RESUMEN
Real-world actions often comprise a series of movements that cannot be entirely planned before initiation. When these actions are executed rapidly, the planning of multiple future movements needs to occur simultaneously with the ongoing action. How the brain solves this task remains unknown. Here, we address this question with a new sequential arm reaching paradigm that manipulates how many future reaches are available for planning while controlling execution of the ongoing reach. We show that participants plan at least two future reaches simultaneously with an ongoing reach. Further, the planning processes of the two future reaches are not independent of one another. Evidence that the planning processes interact is twofold. First, correcting for a visual perturbation of the ongoing reach target is slower when more future reaches are planned. Second, the curvature of the current reach is modified based on the next reach only when their planning processes temporally overlap. These interactions between future planning processes may enable smooth production of sequential actions by linking individual segments of a long sequence at the level of motor planning.
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Brazo , Movimiento , Desempeño Psicomotor , Humanos , Brazo/fisiología , Movimiento/fisiología , Desempeño Psicomotor/fisiología , Masculino , Femenino , Adulto , Adulto JovenRESUMEN
An abundance of degrees of freedom (DOF) exist when executing a countermovement jump (CMJ). This research aims to simplify the understanding of this complex system by comparing jump performance and independent functional DOF (fDOF) present in CMJs without (CMJNoArms) and with (CMJArms) an arm swing. Principal component analysis was used on 39 muscle forces and 15 3-dimensional joint contact forces obtained from kinematic and kinetic data, analyzed in FreeBody (a segment-based musculoskeletal model). Jump performance was greater in CMJArms with the increased ground contact time resulting in higher external (p = 0.012), hip (p < 0.001) and ankle (p = 0.009) vertical impulses, and slower hip extension enhancing the proximal-to-distal joint extension strategy. This allowed the hip muscles to generate higher forces and greater time-normalized hip vertical impulse (p = 0.006). Three fDOF were found for the muscle forces and 3-dimensional joint contact forces during CMJNoArms, while four fDOF were present for CMJArms. This suggests that the underlying anatomy provides mechanical constraints during a CMJ, reducing the demand on the control system. The additional fDOF present in CMJArms suggests that the arms are not mechanically coupled with the lower extremity, resulting in additional variation within individual motor strategies.
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Brazo , Músculo Esquelético , Humanos , Fenómenos Biomecánicos , Brazo/fisiología , Masculino , Músculo Esquelético/fisiología , Adulto , Adulto Joven , Articulación de la Cadera/fisiología , Articulación del Tobillo/fisiología , Movimiento/fisiología , Rango del Movimiento Articular/fisiología , FemeninoRESUMEN
BACKGROUND: Individual maximum joint and segment angular velocities have shown positive associations with throwing arm kinetics and ball velocity in baseball pitchers. PURPOSE: To observe how cumulative maximum joint and segment angular velocities, irrespective of sequence, affect ball velocity and throwing arm kinetics in high school pitchers. STUDY DESIGN: Descriptive laboratory study. METHODS: High school (n = 55) pitchers threw 8 to 12 fastball pitches while being evaluated with 3-dimensional motion capture (480 Hz). Maximum joint and segment angular velocities (lead knee extension, pelvis rotation, trunk rotation, shoulder internal rotation, and forearm pronation) were calculated for each pitcher. Pitchers were classified as overall fast, overall slow, or high velocity for each joint or segment velocity subcategory, or as population, with any pitcher eligible to be included in multiple subcategories. Kinematic and kinetic parameters were compared among the various subgroups using t tests with post hoc regressions and multivariable regression models created to predict throwing arm kinetics and ball velocity, respectively. RESULTS: The lead knee extension and pelvis rotation velocity subgroups achieved significantly higher normalized elbow varus torque (P = .016) and elbow flexion torque (P = .018) compared with population, with equivalent ball velocity (P = .118). For every 1-SD increase in maximum pelvis rotation velocity (87 deg/s), the normalized elbow distractive force increased by 4.7% body weight (BW) (B = 0.054; ß = 0.290; P = .013). The overall fast group was older (mean ± standard deviation, 16.9 ± 1.4 vs 15.4 ± 0.9 years; P = .007), had 8.9-mph faster ball velocity (32.7 ± 3.1 vs 28.7 ± 2.3 m/s; P = .002), and had significantly higher shoulder internal rotation torque (63.1 ± 17.4 vs 43.6 ± 12.0 Nm; P = .005), elbow varus torque (61.8 ± 16.4 vs 41.6 ± 11.4 Nm; P = .002), and elbow flexion torque (46.4 ± 12.0 vs 29.5 ± 6.8 Nm; P < .001) compared with the overall slow group. A multiregression model for ball velocity based on maximum joint and segment angular velocities and anthropometrics predicted 53.0% of variance. CONCLUSION: High school pitchers with higher maximum joint and segment velocities, irrespective of sequence, demonstrated older age and faster ball velocity at the cost of increased throwing shoulder and elbow kinetics. CLINICAL RELEVANCE: Pitchers and coaching staff should consider this trade-off between faster ball velocity and increasing throwing arm kinetics, an established risk factor for elbow injury.
