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An abstract is presented of the article "Postural Dynamics in handstand," by G. Gauthier and R. Thouvarecq.

The aim of this study was to investigate the effects of the virtual reality device on the evolution of motivation, and motor, functional and kinematic parameters of the upper limb in children with cerebral palsy. Twenty children were randomly assigned in VR and control groups. VR group scored higher than the control group in the Movement Assessment Battery for Children - Second Edition (MABC-2; standardized motor skills test), exhibited an increased range of motion, and showed improved results in various movement parameters in the interaction with the 3D virtual space. All participants presented high motivation scores in the iVR sessions. This new Immertrack tool may improve the motor, kinematic parameters, and motivation in children with CP.

Introduction: In the context of young female athletes, namely elite gymnasts, effective stress management strategies not only enhance performance, but also reduce the risk of injuries and promote overall well-being. This study aims to investigate the effects of biofeedback-based training on stress management in prepubescent elite female gymnasts, recognizing its pivotal role in promoting healthy growth and proper training load management., Methods: Eight elite young female athletes from a top flight French national league club participated in an experimental condition involving four-week biofeedback training program to improve self-regulation skills, during both rest and stress phases. Additionally, each subject experienced a control condition, with entailed exposure to domain-specific motivational videos. Comprehensive evaluations of physiological parameters were conducted to assess the impact of biofeedback training, both before and after the training, as well as during the stress and recovery phases. Furthermore, an interoceptive body awareness test, using the MAIA questionnaire, was performed., Results: The results highlight a significant enhancement of the self-regulatory skills of the gymnasts in managing the selected physiological parameters-peripheral temperature ( p  < 0.05) and blood volume pressure ( p  < 0.05)-after the biofeedback treatment. Moreover, psychological data from the MAIA questionnaire revealed a noteworthy increase in interoceptive awareness ( p  < 0.001), particularly in the subscales of Not Distracting ( p  < 0.001), Attention regulation ( p  < 0.05), Emotional awareness ( p  < 0.05), and Self-regulation ( p  < 0.05)., Discussion: Thus, we conclude that biofeedback training improves self-regulatory and psychological resilience under stressful conditions, while reducing sensitivity to gymnastics-specific stress., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Proietti, Borozan, Chaigneau, Cannito, Palumbo, Thouvarecq and Iodice.)

