Extraneous Movement Research Articles

Assessment of ADHD Subtypes Using Motion Tracking Recognition Based on Stroop Color-Word Tests.

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder known for its significant heterogeneity and varied symptom presentation. Describing the different subtypes as predominantly inattentive (ADHD-I), combined (ADHD-C), and hyperactive-impulsive (ADHD-H) relies primarily on clinical observations, which can be subjective. To address the need for more objective diagnostic methods, this pilot study implemented a Microsoft Kinect-based Stroop Color-Word Test (KSWCT) with the objective of investigating the potential differences in executive function and motor control between different subtypes in a group of children and adolescents with ADHD. A series of linear mixture modeling were used to encompass the performance accuracy, reaction times, and extraneous movements during the tests. Our findings suggested that age plays a critical role, and older subjects showed improvements in KSWCT performance; however, no significant divergence in activity level between the subtypes (ADHD-I and ADHD-H/C) was established. Patients with ADHD-H/C showed tendencies toward deficits in motor planning and executive control, exhibited by shorter reaction times for incorrect responses and more difficulty suppressing erroneous responses. This study provides preliminary evidence of unique executive characteristics among ADHD subtypes, advances our understanding of the heterogeneity of the disorder, and lays the foundation for the development of refined and objective diagnostic tools for ADHD.

Isometric Force-Frequency and Dynamic Power-Frequency Relationships in Human Knee Extensors

Under voluntary control the neuromuscular system grades contractile output of recruited motor units by modulating discharge frequency. Electrically evoked (i.e., involuntary) contractions have been used to assess relationships between frequency input and contractile output. During an isometric contraction (i.e., no joint rotation) it is well-established that the force-frequency relationship is sigmoidal. However, there are few data describing the relationship between evoked input and dynamic (i.e., joint rotation) contractile parameters. Thus, the purpose was to examine the relationships between stimulated frequencies and dynamic power (i.e., product of concentric torque and angular velocity) during an isotonic contraction in comparison to an isometric force-frequency relationship. Knee extensors of 7 healthy young adult males were tested in a Cybex dynamometer. The right knee was at 90° and hip at 110°. Seat belts secured to the dynamometer were strapped across the hips and shoulders, and a non-elastic strap was secured across the thigh to avoid extraneous movement. Two stimulation electrodes, which consisted of aluminum wrapped in a conductive gel-soaked cloth were secured transversely to the proximal and distal portion of the knee extensors. For dynamic contractions the dynamometer was set to the “isotonic mode” and range of motion was 60°. The muscles were stimulated at 1, 5, 7.5, 10, 12, 15, 17, 20, 25, 30, 40, 50, 75 and 100 Hz. Besides the 1 Hz (i.e., single pulse) all frequencies during isometric contractions were 2s in duration. During isotonic contractions with the load set to 7.5% maximal voluntary contraction (MVC), pulses were programmed to terminate once range of motion was complete or until full range of motion was unachievable. Electrical current for all frequencies was determined from that required at 100 Hz to produce 50% isometric MVC force. Stimulation was done in ascending order with 20s rest between. The order between contraction modes was randomized and a 5-minute rest was given between modes. Results are presented as a percentage of relative peak force or peak power for 100 Hz during isometric or isotonic contractions, respectively. Both isometric force-frequency and dynamic power-frequency relationships were sigmoidal. During stimulation of increasing frequencies peak power was lower than isometric force by ~82%, ~47%, ~43%, ~38%, ~32%, ~25%, ~30%, ~23%, ~17%, ~12%, ~8% at ascending frequencies from 1 Hz to 40Hz, respectively. From 50 Hz to 100 Hz there were minimal differences (0-4%). These data indicate for the same stimulation frequencies the power-frequency relationship of a moderately loaded isotonic contraction is shifted rightward relative to an isometric force-frequency relationship. Therefore, isometric force-frequency and dynamic power-frequency relationships are not equivalent, and assessments of both relationships may be required to adequately characterize contractile function depending on the task. Supported by NSERC. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

