Whole-body Motion Research Articles

Self-awareness from whole-body movements.

Humans can recognize their whole-body movements even when displayed as dynamic dot patterns. The sparse depiction of whole-body movements, coupled with a lack of visual experience watching ourselves in the world, has long implicated non-visual mechanisms to self-action recognition. We aimed to identify the neural systems for this ability. Using general linear modeling and multivariate analyses on human brain imaging data from male and female participants, we first found that cortical areas linked to motor processes, including frontoparietal and primary somatomotor cortices, exhibit greater engagement and functional connectivity when recognizing self-generated versus other-generated actions. Next, we show that these regions encode self-identity based on motor familiarity, even after regressing out idiosyncratic visual cues using multiple regression representational similarity analysis. Last, we found the reverse pattern for unfamiliar individuals: encoding localized to occipito-temporal visual regions. These findings suggest that self-awareness from actions emerges from the interplay of motor and visual processes.Significance Statement: We report for the first time that self-recognition from visual observation of our whole-body actions implicates brain regions associated with motor processes. On functional neuroimaging data, we found greater activity and unique representational patterns in brain areas and networks linked to motor processes when viewing our own actions relative to viewing the actions of others. These findings introduce an important role of motor mechanisms in distinguishing the self from others.

Gait performance changes after ten cervical retractions

Background and Study Aim. Students are prone to spine overloading, as they often spend prolonged periods in unfavorable postures. They tend to struggle with balancing study time and leisure physical activity. The head and neck regions are particularly rich in proprioceptors. Prolonged forward head posture (protraction) can lead to balance disturbances. This, in turn, affects gait and overall body posture. The aim of this study was to examine the effects of a series of corrective active head exercises on gait, a fundamental form of movement, in a group of healthy university students. Material and Methods. Gait patterns were assessed in 10 healthy male full-time students with an average age of 22.8 years (SD = 1.1). The assessment was based on the regional distribution of plantar pressure across two measurement sessions. One session was conducted before, and one after performing 10 active head retractions. Gait changes were analyzed in ten foot regions for 200 steps of each participant. Results. After 10 cervical retractions, a decrease in pressure, ground reaction force, contact time, and area values was observed in the 1st metatarsal head (1MTH). Conversely, an increase in these quantities was found in the toes. Additionally, there was a tendency toward a decrease in the contact area of the heel and 3rd metatarsal head (3MTH), along with increased contact time in the midfoot. Performing 10 neck retractions altered gait by inducing heel supination. It also increased hallux involvement in propulsion and widened the base of toe support. Conclusions. Even a few movements that correct head protraction have an immediate effect on whole-body movement. This effect suggests potential benefits of incorporating neck retractions into physical education programs for students. Even when time-consuming forms of regular exercise are not feasible, performing just a few neck-correcting movements can positively impact overall body movement.

A Fuzzy Pure Pursuit for Autonomous UGVs Based on Model Predictive Control and Whole-Body Motion Control

In this paper, we propose an adaptive fuzzy pure pursuit trajectory tracking algorithm for autonomous unmanned ground vehicles (UGVs), addressing the challenges of accurate and stable navigation in complex environments. Traditional pure pursuit methods with fixed look-ahead distances struggle to maintain precision in dynamic and uneven terrains. Our approach uniquely integrates a fuzzy control algorithm that allows for real-time adjustments of the look-ahead distance based on environmental feedback, thereby enhancing tracking accuracy and smoothness. Additionally, we combine this with model predictive control (MPC) and whole-body motion control (WBC), where MPC forecasts future states and optimally adjusts control actions, while WBC ensures coordinated motion of the UGV, maintaining balance and stability, especially in rough terrains. This integration not only improves responsiveness to changing conditions but also enables dynamic balance adjustments during movement. The proposed algorithm was validated through simulations in Gazebo and real-world experiments on physical platforms. In real-world tests, our algorithm reduced the average trajectory tracking error by 45% and the standard deviation by nearly 50%, significantly improving stability and accuracy compared to traditional methods.

