Activation Of Muscle Groups Research Articles

Reliability and usefulness of the reaction speed test in young female volleyball players

Reaction speed represents a crucial ability to achieve a high-performance level in volleyball. A reliable computerized test for assessing reaction speed cannot simulate the dynamic environment of the volleyball game. Therefore, tests involving the activation of large muscle groups are needed. This study aimed to determine the reliability of young volleyball players' reaction speed ability using the Stopping the rolling ball test (SRB). Intraclass correlation coefficient (ICC), standard error of measurement (SEM) also expressed as a coefficient of variation (CV%), smallest worthwhile change (SWC), and minimal detectable change (MDC) were calculated. Paired t-test revealed no significant differences between test and re-test for first (t = -0.09, p = 0.92), mean of three (t = -0.37, p = 0.71), and best of three (t = -0.02, p = 0.98) trials. The ICC values showed poor relative reliability when the first trial was observed, while for the mean and best of three trials, reliability was consistently very high (excellent). The absolute reliability parameters (within-individual variation) showed large variations ranging from 5% to almost 10% and greater SEM (12.63 cm) for first trial when compared to other variables. The SEM was higher than SWC for all variables when the small differences (i.e., 0.2 multiplied by between-participants SD) were considered. This test showed a high level of absolute and relative reliability and usefulness, which means that the SRB test is an excellent indicator of reaction speed in young volleyball players.

Transcutaneous Auricular Vagus Nerve Stimulation (tAVNS) Delivered During Upper Limb Interactive Robotic Training Demonstrates Novel Antagonist Control for Reaching Movements Following Stroke.

Implanted vagus nerve stimulation (VNS) delivered concurrently with upper limb rehabilitation has been shown to improve arm function after stroke. Transcutaneous auricular VNS (taVNS) offers a non-invasive alternative to implanted VNS and may provide similar therapeutic benefit. There is much discussion about the optimal approach for combining VNS and physical therapy, as such we sought to determine whether taVNS administered during robotic training, specifically delivered during the premotor planning stage for arm extension movements, would confer additional motor improvement in patients with chronic stroke. Thirty-six patients with chronic, moderate-severe upper limb hemiparesis (>6 months; mean Upper Extremity Fugl-Meyer score = 25 ± 2, range 13–48), were randomized to receive 9 sessions (1 h in length, 3x/week for 3 weeks) of active (N = 18) or sham (N = 18) taVNS (500 ms bursts, frequency 30 Hz, pulse width 0.3 ms, max intensity 5 mA, ∼250 stimulated movements per session) delivered during robotic training. taVNS was triggered by the onset of a visual cue prior to center-out arm extension movements. Clinical assessments and surface electromyography (sEMG) measures of the biceps and triceps brachii were collected during separate test sessions. Significant motor improvements were measured for both the active and sham taVNS groups, and these improvements were robust at 3 month follow-up. Compared to the sham group, the active taVNS group showed a significant reduction in spasticity of the wrist and hand at discharge (Modified Tardieu Scale; taVNS = –8.94% vs. sham = + 2.97%, p < 0.05). The EMG results also demonstrated significantly increased variance for the bicep peak sEMG amplitude during extension for the active taVNS group compared to the sham group at discharge (active = 26.29% MVC ± 3.89, sham = 10.63% MVC ± 3.10, mean absolute change admission to discharge, p < 0.01), and at 3-month follow-up, the bicep peak sEMG amplitude was significantly reduced in the active taVNS group (P < 0.05). Thus, robot training improved the motor capacity of both groups, and taVNS, decreased spasticity. taVNS administered during premotor planning of movement may play a role in improving coordinated activation of the agonist-antagonist upper arm muscle groups by mitigating spasticity and increasing motor control following stroke.Clinical Trial Registration: www.ClinicalTrials.gov, identifier (NCT03592745).