MP41-11 ANALYSIS OF FLEXIBLE URETEROSCOPIC MOTION AND KINEMATIC EFFICIENCY - A SIMULATION-BASED PILOT STUDY

You have accessJournal of UrologyCME1 May 2022MP41-11 ANALYSIS OF FLEXIBLE URETEROSCOPIC MOTION AND KINEMATIC EFFICIENCY - A SIMULATION-BASED PILOT STUDY Marie-Therese Valovska, Gricelda Gomez, Richard Fineman, William Woltmann, Leia Stirling, and Daniel Wollin Marie-Therese ValovskaMarie-Therese Valovska More articles by this author , Gricelda GomezGricelda Gomez More articles by this author , Richard FinemanRichard Fineman More articles by this author , William WoltmannWilliam Woltmann More articles by this author , Leia StirlingLeia Stirling More articles by this author , and Daniel WollinDaniel Wollin More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002607.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Flexible ureteroscopy (fURS) is the most common surgical procedure for treatment of urolithiasis. Various surgical disciplines and subspecialties have examined surgeon kinematics to improve assessment and generate measures of skill. Despite frequency of utilization, there is no undisputed method for evaluating fURS skills. Our pilot study utilized kinematic evaluations of fURS simulation to determine whether specific surgeon movements, techniques, and strategies correlate with measures of ureteroscopic efficiency. METHODS: A motion capture system with 41 reflective markers and standard GoPro video camera were employed to characterize surgeon movement variables. A ureteroscopic simulation box was used by practicing urologists at various skill levels to perform a series of simple and complex ureteroscopic movement tasks. Two tasks were chosen for this initial pilot analysis. Body kinematics, time to task completion, and ureteroscopic movements were analyzed. Task efficiency was defined as quicker time to task completion and smaller ureteroscope end effector travel distance. A novel combined performance efficiency score (PES) was calculated using the root sum square of these two measures to characterize efficiency and skill. RESULTS: Twelve practicing urologists were enlisted. Average urologist age was 37 years with an average of 10.1 years of training; 50% were female, 50% were residents; and 33% had completed an Endourology fellowship. For the simple task, no kinematic data correlated with PES; for the complex task, participant head and torso movement correlated with PES (r=0.60, p=0.04 for head; r=0.65, p=0.02 for torso), with decreased body movement associated with higher efficiency. CONCLUSIONS: Our findings suggest that movement economy measures are associated with efficient ureteroscopic manipulation for complex tasks in a simulated setting. Decreased head and torso movement were associated with higher efficiency, suggesting that excess body movement may signal extraneous or improper ureteroscopic movements. Additional assessment of these variables, including analysis in a clinical setting, is warranted as this may serve as a basis for improvement in endoscopic training and evaluation. Source of Funding: The simulation box and single-use ureteroscopes were provided by Boston Scientific © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e723 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Marie-Therese Valovska More articles by this author Gricelda Gomez More articles by this author Richard Fineman More articles by this author William Woltmann More articles by this author Leia Stirling More articles by this author Daniel Wollin More articles by this author Expand All Advertisement PDF DownloadLoading ...

Analysis of Flexible Ureteroscopic Motion and Kinematic Efficiency: A Simulation-Based Pilot Study.

Introduction: Flexible ureteroscopy (fURS) is the most common surgical procedure for treatment of urolithiasis. Various surgical disciplines and subspecialties have examined surgeon kinematics to improve assessment and generate measures of skill. Despite frequency of utilization, there is no undisputed method for evaluating fURS skills. Our pilot study utilized kinematic evaluations of fURS simulation to determine whether specific surgeon movements, techniques, and strategies correlate with measures of ureteroscopic (URS) efficiency. Methods: A motion capture system and standard video camera were employed to characterize surgeon movement variables. A URS simulation box was used by practicing urologists at various skill levels to perform a series of simple and complex URS movement tasks. Two tasks were chosen for this initial pilot analysis. Body kinematics, time to task completion, and URS movements were analyzed. Task efficiency was defined as quicker time to task completion and smaller ureteroscope end effector travel distance. A combined performance efficiency score (PES) was calculated using the root sum square of these two measures. Results: Twelve practicing urologists were enlisted. Average urologist age was 37 years with an average of 10.1 years of training; 50% were women, 50% were residents; and 33% had completed an Endourology fellowship. For the simple task, no kinematic data correlated with PES; for the complex task, participant head and torso movement correlated with PES (r = 0.60, p = 0.04 for head; r = 0.65, p = 0.02 for torso), with decreased body movement associated with higher efficiency. Conclusion: Our findings suggest that movement economy measures are associated with efficient URS manipulation for complex tasks. Decreased head and torso movement were associated with higher efficiency, suggesting that excess body movement may signal extraneous or improper URS movements. Additional assessment of these variables, including analysis in a clinical setting, is warranted as this may serve as a basis for improvement in endoscopic training and evaluation.