Impact of chronic low back pain on implicit motor imagery assessed by a new laterality judgment task

It is clear that implicit motor imagery (IMI) is impaired by chronic pain in peripheral regions (hand, feet), but unclear in axial regions (neck, shoulder, back). Previous IMI tasks displayed small-amplitude movements of axial regions, which limits person-centered IMI processes mobilization. This study aimed to assess the impact of chronic low back pain (CLBP) on IMI processes with a new task displaying large-amplitude whole-body movements mobilizing the lumbar spine. Twenty patients with CLBP and twenty age-matched controls performed a laterality judgment task on four distinct whole-body movements (trunk flexion, trunk rotation, capoeira, kickboxing). Participants viewed images from four different body viewpoints (back, left, right and front), randomly presented. Mixed ANOVAs were used to compare judgment accuracy and response times between groups and conditions. In participants with CLBP, response times were longer than in controls. The response times of participants with CLBP were also associated with DN4 scores, a self-reported questionnaire assessing neuropathic pain. We validated the use of a person-centered IMI because, for all participants, the accuracy decreased and the response times increased for images presented in the front viewpoint, i.e. when a 180° turn in IMI was required, compared to other viewpoints. The laterality judgment task proposed here confirmed that CLBP impacts IMI processes, and that the nature of pain (neuropathic or mechanical) needs to be considered because it seems to modulate IMI processes. PerspectivesA laterality judgment task with large-amplitude lumbar movements is key to show that CLBP alters processing speed of sensorimotor information originating from the painful region. This task could become an objective tool, transferable in clinical settings, for assessing the impact and the progression of CLBP on motor control processes.

A proximal external focus does not benefit skilled skiers

The potential performance benefit of an external focus of attention remains unexamined for skilled junior performers, especially those executing ballistic, whole-body continuous movements. Skilled junior skiers (M age = 14.09) completed slalom runs under external focus, internal focus, and control focus conditions. Repeated measures ANOVA revealed no significant difference between attentional foci on performance times. Our data challenges the commonly held belief regarding the superiority of an external focus. Instead, we offer researchers and practitioners a more nuanced discussion concerning possible distance effects (proximal vs. distal) associated with external foci in skilled junior performers executing ballistic, whole-body movements.

Evolutionary Cognitive Enhancement: Stimulating Whole-Body Problem-Solving Capacities

AbstractThis article argues that understanding the primary functions of cognitive processes in our evolutionary past can help to develop effective cognitive enhancement methods. The adaptive problems our ancestors faced forged interconnected cognitive and motor mechanisms supporting various movement-based problem-solving processes. However, the physical and social challenges these cognitive-motor capacities originally evolved to address are no longer prevalent in modern societies. Consequently, many adaptive problem-solving mechanisms linked to a wide range of body movements are often underused and insufficiently developed in modern contexts, contributing to age-related cognitive decline. From this view, and considering current cognitive enhancement techniques such as cognitive training, neurostimulation, physical exercise, and combined cognitive and physical training, the present article introduces an evolutionary-inspired cognitive enhancement framework. This framework advocates for developing strategies and training methods that stimulate our evolved cognitive-motor adaptations. In particular, therapeutic interventions should incorporate adaptive problems and whole-body movement solutions into modern technologies and computer-based tasks.

Aging of upper-limb and whole-body movement efficiency

Aging of upper-limb and whole-body movement efficiency

Joint angle synergy-based humanoid robot motion generation with fascia-inspired nonlinear constraints

AbstractWhen generating simultaneous joint movements of a humanoid with multiple degrees of freedom to replicate human-like movements, the approach of joint synergy can facilitate the generation of whole-body robotic movement with a reduced number of control inputs. However, the trade-off of minimizing control inputs and keeping characteristics of movements makes it difficult to improve movement performance in a simple control manner. In this paper, we introduce an approach by connecting and constraining these joints. It is inspired by the fascia network of the human body, which constrains the whole-body movements of a human. Compared to when only joint synergy is used, the effectiveness of the proposed method is verified by calculating the errors of joint positions of generated movements and human movements. The paper provides a detailed exploration of the proposed method, presenting simulation-experimental results that affirm its effectiveness in generated movements that closely resemble human movements. Furthermore, we provide one possible method on how these concepts can be implemented in actual robotic hardware, offering a pathway to improve movement control in humanoid robots within their mechanical limitations.