Targeted muscle effort distribution with exercise robots: Trajectory and resistance effects

The objective of this work is to relate muscle effort distributions to the trajectory and resistance settings of a robotic exercise and rehabilitation machine. Muscular effort distribution, representing the participation of each muscle in the training activity, was measured with electromyography sensors (EMG) and defined as the individual activation divided by the total muscle group activation. A four degrees-of-freedom robot and its impedance control system are used to create advanced exercise protocols whereby the user is asked to follow a path against the machine’s neutral path and resistance. In this work, the robot establishes a zero-effort circular path, and the subject is asked to follow an elliptical trajectory. The control system produces a user-defined stiffness between the deviations from the neutral path and the torque applied by the subject. The trajectory and resistance settings used in the experiments were the orientation of the ellipse and a stiffness parameter. Multiple combinations of these parameters were used to measure their effects on the muscle effort distribution. An artificial neural network (ANN) used part of the data for training the model. Then, the accuracy of the model was evaluated using the rest of the data. The results show how the precision of the model is lost over time. These outcomes show the complexity of the muscle dynamics for long-term estimations suggesting the existence of time-varying dynamics possibly associated with fatigue.

Gluteal Muscle Activation During Common Yoga Poses.

BackgroundApproximately 24% of physical therapists report regularly using yoga to strengthen major muscle groups. Although clinicians and athletes often use yoga as a form of strength training, little is known about the activation of specific muscle groups during yoga poses, including the gluteus maximus and medius.Hypothesis/PurposeThe purpose of this study was to measure gluteus maximimus and gluteus medius activation via electromyography (EMG) during five common yoga poses. A secondary purpose of the current study was to examine differences in muscle activation between sexes and experience levels.Study DesignCross-SectionalMethodsThirty-one healthy males and females aged 18-35 years were tested during five yoga poses performed in a randomized order. Surface EMG electrodes were placed on subjects’ right gluteus maximus and gluteus medius. Subjects performed the poses on both sides following a maximal voluntary isometric contraction (MVIC) test for each muscle. All yoga pose EMG data were normalized to the corresponding muscle MVIC data.ResultsHighest gluteus maximus activation occurred during Half Moon Pose on the lifted/back leg (63.3% MVIC), followed by the stance/front leg during Half Moon Pose (61.7%), then the lifted/back leg during Warrior Three Pose (46.1%). Highest gluteus medius activation occurred during Half Moon Pose on the lifted/back leg (41.9%), followed by the lifted/back leg during the Warrior Three Pose (41.6%). A significant difference was found in %MVIC of gluteus medius activity between male and female subjects (p = 0.026), and between experienced and inexperienced subjects (p = 0.050), indicating higher activation among males and inexperienced subjects, respectively.ConclusionHalf Moon Pose and Warrior Three Pose elicited the highest activation for both the gluteus maximus and the gluteus medius. Higher gluteus medius activation was seen in males and inexperienced subjects compared to their female and experienced counterparts.Level of Evidence3

Using a reverse run during athlets workouts and in physical rehabilitation

The proposed article is devoted to the reverse run as a training mean for athletes and as a mean of physical rehabilitation, based on the early experience of foreign colleagues. Recent time, in medicine, sports medicine, physical rehabilitation and sports, more widely walking and running backwards is being used. The purpose of the article was to investigate the use of reverse run during sports workout of athletes. The task was to determine the level of coordination and physical fitness of athletes, using the technique of reverse running. Research methods: analysis of literary sources for English-language bibliographic databases PubMed, Web of Science and Elsevier and pedagogical experiment. Conclusions. Reverse run really eliminates the injury of the joints, has a positive effect on the posture. Students of the experimental group showed numerical and qualitative differences in indicators when conducting a pedagogical experiment. According to the reviews of students of both studied groups, the reverse run diversified monotonous training classes, opening new perspectives, and allowed the body in a new way. This method of moving helps to improve the balance and increase coordination. Reverse running helps compensate for a frequent disadvantage that occurs between the groups of the front and back of the thigh, popliteal bonds and calm muscles. Was also noticed that during workouts energy consumption due to the activation of muscle groups increases, which usually do not participate in a conventional run, which led to an increase in energy consumption, which was reflected in the results of a decrease in the body weight of the experimental group.