Objective: To examine the characteristics and the effectiveness of virtual reality systems on upper limb impairments in children and young adults with cerebral palsy., Data Sources: An electronic search was conducted on PubMed, PEDro, Web of Science, Central, and EMBASE., Methods: The protocol of this review was prospectively registered in the PROSPERO database (CRD42022302271). Randomized controlled trials that tested the effects of virtual reality-based interventions on the upper limb of participants with cerebral palsy were included. The methodological quality of the studies was measured by the PEDro scale. The certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation. The data of the studies were analyzed in meta-analysis and presented in forest plots and narrative synthesis., Results: Twenty-two studies involving 746 participants were included. Ten different virtual reality systems were used in the interventions, of which six were designed specifically for rehabilitation and four commercial video games. We found an effect in favor of virtual reality when it was used in combination with conventional therapy for upper limb activity (SMD = 0.65; 95% CI (0.19 to 1.11)). However, the certainty of the evidence of the comparisons ranged from very low to low., Conclusion: Virtual reality seems to be an effective tool for upper limb activity in children and young adults with cerebral palsy. Nevertheless, future studies should present a better methodological quality, a larger sample size, and well-defined rehabilitation programs to reduce the inconsistency of the evidence in this domain., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Economic risk proneness is displayed by human children and some nonhuman primate species. To explore the role of attraction toward the unknown and the unexpected in economic choices, 2.5-year-old children and capuchin monkeys were presented in Experiment 1 with a gambling task in which participants had to choose between 2 options, a secure option and a risky option characterized by an unexpected event. In contrast to capuchins, toddlers showed a strong preference for the risky option over the safe option. In Experiment 2, toddlers maintained their risky choices despite the increased salience of the safe option. In contrast to toddlers, capuchins preferentially chose the safe option in this second experiment. We argue that capuchins' risk aversion reflects an exploitation strategy of known and safe options. In human children, the attractiveness of uncertain reward appears to be linked to their novelty seeking. We argue that toddlers' risk proneness in the gain domain reflects an exploratory search strategy. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Correct rider oscillation and position are the basics for a good horseback riding performance. In this paper, we propose a framework for the automatic analysis of athletes behaviour based on cluster analysis. Two groups of athletes (riders vs non-riders) were assigned to a horseback riding simulator exercise. The participants exercised four different incremental horse oscillation frequencies. This paper studies the postural coordination, by computing the different discrete relative phases of head-horse, elbow-horse and trunk-horse oscillations. Two clustering algorithms are then applied to automatically identify the change of rider and non-rider behaviour in terms of postural coordination. The results showed that the postural coordination was influenced by the level of rider expertise. More diverse behaviour was observed for non-riders. At the opposite, riders produced lower postural displacements and deployed more efficient postural control. The postural coordination for both groups was also influenced by the oscillation frequencies., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The present research aims at quantifying the impact of practicing a new coordination pattern with an online visual feedback on the postural coordination performed on a mechanical horse. Forty-four voluntary participants were recruited in this study. They were randomly assigned to four practice groups based on i) with or without feedback (i.e., group 1, control, did not receive the feedback; group 2, 3 and 4 received an online feedback during practice) and ii) the specific trunk/horse coordination to target during practice (group 1, target coordination = 180° (without feedback); group 2, target coordination = 0°; group 3, target coordination = 90°; group 4, target coordination = 180°). All participants performed pre-, practice, post- and retention sessions. The pre-, post- and retention sessions consisted of four trials, with one trial corresponding to one specific target coordination to maintain between their own oscillations and the horse oscillations (spontaneous, 0°, 90°, and 180°). The practice phase was composed of three different sessions during which participants received an online feedback about the coordination between their own oscillations and the horse oscillations. Results showed a significant change with practice in the trunk/horse coordination patterns which persisted even after one month (retention-test). However, all the groups did not show the same nature of change, evidenced by a high postural variability during post-test for 0° and 90° target coordination groups, in opposition to the 180° and spontaneous groups who showed a decrease in coordination variability for the 180° group. The coordination in anti-phase was characterized as spontaneously adopted by participants on the mechanical horse, explaining the ease of performing this coordination (compared to the 0° and 90° target coordination). The effect of online visual feedback appeared not only on the coordination pattern itself, but most importantly on its variability during practice, including concerning initially stable coordination patterns., Competing Interests: The authors have declared that no competing interests exist.

Objective: From a dynamic system approach, this study evaluated the impact of a new training protocol using a mechanical horse on the postural coordination of brain-damaged patients. Methods: Eighteen volunteer brain-damaged patients (i.e., post-stroke or traumatic brain injury) were recruited and randomly divided into an experimental group (horse group; n = 10, conventional therapy associated with horse-riding exercise on the mechanical horse for 30 min, twice a week, for 12 weeks) and a control group ( n = 8; conventional therapy without intervention on the mechanical horse). Postural coordination was evaluated during pre- and post-tests through discrete relative phase (DRP) computation: ϕ Head-Horse , ϕ Trunk-Horse. Results: A significant effect of used training has been showed, F (1, 15) = 16.6 ( p < 0.05) for all patients, concerning the trunk/horse coordination. Conclusion: This pilot study results showed the impact of this new training method on the postural coordination of these patients. After 24 sessions, the coordination of the horse group patients differed from that of the control group, showing their ability to adapt to constraints and develop specific modes of postural coordination (trunk/horse antiphase ) to optimize their posture.

We compared the visuomotor coordination of tennis players with different levels of expertise (Super-Experts, Experts and Non-Experts) in a visuomotor tracking (VMT) task. Participants were asked to track a moving target which could rebound on the sides of a 2D screen. Results indicated that the VMT task allowed the discrimination of expertise. Multiple regression analysis revealed that performance could be explained by the temporal adaptation of participants to rebounds and the number of movement adaptations. Compared to Non-Experts, the Experts had a shorter perturbation time with higher adaptation and regulation. This corresponds to a better perception-action coupling and the predominant use of a prospective control process. Results also indicate that perception-action coupling capacities are transferable to virtual tasks, and allow us to reveal processes of visuomotor coordination that differentiate experts and novices.

