Anticipation training for expert tennis players when facing a specific player.

Introduction: In fast ball sports, such as tennis, when spatiotemporal constraints are high, players have to anticipate the opponent action. Not much is known about how players acquire and improve this ability. The aim of this study was to use an implicit training protocol (no information was given to participants) based on the knowledge of one particular opponent to analyse how experts could improve their anticipation ability.

Using 3D immersive virtual reality interactive tasks for upper limb rehabilitation in children with cerebral palsy: A randomized controlled trial.

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.

Angle-of-approach and reversal-movement effects in lateral manual interception.

The present study sought to replicate two non-intuitive effects reported in the literature on lateral manual interception of uniformly moving targets, the angle-of-approach (AoA) effect and the reversal-movement (RM) effect. Both entail an influence of the target trajectory's incidence angle on the observed interceptive hand movements along the interception axis; they differ in the interception location considered. The AoA effect concerns all trajectory conditions requiring hand movement to allow successful interception, while the RM effect concerns the particular condition where the target will in fact arrive at the hand's initial position and no hand movement is therefore required but nevertheless regularly produced.

Henri Cochet's theory of angles in tennis (1933) reveals a new facet of anticipation.

In this study, we tested the theory of angles that was proposed almost a century ago by the tennis player Henri Cochet. This theory proposes that expert tennis players should position themselves on the bisector of the angle of the opponent's possibilities in order to optimize shot return, suggesting a geometric occupation of the court relative to the opponent's affordances; namely what he/she is capable of doing. We tested this hypothesis by analysing player and ball positioning data from professional tennis matches recorded with a Hawk-Eye system.

Effectiveness of virtual reality interventions of the upper limb in children and young adults with cerebral palsy: A systematic review with meta-analysis.

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).

Effects of practice on a mechanical horse with an online feedback on performing a sitting postural coordination.

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.

Effect of Mechanical Horse Practice as New Postural Training in Patients With Neurological Disorders: A Pilot Study.

From a dynamic system approach, this study evaluated the impact of a new training protocol on the postural coordination of brain-damaged patients. Eighteen volunteer brain-damaged patients (i.e.

Relationship between split-step timing and leg stiffness in world-class tennis players when returning fast serves.

This study investigated split-step timing when returning serves and whether this timing is related to neuromechanical capabilities in world-class tennis players. In Experiment 1, the split-step timing of four groups of world-class players (male and female ATP/WTA seniors, and ITF juniors) was measured on court when returning serves of the same level players. The four groups initiated the split-step at a similar time, starting around the time ball-racket contact in the serve stroke and landed when early ball-flight information was available.

Sport expertise in perception-action coupling revealed in a visuomotor tracking task.

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.

Contextual information and perceptual-cognitive expertise in a dynamic, temporally-constrained task.

Skilled performers extract and process postural information from an opponent during anticipation more effectively than their less-skilled counterparts. In contrast, the role and importance of contextual information in anticipation has received only minimal attention. We evaluate the importance of contextual information in anticipation and examine the underlying perceptual-cognitive processes.

Human Energy Expenditure and Postural Coordination on the Mechanical Horse.

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.

Spatial Estimation of Accelerated Stimuli Is Based on a Linear Extrapolation of First-Order Information.

We examined spatial estimation of accelerating objects (-8, -4, 0, +4, or +8 deg/s(2)) during occlusion (600, 1,000 ms) in a spatial prediction motion task. Multiple logistic regression indicated spatial estimation was influenced by these factors such that participants estimated objects with positive acceleration to reappear behind less often than those with negative acceleration, and particularly after the longer occlusion. Individual-participant logistic regressions indicated spatial estimation was better predicted by a first-order extrapolation of the occluded object motion based on pre-occlusion velocity rather than a second-order extrapolation that took account of object acceleration.

Multiple Object Tracking While Walking: Similarities and Differences Between Young, Young-Old, and Old-Old Adults.

Objective: Walking while simultaneously engaged in another activity becomes more difficult as one grows older. Here, we address the issue of changes in dual-task behavior at different stages of life, particularly in the latter stages.

Methods: We developed a dual task that combined walking along an 8-m walkway with a multiple object tracking (MOT) task of increasing difficulty.

Major changes in a rhythmic ball-bouncing task occur at age 7 years.

The aim of the study was to investigate the development of a rhythmical skill of children aged from 5 to 12 years old. Five age groups (5-6, 7-8, 9-10, 11-12, and young adults) performed a virtual ball bouncing task (16 forty-second long test trials). Task performances, racket oscillation, ball-racket impacts as well as the ball-racket coupling were analysed.

Is acceleration used for ocular pursuit and spatial estimation during prediction motion?

Here we examined ocular pursuit and spatial estimation in a linear prediction motion task that emphasized extrapolation of occluded accelerative object motion. Results from the ocular response up to occlusion showed that there was evidence in the eye position, velocity and acceleration data that participants were attempting to pursue the moving object in accord with the veridical motion properties. They then attempted to maintain ocular pursuit of the randomly-ordered accelerative object motion during occlusion but this was not ideal, and resulted in undershoot of eye position and velocity at the moment of object reappearance.