Evaluation of muscle activity and bite force in masticatory muscle after massage therapy or occlusal splint in sleep bruxism childhood

Objective: Sleep bruxism (SB) is considered masticatory muscle activities that occur during sleep, which can interfere in stomatognathic system function. When treatment occurs earlier, most of the signs and symptoms can be prevented. However, there are few studies about treatment in early ages. Thus, the present study aimed to evaluate muscle activity and bite force changes after massage therapy (MT) and the use of occlusal splints (OST) for children with SB. Methodology: Forty-eight children were divided into 4 groups after SB diagnosis, according to the American Academy of Sleep Medicine’s criteria: Group 1–without bruxism; Group 2–SB, MT treated; Group 3–SB, OST treated for 30 days; Group 4–SB, not treated. Children were submitted to initial and final bite force (BF) evaluations and muscular activity, using a digital dynamometer and BiteStrip®, respectively. The results were computed and statistical analysis performed using SPSS 20.0 program, with a significant level of 95% (p ≤ 0.05). Results: Significant differences were statistically found in muscle activity in Group 3 (p = 0.003) and BF in both Groups 2 (p = 0.001) and 3 (p = 0.007). Conclusion: Results indicate that the use of OST led to a reduction in muscle activity and increase on BF in children with SB, whereas MT did not alter muscle activity, but provided an increase on BF in these children.

Razlike između konvencionalne i sumo varijante tehnike mrtvog dizanja - kinematička, kinetička i elektromiografska studija

Deadlift is a measure of the overall strength of the whole body and it is one of the three exercises in the powerlifting competition. There are conventional and sumo variant of deadlift. The aim of this study was to determine the differences between the two lifting techniques from the aspect of kinematics, kinetics and electromyography. Nine physically active men, average age 29.1 ± 3.3 years, body height 181.0 ± 1.0 cm, body weight 82.3 ± 13.3 kg and body massindex 25.0 ± 3.8 kg/m2 were recruited forthisstudy. Each subject lifted weight close to his own body weight with three repetitions, in three series, for each of the techniques. The speed of one lift was 3 seconds for each of the phases (concentric and eccentric). The angles and amplitudes for the following figurative points were monitored: trunk in relation to the horizontal plane (angle), center of the hip joint and center of the knee joint in the "liftoff" (LO - position in which the weight separates from the ground) and "knee passing" (KP - position in which the weight passes in front of the knee position), i.e. in the liftoff-knee passing (LO-KP), knee passing-lift completion (KP-LC; LC - final, i.e. completely upright body position) and liftoff-lift completion (LOLC) phase. The mechanical work was monitored as a one of the kinetic variables. Electromyographic activity was monitored for the following muscles: m. vastus medialis, m. vastus lateralis, m. rectus femoris, m. gluteus Maximus, m. erector spinae (L3-L4), m. semimembranosus and m. biceps femoris caput longum. The monitored electromyographic variablewasthe average normalized amount of muscle activation in relation to maximal voluntary contraction, for all 18 individual deadlift repetitions (3 series × 3 repetitions × 2 techniques). One-way analysis of variance with repeated measurements (for the amount of muscle activation and performed mechanical work) and two-way analysis of variance with repeated measurements (for angles and amplitudes) were used for statistical data processing. Significant differences were found between techniques in the initial angular positions in all monitored joints (p&lt;0.05), except for the angle in the knee joint where the trend was observed (p=0.0996), as well as in the transit position for the trunk angle relative to the horizontal plane and angle at the hip joint (p&lt;0.05). There was a statistically significant difference between techniques in amplitudes in the hip joint during KP-LC phase (p&lt;0.05) and total amplitude (p&lt;0.05), as well as in the knee joint during LO-KP phase (p&lt;0.05) and total amplitude in the form of a trend (p=0.0996). The performed mechanical work is significantly higher when lifting the load with the conventional deadlift technique (DLcon) (p&lt;0.05). Activation of medial and lateral heads of m. quadriceps femoris is significantly higher (p&lt;0.05) when lifting with sumo deadlift technique (DLsu). It was noticed that activation of postural muscle groups (m. erector spinae, m. gluteus maximum, m. semitendinosus and m. biceps femoris caput longum) is higher when lifting the load with DLcon, but not significantly (p&gt;0.05).

