variance (ANOVA) (time × group) was applied. Results: The TG improved body composition, trunk lean mass (mean differences MD = −0.31; p = 0.040), lean mass (MD = 0.43; p = 0.037) and bone mass (MD = −0.06; p < 0.001) after training. Core training increased isometric strength of trunk, flexion test (MD = −21.53; p = 0.019) and extension test (MD = 22.7; p = 0.049), as well as the prone bridge core endurance test (MD = −11.27; p = 0.040). The EMG values also increased in the TG in prone bridge for front trunk (MD = −58.58; p = 0.026). Conclusions: Core strength training leads to improvements in body composition, as well as improvements in trunk strength and increases in muscle electromyographic activity. These improvements could therefore improve performance during competitive rhythmic gymnastics exercises.

The aim of this study was to analyze the inter-temporal neuromuscular and motor patterns in breaststroke technique. Five national level male swimmers performed 200 m breaststroke at maximal effort. Electromyography data onbiceps brachii, deltoid anterior, pectoralis major and triceps brachiiwere analysed. The relative duration of active and non-active phase and the average rectified value for the neuromuscular patterns were recorded. The swim bouts were videotaped in sagittal plane with a pair of cameras and the Theme software 5.0 was used toanalyse the detected patterns in each swimmer. The neuromuscular pattern revealed that by the average rectified value the biceps brachiiand triceps brachiiwere increased at the end of the test for swimmers 1 and 5, while biceps brachii, deltoid anteriorand pectoralis majorwere increased for swimmers 2 and 4. Different motor patterns between cycles, and between swimmers were observed.We found similarities between the swimmers, adjusting their style to the technical model. The absence of a neuromuscular pattern for all swimmers could be related to different technical models used by each swimmer, as presented in the motor patterns. These findings suggested that each swimmers adapted their own motor and neuromuscular pattern in a unique and distinct way.

The improvement of power is an objective in training of athletes. In order to detect effective methods of exercise, basic research is required regarding the mechanisms of muscular activity. The purpose of this study is to investigate whether or not a muscular pre-activation prior to an external impulse-like force impact has an effect on the maximal explosive eccentric Adaptive Force (xpAFeccmax). This power capability combines different probable power enhancing mechanisms. To measure the xpAFeccmax an innovative pneumatic device was used. During measuring, the subject tries to hold an isometric position as long as possible. In the moment in which the subjects’ maximal isometric holding strength is exceeded, it merges into eccentric muscle action. This process is very close to motions in sports, where an adaptation of the neuromuscular system is required, e.g., force impacts caused by uneven surfaces during skiing. For investigating the effect of pre-activation on the xpAFeccmax of the quadriceps femoris muscle, n = 20 subjects had to pass three different pre-activation levels in a randomized order (level 1: 0.4 bar, level 2: 0.8 bar, level 3: 1.2 bar). After adjusting the standardized pre-pressure by pushing against the interface, an impulse-like load impacted on the distal tibia of the subject. During this, the xpAFeccmax was detected. The maximal voluntary isometric contraction (MVIC) was also measured. The torque values of the xpAFeccmax were compared with regard to the pre-activation levels. The results show a significant positive relation between the pre-activation of the quadriceps femoris muscle and the xpAFeccmax (male: p = 0.000, η2= 0.683; female: p = 0.000, η2= 0.907). The average percentage increase of torque amounted +28.15 ± 25.4% between MVIC and xpAFeccmax with pre-pressure level 1, +12.09 ± 7.9% for the xpAFeccmax comparing pre-pressure levels 1 vs. 2 and +2.98 ± 4.2% comparing levels 2 and 3. A higher but not maximal muscular activation prior to a fast impacting eccentric load seems to produce an immediate increase of force outcome. Different possible physiological explanatory approaches and the use as a potential training method are discussed.