Guidelines for the Measurement of Rein Tension in Equestrian Sport.

Simple SummaryThe reins are used to control speed and direction of the horse’s movement through the application of tension by the rider. When the rider holds the reins with a constant light contact, the mechanics of each gait is associated with a cyclic pattern of head and neck movements that is revealed in rein tension oscillations that have a typical shape and repetition frequency in each gait. The effects of the rider’s aids, rider imbalance and extraneous movements of the horse’s head and neck are superimposed on the basic patterns of the gaits. Rein tension is of interest to scientists and horsemen alike. Tension is relatively easy to measure but the equipment, analytic techniques and reporting of rein tension vary greatly. This paper makes recommendations to guide the selection of suitable equipment and appropriate methods for the collection, analysis and reporting of rein tension data. The goals are to describe correct procedures and common pitfalls in the collection, analysis and reporting of rein tension data that will facilitate comparisons between different studies.Rein tension is relatively easy to measure, and the resulting data are useful for evaluating the interaction between horse and rider. To date, there have been a number of studies using different transducers, calibration methods and analytical techniques. The purpose of this paper is to make recommendations regarding the collection, analysis and reporting of rein tension data. The goal is to assist users in selecting appropriate equipment, choosing verified methods of calibration, data collection and analysis, and reporting their results consistently to facilitate comparisons between different studies. Sensors should have a suitable range and resolution together with a fast enough dynamic response, according to the gait, speed and type of riding for which they will be used. An appropriate calibration procedure is necessary before each recording session. A recording frequency of 50 Hz is adequate for most rein tension studies. The data may be analyzed using time-series methods or by extracting and analyzing discrete variables chosen in accordance with the study objectives. Consistent reporting facilitates comparisons between studies.

Geodesic Distance Field-Based Process Planning for Five-Axis Machining of Complicated Parts

Abstract A critical task in multi-pass process planning for the five-axis machining of complicated parts is to determine the intermediate surfaces for rough machining. Traditionally, the intermediate surfaces are simply parallel Z-level planes, and the machining is of the simplest three-axis type. However, for complicated parts, this so-called Z-level method lacks flexibility and causes isolated islands on layers, which require extraneous air movements by the tool. Moreover, the in-process workpiece machined according to the Z-level method suffers from the staircase effect, which often induces unstable dynamic problems on the tool-spindle system. In this paper, we propose a new method of planning a five-axis machining process for a complicated freeform solid part. In our method, the intermediate surfaces are no longer planar but curved, and they are intrinsically influenced by the convex hull of the part. The powerful algebraic tool of geodesic distance field is utilized to generate the desired intermediate surfaces, for which collision-free five-axis machining tool paths are then planned. In addition, we propose a novel idea of alternating between the roughing and finishing machining operations, which helps improve the stiffness of the in-process workpiece. Ample physical cutting experiments are performed, and the experimental results convincingly confirm the advantages of our method.

Limitations of surface EMG estimate of parasternal intercostal to infer neural respiratory drive

