Blanc SIMI 9 - Sciences de l'information, de la matière et de l'ingénierie : Sciences de l'ingénierie, matériaux, procédés, énergie

Les obligations de confidentialités inhérentes au partenariat avec la société Babolat rendent difficiles l'expertise par des personnes étrangères, susceptibles de collaborer avec des concurrents de la société Babolat. – ACE

Ecological study of the Material-Human Interaction: Application to the ergonomics of tennis rackets.

In tennis activity, the shoulder complex funnels the kinetic energy from the lower limbs and trunk to the upper limb and then the ball. The shoulder joint is characterized by large multidirectional ranges of motion. As a consequence, powerful, valid and reliable methods must be developed to describe the kinematics of tennis strokes, quantify the musculoskeletal loadings, and then establish the relationships between the racket characteristics, and muscle and joint stress.

Development of tools to quantify the joint loadings and to normalize electromyographic signals of upper limb muscles

The maximal EMG activity to normalize the EMG signals for eight shoulder muscles was obtained during two dynamic movements and one isometric voluntary maximal contraction. A geometrical model of the thorax, shoulder and arm based on Visible Human dataset has been developed to define the kinematic constraints including in a multibody optimization.

14 tennis players hit sets of forehand drives and services using three rackets having different polar moment. The players were equipped with 15 spherical passive reflective markers located on trunk and dominant upper limb in accordance with the ISB recommendations, and three markers were glued on the racket frame. The videographic recordings were synchronized with the electromyographic recordings of eight muscles.

The tracking of the video-markers is in progress.

Validation of a rotation sequence for the thoraco-humeral joint during tennis forehand drive.
Description of the scapular kinematics during tennis forehand drive and service.
Quantification of the influence of tennis racket polar moment on the musculoskeletal loadings during tennis forehand drive and service.

Rogowski I, Rota S, Champely S, Genevois C, Macé P, Hautier C. (en révision). Lowering shoulder muscle activation during tennis serve by controlling racket specifications. Journal of Applied Biomechanics.
Creveaux T, Dumas R, Hautier C, Chèze L, Rogowski I. (2011) Influence of racket mass, balance and moment of inertia on shoulder loadings during tennis serve: a case study. 12e World Congress of the Society for Tennis Medicine and Science, 10-12 November 2011. Paris, France.

Sixty millions of people play tennis in more 200 countries in the World and France counts five millions of players. People who choose to play tennis appear to have significant health benefits, including improved aerobic fitness, a lower body fat percentage, a more favorable lipid profile, reduced risk for developing cardiovascular disease, and improved bone health. However, the tennis injuries are numerous. Even if a lot of factors involve injuries in upper limb, the inadequacy between the tennis racket and player characteristics is often cited in the scientific literature as a potential factor of injury risk. Despite the recent technological innovations, tennis rackets behave differently during actual play compared with the performance predicted by physics during laboratory testing. These differences in behavior show that the interactions between player and his racket must be understood in order to allow the development of some powerful and safety rackets.
Actually, few scientific studies have focused on the interaction between tennis player and racket, and they are mainly based on sensorial analysis. These sensorial analysis result in some conclusions those are difficult to transfer and generalize to the whole tennis players. The interaction between tennis player and racket is difficult because a lot of factors must be controlled and because the electromyographic and dynamic tools, actually available, are not reliable enough to study the biomechanics of the tennis player upper limb. However, a work in progress, undertaken by the three partners implied in this project, focused on the influence of three rackets, with different mass, balance and moment of inertia, on the electromyographic and kinematic parameters during the tennis serve. The preliminary results showed that the lightest racket with the balance point closer to the head, would induce the weakest muscle activity for the pectoralis major, extensor and flexor carpi radialis during the acceleration phase, and for the latissimus dorsi, superior trapezius, biceps brachii and extensor carpi radialis during the follow-through phase. In the same way, the weaker wrist and shoulder joint torques were observed for the same racket. Consequently, it is possible to study the relationship between the tennis player and racket with experimental protocols conducted in the field-conditions.
The aim of this project will be to design powerful, comfortable and safety tennis rackets. The first objective will be to develop some reliable tools to analyze the muscle activity and joint loadings as well as an innovative and original interdisciplinary methodology to study the interaction between tennis player and racket during field situations. The second objective will be the quantification of the variations in muscle activity and joint loadings of the tennis player upper limb as a function of the variations in the racket characteristics. The third objective will be to capitalize the experimental data in order to evaluate the biomechanical models, developed during the first objective of this project, and to estimate the joint constraints that would be obtained with virtual rackets or real and non-tested rackets.
This project will be developed by the collaboration between the ‘Centre de Recherche et d’Innovation sur le Sport (E.A. 647)’, the ‘Laboratoire de Biomécanique et Mécanique des Chocs (UMR-T 9406)’, two laboratories specialised in the study of human movement, and the Babolat society, French enterprise specialised in the conception, manufacture and sale of sport racket implements.
This project is being labeled by the pole of competitiveness SPORALTEC.

Project coordinator

Madame Isabelle ROGOWSKI (UNIVERSITE CLAUDE BERNARD - LYON I) – rogowski@univ-lyon1.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

LBMC - UCBL UNIVERSITE CLAUDE BERNARD - LYON I
Babolat VS BABOLAT VS
CRIS - UCBL UNIVERSITE CLAUDE BERNARD - LYON I

Help of the ANR 410,000 euros
Beginning and duration of the scientific project: - 48 Months

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