Background This study aimed to determine if individuals with skeletal Class II and skeletal Class III malocclusions had different levels of masticatory muscle activity. Materials and methods This cross-sectional study, conducted at the University of Damascus, investigated the myoelectric activity of perioral muscles in patients with Class II and III malocclusions. The sample size of 60 patients was determined according to a prior sample size calculation. Patients were selected based on specific inclusion and exclusion criteria and divided into Class II and III groups. Electromyography was used to monitor the activity of various muscles, including the temporalis, masseter, orbicularis oris, buccinator, mentalis, and digastric muscles. Results The study found similar muscle activity within the same group in the temporalis, masseter, buccinator, digastric, and orbicularis oris muscles. No significant differences were observed between the Class II and III groups for several oral and perioral muscles (P > 0.05). However, the mean activity of the digastric muscle was significantly greater in the Class II group (P < 0.05), whereas the mean activity of the mentalis muscle was smaller in the Class II group (P < 0.05). Conclusions Perioral muscles influence facial complex development and jaw relationship, affecting orthodontic treatment. Digastric muscle activity is greater in Class II patients, while mental muscle activity is smaller in Class III patients. Further studies are needed for older age groups and other skeletal malocclusion types., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Saker et al.)

Suspension training is an adjunct to traditional strength and conditioning. The effect of added instability on muscle activation during traditional exercises is unclear and depends on the exercise and type of instability. The purpose of this review was to compare the activations of different muscles in suspension training exercises and their traditional counterparts. A search of the current literature was performed without language restrictions using the electronic databases PubMed (1969—12 January 2017), SPORTDiscus (1969—12 January 2017) and Scopus (1969—12 January 2017). The inclusion criteria were: (1) descriptive studies; (2) physically active participants; and (3) studies that analysed muscle activation using normalised electromyographic signals during different suspension training exercises. Eighteen studies met the inclusion criteria. For the push-up, inverted row, prone bridge and hamstring curl in suspension, the activation of upper-body and core muscles ranged between moderate (21–40% maximum voluntary isometric contraction (MVIC)) and very high (>60% MVIC). Muscle activation in these same muscle groups was greater with suspension exercises relative to comparable traditional exercises, except for the inverted row. Muscle activation in the upper extremity and core muscles varied greatly amongst studies. [ABSTRACT FROM AUTHOR]

The improvement of power is an objective in training of athletes. In order to detect effective methods of exercise, basic research is required regarding the mechanisms of muscular activity. The purpose of this study is to investigate whether or not a muscular pre-activation prior to an external impulse-like force impact has an effect on the maximal explosive eccentric Adaptive Force (xpAFeccmax). This power capability combines different probable power enhancing mechanisms. To measure the xpAFeccmax an innovative pneumatic device was used. During measuring, the subject tries to hold an isometric position as long as possible. In the moment in which the subjects' maximal isometric holding strength is exceeded, it merges into eccentric muscle action. This process is very close to motions in sports, where an adaptation of the neuromuscular system is required, e.g., force impacts caused by uneven surfaces during skiing. For investigating the effect of pre-activation on the xpAFeccmax of the quadriceps femoris muscle, n = 20 subjects had to pass three different pre-activation levels in a randomized order (level 1: 0.4 bar, level 2: 0.8 bar, level 3: 1.2 bar). After adjusting the standardized pre-pressure by pushing against the interface, an impulse-like load impacted on the distal tibia of the subject. During this, the xpAFeccmax was detected. The maximal voluntary isometric contraction (MVIC) was also measured. The torque values of the xpAFeccmax were compared with regard to the pre-activation levels. The results show a significant positive relation between the pre-activation of the quadriceps femoris muscle and the xpAFeccmax (male: p = 0.000, η2= 0.683; female: p = 0.000, η2= 0.907). The average percentage increase of torque amounted +28.15 ± 25.4% between MVIC and xpAFeccmax with pre-pressure level 1, +12.09 ± 7.9% for the xpAFeccmax comparing pre-pressure levels 1 vs. 2 and +2.98 ± 4.2% comparing levels 2 and 3. A higher but not maximal muscular activation prior to a fast impacting eccentric load seems to produce an immediate increase of force outcome. Different possible physiological explanatory approaches and the use as a potential training method are discussed. [ABSTRACT FROM AUTHOR]