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Béisbol , Humanos , Béisbol/fisiología , Fenómenos Biomecánicos , Adolescente , Masculino , Rotación , Brazo/fisiología , Torque , Antebrazo/fisiología , Pelvis/fisiología , Articulación del Codo/fisiología , Hombro/fisiología , Rango del Movimiento Articular/fisiología , Codo/fisiología , CinéticaRESUMEN
Background: In volleyball, the jump serve is a crucial and commonly used serving technique. Nonetheless, the angular momentum developed during the jump serve remains unexplored. The objectives of the current study were to determine the angular momentum manifesting during the airborne phase of the jump serve and to analyse the correlations between the angular momentum variables and arm swing speed. Methods: Three-dimensional coordinate data were obtained during the jump serves of 17 professional male volleyball players. Correlation and linear regression analyses were used to identify the angular momentum variables linked to the arm swing speed at ball impact (BI). Results: The arm swing speed at BI exhibited significant correlations with the peak angular momentum of the attack arm (r = 0.551, p = 0.024), non-attack arm (r = 0.608, p = 0.011), non-attack leg (r = -0.516, p = 0.034), forearm (r = 0.527, p = 0.032), and hand (r = 0.824, p < 0.001). A stepwise regression model (R2 = 0.35, p = 0.043) predicted arm swing speed based on the peak angular momentum of the non-attack leg, forearm, and hand. Conclusions: The study results suggest that during the arm-acceleration phase, (1) increasing angular momentum with the non-attack leg helps maintain aerial body balance, thereby enhancing arm swing execution, and (2) controlling the magnitude and timing of the force exerted by the elbow and wrist is crucial for effectively transmitting angular momentum, contributing to an increase in arm swing speed.
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Brazo , Voleibol , Humanos , Voleibol/fisiología , Masculino , Fenómenos Biomecánicos/fisiología , Brazo/fisiología , Adulto Joven , Movimiento/fisiología , Adulto , Rendimiento Atlético/fisiologíaRESUMEN
Current control approaches for gross prosthetic arm movement mainly regulate movement over a continuous range of target poses. However, these methods suffer from output fluctuation caused by input signal variations during gross arm movements. Prosthesis control approaches with a finite number of discrete target poses can address this issue and reduce the complexity of the pose control process. However, it remains under-explored in the literature and suffers from the consequences of misclassifying the target poses. Here, we propose a novel Uncertainty-Aware Discrete-Target Prosthesis Control (UA-DPC) approach. This approach consists of (1) an uncertainty-aware classification scheme to reduce unintended pose switches caused by misclassifications, and (2) real-time trajectory planning that adjusts motion to be rapid or conservative based on low or high quantified uncertainty, respectively. By addressing the impact of misclassification, this approach facilitates more efficient and smooth movements. Human-in-the-loop experiments were conducted in a virtual reality environment with 12 non-disabled participants. The participants controlled a transhumeral prosthesis using three approaches: the proposed UA-DPC, a discrete-target approach based on a traditional off-the-shelf classifier, and a continuous-target approach. The results demonstrate the superior performance of UA-DPC, which provides more efficient task completion with fewer misclassification instances as well as smoother residual limb and prosthesis movement.