The authors investigated and compared the energy expenditure and postural coordination of two groups of healthy subjects on a mechanical horse at 4 increasing oscillation frequencies. Energy expenditure was assessed from the oxygen consumption, respiratory quotient, and heart rate values, and postural coordination was characterized by relative phase computations between subjects (elbow, head, trunk) and horse. The results showed that the postural coordination of the riders was better adapted (i.e., maintenance of in-phase and antiphase) than that of the nonriders, but the energy expenditure remains the same. Likewise, we observed an energy system shifting only for nonriders (from aerobic to lactic anaerobic mode). Finally, cross-correlations showed a link between energy expenditure and postural coordination in the riders (i.e., effectiveness).

The principal aim of this study was to examine the impact of variability in interpersonal coordination and individual organization on rowing performance. The second aim was to analyze crew phenomenology in order to understand how rowers experience their joint actions when coping with constraints emerging from the race. We conducted a descriptive and exploratory study of two coxless pair crews during a 3000-m rowing race against the clock. As the investigation was performed in an ecological context, we postulated that our understanding of the behavioral dynamics of interpersonal coordination and individual organization and the variability in performance would be enriched through the analysis of crew phenomenology. The behavioral dynamics of individual organization were assessed at kinematic and kinetic levels, and interpersonal coordination was examined by computing the relative phase between oar angles and oar forces and the difference in the oar force impulse of the two rowers. The inter-cycle variability of the behavioral dynamics of one international and one national crew was evaluated by computing the root mean square and the Cauchy index. Inter-cycle variability was considered significantly high when the behavioral and performance data for each cycle were outside of the confidence interval. Crew phenomenology was characterized on the basis of self-confrontation interviews and the rowers' concerns were then analyzed according to course-of-action methodology to identify the shared experiences. Our findings showed that greater behavioral variability could be either " perturbing " or " functional " depending on its impact on performance (boat velocity); the rowers experienced it as sometimes meaningful and sometimes meaningless; and their experiences were similar or diverging. By combining phenomenological and behavioral data, we explain how constraints not manipulated by an experimenter but emerging from the ecological context of a race can be associated with functional adaptations or perturbations of the interpersonal coordination.

The spatial-occlusion paradigm makes use of two techniques (masking and removing visual cues) to provide information about the anticipatory cues used by viewers. The visual scene resulting from the removal technique appears to be incongruous, but the assumed equivalence of these two techniques is spreading. The present study was designed to address this issue by combining eye-movement recording with the two types of occlusion (removal versus masking) in a tennis serve-return task. Response accuracy and decision onsets were analysed. The results indicated that subjects had longer reaction times under the removal condition, with an identical proportion of correct responses. Also, the removal technique caused the subjects to rely on atypical search patterns. Our findings suggest that, when the removal technique was used, viewers were unable to systematically count on stored memories to help them accomplish the interception task. The persistent failure to question some of the assumptions about the removal technique in applied visual research is highlighted, and suggestions for continued use of the masking technique are advanced.

The present case study fell within the framework of the "absolute approach of expertise" because it assesses a "truly exceptional individual" (Chi, MTH, Cambridge Handbook of Expertise and Expert Performance, London, United Kingdom: Cambridge University Press, 2006, pp. 121-130). This technique analysis examined the movement-production strategy used by a professional tennis player performing serve-return strokes. This research enabled us to establish the relation between tennis serve-return technique and successful performance. An optoelectronic system was used to capture and analyze the expert player's stroke production in a live situation to determine the temporal trajectory of the serve-return initiation movement. Some differences between the serve-return shots were observed concerning the occurrence time of the lateral racquet displacement, the amplitude of the racquet movement, and the average latency time. No difference was observed for the gravity center (GC) movements. Backhand, forehand, and reprogramming strokes were executed with a general constancy of occurrence and average times of the GC and racquet movements. This expert player used a predictive movement-production strategy specified by a high level of reproducibility of the movement with nevertheless adaptive skills during reprogramming strokes. This adaptation supported either the development of highly consistent motor programs or the use of a more flexible strategy based on the perception-action coupling.