Background: This study examined the relationship between interhandle distances and upper limb exertion during simply pushing and pulling of a cart with four swivel wheels, defined by a roll box pallet (RBP) in a Japanese industrial standard. Methods: Six healthy young male participants were asked to push and pull an RBP at a distance of 5.2 m under six conditions corresponding to different interhandle distances (40 cm, 60 cm, and 80 cm) and weights (130 kg and 250 kg). The upper limb exertion was studied by shoulder abduction and flexion, and elbow flexion, as well as surface electromyogram (EMG) in shoulder extensor, and elbow flexor and extensor. Participants were required to provide subjective evaluations on operability after each trial. Results: Subjective operability indicated that a narrower interhandle distance had a better operability for pushing. Interhandle distance was also related to upper limb exertion especially for pushing. A narrow interhandle distance caused smaller shoulder adduction but larger elbow flexion. The normalized EMG data revealed that muscular activity became smaller with a narrow interhandle distance in shoulder extensor. During the pulling task, elbow flexion was smaller at a narrow interhandle distance, although subjective operability and normalized EMG were not significantly varied. Conclusion: A wider interhandle distance, such as 80 cm, was not suitable in the forwardbackward movement of the RBP. Therefore, this study concluded that an interhandle distance of 40 cm would be suitable for pushing and pulling an RBP to protect the workers' hands against the risk of injury by installing inner handles.

In volleyball matches, there are three minute intervals between sets. Therefore, the improvement of the muscle output ratio is one of the most import foundational physical elements for the players. The purpose of this study was to investigate the effects of plyometric training on the changes in electrical signals in the lower limb muscles of male college volleyball players during continuous blocking and to examine the benefits of plyometric training on blocking agility and maximum vertical jump height. In this study, twenty elite male college volleyball players were recruited and divided into a plyometric training group (PTG) and a control group (CG). The wireless electromyography was used for data acquisition, and the electrodes were applied to the left and right rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius. The median frequency was used as the measurement of the electromyographic signals during the jumping blocks. This study used covariate analysis methods, with previously measured results used as covariates to perform a two-way analysis of covariance for the independent samples. Based on the results of this study, after 6 weeks of training, the median frequency of the rectus femoris (2.13% to 4.75% improved) and that of the tibialis anterior muscles (4.14% to 7.71% improved) were significantly lower in the PTG than in the CG. Additionally, the blocking agility increased by 6.26% and the maximum vertical jump height increased by 3.33% in the PTG compared to the CG. The findings provide important insights on the neuromuscular status for volleyball players during continuous blocking jumps. Six weeks of appropriate plyometric training can facilitate the performance of volleyball players.

Objectives: This study aimed to investigate whether there was a difference in the muscular activity of the masticatory muscles between patients with skeletal Class II and skeletal Class I malocclusion., Materials and Methods: A cross-sectional study was conducted using a sample of 56 selected patients referred to the Department of Orthodontics and Dentofacial Orthodontics, Faculty of Dentistry at the University of Damascus, Damascus, Syria. An electromyographic device measured the myoelectric activity of the perioral muscles on patients in the two created groups: the skeletal Class I malocclusion group (n=28 patients) and the skeletal Class II malocclusion group (n=28 patients)., Results: The study found a similarity in the muscular activity between the right and left sides within the same group, without significant differences between both sides for each muscle (P>0.05). The Class II group had significantly greater activity in the buccinator and digastric muscles than the Class I group (p<0.05). On the other hand, the Class I group had significantly greater activity in the orbicularis and mentalis muscles than the Class II group (P<0.05)., Conclusion: Patients with skeletal Class II malocclusion and skeletal Class I showed differences in muscular activity. The buccinator and digastric muscles were more active in skeletal Class II patients, while orbicularis oris and mentalis were less active. The temporalis and masseter muscles showed similar activity in both groups., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Saker et al.)