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Algoritmos , Brazo , Miembros Artificiales , Movimiento , Diseño de Prótesis , Humanos , Brazo/fisiología , Movimiento/fisiología , Incertidumbre , Masculino , Adulto , Femenino , Adulto Joven , Realidad Virtual , Fenómenos Biomecánicos , Voluntarios SanosRESUMEN
It was previously hypothesized that the cross-education of strength is asymmetrical, where a greater transfer of strength is observed from the dominant to the non-dominant limb. The purpose of this study was to examine if the magnitude of cross-education of strength differed between dominant and non-dominant limbs following unilateral high-load resistance training. One hundred and twenty-two participants were randomized to one of the three groups: 1) training on the dominant arm (D-Only), 2) training on the non-dominant arm (ND-Only) and 3) a time-matched non-exercise control (Control). The training groups completed 6 weeks (18 sessions) of unilateral elbow flexion exercise. Each training session started with one-repetition maximum (1RM) training (≤ five attempts), followed by four sets of high-load exercise (i.e. 8-12RM). Strength changes of the untrained arm were compared between groups. Changes in the strength of the untrained arm were greater in D-Only (1.5 kg) and ND-Only (1.3 kg) compared to Control (-0.2 kg), without differences between D-Only and ND-Only. Unilateral resistance training increased strength in the opposite untrained arm, and the magnitude of this effect was similar regardless of which arm was trained. However, there is still considerable uncertainty on this topic and additional research is warranted to confirm the current findings.
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Brazo , Fuerza Muscular , Entrenamiento de Fuerza , Humanos , Entrenamiento de Fuerza/métodos , Fuerza Muscular/fisiología , Brazo/fisiología , Masculino , Femenino , Adulto Joven , Lateralidad Funcional/fisiología , AdultoRESUMEN
The primary motor cortex does not uniquely or directly produce alpha motoneurone (α-MN) drive to muscles during voluntary movement. Rather, α-MN drive emerges from the synthesis and competition among excitatory and inhibitory inputs from multiple descending tracts, spinal interneurons, sensory inputs, and proprioceptive afferents. One such fundamental input is velocity-dependent stretch reflexes in lengthening muscles, which should be inhibited to enable voluntary movement. It remains an open question, however, the extent to which unmodulated stretch reflexes disrupt voluntary movement, and whether and how they are inhibited in limbs with numerous multiarticular muscles. We used a computational model of a Rhesus Macaque arm to simulate movements with feedforward α-MN commands only, and with added velocity-dependent stretch reflex feedback. We found that velocity-dependent stretch reflex caused movement-specific, typically large and variable disruptions to arm movements. These disruptions were greatly reduced when modulating velocity-dependent stretch reflex feedback (i) as per the commonly proposed (but yet to be clarified) idealized alpha-gamma (α-γ) coactivation or (ii) an alternative α-MN collateral projection to homonymous γ-MNs. We conclude that such α-MN collaterals are a physiologically tenable propriospinal circuit in the mammalian fusimotor system. These collaterals could still collaborate with α-γ coactivation, and the few skeletofusimotor fibers (ß-MNs) in mammals, to create a flexible fusimotor ecosystem to enable voluntary movement. By locally and automatically regulating the highly nonlinear neuro-musculo-skeletal mechanics of the limb, these collaterals could be a critical low-level enabler of learning, adaptation, and performance via higher-level brainstem, cerebellar, and cortical mechanisms.