The effects of age and traffic density on street-crossing behavior.

Past research has shown that road users accept shorter time gaps when the waiting time/number of vehicles they let pass before attempting to merge into the traffic increases. While elderly pedestrians are known to be an extremely vulnerable group of road users, very few studies dealt with the effect of environmental constraints and crossing complexity on this population's safety. The present study aimed at determining whether or not street-crossing decisions and behavior of younger and older pedestrians were differently affected by a traffic flow.

Quantifying the nature of anticipation in professional tennis.

We quantify the nature and frequency of anticipation behaviours in professional tennis using video coding of incidents where the time delay between the opponent's stroke and the reaction of the player were recorded. We argue that anticipation is based on uncertain information and should lead in some situations to erroneous decisions. We identified the transition between reaction (with 100% accuracy in the selection of where the ball is played on the court) and anticipation (with less than 100% accuracy) as being 140-160 ms after ball contact.

Eye movements influence estimation of time-to-contact in prediction motion.

In many situations, it is necessary to predict when a moving object will reach a given target even though the object may be partially or entirely occluded. Typically, one would track the moving object with eye movements, but it remains unclear whether ocular pursuit facilitates accurate estimation of time-to-contact (TTC). The present study examined this issue using a prediction-motion (PM) task in which independent groups estimated TTC in a condition that required fixation on the arrival location as an object approached, or a condition in which participants were instructed to pursue the moving object.

Visuo-motor delay, information-movement coupling, and expertise in ball sports.

We compared the performance of tennis experts and non-experts using a simulated interceptive task, in which the ball could be unexpectedly deviated 400 ms before contact. The results showed that experts were more accurate than non-experts when intercepting balls that deviated in their trajectory and that this could be explained by their shorter visuo-motor delay in adapting their interceptive movement. In addition, multiple regression analyses revealed that visuo-motor delay was a good predictor of accuracy in this task.

Ocular pursuit and the estimation of time-to-contact with accelerating objects in prediction motion are controlled independently based on first-order estimates.

The present study examined for the first time both the ocular and manual responses in a prediction motion (PM) task requiring participants to estimate time-to-contact (TTC) of an accelerating object. Results showed that while the ocular response initially matched well the object motion, smooth pursuit decayed towards zero following object occlusion, during which participants exhibited a saccadic response that placed the eyes in the region of the point of contact. The primary saccade was completed in advance of the object reaching the point of contact, and was best predicted by a first-order estimate of TTC (TTC1).

Intercepting real and simulated falling objects: what is the difference?

The use of virtual reality is nowadays common in many studies in the field of human perception and movement control, particularly in interceptive actions. However, the ecological validity of the simulation is often taken for granted without having been formally established. If participants were to perceive the real situation and its virtual equivalent in a different fashion, the generalization of the results obtained in virtual reality to real life would be highly questionable.

Intercepting free falling objects: better use Occam's razor than internalize Newton's law.

Several studies have recently provided empirical data supporting the view that gravity has been embodied in a quantitative internal model of gravity thereby permitting access to exact time-to-contact (TTC) when intercepting a free falling object. In this review, we discuss theoretical and methodological concerns with the experiments that supposedly support the assumption of a predictive and accurate model of gravity. Having done so, we then propose that only a "qualitative implicit physics knowledge" of the effects of gravity is used as an approximate pre-information that influences timing of interceptive actions in the specific case of free falling objects.

Collision avoidance behavior as a function of aging and tennis playing.

Daily living often requires pedestrians and drivers to adapt their behavior to the displacement of other objects in their environment in order to avoid collision. Yet little research has paid attention to the effect of age on the completion of such a challenging task. The purpose of this study was to examine the relationship between age and collision avoidance skill and whether a sporting activity affects this.

Aging and tennis playing in a coincidence-timing task with an accelerating object: the role of visuomotor delay.

The purpose of the present study was to determine whether playing a specific ball sport, such as tennis, could maintain the coincidence-timing (CT) performance of older adults at a similar level to that of younger ones. To address this question, tennis players and nonplayers of three different age ranges (ages 20-30, 60-70, and 70-80 years) performed a simple CT task consisting of timing their response (pressing a button) to coincide with the arrival of a stimulus at a target. The stimulus moved at either an accelerating, constant, or decelerating velocity.

The effect of aging and tennis playing on coincidence-timing accuracy.

This study examined the effect of tennis playing on the coincidence timing (CT) of older adults. Young, younger-old and older-old (20-30, 60-69, and 70-79 years old, respectively) tennis players and nonplayers were asked to synchronize a simple response (pressing a button) with the arrival of a moving stimulus at a target. Results showed that the older tennis players responded with a slight bias similar to that of the young players.