Applying learning-from-observation to household service robots: three task common-sense formulations

Utilizing a robot in a new application requires the robot to be programmed at each time. To reduce such programmings efforts, we have been developing “Learning-from-observation (LfO)” that automatically generates robot programs by observing human demonstrations. So far, our previous research has been in the industrial domain. From now on, we want to expand the application field to the household-service domain. One of the main issues with introducing this LfO system into the domain is the cluttered environments, which makes it difficult to discern which movements of the human body parts and their relationships with environment objects are crucial for task execution when observing demonstrations. To overcome this issue, it is necessary for the system to have task common-sense shared with the human demonstrator to focus on the demonstrator's specific movements. Here, task common-sense is defined as the movements humans take almost unconsciously to streamline or optimize the execution of a series of tasks. In this paper, we extract and define three types of task common-sense (semi-conscious movements) that should be focused on when observing demonstrations of household tasks and propose representations to describe them. Specifically, the paper proposes to use labanotation to describe the whole-body movements with respect to the environment, contact-webs to describe the hand-finger movements with respect to the tool for grasping, and physical and semantic constraints to describe the movements of the hand with the tool with respect to the environment. Based on these representations, the paper formulates task models, machine-independent robot programs, that indicate what-to-do and where-to-do. In this design process, the necessary and sufficient set of task models to be prepared in the task-model library are determined on the following criteria: for grasping tasks, according to the classification of contact-webs along the purpose of the grasping, and for manipulation tasks, corresponding to possible transitions between states defined by either physical constraints and semantic constraints. The skill-agent library is also prepared to collect skill-agents corresponding to tasks. The skill-agents in the library are pre-trained using reinforcement learning with the reward functions designed based on the physical and semantic constraints to execute the task when specific parameters are provided. Third, the paper explains the task encoder to obtain task models and task decoder to execute the task models on the robot hardware. The task encoder understands what-to-do from the verbal input and retrieves the corresponding task model in the library. Next, based on the knowledge of each task, the system focuses on specific parts of the demonstration to collect where-to-do parameters for executing the task. The decoder constructs a sequence of skill-agents retrieving from the skill-agnet library corresponding and inserts those parameters obtained from the demonstration into these skill-agents, allowing the robot to perform task sequences with following the Labanotation postures. Finally, this paper presents how the system actually works through several example scenes.

Unveiling individuality in the early phase of motor learning: a machine learning approach for analysing weightlifting technique in novices.

Despite the growing body of evidence highlighting the individuality in movement techniques, predominant models of motor learning, particularly during the acquisition phase, continue to emphasise generalised, person-independent approaches. Biomechanical studies, coupled with machine learning approaches, have demonstrated the uniqueness of movement techniques exhibited by individuals. However, this evidence predominantly pertains to already stabilised movement techniques, particularly evident in cyclic daily activities such as walking, running, or cycling, as well as in expert-level sports movements. This study aims to evaluate the hypothesis of individuality in whole-body movements necessitating intricate coordination and strength among novice participants at the very beginning of an acquisition phase. In a within-subject design, sixteen highly active male participants (mean age: 23.1 ± 2.1 years), all absolute novices in the learning task (i.e., power snatch of Olympic weightlifting), participated in randomised snatch learning bouts. These bouts comprised 36 trials across various motor learning models: differential learning contextual interference (serial, sCIL; and blocked, bCIL), and repetitive learning. Kinematic and kinetic data were collected from three standardised snatch trials performed following each motor learning model bout. The time-continuous data were input to a linear Support Vector Machine (SVM). We conducted analyses on two classification tasks: participant and motor learning model. The Support Vector Machine classification revealed a notably superior participant classification compared to the motor learning model classification, with an averaged prediction accuracy of 78% (in average ≈35 out of 45 test trials across the folds) versus 27.3% (in average ≈9 out of 36 test trials across the folds). In specific fold and input combinations, accuracies of 91% versus 38% were respectively achieved. Methodically, the crucial role of selecting appropriate data pre-processing methods and identifying the optimal combinations of SVM data inputs is discussed in the context of future research. Our findings provide initial support for a dominance of individuality over motor learning models in movement techniques during the early phase of acquisition in Olympic weightlifting power snatch.