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Macaca mulatta , Neuronas Motoras , Reflejo de Estiramiento , Reflejo de Estiramiento/fisiología , Animales , Neuronas Motoras/fisiología , Movimiento/fisiología , Músculo Esquelético/fisiología , Corteza Motora/fisiología , Simulación por Computador , Modelos Neurológicos , Brazo/fisiologíaRESUMEN
BACKGROUND: In the last decade, notable progress in mechatronics paved the way for a new generation of arm prostheses, expanding motor capabilities thanks to their multiple active joints. Yet, the design of control schemes for these advanced devices still poses a challenge, especially with the limited availability of command signals for higher levels of arm impairment. When addressing this challenge, current commercial devices lack versatility and customizing options to be employed as test-beds for developing novel control schemes. As a consequence, researchers resort to using lab-specific experimental apparatuses on which to deploy their innovations, such as virtual reality setups or mock prosthetic devices worn by unimpaired participants. METHODS: To meet this need for a test-bed, we developed the Smart Arm platform, a human-like, multi-articulated robotic arm that can be worn as a trans-humeral arm prosthesis. The design process followed three principles: provide a reprogrammable embedded system allowing in-depth customization of control schemes, favor easy-to-buy parts rather than custom-made components, and guarantee compatibility with industrial standards in prosthetics. RESULTS: The Smart ArM platform includes motorized elbow and wrist joints while being compatible with commercial prosthetic hands. Its software and electronic architecture can be easily adapted to build devices with a wide variety of sensors and actuators. This platform was employed in several experiments studying arm prosthesis control and sensory feedback. We also report our participation in Cybathlon, where our pilot with forearm agenesia successfully drives the Smart Arm prosthesis to perform activities of daily living requiring both strength and dexterity. CONCLUSION: These application scenarios illustrate the versatility and adaptability of the proposed platform, for research purposes as well as outside the lab. The Smart Arm platform offers a test-bed for experimenting with prosthetic control laws and command signals, suitable for running tests in lifelike settings where impaired participants wear it as a prosthetic device. In this way, we aim at bridging a critical gap in the field of upper limb prosthetics: the need for realistic, ecological test conditions to assess the actual benefit of a technological innovation for the end-users.
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Miembros Artificiales , Diseño de Prótesis , Robótica , Humanos , Diseño de Prótesis/métodos , Robótica/instrumentación , Brazo/fisiologíaRESUMEN
In this study, we investigated how the temporal properties of the preparation phase for upper limb movements are affected by the reaching direction and distance. Twelve right-handed participants performed three motor tasks: two types of reaching movements and one finger-lifting movement. The reaching movements were performed from the home position to 15 target locations (five directions and three distances) as quickly and precisely as possible under two conditions: pre-cueing the target to allocate the sufficient time for the motor-planning process before movement initiation, and no-cuing. The finger lifting movement was performed by lifting the index finger (from the home position) upward in the air as quickly as possible. The reaction time (RT), movement time (MT), and kinematics of the index finger were obtained for each condition. In addition, differential RTs (DRT) were calculated by subtracting the RT for no-cue lifting from that for no-cue reaching, thereby implicitly representing the time required for the motor-planning process for reaching movements. The results indicated the anisotropy of the DRTs being larger in the forward and left-forward directions than that in the right-forward direction, and larger in the forward direction than that in the right direction for the middle distance. It is suggested that the temporal costs of the motor-planning process depend on the movement direction and distance. In the kinematic analysis, the MTs showed the anisotropy being the largest in the left-forward among all directions. Meanwhile, the time from peak velocity to terminate the movement (TFPV) was significantly longer in the left-forward direction when no-cueing the target than when pre-cueing. These results suggest that reaching movement is refined during the online-control process to accomplish the intended performance if a reaching movement under the no-cue condition is initiated before building sufficient motor planning, especially in the direction requiring large temporal costs. It is likely that humans achieve their intended movements by allocating the temporal costs required before and after movement initiation according to the difficulty of motor control which varies with the direction and distance.
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Desempeño Psicomotor , Tiempo de Reacción , Humanos , Fenómenos Biomecánicos , Desempeño Psicomotor/fisiología , Masculino , Adulto Joven , Femenino , Adulto , Brazo/fisiología , Señales (Psicología) , Orientación , Movimiento/fisiología , Dedos/fisiologíaRESUMEN
3D-ARM-Gaze is a public dataset designed to provide natural arm movements together with visual and gaze information when reaching objects in a wide reachable space from a precisely controlled, comfortably seated posture. Participants were involved in picking and placing objects in various positions and orientations in a virtual environment, whereby a specific procedure maximized the workspace explored while ensuring a consistent seated posture by guiding participants to a predetermined neutral posture via visual feedback from the trunk and shoulders. These experimental settings enabled to capture natural arm movements with high median success rates (>98% objects reached) and minimal compensatory movements. The dataset regroups more than 2.5 million samples recorded from 20 healthy participants performing 14 000 single pick-and-place movements (700 per participant). While initially designed to explore novel prosthesis control strategies based on natural eye-hand and arm coordination, this dataset will also be useful to researchers interested in core sensorimotor control, humanoid robotics, human-robot interactions, as well as for the development and testing of associated solutions in gaze-guided computer vision.