The first aim of this study was to investigate how visual and somatosensory information influence handstand performance according to the expertise level of gymnasts. The second aim was to determine whether the general perceptual characteristics of gymnasts are linked with their handstand performances. In the first experiment, expert and nonexpert gymnasts performed a handstand on a force platform in 4 conditions: open or closed eyes on a firm or foam support. To assess the gymnasts' performance, the surface area (mm) covered by the trajectory of the center of pressure (CoP) was recorded. The results showed that (a) experts had significantly (p<0.05) better postural performance during the handstand than did nonexperts, whatever the visual condition, (b) nonexperts were unable to maintain the handstand without vision, whatever the support, and (c) the CoP surface was significantly greater on the foam surface than on the firm surface for both experts and nonexperts and, only for experts, whatever the visual condition. In the second experiment, the gymnasts' general perceptual characteristics (field dependence-independence) were evaluated using the rod-and-frame test (RFT). Experts were less field dependent than nonexperts, and the RFT results were positively correlated with postural performance. We thus suggest that, although they did not cope more efficiently with the somatosensory perturbation, expert gymnasts had developed a capacity to use the remaining sensory modalities efficiently when vision was removed. Also, a high level of gymnastics training may improve the ability to change the frame of reference. For the handstand, exercises alternating the use of visual and nonvisual information could be an interesting technique for trainers to improve gymnasts' performance.

The movement amplitude is a key component of numerous elements in gymnastics. The purpose of the present study is to highlight the most pertinent amplitude variable of the circle performed on the pedagogic pommel horse. Twelve gymnasts (6 expert gymnasts vs. 6 nonexpert gymnasts) performed 10 circles on this event. A Vicon 512 system was used to record the 3-dimensional position of 11 markers fixed on the gymnasts. Our results revealed than 4 amplitude variables permitted us to significantly discriminate the levels of performance of the gymnasts (p < 0.05): shoulder extension in front phase, body alignment, shoulder diameter, and ankle diameter. In a training perspective, this result could help coaches focus their advice and pedagogic situations on the pertinent technical criteria. Then, a stepwise discriminant analysis performed on the 4 previously selected variables showed that 2 variables allowed us to accurately discriminate the circle amplitude: ankle diameter and body alignment. These 2 variables can be used by coaches as a specific index to objectively determine the performance levels of gymnasts and to measure improvement in movements after specific training.

A notational analysis of singles events at the French Open Grand Slam tournament was undertaken in 2005 and 2006 to characterize the game patterns and strategies of serve and serve-return and to determine their influence on the point issue on a clay court surface. One hundred sixteen men's singles matches were video analyzed. The flat serve (57.6%), particularly down the "T" location (50.3%), allowed servers to win significantly more points than the topspin (24.1%) and slice serves (18.3%). When the topspin was the first serve strategy, servers kept a high percentage of points won from the serve (52.4%). This strategy was essentially used on the second serve (91.6%) by playing the "T" location in the deuce court and the wide zone in the advantage court. Returns to the central zone allowed receivers to win more points (73.3% on first serve and 65.9% on second serve) than plays to external locations. The results highlight the high impact of the first shots of all opponents on the rally. Even on clay, the slowest court surface, serves and serve-returns remain the strokes that most influence the match results in modern tennis games.

The aim of the present study was to investigate the effect of expertise on coordination patterns. We thus tested the coordination dynamics of two groups: experts in the handstand also having high expertise in gymnastics and experts in the handstand but only intermediate expertise in gymnastics. All participants were instructed to track a target with their ankles while maintaining the handstand. The target moved on the anterior-posterior axis according to three frequency conditions: 0.2, 0.4 and 0.6 Hz. The results showed that the suprapostural task was performed better by the group with high gymnastics expertise. Moreover, the spontaneous coordination was specific to the level of gymnastics expertise. We concluded that (i) the dynamics of coordination progress with the overall level of expertise in a sport discipline, independently of the mastery of a single skill, (ii) persistence and change are seen in related movement properties, and (iii) high expertise offers greater adaptability relative to the task.