Individual differences and motor planning influence self-recognition of actions.

Although humans can recognize their body movements in point-light displays, self-recognition ability varies substantially across action types and participants. Are these variations primarily due to an awareness of visually distinct movement patterns, or to underlying factors related to motoric planning and/or individual differences? To address this question, we conducted a large-scale study in self-action recognition (N = 101). We motion captured whole-body movements of participants who performed 27 different actions across action goals and degree of motor planning. After a long delay period (~ 1 month), participants were tested in a self-recognition task: identifying their point-light action amongst three other point-light actors performing identical actions. We report a self-advantage effect from point-light actions, consistent with prior work in self-action recognition. Further, we found that self-recognition was modulated by the action complexity (associated with the degree of motor planning in performed actions) and individual differences linked to motor imagery and subclinical autism and schizotypy. Using dynamic time warping, we found sparse evidence in support of visual distinctiveness as a primary contributor to self-recognition, though speed distinctiveness negatively influenced self-recognition performance. Together, our results reveal that self-action recognition involves more than an awareness of visually distinct movements, with important implications for how the motor system may be involved.

Weak grip strength among persons with multiple sclerosis having minimal disability is not related to agility or integrity of the corticospinal tract

IntroductionMobility impairment is common in multiple sclerosis (MS); however, agility has received less attention. Agility requires strength and neuromuscular coordination to elicit controlled propulsive rapid whole-body movement. Grip strength is a common method to assess whole body force production, but also reflects neuromuscular integrity and global brain health. Impaired agility may be linked to loss of neuromuscular integrity (reflected by grip strength or corticospinal excitability). ObjectivesWe aimed to determine whether grip strength would be associated with agility and transcranial magnetic stimulation (TMS)-based indices of corticospinal excitability and inhibition in persons with MS having low disability. We hypothesized that low grip strength would predict impaired agility and reflect low corticospinal excitability. MethodsWe recruited 34 persons with relapsing MS (27 females; median [range] age 45.5 [21.0-65.0] years) and mild disability (median [range] Expanded Disability Status Scale 2.0 [0-3.0]), as well as a convenience sample of age- and sex-matched apparently healthy controls. Agility was tested by measuring hop length during bipedal hopping on an instrumented walkway. Grip strength was measured using a calibrated dynamometer. Corticospinal excitability and inhibition were examined using TMS-based motor evoked potential (MEP) and corticospinal silent period (CSP) recruitment curves, respectively. ResultsMS participants had significantly lower grip strength than controls independent of sex. Females with and without MS had weaker grip strength than males. There were no statistically significant sex or group differences in agility. After controlling for sex, weaker grip strength was associated with shorter hop length in controls only (r = 0.645, p < .05). Grip strength did not significantly predict agility in persons with MS, nor was grip strength predicted by corticospinal excitability or inhibition. ConclusionsIn persons with MS having low disability, grip strength (normalized to body mass) was reduced despite having intact agility and walking performance. Grip strength was not associated with corticospinal excitability or inhibition, suggesting peripheral neuromuscular function, low physical activity or fitness, or other psychosocial factors may be related to weakness. Low grip strength is a putative indicator of early neuromuscular aging in persons with MS having mild disability and normal mobility

Sensitivity of principal component analysis outcomes to data pre-processing conditions when quantifying trial-to-trial variability in whole-body kinematics

This study investigated whether modes of variance in trial-to-trial whole-body kinematic variability identified by principal component analysis (PCA) were consistent across data pre-processing conditions generated from a common dataset. Comparisons made included 1) when trajectory data was expressed in a global vs. local reference frame; 2) when the number of landmarks used to represent whole-body motion differed, and; 3) whether input trajectory data were normalized to participant stature. Varying data pre-processing conditions prior to PCA does not bias the total variance identified. However, it can influence how modes of variance are dispersed across PCs, which in turn, can influence interpretation.