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Brazo , Movimiento , Realidad Virtual , Humanos , Brazo/fisiología , Fijación Ocular , Masculino , AdultoRESUMEN
Some evidence indicates that lower back muscles located at the nondominant side of the body are more fatigue resistant than their opposite counterparts presumably due to preferential use of the dominant hand. The aim of the study was to determine if any distinction exists in the surface electromyographic activity of corresponding contralateral nonfatigued lumbar multifidus (LM) muscles as a function of hand dominance. The relative to maximum root mean square, the median frequency (MdF) and spike shape parameters were computed from the surface myoelectric signals of ipsilateral and contralateral lumbar multifidus muscle of 46 adult healthy subjects (27 righthanded, 19 lefthanded) during voluntary contractions evoked by the single arm lifts in prone position. Activation of LM as a contralateral muscle to lifted arm was greater than as ipsilateral muscle, independently of handedness. Regardless if LM performed ipsi or contralateral action to the lifted arm, the mean spike amplitude, slope, number of peaks per spike and spike duration were greater and mean spike frequency as well as MdF were smaller in the muscle of dominant than nondominant side. Combined changes of spike shape measures indicate increased recruitment, lower firing rates and higher synchronization of motor units in the LM of dominant side as compared to its counterpart.
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Brazo , Electromiografía , Lateralidad Funcional , Músculos Paraespinales , Humanos , Electromiografía/métodos , Masculino , Femenino , Adulto , Lateralidad Funcional/fisiología , Músculos Paraespinales/fisiología , Brazo/fisiología , Adulto Joven , Contracción Muscular/fisiología , Músculo Esquelético/fisiología , Región LumbosacraRESUMEN
This study evaluates the R3THA™ assessment protocol (R3THA-AP™), a technology-supported testing module for personalized rehabilitation in children with cerebral palsy (CP). It focuses on the reliability and validity of the R3THA-AP in assessing hand and arm function, by comparing kinematic assessments with standard clinical assessments. Conducted during a 4-week summer camp, the study assessed the functional and impairment levels of children with CP aged 3-18. The findings suggest that R3THA is more reliable for children aged 8 and older, indicating that age significantly influences the protocol's effectiveness. The results also showed that the R3THA-AP's kinematic measurements of hand and wrist movements are positively correlated with the Box and Blocks Test Index (BBTI), reflecting hand function and dexterity. Additionally, the R3THA-AP's accuracy metrics for hand and wrist activities align with the Melbourne Assessment 2's Range of Motion (MA2-ROM) scores, suggesting a meaningful relationship between R3THA-AP data and clinical assessments of motor skills. However, no significant correlations were observed between the R3THA-AP and MA2's accuracy and dexterity measurements, indicating areas for further research. These findings validate the R3THA-AP's utility in assessing motor abilities in CP patients, supporting its integration into clinical practice.
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Brazo , Parálisis Cerebral , Mano , Humanos , Parálisis Cerebral/rehabilitación , Parálisis Cerebral/fisiopatología , Niño , Adolescente , Mano/fisiopatología , Mano/fisiología , Masculino , Femenino , Fenómenos Biomecánicos , Brazo/fisiopatología , Brazo/fisiología , Preescolar , Rehabilitación Neurológica/métodos , Rehabilitación Neurológica/instrumentación , Rango del Movimiento Articular/fisiología , Reproducibilidad de los ResultadosRESUMEN
The fluid movement of an arm requires multiple spatiotemporal parameters to be set independently. Recent studies have argued that arm movements are generated by the collective dynamics of neurons in motor cortex. An untested prediction of this hypothesis is that independent parameters of movement must map to independent components of the neural dynamics. Using a task where three male monkeys made a sequence of reaching movements to randomly placed targets, we show that the spatial and temporal parameters of arm movements are independently encoded in the low-dimensional trajectories of population activity in motor cortex: each movement's direction corresponds to a fixed neural trajectory through neural state space and its speed to how quickly that trajectory is traversed. Recurrent neural network models show that this coding allows independent control over the spatial and temporal parameters of movement by separate network parameters. Our results support a key prediction of the dynamical systems view of motor cortex, and also argue that not all parameters of movement are defined by different trajectories of population activity.