Junji Katsuhira,1 Ko Matsudaira,2 Tadashi Yasui,3 Shinno Iijima,4 Akihiro Ito4 1Department of Nursing and Rehabilitation Science at Odawara, International University of Health and Welfare, Odawara, Kanagawa, 2Department of Medical Research and Management for Musculoskeletal Pain, 22nd Century Medical and Research Center, The University of Tokyo, Tokyo, 3Kawamura-Gishi Company, Ltd., Daito-shi, Osaka, 4Graduate School of International University of Health and Welfare, Otawara, Tochigi, Japan Purpose: Postural alignment of elderly people becomes poor due to aging, possibly leading to low-back pain and spinal deformity. Although there are several interventions for treating these conditions, no previous study has reported the effectiveness of a spinal orthosis or lumbosacral orthosis (LSO) in healthy elderly people without specific spinal deformity. We therefore developed a trunk orthosis to decrease low-back muscle activity while training good postural alignment through resistive force provided by joints with springs (here, called the ORF, which stands for orthosis with joints providing resistive force) as a preventive method against abnormal posture and low-back pain in healthy elderly persons. Patients and methods: Fifteen community-dwelling elderly men participated in this study. Participants stood freely for 10 seconds in a laboratory setting under three conditions: without an orthosis, with the ORF, and with an LSO. The Damen corset LSO was selected as it is frequently prescribed for patients with low-back pain. Postural alignment during static standing was recorded using a three-dimensional motion capture system employing infrared cameras. Two force plates were used to record center of pressure. Electromyograms were obtained for bilateral erector spinae (ES), left internal abdominal oblique, and right gluteus medius muscles. Results: Pelvis forward tilt angle tended to increase while wearing the ORF and decrease while wearing the LSO, but these results were not significant compared to no orthosis. Thorax extension angle and thorax angle on pelvis coordinate system significantly increased while wearing the ORF compared to the other two conditions. ES activity significantly decreased while wearing the ORF compared to the other two conditions. Internal oblique activity was significantly smaller while wearing the LSO than with no orthosis. Center of pressure did not significantly differ among the conditions. Conclusion: The ORF significantly improved trunk alignment and decreased ES activity in healthy elderly subjects during static standing. Keywords: muscular activity, center of pressure, standing posture, spine

INTRODUCTION: Muscle activity associated with mandible mobility depends on age. In the period of puberty and development of the masticatory system, a general increase in activity is observed, followed by relative stability until about 40-50 years of age. In subsequent years, the value of bioelectrical potentials decreases. OBJECTIVES: The aim of the study was to evaluate activity of the chewing muscles in complete denture wearers before and after prosthetic treatment. MATERIAL AND METHODS: The study group consisted of 50 edentulous people including 35 women and 15 men (age 44-86 years, mean 69.18 ± 10.00). All the patients received a new set of complete dentures. The activity of the following pairs of muscles were measured: anterior part of the temporal, masseter, digastric, and sternocleidomastoid. All registrations were performed three times: with the presence of currently used old dentures, in the first day of using new dentures, and three months after adaptation. Activity of the muscles was noted in the maximum intercuspation and with opened mouth. RESULTS: The results of this study revealed statistically significant differences in activity of the temporal, masseter, and digastric muscles before and in the first day of using new dentures. After three months of adaptation statistical differences were observed only in the case of masseter muscles, right temporal, and left digastric. In the first day of using new complete dentures a decreasing tendency of muscular activity was noted. After three months of adaptation the muscular activity increased. CONCLUSIONS: Fabrication of new complete dentures associated with reconstruction of vertical occlusal dimension, changes in the central position of the mandible, and modification of the occlusion of the artificial teeth leads to a temporary reduction of activity in the chewing muscles and then, after a period of adaptation and incorporation, to growth. [ABSTRACT FROM AUTHOR]

Highlights • New data-driven method improves REM sleep behavior disorder (RBD) identification. • Muscular activity during non-REM sleep contributes to identify RBD patients. • The method is robust to apnea and arousal-related movements. Abstract Background Documentation of REM sleep without atonia is fundamental for REM sleep behavior disorder (RBD) diagnosis. The automated REM atonia index (RAI), Frandsen index (FRI) and Kempfner index (KEI) were proposed for this, but achieved moderate performances. New method Using sleep data from 27 healthy controls (C), 29 RBD patients and 36 patients with periodic limb movement disorder (PLMD), we developed and validated a new automated data-driven method for identifying movements in chin and tibialis electromyographic (EMG) signals. A probabilistic model of atonia from REM sleep of controls was defined and movements identified as EMG areas having low likelihood of being atonia. The percentages of movements and the median inter-movement distance during REM and non-REM (NREM) sleep were used for distinguishing C, RBD and PLMD by combining three optimized classifiers in a 5-fold cross-validation scheme. Results The proposed method achieved average overall validation accuracies of 70.8% and 61.9% when REM and NREM, and only REM features were used, respectively. After removing apnea and arousal-related movements, they were 64.2% and 59.8%, respectively. Comparison with existing method(s) The proposed method outperformed RAI, FRI and KEI in identifying RBD patients and in particular achieved higher accuracy and specificity for classifying RBD. Conclusions The results show that i) the proposed method has higher performances than the previous ones in distinguishing C, RBD and PLMD patients, ii) removal of apnea and arousal-related movements is not required, and iii) RBD patients can be better identified when both REM and NREM muscular activities are considered. [ABSTRACT FROM AUTHOR]

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