The effect of football heading on sidestep cutting biomechanics

Heading is an integral part of football, with ~20 headers or aerial duels executed per game to intercept, pass or score. However, concerns have recently been raised about the potential short and long-term health impacts of repeated heading. There is evidence suggesting increased risks of sub-concussive trauma – head impacts that do not result in obvious symptoms of concussion but affect cognition and motor function (Montenigro et al., 2017, J Neurotra, 34, 328-340). Repeated heading has been demonstrated to alter brain-muscle communication and affect movement control (Parr et al., 2023, Front Hu Neuro, 17, 1145700) and mechanics of simple tasks such as jumping (Lapointe et al., 2018, Int J Psychophys, 132, 93-98). However, whether these observed cognition and motor impairments translate to the biomechanics of complex multidirectional sport-specific movements such as sidestep cutting is not known. This is an important area to understand because sidestep cutting, an acute change of direction which is ubiquitous in football, is an important performance-determining factor and also a common inciting event for lower-limb injuries (Alentorn-Geli et al., 2009, Knee Sur Sports Trauma, Arth, 17, 705-729) such as the anterior cruciate ligament (ACL) rupture. Due to its propensity to generate high multiplanar knee joint loading during the stance phase of the manoeuvre (Dempsey et al., 2009, Am J Sports Med, 37, 2194-2200), there are often high stresses on the lower limbs which can result in musculoskeletal injury. To date, a copious number of studies have analysed the biomechanics of the sidestep cutting manoeuvre, showing that knee loading is sensitive to the constraints and strategies used to manoeuvre (Dos’Santos et al., 2019, Strength Cond J, 41, 40-54). Accordingly, this present study aims to determine whether there is an effect of repeated heading on sidestep-cutting biomechanics and, if so, the nature of this effect. Participants (n=40) will perform reactive and pre-planned sidestep cutting manoeuvres before completing 15 virtual (n=20) or physical (n=20) ball-heading. They will then repeat the cutting tasks immediately after the bout of heading. Whole-body optical motion capture, ground reaction forces, tri-planar lower-limb joint angles and moments during the stance phase will be analysed to test the effects of football heading on sidestep cutting biomechanics. Results may indicate whether exposure to football heading is a potential risk factor for lower-limb/ACL injury and thus inform the development of training sessions, athlete monitoring, and organisational/national heading guidance and policy for matches and training.

3-Dimensional Biomechanics of Noncontact Anterior Cruciate Ligament Injuries in Male Professional Soccer Players

Background: The understanding of noncontact anterior cruciate ligament (ACL) injury causation in soccer has improved over the past decades. Bidimensional video analyses have significantly augmented our awareness, representing to date the only practical method to describe injury biomechanics. However, the extent of the problem continues to raise serious concerns. Purpose: To advance our understanding of the causal pathways leading to ACL injury with a large-scale reconstruction of 3-dimensional (3D) whole-body joint kinematics of injuries that occurred to male elite soccer players, as well as to compare the joint angle time course among situational patterns. Study Design: Descriptive laboratory study. Methods: A total of 33 consecutive noncontact and indirect contact ACL injuries that occurred in 6 national and 2 international professional leagues (seasons 2020-2021 to 2022-2023 until December 2022) were analyzed: (1) multiview noncoaxial television images were inspected; (2) multiple camera views were taken from 400 ms before the initial ground contact to 200 ms after the injury frame; (3) a size-matched pitch was modeled and used to calibrate cameras; (4) a 3D skeletal model was adjusted to fit the player's pose in each frame/view; and (5) poses were interpolated, and Euler joint angles were extracted. Results: The authors reconstructed the 3D lower limb joint kinematic curves preceding and during ACL injuries in 33 cases; notably, a sudden external (up to 5°) and then internal knee rotation was observed after the initial contact and before the injury frame. The overall kinematics at injury were knee moderately flexed (45.9°± 21.7°), abducted (4.3°± 5.1°), and externally rotated (3.0°± 6.4°); trunk shallowly flexed (17.4°± 12.5°) and rotated and tilted toward the injured side; and hip flexed (32.0°± 18.7°), abducted (31.1°± 12.0°), and slightly internally rotated (6.6°± 12.2°). Variable behaviors were observed at the ankle level. Conclusion: Via reconstruction of the sequence of whole-body joint motion leading to injury, we confirmed the accepted gross biomechanics (dynamic valgus trend). This study significantly enriches the current knowledge on multiplanar kinematic features (transverse and coronal plane rotations). Furthermore, it was shown that ACL injuries in male professional soccer players manifest through distinct biomechanical footprints related to the concurrent game situation. Clinical Relevance: Interventions aimed at reducing ACL injuries in soccer should consider that environmental features (ie, situational patterns) affect injury mechanics.