Research on the mechanism of elbow flexion based on AnyBody

In order to analyze the dynamic characteristics of the upper limbs including the musculoskeletal system in elbow flexion, a human upper limb movement model including the musculoskeletal system was established based on the biomechanical analysis software AnyBody, and the overall model was subjected to inverse dynamics simulation and muscle force analysis to obtain the human body Muscle strength and muscle activity of upper limb muscle groups during elbow flexion exercise. Taking the human biceps as an example for analysis, the muscle strength of the biceps during elbow flexion exercise was obtained. When the loaded load is within a reasonable range, the muscle force will change regularly with the increase and decrease of the load, indicating that the training effect of flexion exercise needs to control the loading load within a certain range, which provides scientific theoretical support for upper limb muscle rehabilitation training.

Abstract B22: A novel measurement neck brace for detecting range-of-motion changes with electromyography correlates in head and neck cancer patients undergoing neck dissection: A prospective pilot study

Abstract Introduction: Postoperative neck and shoulder dysfunction is recognized as a morbidity of neck dissection (ND) in head and neck cancer patients. However, the precise biomechanics and duration of neck mobility limitation have not been fully described. In current practices of more selective NDs, studies employing precise measurement techniques are needed to quantify the risk of postoperative neck range of motion (ROM) impairment in this patient population. Study Design: A prospective pilot study of five patients undergoing selective ND for head and neck cancer was conducted. A novel measurement brace was used to collect kinematic and concurrent EMG data on active ROM during standardized tasks for prespecified neck muscle groups at baseline and following ND. Methods: Patients without prior surgery or radiation undergoing unilateral ND for head and neck cancer were included. Patients were evaluated preoperatively and four weeks postoperatively. A novel neck brace developed for the purposes of this study was utilized to measure flexion, extension, lateral bending, axial rotation, and rolling movements. Angle of motion was measured from the neutral position to the end of each movement type as well as during total ROM from one movement type to the other (i.e., from neutral position to flexion as well as from flexion to extension). Baseline and postoperative EMG onset/offset data were collected for bilateral SCM, splenius capitis, and trapezius muscles to correlate muscle activation with angle of motion. Results: Five patients undergoing unilateral modified ND for cutaneous, oral cavity, or oropharyngeal squamous cell carcinoma completed preoperative and postoperative assessments. The average age was 57 years (54-60; sd 2.6). The greatest change in total ROM following surgery was seen in lateral bending, with a mean angle change of 17.3 (6.9-30.6; sd 8.5). Differences in lateral bending from neutral position were also seen for both the dissected and nondissected sides. Although degree of flexion and extension ROM were not affected by surgery overall, changes in the pattern of muscle group activation were evident. Conclusions: Measurement brace recordings suggest that active ROM limitation is most pronounced with lateral neck bending both to the ipsilateral and contralateral side of ND compared to other neck movements. EMG correlate data show increased variability in activation of muscle groups with flexion and extension movements. These preliminary results suggest that this device may serve as a useful diagnostic tool for patients undergoing ND. Additional data are needed to determine statistical and clinical significance of changes measured using this device. Future results may help guide clinicians in counseling patients about expectations following surgery as well as lead us to potential therapeutic targets from changes in muscle activation. Citation Format: Biing-Chwen Chang, Haohan Zhang, Ade Obayemi, Sallie Long, Scott Troob, Sunil Agrawal. A novel measurement neck brace for detecting range-of-motion changes with electromyography correlates in head and neck cancer patients undergoing neck dissection: A prospective pilot study [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr B22.