BackgroundRecently, surface EMG of parasternal intercostal muscle has been incorporated in the "ERS Statement of Respiratory Muscle Testing" as a clinical technique to monitor the neural respiratory drive (NRD). However, the anatomy of the parasternal muscle risks confounding EMG "crosstalk" activity from neighboring muscles. ObjectivesTo determine if surface “parasternal” EMG: 1) reliably estimates parasternal intercostal EMG activity, 2) is a valid surrogate expressing neural respiratory drive (NRD). MethodsFine wire electrodes were implanted into parasternal intercostal muscle in 20 severe COPD patients along with a pair of surface EMG electrodes at the same intercostal level. We recorded both direct fine wire parasternal EMG (EMGPARA) and surface estimated “parasternal” EMG (SurfEMGpara) simultaneously during resting breathing, volitional inspiratory maneuvers, apnoea with extraneous movement of upper extremity, and hypercapnic ventilation. ResultsSurface estimated “parasternal” EMG showed spurious "pseudobreathing" activity without any airflow while real parasternal EMG was silent, during apnoea with body extremity movement. Surface estimated “parasternal” EMG did not faithfully represent real measured parasternal EMG. Surface estimated “parasternal” EMG was significantly less active than directly measured parasternal EMG during all conditions including baseline, inspiratory capacity and hypercapnic ventilation. Bland-Altman analysis showed consistent bias between direct parasternal EMG recording and surface estimated EMG during stimulated breathing. ConclusionSurface “parasternal” EMG does not consistently or reliably express EMG activity of parasternal intercostal as recorded directly by implanted fine wires. A chest wall surface estimate of parasternal intercostal EMG may not faithfully express NRD and is of limited utility as a biomarker in clinical applications.

Absent Arm Swing and Dual Tasking Decreases Trunk Postural Control and Dynamic Balance in People With Parkinson's Disease.

Introduction: Falling during walking is a common occurrence in people with Parkinson's disease and is closely associated with severe social and medical consequences. Recent evidence demonstrates that arm swing affects dynamic balance in healthy young adults; however, it remains unexamined what its effect is in people with Parkinson's disease, particularly when combined with a secondary dual task.Methods: Twenty people with Parkinson's disease (63.78 ± 8.97) walked with two arm swing conditions (absent and normal) with and without a secondary dual task. Data were collected on a split-belt treadmill CAREN Extended-System (Motek Medical, Amsterdam, NL). Average and standard deviations for trunk linear and angular velocity were calculated along with their instantaneous values (during foot strikes) in all three axes. Averages and coefficient of variations for step length, time, and width; margin of stability; and harmonic ratios were also calculated.Results: Compared with normal arm swing, absent arm swing reduced the least affected leg's average step length and increased its step length coefficient of variation while increasing step time coefficient of variation in the most affected leg. Further, absent arm swing reduced trunk anteroposterior instantaneous angular velocity (least affected leg) and reduced anteroposterior instantaneous linear velocity (bilaterally). For the vertical axis, absent arm swing increased the trunk's average angular velocity but reduced its instantaneous linear velocity and angular velocity standard deviation (least affected leg). Additionally, the margin of stability increased when the arms were absent (least affected leg). Alternatively, dual tasking reduced average step time (most affected leg) and increased the step width coefficient of variation (bilaterally). Additionally, dual tasking increased the mediolateral average angular velocity, instantaneous linear velocity standard deviation (bilaterally), and instantaneous angular velocity standard deviation (least affected leg). For the vertical axis, dual tasking increased average linear and angular velocity standard deviation as well as instantaneous angular velocity standard deviation (bilaterally).Conclusion: Findings suggest that participants attempted to control extraneous trunk movement (due to absent arm swing) through compensatory responses in both lower and upper extremities. However, participants appeared to predominately compensate on their least affected side. Contrastingly, modifying mediolateral foot placement appeared to be the main means of maintaining walking stability while dual tasking.

Cortical thickness and its associations with age, total cognition and education across the adult lifespan.

Early-life education (years of schooling) has been investigated in regards to cognition, health outcomes and mortality. It has been shown to confer cognitive reserve that might lessen the impact of brain pathology and its impact on cognitive and motor functioning in a variety of neurodegenerative diseases and, for instance, to influence electrical activity [Begum, T., Reza, F., Ahmed, I., & Abdullah, J. M. (2014). Influence of education level on design-induced N170 and P300 components of event related potentials in the human brain. J Integr Neurosci, 13(1), 71–88. doi:10.1142/S0219635214500058]. On the other hand, demonstrations of a direct association between education and brain-structural measures have been more equivocal and scant. The current study sought to identify univariate cortical-thickness patterns underlying education and general intelligence after adjusting for age, gender and possible in-scanner movement in 353 individuals aged 40 to 80. We followed up this idea with multivariate analyses as well. For univariate analyses, our analyses yielded no robust associations between education and general intelligence beyond confounding effects of gender, age and extraneous in-scanner movement. A subsequent multivariate analyses showed a relationship between education and regional cortical thickness with a robust pattern of negative as well as positive loadings in several right-sided brain areas, speaking to a subtle but robust distributed effect of education on cortical thickness. Cortical thickness variance that is the residual of this education-related pattern was shown to be positively associated with age and extraneous in-scanner movement. Our study thus presents a complex picture of the association of education with regional cortical thickness: education was associated with a distributed brain-wide pattern of positive as well as negative loadings with unaccounted residuals being larger for older participants. Focal regional associations beyond demographic and age covariates were not identified.