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Brazo , Macaca mulatta , Corteza Motora , Movimiento , Desempeño Psicomotor , Animales , Corteza Motora/fisiología , Masculino , Movimiento/fisiología , Brazo/fisiología , Desempeño Psicomotor/fisiología , Modelos NeurológicosRESUMEN
While resistance training promotes muscle hypertrophy and strength, accessibility of equipment is a barrier. This study evaluated a wearable VAriable Resistance Suit (VARS) as a novel and alternative method to achieve muscle strength improvement. It was hypothesized that by providing adjustable, bi-directional and speed dependent resistance, VARS can target specific muscles to improve muscle strength via an accessible and portable device. Twelve untrained healthy male adults (22.08 ± 4.1 years old) participated in an 8-week long resistance training using VARS to strengthen four muscles (biceps brachii, triceps brachii, biceps femoris, rectus femoris) of their non-dominant arm and leg using VARS. The results showed significant improvements in the muscle strength measured by isokinetic dynamometer - 49.9±9.6% increase in isokinetic force and 30.6±7.6% increase in isometric force. Muscle size and body composition were also assessed using ultrasound imaging and bioelectrical impedance analysis, which did not show significant changes. The study demonstrates the efficacy and feasibility of VARS as a resistance training tool to achieve muscle strength improvement and its potential extension to clinical populations.
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Voluntarios Sanos , Contracción Isométrica , Fuerza Muscular , Músculo Esquelético , Entrenamiento de Fuerza , Humanos , Masculino , Entrenamiento de Fuerza/métodos , Fuerza Muscular/fisiología , Adulto Joven , Contracción Isométrica/fisiología , Adulto , Músculo Esquelético/fisiología , Dinamómetro de Fuerza Muscular , Dispositivos Electrónicos Vestibles , Composición Corporal , Impedancia Eléctrica , Brazo/fisiología , Pierna/fisiologíaRESUMEN
Following events such as fatigue or stroke, individuals often move their trunks forward during reaching, leveraging a broader muscle group even when only arm movement would suffice. In previous work, we showed the existence of a "force reserve": a phenomenon where individuals, when challenged with a heavy weight, adjusted their motor coordination to preserve approximately 40% of their shoulder's force. Here, we investigated if such reserve can predict hip, shoulder, and elbow movements and torques resulting from an induced shoulder strength deficit. We engaged 20 healthy participants in a reaching task with incrementally heavier dumbbells, analyzing arm and trunk movements via motion capture and joint torques through inverse dynamics. We simulated these movements using an optimal control model of a 3-degree-of-freedom upper body, contrasting three cost functions: traditional sum of squared torques, a force reserve function incorporating a nonlinear penalty, and a normalized torque function. Our results demonstrate a clear increase in trunk movement correlated with heavier dumbbell weights, with participants employing compensatory movements to maintain a shoulder force reserve of approximately 40% of maximum torque. Simulations showed that while traditional and reserve functions accurately predicted trunk compensation, only the reserve function effectively predicted joint torques under heavier weights. These findings suggest that compensatory movements are strategically employed to minimize shoulder effort and distribute load across multiple joints in response to weakness. We discuss the implications of the force reserve cost function in the context of optimal control of human movements and its relevance for understanding compensatory movements poststroke.NEW & NOTEWORTHY Our study reveals key findings on compensatory movements during upper limb reaching tasks under shoulder strength deficits, as observed poststroke. Using heavy dumbbells with healthy volunteers, we demonstrate how forward trunk displacement conserves around 40% of shoulder strength reserve during reaching. We show that an optimal controller employing a cost function combining squared motor torque and a nonlinear penalty for excessive muscle activation outperforms traditional controllers in predicting torques and compensatory movements in these scenarios.