Cumulative loading increases and loading asymmetries persist during walking for people with a transfemoral bone-anchored limb

BackgroundA bone-anchored limb (BAL) is an alternative to a traditional socket-type prosthesis for people with transfemoral amputation. Early laboratory-based evidence suggests improvement in joint and limb loading mechanics during walking with a BAL compared to socket prosthesis use. However, changes in cumulative joint and limb loading measures, which may be predictive of degenerative joint disease progression, remain unknown. Research questionDo cumulative total limb and hip joint loading during walking change using a BAL for people with unilateral transfemoral amputation, compared to prior socket prosthesis use? MethodsA case-series cohort of eight participants with prior unilateral transfemoral amputation who underwent BAL hardware implantation surgery were retrospectively analyzed (4 M/4 F; BMI: 27.7 ± 3.1 kg/m2; age: 50.4 ± 10.2 years). Daily step count and whole-body motion capture data were collected before (using socket prosthesis) and one-year after BAL hardware implantation. Cumulative total limb and hip joint loading and between-limb loading symmetry metrics were calculated during overground walking at both time points and compared using Cohen’s d effect sizes. ResultsOne year after BAL hardware implantation, participants demonstrated bilateral increases in cumulative total limb loading (amputated: d = -0.65; intact: d = -0.72) and frontal-plane hip moment (amputated: d = -1.29; intact: d = -1.68). Total limb loading and hip joint loading in all planes remained asymmetric over time, with relative overloading of the intact limb in all variables of interest at the one-year point. SignificanceDespite increases in cumulative total limb and hip joint loading, between-limb loading asymmetries persist. Habitual loading asymmetry has been implicated in contributing to negative long-term joint health and onset or progression of degenerative joint diseases. Improved understanding of methods to address habitual loading asymmetries is needed to optimize rehabilitation and long-term joint health as people with transfemoral amputation increase physical activity when using a BAL.

Leveraging Physical Activities to Support Learning for Young People via Technologies: An Examination of Educational Practices Across the Field

Many technological interventions have leveraged physical activity (PA, i.e., activities that involve whole-body movements) to provide young people with active and productive learning experiences. However, there is a lack of systematic understanding of how PA can serve as a learning medium—for example, how PA can support learning and how to design technologies to support PA-based learning. This paper conducts a systematic literature review (N = 141) of PA-based, technology-mediated learning experiences for young people with a focus on how PA supports learning, what technologies are involved, and the associated challenges. Through content analysis, we identified four approaches of how PA and learning were combined (i.e., PA embodied learning content, served as a functional input method for learning tasks, guided learners through different learning sites, and generated data for learning activities) and supporting technologies like full-body interaction learning environments and mobile apps. However, many challenges might arise, such as balancing learning and PA, as well as the scalability and reliability of technologies. We conclude with a discussion and reflection on design implications for more PA-based learning experiences and technologies. Overall, this paper provides a systematic overview of the different ways to design physically active learning experiences for young people and can serve as a reference for future designs of physically active learning experiences and technologies.