Association of uncoordinated sucking pattern with developmental outcome in premature infants: a retrospective analysis

BackgroundStress signals during sucking activity such as nasal flaring, head turning, and extraneous movements of the body have been attributed to incoordination of sucking, swallowing, and respiration (SSR) in premature infants. However, the association of uncoordinated sucking pattern with developmental outcomes has not yet been investigated. The aim of this study was to investigate whether uncoordinated sucking pattern during bottle-feeding in premature infants is associated with the developmental outcomes at 8–12 and 18–24 months of age (corrected for prematurity).MethodsWe retrospectively reviewed the medical records and video recordings for the Neonatal Oral-Motor Assessment Scale (NOMAS) of premature infants and divided them into two groups based on the presence or absence of incoordination. The Bayley-III cognition composite scores of the incoordination-positive and incoordination-negative group were compared at 8–12 and 18–24 months of age.ResultsSeventy premature infants exhibited a disorganized sucking pattern according to the NOMAS. The average Bayley-III cognition composite scores at 8–12 months of age were 92.5 ± 15.6 and 103.0 ± 11.3 for the incoordination-positive (n = 22) and incoordination-negative groups (n = 48), respectively (p = 0.002). The average Bayley-III cognition composite scores at 18–24 months were 90.0 ± 17.9 and 100.7 ± 11.5 for the incoordination-positive (n = 21) and incoordination-negative groups (n = 46), respectively (p = 0.005). A multiple linear regression analysis indicated that the presence of uncoordinated sucking pattern, grade 3 or 4 germinal matrix hemorrhage–intraventricular hemorrhage, and moderate to severe bronchopulmonary dysplasia were independently associated with cognitive development at 18–24 months of age.ConclusionsUncoordinated sucking pattern in premature infants was independently associated with a higher risk of abnormal developmental outcome in the cognitive domain of the Bayley-III at both 8–12 and 18–24 months. There may be a need for periodic follow-up and early intervention for developmental delay when incoordination of SSR that results in stress signals on the NOMAS is observed before 40 weeks postmenstrual age.

The Impact of Speech-Irrelevant Head Movements on Speech Intelligibility in Multi-Talker Environments

The Coordinate Response Measure corpus was used to measure how extraneous head movements affect speech intelligibility in a simulated cocktail party situation in which two, four, or six concurrent talkers were spatialized over headphones using virtual 3D audio. In two conditions, participants oscillated their head along the yaw axis, aided by a visual target tracking task. In one condition, the changes in the spatial location of the talkers were compensated for (i.e., the talkers were world-fixed) while in the other there was no such compensation (i.e., the talkers were head-fixed). In an additional baseline condition, participants did not move their heads. The results show that extraneous head movements do not impair speech intelligibility in a cocktail party situation.

Face-making: task-specific facial tensions and grimacing in musicians

> I have been told that my facial expressions while playing are quite pronounced, and numerous audience members have asked me what in the world I am saying to myself...

Sit Still and Pay Attention! Trunk Movement and Attentional Resources in Infants with Typical and Delayed Development

ABSTRACTAims: (1) examine infant movement during an early posture (sitting) utilizing a novel video assessment technique; and (2) document the differences between infants with typical development (TD), premature infants with motor delay, and infants with cerebral palsy (CP) during focused and nonfocused attention (NFA). Methods: Infants were tested when they began to sit independently. We utilized Eulerian Video Magnification (EVM) to accentuate small trunk and pelvic movements for visual coding from video taken during a natural play task with and without focused attention (FA). Results: Trunk/pelvic movement varied as a function of both motor skill and attention. Infants with TD and CP made fewer trunk movements during periods of FA than NFA. Preterm infants exhibited more trunk/pelvic movement than the other groups and their movement did not differ based on attention type. Conclusions: The EVM technique allowed for replicable coding of real-time “hidden” motor adjustments from video. The capacity to minimize extraneous movements in infants, or “sitting still” may allow greater attention to the task at hand, similar to older children and adults. Premature infants' excessive trunk/pelvic movement that did not adapt to task requirements could, in the long term, impact tasks requiring attentional resources.