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Movimiento , Hombro , Torque , Humanos , Masculino , Femenino , Adulto , Hombro/fisiología , Movimiento/fisiología , Fuerza Muscular/fisiología , Fenómenos Biomecánicos/fisiología , Adulto Joven , Músculo Esquelético/fisiología , Desempeño Psicomotor/fisiología , Brazo/fisiología , Torso/fisiologíaRESUMEN
PURPOSE: We investigated the influence of passive arm-support exoskeleton (ASE) with different levels of torque (50, 75, and 100%) on upper arm osteokinematics. METHODS: Twenty participants completed a cyclic overhead drilling task with and without ASE. Task duration, joint angles, and angular acceleration peaks were analyzed during ascent and descent phases of the dominant upper arm. RESULTS: Maximum ASE torque was associated with decreased peak acceleration during ascent (32.2%; SD 17.8; p < 0.001) and descent phases (38.8%; SD 17.8; p < 0.001). Task duration remained consistent. Increased torque led to a more flexed (7.2°; SD 5.5; p > 0.001) and internally rotated arm posture (17.6°; SD 12.1; p < 0.001), with minimal changes in arm abduction. CONCLUSION: The small arm accelerations and changes in osteokinematics we observed, support the use of this ASE, even while performing overhead cyclic tasks with the highest level of support.
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Dispositivo Exoesqueleto , Torque , Humanos , Masculino , Fenómenos Biomecánicos , Adulto , Femenino , Adulto Joven , Análisis y Desempeño de Tareas , Hombro/fisiología , Postura/fisiología , Aceleración , Rango del Movimiento Articular , Brazo/fisiologíaRESUMEN
Objective. Traditionally known for its involvement in emotional processing, the amygdala's involvement in motor control remains relatively unexplored, with sparse investigations into the neural mechanisms governing amygdaloid motor movement and inhibition. This study aimed to characterize the amygdaloid beta-band (13-30 Hz) power between 'Go' and 'No-go' trials of an arm-reaching task.Approach. Ten participants with drug-resistant epilepsy implanted with stereoelectroencephalographic (SEEG) electrodes in the amygdala were enrolled in this study. SEEG data was recorded throughout discrete phases of a direct reach Go/No-go task, during which participants reached a touchscreen monitor or withheld movement based on a colored cue. Multitaper power analysis along with Wilcoxon signed-rank and Yates-correctedZtests were used to assess significant modulations of beta power between the Response and fixation (baseline) phases in the 'Go' and 'No-go' conditions.Main results. In the 'Go' condition, nine out of the ten participants showed a significant decrease in relative beta-band power during the Response phase (p⩽ 0.0499). In the 'No-go' condition, eight out of the ten participants presented a statistically significant increase in relative beta-band power during the response phase (p⩽ 0.0494). Four out of the eight participants with electrodes in the contralateral hemisphere and seven out of the eight participants with electrodes in the ipsilateral hemisphere presented significant modulation in beta-band power in both the 'Go' and 'No-go' conditions. At the group level, no significant differences were found between the contralateral and ipsilateral sides or between genders.Significance.This study reports beta-band power modulation in the human amygdala during voluntary movement in the setting of motor execution and inhibition. This finding supplements prior research in various brain regions associating beta-band power with motor control. The distinct beta-power modulation observed between these response conditions suggests involvement of amygdaloid oscillations in differentiating between motor inhibition and execution.