Formant-Estimated Vocal Tract Length and Extrinsic Laryngeal Muscle Activation During Modulation of Vocal Effort in Healthy Speakers.

Purpose The goal of this study was to explore the relationships among vocal effort, extrinsic laryngeal muscle activity, and vocal tract length (VTL) within healthy speakers. We hypothesized that increased vocal effort would result in increased suprahyoid muscle activation and decreased VTL, as previously observed in individuals with vocal hyperfunction. Method Twenty-eight healthy speakers of American English produced vowel-consonant-vowel utterances under varying levels of vocal effort. VTL was estimated from the vowel formants. Three surface electromyography sensors measured the activation of the suprahyoid and infrahyoid muscle groups. A general linear model was used to investigate the effects of vocal effort level and surface electromyography on VTL. Two additional general linear models were used to investigate the effects of vocal effort on suprahyoid and infrahyoid muscle activities. Results Neither vocal effort nor extrinsic muscle activity showed significant effects on VTL; however, the degree of extrinsic muscle activity of both suprahyoid and infrahyoid muscle groups increased with increases in vocal effort. Conclusion Increasing vocal effort resulted in increased activation of both suprahyoid and infrahyoid musculature in healthy adults, with no change to VTL.

Observational study with the objective of determining possible correlations between GRF and muscle activation at reception after a jump in an ACL injury

The ACL injury is considered one of the most serious injuries and usually occurs in actions that include movements with changes of direction, jump and landing. It is a common injury between the young active population and the risk in women of suffering from non-contact injury is superior to that of men. Athletes who suffer from non-contact injuries of the ACL usually have common biomechanical profiles, with landings with large values in ground reaction force (GRF) and therefore, low cushioning on landing. To determine possible correlations between GRF and muscular activation at lading after a jump. The type of study carried out is an observational study in which, using surface electromyography (EMG), a force platform and an electrogoniometer, the aim is to assess muscle activation and its relationship with GRF (specifically the vertical component Fz). Correlations have been observed between the reaction force of the soil (Fz) in the moments where the reaction force of the soil is greater and the instant where the knee reaches maximum flexion after landing, with the activation of certain muscle groups and differences depending on the gender of the subject. The neuromuscular recruitment strategies in the phases of maximum GRF load and knee flexion are different depending on the sex of the individual, so it should be considered when scheduling prevention and recovery work. The evaluation of GRF and muscle activation patterns, allows to assess the dynamics of landing after a jump and to be able to detect different patterns according to sex, with the consequent importance that it can have in the injury mechanism.

Neuromuscular activation analysis of the trunk muscles during hippotherapy sessions

IntroductionHippotherapy allows the development of affective, sensory, motor, and cognitive areas, besides providing the practitioner with several movements and stimuli necessary for therapeutic progress. However, there is a limited amount of scientific evidence regarding the suitability of the mount material, mount type, and hippotherapy session duration, as well as regarding the activation of specific muscle groups during the practice and its applicability to activities of daily living. ObjectiveThis study aimed to study the neuromuscular activation behavior of the iliocostalis, longissimus, multifidus, and upper trapezius muscles of children during four hippotherapy session time points using a functional task. It also compared two different mount materials for riding. MethodologyA total of 30 children were randomly assigned to one of three groups: Saddle Hippotherapy Group, Blanket Hippotherapy Group, and Control Group. Data were collected with an electromyograph in a functional task that comprised trunk movements to pick up an object. Assessments took place at four times during the session. ResultsThere was a significant increase in the neuromuscular activation of the iliocostalis, longissimus, and multifidus muscles after a 30-min session. The trapezius muscle showed increased neuromuscular activation after only 10 min. It continued to increase (but without a statistical difference) after and 20 and 30 min. ConclusionHippotherapy promoted neuromuscular activation of the trunk muscles in children, assessed through a functional task, and was influenced by both session time and mount material. Specifically, the greater neuromuscular performance occurred when an exercise was performed using saddle and stirrup and lasted 30 min.