A cross-linguistic preference for torso stability in the lexicon

When the arms move in certain ways, they can cause the torso to twist or rock. Such extraneous torso movement is undesirable, especially during sign language communication, when torso position may carry linguistic significance, so we expend effort to resist it when it is not intended. This so-called “reactive effort” has only recently been identified by Sanders and Napoli (2016), but their preliminary work on three genetically unrelated languages suggests that the effects of reactive effort can be observed cross-linguistically by examination of sign language lexicons. In particular, the frequency of different kinds of manual movements in the lexicon correlates with the amount of reactive effort needed to resist movement of the torso. Following this line of research, we present evidence from 24 sign languages confirming that there is a cross-linguistic preference for minimizing the reactive effort needed to keep the torso stable.

Specialization of the motor system in infancy: from broad tuning to selectively specialized purposeful actions.

In executing purposeful actions, adults select sufficient and necessary limbs. But infants often move goal-irrelevant limbs, suggesting a developmental process of motor specialization. Two experiments with 9- and 12-month-olds revealed gradual decreases in extraneous movements in non-acting limbs during unimanual actions. In Experiment 1, 9-month-olds produced more extraneous movements in the non-acting hand/arm and feet/legs than 12-month-olds. In Experiment 2, analysis of the spatiotemporal dynamics of infants' movements revealed developmental declines in the spatiotemporal coupling of movements between acting and non-acting arms. We also showed that the degree of specialization in infants' unimanual actions is associated with individual differences in motor experience and visual attention, indicating the experience-dependent and broad functional nature of these developmental changes. Our study provides important new insights into motor development: as in cognitive domains, motor behaviours are initially broadly tuned to their goal, becoming progressively specialized during the first year of life.

Use of probabilistic weights to enhance linear regression myoelectric control

Objective. Clinically available prostheses for transradial amputees do not allow simultaneous myoelectric control of degrees of freedom (DOFs). Linear regression methods can provide simultaneous myoelectric control, but frequently also result in difficulty with isolating individual DOFs when desired. This study evaluated the potential of using probabilistic estimates of categories of gross prosthesis movement, which are commonly used in classification-based myoelectric control, to enhance linear regression myoelectric control. Approach. Gaussian models were fit to electromyogram (EMG) feature distributions for three movement classes at each DOF (no movement, or movement in either direction) and used to weight the output of linear regression models by the probability that the user intended the movement. Eight able-bodied and two transradial amputee subjects worked in a virtual Fitts’ law task to evaluate differences in controllability between linear regression and probability-weighted regression for an intramuscular EMG-based three-DOF wrist and hand system. Main results. Real-time and offline analyses in able-bodied subjects demonstrated that probability weighting improved performance during single-DOF tasks (p < 0.05) by preventing extraneous movement at additional DOFs. Similar results were seen in experiments with two transradial amputees. Though goodness-of-fit evaluations suggested that the EMG feature distributions showed some deviations from the Gaussian, equal-covariance assumptions used in this experiment, the assumptions were sufficiently met to provide improved performance compared to linear regression control. Significance. Use of probability weights can improve the ability to isolate individual during linear regression myoelectric control, while maintaining the ability to simultaneously control multiple DOFs.

Using Wearable Sensors and Machine Learning Models to Separate Functional Upper Extremity Use From Walking-Associated Arm Movements