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Amígdala del Cerebelo , Brazo , Ritmo beta , Desempeño Psicomotor , Humanos , Amígdala del Cerebelo/fisiología , Masculino , Femenino , Adulto , Ritmo beta/fisiología , Desempeño Psicomotor/fisiología , Brazo/fisiología , Adulto Joven , Movimiento/fisiología , Persona de Mediana Edad , Epilepsia Refractaria/fisiopatología , Electroencefalografía/métodosRESUMEN
OBJECTIVE: This study examines how maintaining a straight leading arm affects the muscle strength balance between the biceps and triceps in golfers and its influence on golf performance. METHODS: We recruited 20 male participants aged 18-45, including 10 golfers and 10 non-golfers. The participants' average age was 25.6±6.2 years, height 1.8±0.07 m, and weight 75.6±10.2 kg. We measured isometric and isokinetic muscle strength using the Primus RS Dynamometer (BTE Technologies, Hanover, MD, USA) and assessed golf swing performance with the Optishot 2 Golf Simulator (Optishot, Brighton, MI, USA). RESULTS: Golfers exhibited significantly greater triceps strength (P = 0.02) and a lower biceps-to-triceps strength ratio (P = 0.002) than non-golfers. Low-handicap golfers showed more centered and consistent ball impacts compared to mid-handicap golfers. There were no significant differences in swing path and face angles between low- and mid-handicap golfers. Muscle strength and the biceps-to-triceps strength ratio correlated with driving distance, as well as the frequencies of specific swing paths, face angles, and ball impact points, highlighting the complex interplay between muscle balance and swing performance. CONCLUSION: Greater triceps strength and a lower biceps-to-triceps strength ratio are key for maintaining a straight leading arm, especially in skilled golfers. While increased muscle strength tends to enhance driving distance, it does not necessarily improve accuracy. Consistent ball impact points may indicate higher skill levels. Future research should involve a larger, more diverse participant pool to validate these findings and further explore the complex nature of golf swing performance.
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Rendimiento Atlético , Golf , Fuerza Muscular , Músculo Esquelético , Humanos , Golf/fisiología , Masculino , Adulto , Fuerza Muscular/fisiología , Rendimiento Atlético/fisiología , Adulto Joven , Músculo Esquelético/fisiología , Adolescente , Persona de Mediana Edad , Fenómenos Biomecánicos , Brazo/fisiologíaRESUMEN
Ulnar collateral ligament (UCL) tears occur due to the prolonged exposure and overworking of joint stresses, resulting in decreased strength in the flexion and extension of the elbow. Current rehabilitation approaches for UCL tears involve subjective assessments (pain scales) and objective measures such as monitoring joint angles and range of motion. The main goal of this study is to find out if using wearable near-infrared spectroscopy technology can help measure digital biomarkers like muscle oxygen levels and heart rate. These measurements could then be applied to athletes who have been injured. Specifically, measuring muscle oxygen levels will help us understand how well the muscles are using oxygen. This can indicate improvements in how the muscles are healing and growing new blood vessels after reconstructive surgery. Previous research studies demonstrated that there remains an unmet clinical need to measure biomarkers to provide continuous, internal data on muscle physiology during the rehabilitation process. This study's findings can benefit team physicians, sports scientists, athletic trainers, and athletes in the identification of biomarkers to assist in clinical decisions for optimizing training regimens for athletes that perform overarm movements; the research suggests pathways for possible earlier detection, and thus earlier intervention for injury prevention.
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Biomarcadores , Músculo Esquelético , Espectroscopía Infrarroja Corta , Humanos , Proyectos Piloto , Biomarcadores/metabolismo , Espectroscopía Infrarroja Corta/métodos , Músculo Esquelético/fisiología , Músculo Esquelético/metabolismo , Masculino , Saturación de Oxígeno/fisiología , Adulto , Oxígeno/metabolismo , Oxígeno/análisis , Femenino , Dispositivos Electrónicos Vestibles , Adulto Joven , Brazo/fisiología , Rango del Movimiento Articular/fisiologíaRESUMEN
In two-handed actions like baseball batting, the brain can allocate the control to each arm in an infinite number of ways. According to hemispheric specialization theory, the dominant hemisphere is adept at ballistic control, while the non-dominant hemisphere is specialized at postural stabilization, so the brain should divide the control between the arms according to their respective specialization. Here, we tested this prediction by examining how the brain shares the control between the dominant and non-dominant arms during bimanual reaching and postural stabilization. Participants reached with both hands, which were tied together by a stiff virtual spring, to a target surrounded by an unstable repulsive force field. If the brain exploits each hemisphere's specialization, then the dominant arm should be responsible for acceleration early in the movement, and the non-dominant arm will be the prime actor at the end when holding steady against the force field. The power grasp force, which signifies the postural stability of each arm, peaked at movement termination but was equally large in both arms. Furthermore, the brain predominantly used the arm that could use the stronger flexor muscles to mainly accelerate the movement. These results point to the brain flexibly allocating the control to each arm according to the task goal without adhering to a strict specialization scheme.