Study of Ballet Dancers During Cou-De-Pied Derrière with Demi-Plié to Piqué Arabesque.

Dancers are highly trained athletes who are at significant risk of injury due to the repetitive nature of their movement patterns. Most ballet injuries result from overuse and occur in the lower limbs. Therefore, the behavior of the lower limbs during a basic ballet movement should be studied in order to identify and subsequently correct mechanical factors that may contribute to injuries. This study analyzed a cou-de-pied derrière with demi-plié to piqué arabesque gesture executed by 18 ballet dancers identified in two groups: experienced dancers (EDs) and beginner dancers (BDs). Kinematic, baropodometric, and electromyographic analyses enabled the observation of differences between these study groups with regard to joint angles, velocities, foot pressure behavior, and muscle activation during execution of the gesture. Experienced dancers reached greater hip and lumbar spine hyperextension and demonstrated less forward torso flexion, which enables better execution of the gesture compared to BDs. The highest foot pressure in both groups was found in the first metatarsal, with a tendency toward the great toe. In terms of muscular activation, BDs exhibited lower electrical activity than EDs. It is concluded that: 1. ankle and knee angles in demi-plié are not defined by dancers' expertise; 2. the faster the leg is raised during piqué-arabesque the better the gesture; 3. special attention to the metatarsal heads is required due to the high pressures found in this study; and 4. activation of different muscle groups depends on the complexity of the gesture and dancer's expertise.

The effects of sand surface training on changes in the muscle activity of the paretic side lower limb and the improvement of dynamic stability and gait endurance in stroke patients.

Subjects were divided into two groups, for sand or general surface training. The gait abilities of the patients were evaluated with the Timed Up and Go (TUG) tests and the 6-min walk test (6MWT). Muscle activity in the lower limbs was evaluated with surface electromyography obtained during general surface gait. Gait ability and muscle activity were re-evaluated after gait training for 6 weeks on a sand or general surface. The TUG test was performed 3 times, and an average of the three values was used for analysis. 6MWT was measured once under maximum effort. Electromyography was evaluated using average gait cycle values. In the TUG test, performance times decreased in both groups, while in the 6MWT, performance distance significantly increased only in the sand surface training group. Results from surface electromyography showed that activity of the rectus femoris, biceps femoris, and tibialis anterior muscles of the paretic side lower limb significantly decreased after the both interventions. When environments are similar, gait training is helpful for increasing dynamic stability; however, repeated training does not significantly improve gait endurance. Training on a continuously unstable bearing surface such as sand can improve gait endurance by utilizing diverse muscle groups and increasing joint motility. Sand surface training recruited the activity of more muscle groups than did general surface training, and sand-trained participants showed longer gait distances with lower muscle activity levels when they resumed general training than their general-surface-trained counterparts.

'Mini-interval gait' switching: understanding the positive implications of a novel training regime.

The neuromechanical reorganization required to change gaits imposes an energetic cost 75% greater than either a walking or running step at the same speed. By combining walking and running with the requisite gait switching transition steps, an exercise protocol can be generated with virtually any desired metabolic output even at relatively slow treadmill speed. Gait switching increases metabolic demand through discrete events, which can be tolerated more easily by individuals recovering from health problems, just as interval training allows greater work production for healthy individuals. In addition to cardio-respiratory benefits, ‘mini-intervals’ with frequent gait switching also provides positive effects and attributes such as distributing muscle group activation, re-training neural coordination, and avoiding repetitive joint overloading. It has the added benefit of developing stability during transitions while a safety hand rail is present which can lead to greater stability in more complex natural environments. Finally, increased mental focus may help avoid the monotony of usual treadmill workouts, aiding adherence to an exercise program. We review evidence for the cost increase of the gait transition step and explain the mechanisms involved. We also discuss literature supporting the range of benefits for mini-interval gait switching as a training and rehabilitation tool.

