Régis Thouvarecq

A Notational Analysis of Elite Tennis Serve and Serve-return Strategies on Slow Surface

Gillet, E, Leroy, D, Thouvarecq, R, and Stein, J-F. A notational analysis of elite tennis serve and serve-return strategies on slow surface. J Strength Cond Res 23(2): 532-539, 2009-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 mens 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.

Influence of experience on postural control: effect of expertise in gymnastics.

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.

Influence of cholinergic system on motor learning during aging in mice

Three, 12- and 20-month-old C57Bl6 mice, reared in standard conditions or in an enriched environment, were administered subcutaneously either scopolamine hydrobromide (SIGMA), 0.6 and 1.2 mg kg(-1), or physiological saline 15 min before testing their motor skills (muscular strength, dynamic equilibrium and motor coordination) and motor learning abilities (number of trials needed to reach a learning criterion on a rotorod rotating at 27 revolutions per min). The results demonstrated a lack of correlation between motor skill scores and between motor skill and motor learning scores, suggesting that the rotorod training procedure measures motor learning and not motor skills or is insensitive to changes in motor skills. They also demonstrated that motor skills decreased with age but were insensitive to environmental rearing and to scopolamine. In contrast, the learning scores, which also decreased with age, were very sensitive to scopolamine, particularly in the oldest mice. These results are discussed according to the role of cholinergic system in motor learning during aging.

Visual and postural control of an arbitrary posture: The handstand

Abstract The aim of this study was to increase our understanding of postural regulation by analysing an arbitrary posture – the handstand. We assessed the relative influence of peripheral vision and central visual anchoring on the postural balance of gymnasts in the inverted-stand posture. Displacements of the centre of pressure, the angles between the body segments, and the gymnasts height in the handstand were analysed. Postural regulation in the handstand appeared to be organized according to a system similar to that in erect posture, with three articular levels suggesting the existence of a typical organization of human posture. Moreover, both intra-modal (central and peripheral vision) and inter-modal sensory systems (vision and other balance systems) contributed to the postural regulation. The results are interpreted in terms of an ecological approach to posture in which postural regulation can be considered as an emergent phenomenon.

Dynamics of expertise level: Coordination in handstand

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.

Amplitude variables of circle on the pedagogic pommel horse in gymnastics.

Baudry, L, Sforza, C, Leroy, D, Lovecchio, N, Gautier, G, and Thouvarecq, R. Amplitude variables of circle on the pedagogic pommel horse in gymnastics. J Strength Cond Res 23(3): 705-711, 2009-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.

Postural organisation during cascade juggling: Influence of expertise

The present study investigated how posture is organised during three-ball cascade juggling according to expertise. We hypothesized that the juggling task would place constraints on the postural organisation mode and that the posture-juggling coupling would be increased with expertise. Two groups, intermediates and experts, were asked to perform a postural-cascade juggling task. A three-dimensional motion recording system recorded the position of five light-reflecting markers for 30s to analyse the ball movements, the lateral oscillations of the sacrum and the flexion/extension of the right elbow. The spatial pattern of the cascade juggling showed no significant difference between groups. Moreover, both groups presented lateral oscillations of the sacrum during the task. The latencies between the maximal flexion/extension of the right elbow and the maximal lateral oscillations of the sacrum and their standard deviations were significantly lower for the experts than for the intermediates. We conclude that postural adaptations occur to facilitate the postural-suprapostural task and that experience modifies the posture-juggling coupling.

Cholinergic system, rearing environment and trajectory learning during aging in mice.

Three, 12- and 20-month-old C57BL6/J mice, reared in standard conditions or in enriched environments, were administered subcutaneously either scopolamine hydrobromide, 0.6 or 1.2 mg kg(-1), or physiological saline (control mice) 15 min before testing their abilities to find an invisible platform in a modified version of the Morris water maze, the starting point being kept unchanged throughout the experiment to allow the aged animals to solve the task. The results demonstrated that: 1) All control mice, whatever their age, were able to learn the platform location, but the number of trials needed to reach the learning criterion (3 consecutive trials in less than 8 s) increased with age; 2) All the scopolamine-treated mice, whatever their age, were also able to learn the platform location. However, compared to age-matched controls, the number of trials needed to reach the learning criterion was greater; 3) Rearing the animals in an enriched environment antagonized the effect of scopolamine, but only in the youngest (3 month-old) mice. All control and scopolamine-treated mice, whatever their age and their rearing environment, remembered, 7 days later, the platform location.

Movement-Production Strategy in Tennis: a Case Study

Gillet, E, Leroy, D, Thouvarecq, R, Mégrot, F, and Stein, J-F. Movement-production strategy in tennis: a case study. J Strength Cond Res 24(7): 1942-1947, 2010-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 players 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.

Kinaesthetic and visual perceptions of orientations.

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°, 45°, 67°, and 90°) 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.