In the present study we compare the kinaesthetic and visual perception of the vertical and horizontal orientations (subjective vertical and subjective horizontal) to determine whether the perception of cardinal orientations is amodal or modality-specific. The influence of methodological factors on the accuracy of perception is also investigated by varying the stimulus position as a function of its initial tilt (clockwise or counterclockwise) and its angle (22 degrees, 45 degrees, 67 degrees, and 90 degrees) in respect to its physical orientation. Ten participants estimated the vertical and horizontal orientations by repositioning a rod in the kinaesthetic condition or two luminous points, forming a 'virtual line' in the visual condition. Results within the visual modality replicated previous findings by showing that estimation of the physical orientations is very accurate regardless of the initial position of the virtual line. In contrast, the perception of orientation with the kinaesthetic modality was less accurate and systematically influenced by the angle between the initial position of the rod and the required orientation. The findings question the assumption that the subjective vertical is derived from an internal representation of gravity and highlight the necessity of taking into account methodological factors in studies on subjective orientations.

The authors investigated how expertise in motor skills that require fine postural control, such as gymnastics, influences postural regulation. Gymnasts and nongymnasts performed a postural stabilization task after anterior-posterior destabilization while looking at a target in front of them. The authors recorded and analyzed the center of pressure and the ankle, knee, and hip displacements. Gymnasts were able to react rapidly after destabilization to decrease their center of pressure and the angular movements. Moreover, they used their knees to stabilize posture, whereas the nongymnasts used their hips. These findings suggest that specific postural experience modifies the ability to coordinate and regulate posture. The authors discuss these results from an ecological perspective.

The purpose of the present experiment was to investigate how postural adaptations to the perceptive configuration are modified by specific gymnastics experience. Two groups, one expert in gymnastics and the other non-expert, had to maintain the erected posture while optical flow was imposed as follows: 20s motionless, 30s approaching motion, and 20s motionless. The centre of pressure and head displacements were analysed. The postural adaptations were characterised by the variability of movements for the flow conditions and by the postural latencies for the flow transitions. The results showed that the gymnasts tended to minimise their body movements and were more stationary (head) but not more stable (COP) than the non-gymnasts. These results suggest that gymnastics experience develops a specific postural adaptability relative to the perceptive configuration. We conclude that a specific postural experience could be considered as an intrinsic constraint, which leads to modification in the patterns of functional adaptation in the perceptive motor space.

In this study, we examined the effectiveness of auditory concurrent feedback on body segmental alignment during the circle movement performed on a pommel horse. Eighteen gymnasts were assigned to one of two groups: a concurrent auditory feedback group (experimental) or a control group that received no concurrent feedback. After 2 weeks of training (300 circles), the body segmental alignment (BSA) of the experimental group had improved by 2.3% between the pre test (85.7 +/- 4.8% BSA(max)) and the post test (87.7 +/- 4.0% BSA(max)). Furthermore, the results of a retention test administered 2 weeks after the post test revealed no decline in performance for the experimental group. No gains in body segmental alignment were found for the control group. It was concluded that augmented auditory feedback made available in real time can be used to correct complex movements, such as the circle movement on a pommel horse, and does not appear to lead to information-dependence despite the frequent administration of feedback. The auditory signal available in real time could help gymnasts to become more objective about their own intrinsic information necessary for the refinement of the circle movement.

This work investigated the accuracy of the perception of the main orientations (i.e., vertical and horizontal orientations) with the kinesthetic modality--a modality not previously used in this field of research. To further dissociate the influence of the postural and physical verticals, two body positions were explored (supine and upright). Twenty-two blindfolded participants were asked to set, as accurately as possible, a rod to both physical orientations while assuming one of the two body positions. The horizontal was perceived more accurately than the vertical orientation in the upright position but not in the supine position. Essentially, there were no differences in the supine position because the adjustments to the physical vertical were much more accurate than they were in the upright position. The lower accuracy in the estimation of the vertical orientation observed in the upright position might be linked to the dynamics associated with the maintenance of posture.