ObjectiveTo improve measurement of upper extremity (UE) use in the community by evaluating the feasibility of using body-worn sensor data and machine learning models to distinguish productive prehensile and bimanual UE activity use from extraneous movements associated with walking. DesignComparison of machine learning classification models with criterion standard of manually scored videos of performance in UE prosthesis users. SettingRehabilitation hospital training apartment. ParticipantsConvenience sample of UE prosthesis users (n=5) and controls (n=13) similar in age and hand dominance (N=18). InterventionsParticipants were filmed executing a series of functional activities; a trained observer annotated each frame to indicate either UE movement directed at functional activity or walking. Synchronized data from an inertial sensor attached to the dominant wrist were similarly classified as indicating either a functional use or walking. These data were used to train 3 classification models to predict the functional versus walking state given the associated sensor information. Models were trained over 4 trials: on UE amputees and controls and both within subject and across subject. Model performance was also examined with and without preprocessing (centering) in the across-subject trials. Main Outcome MeasurePercent correct classification. ResultsWith the exception of the amputee/across-subject trial, at least 1 model classified >95% of test data correctly for all trial types. The top performer in the amputee/across-subject trial classified 85% of test examples correctly. ConclusionsWe have demonstrated that computationally lightweight classification models can use inertial data collected from wrist-worn sensors to reliably distinguish prosthetic UE movements during functional use from walking-associated movement. This approach has promise in objectively measuring real-world UE use of prosthetic limbs and may be helpful in clinical trials and in measuring response to treatment of other UE pathologies.

Snatch Trajectory of Elite Level Girevoy (Kettlebell) Sport Athletes and its Implications to Strength and Conditioning Coaching

Girevoy sport (GS) has developed only recently in the West, resulting in a paucity of English scientific literature available. The aim was to document kettlebell trajectory of GS athletes performing the kettlebell snatch. Four elite GS athletes (age = 29–47 years, body mass = 68.3–108.1 kg, height 1.72–1.89 m) completed one set of 16 repetitions with a 32.1 kg kettlebell Trajectory was captured with the VICON motion analysis system (250 Hz) and analysed with VICON Nexus (1.7.1). The kettlebell followed a ‘C’ shape trajectory in the sagittal plane. Mean peak velocity in the upwards phase was 4.03 ± 0.20 m s−1, compared to 3.70 ± 0.30 m s−1 during the downwards phase, and mean radial error across the sagittal and frontal planes was 0.022 ± 0.006 m. Low error in the movement suggests consistent trajectory is important to reduce extraneous movement and improve efficiency. While the kettlebell snatch and swing both require large anterior-posterior motion, the snatch requires the kettlebell to be held stationary overhead. Therefore, a different coaching application is required to that of a barbell snatch.

Inhibition during response preparation is sensitive to response complexity.

Motor system excitability is transiently suppressed during the preparation of movement. This preparatory inhibition is hypothesized to facilitate response selection and initiation. Given that demands on selection and initiation processes increase with movement complexity, we hypothesized that complexity would influence preparatory inhibition. To test this hypothesis, we probed corticospinal excitability during a delayed-response task in which participants were cued to prepare right- or left-hand movements of varying complexity. Single-pulse transcranial magnetic stimulation was applied over right primary motor cortex to elicit motor evoked potentials (MEPs) from the first dorsal interosseous (FDI) of the left hand. MEP suppression was greater during the preparation of responses involving coordination of the FDI and adductor digiti minimi relative to easier responses involving only the FDI, independent of which hand was cued to respond. In contrast, this increased inhibition was absent when the complex responses required sequential movements of the two muscles. Moreover, complexity did not influence the level of inhibition when the response hand was fixed for the trial block, regardless of whether the complex responses were performed simultaneously or sequentially. These results suggest that preparatory inhibition contributes to response selection, possibly by suppressing extraneous movements when responses involve the simultaneous coordination of multiple effectors.

Restless mind, restless body.

In the present work, we investigate the hypothesis that failures of task-related executive control that occur during episodes of mind wandering are associated with an increase in extraneous movements (fidgeting). In 2 studies, we assessed mind wandering using thought probes while participants performed the metronome response task (MRT), which required them to synchronize button presses with tones. Participants performed this task while sitting on a Wii Balance Board providing us with an index of fidgeting. Results of Study 1 demonstrate that relative to on-task periods, mind wandering is indeed accompanied by increases in fidgeting, as well as increased response variability in the MRT. In Study 2, we observed that only deep mind wandering was associated with increases in fidgeting, whereas task-related response variability increased even during mild mind wandering. We interpret these findings in the context of current theories of mind wandering and suggest that (a) mind wandering is associated with costs not only to primary-task performance but also to secondary-task goals (e.g., controlling extraneous movements) and (b) these costs may depend on the degree to which task-related executive control processes are disengaged during mind wandering (i.e., depth of mind wandering).