Differences in muscle activity and fatigue of the upper limb between Task-Specific training and robot assisted training among individuals post stroke

ObjectiveTo compare the activity and fatigue of upper extremity muscles, pain levels, subject satisfaction levels, perceived exertion, and number of repetitions in Task-Specific Training (TST) compared with Robot-Assisted Training (RAT) in individuals post-stroke. MethodsTwenty sub-acute post stroke subjects (16 men; median (interquartile range) age 64.0 (71.5–57.0) years) received two 30-min treatment sessions, one TST and one RAT. Before each session, the Visual Analogue Scale (VAS) was administered. Activity levels and fatigue of six muscles were monitored using surface electromyography and the number of repetitions was counted. After each session, the subjective assessment questionnaire of treatment, the Borg scale and VAS were administered. ResultsDuring TST, the Anterior Deltoid, Upper Trapezius and Biceps were more active, while during the RAT, the Triceps was more active. The Triceps activity increased during TST towards the end of the session. The pain levels increased after TST and the number of repetitions was higher compared to RAT. There were no significant differences in muscle fatigue, perceived physical exertion and subject satisfaction levels between both treatment sessions. ConclusionThis is the first study to explore the biomechanics of both treatment methods and might therefore shed light on the mechanisms behind their positive outcomes. Due to the differences in the biomechanics of the treatments, a combination of both treatments may be beneficial to the activation of different muscle groups, thereby contributing to the rehabilitation program post stroke.

Characterizing the Motor Points of Forearm Muscles for Dexterous Neuroprostheses.

Surface stimulation systems facilitate dexterous manipulation by achieving targeted and isolated activation of muscle groups through motor-point-based stimulation. Existing catalogs on motor points lack generalization and reproducibility, as they are mostly based on anatomical charts and were obtained from heterogeneous studies. By systematically identifying and characterizing the motor points, the aim of this study is to address these limitations and improve the utilization of motor point catalogs toward the design and control for surface stimulation systems, which are targeted to restore complete hand function. Sites that allowed motor-point-based stimulation were identified among nine healthy participants. Using bipolar stimulation, a tracing electrode was used to locate these sites along the forearm surface, and the muscle response to motor-point-based stimulation was also graded using isokinetic dynamometry. Ultimately, using machine-learning-based clustering algorithms, the motor point locations were grouped into clusters, and their centroids and confidence regions were derived. Such experimentally derived clusters had physiological correlations, and further cross validation was also in agreement with two test subjects. By clustering motor point locations, the potential for deriving a generalized catalog has been demonstrated. With current literature lacking such data, the novelty of this study lies in the representation of baseline information on location, shape, and the recruitment of stimulation zones for various muscle groups using bipolar stimulation. This information can improve the design of electrode arrays and existing stimulation mapping algorithms, and aid clinicians toward electrode placement for patient-specific treatments.