Markerless 3D kinematics and force estimation in cheetahs

The complex dynamics of animal manoeuvrability in the wild is extremely challenging to study. The cheetah (Acinonyx jubatus) is a perfect example: despite great interest in its unmatched speed and manoeuvrability, obtaining complete whole-body motion data from these animals remains an unsolved problem. This is especially difficult in wild cheetahs, where it is essential that the methods used are remote and do not constrain the animal’s motion. In this work, we use data obtained from cheetahs in the wild to present a trajectory optimisation approach for estimating the 3D kinematics and joint torques of subjects remotely. We call this approach kinetic full trajectory estimation (K-FTE). We validate the method on a dataset comprising synchronised video and force plate data. We are able to reconstruct the 3D kinematics with an average reprojection error of 17.69 pixels (62.94% PCK using the nose-to-eye(s) length segment as a threshold), while the estimates produce an average root-mean-square error of 171.3N (≈\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\approx$$\\end{document} 17.16% of peak force during stride) for the estimated ground reaction force when compared against the force plate data. While the joint torques cannot be directly validated against ground truth data, as no such data is available for cheetahs, the estimated torques agree with previous studies of quadrupeds in controlled settings. These results will enable deeper insight into the study of animal locomotion in a more natural environment for both biologists and roboticists.

Cellulose nanofiber-mediated manifold dynamic synergy enabling adhesive and photo-detachable hydrogel for self-powered E-skin

Self-powered skin attachable and detachable electronics are under intense development to enable the internet of everything and everyone in new and useful ways. Existing on-demand separation strategies rely on complicated pretreatments and physical properties of the adherends, achieving detachable-on-demand in a facile, rapid, and universal way remains challenging. To overcome this challenge, an ingenious cellulose nanofiber-mediated manifold dynamic synergy strategy is developed to construct a supramolecular hydrogel with both reversible tough adhesion and easy photodetachment. The cellulose nanofiber-reinforced network and the coordination between Fe ions and polymer chains endow the dynamic reconfiguration of supramolecular networks and the adhesion behavior of the hydrogel. This strategy enables the simple and rapid fabrication of strong yet reversible hydrogels with tunable toughness ((Valuemax-Valuemin)/Valuemax of up to 86%), on-demand adhesion energy ((Valuemax-Valuemin)/Valuemax of up to 93%), and stable conductivity up to 12 mS cm−1. We further extend this strategy to fabricate different cellulose nanofiber/Fe3+-based hydrogels from various biomacromolecules and petroleum polymers, and shed light on exploration of fundamental dynamic supramolecular network reconfiguration. Simultaneously, we prepare an adhesive-detachable triboelectric nanogenerator as a human-machine interface for a self-powered wireless monitoring system based on this strategy, which can acquire the real-time, self-powered monitoring, and wireless whole-body movement signal, opening up possibilities for diversifying potential applications in electronic skins and intelligent devices.

The effects of jaw clenching and mouthpiece use on bat swing velocity in Division II athletes

ABSTRACT Research assessing the effects of mouthpieces on an individual’s aerobic, anaerobic, or muscular performance have attributed cited improvements to the participant’s ability to jaw clench. Jaw clenching research finds positive outcomes with the task of jaw clenching with targeted muscle groups in a controlled laboratory setting. Thus, the study’s goal was to determine if the addition of a mouthpiece would positively affect performance outcomes in a field-based whole-body muscle movement. Fourteen participants (8=F and 6=M) NCAA softball and baseball athletes completed 5 maximal bat swings with and without a mouthpiece in 4 conditions: no jaw clenching (NC), mouthpiece and jaw clenching (MP+C), mouthpiece only (MP), and jaw clenching only (C). Significant differences occurred in conditions, with the highest velocity noted in the combined condition of MP+C (71.9 mph) as compared to NC (67.9 mph), MP (68.6 mph), and C (70.9 mph). A repeated measures ANOVA demonstrated significant differences with bat swing velocity (F = 13.19, df 3, p < 0.0001). Pairwise comparisons revealed significant differences in MP+C with MP (p = 0.007); MP+C with NC (p = 0.001), and C with NC (p = 0.009). The results of this study provide evidence of jaw clenching’s positive effects on the dynamic, whole-body explosive activity of a bat swing.