04:12 PM Abstract No. 401 Natural history of motor nerve cryoablation: a retrospective cohort analysis

There are no reported descriptions of motor nerve cryoablation in humans. As a result, physicians faced with inadvertent motor nerve cryoablation during palliative or therapeutic procedures for established indications are forced to rely on preclinical studies to manage patient expectations. (1, 2) In addition, potential applications of motor nerve cryoablation, such as for management of spasticity and pain, have been avoided because of the unknown prognosis following cryoneurolysis of mixed or motor nerves. The purpose of this study was to retrospectively analyze and report the outcomes of patients who have undergone inadvertent or deliberate motor nerve cryoablation at our institutions, and generate a predictive model for recovery. Patients who underwent inadvertent or deliberate motor nerve cryoablation were identified (n=7) and a detailed chart review performed. Neurological exam muscle activation assessments from follow up visits were extracted and plotted against time and approximate distance from the ablation site. The rate of recovery was calculated by performing a standard least-squares regression and compared to established rates of nerve regeneration following reversible injury (1mm/day). In addition, numerical strength scores immediately following ablation and the most recent interval for the most improved muscle group in each patient were compared using a Mann-Whitney t-test. At the time of analysis, the range of subject follow up post injury was 4-36 months (15± 9.9). Nerve regeneration as reflected by muscle group activation was not significantly different than the predicted 1mm/day (p=0.0002). A standard least-squares regression analysis, showed there was a valid model (p=0.0002, by ANOVA) that demonstrated the rate of nerve regeneration to be 1.0mm/d (95% CI 0.57-1.48mm/d). Muscle groups more proximal to the ablation site regained full function faster than distal muscle groups, and muscular strength at the end of the follow-up period was significantly improved compared to immediately following cryoablation (p < 0.0006). Regeneration of motor nerves following cryoablation occurs at the expected rate for nerves that undergo reversible injury.

Scaling Our World View: How Monoamines Can Put Context Into Brain Circuitry.

Monoamines are presumed to be diffuse metabotropic neuromodulators of the topographically and temporally precise ionotropic circuitry which dominates CNS functions. Their malfunction is strongly implicated in motor and cognitive disorders, but their function in behavioral and cognitive processing is scarcely understood. In this paper, the principles of such a monoaminergic function are conceptualized for locomotor control. We find that the serotonergic system in the ventral spinal cord scales ionotropic signals and shows topographic order that agrees with differential gain modulation of ionotropic subcircuits. Whereas the subcircuits can collectively signal predictive models of the world based on life-long learning, their differential scaling continuously adjusts these models to changing mechanical contexts based on sensory input on a fast time scale of a few 100 ms. The control theory of biomimetic robots demonstrates that this precision scaling is an effective and resource-efficient solution to adapt the activation of individual muscle groups during locomotion to changing conditions such as ground compliance and carried load. Although it is not unconceivable that spinal ionotropic circuitry could achieve scaling by itself, neurophysiological findings emphasize that this is a unique functionality of metabotropic effects since recent recordings in sensorimotor circuitry conflict with mechanisms proposed for ionotropic scaling in other CNS areas. We substantiate that precision scaling of ionotropic subcircuits is a main functional principle for many monoaminergic projections throughout the CNS, implying that the monoaminergic circuitry forms a network within the network composed of the ionotropic circuitry. Thereby, we provide an early-level interpretation of the mechanisms of psychopharmacological drugs that interfere with the monoaminergic systems.

Muscle Activity Patterns do not Differ Between Push-Up and Bench Press Exercises.

Popular topics for upper-body resistance training involve the differences between hand positions, open versus closed chain exercises, and movement variations for the novice to the advanced. It was hypothesized that there will be no difference between closed (push-up) versus open (bench press) chain exercises for the primary muscle group activity nor would there be a difference between push-ups on the toes versus knees with respect to the percent contribution of each muscle. Surface muscle activity was measured for 8 upper-body and core muscles during a sequence of push-up and bench press variations with a normalized weight for 12 active men. Each participant completed push-ups and bench press exercises at each of 3 hand positions. The results demonstrated that there were few differences between closed versus open chain exercises for the primary muscle groups with the exception of core activation. In addition, in general, narrow hand positions yielded greater activation, and there were no significant differences between push-ups on the toes versus knees with respect to the percent contribution for the primary muscle groups. In conclusion, closed chain exercises may be preferred for functional training, and knee push-ups may be ideal as a novice push-up variation.