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11:30   Kinematics in soccer and tennis Chair: Dirkjan Veeger 11:30 20 mins A SIMULATOR DEDICATED TO STRENGTHENING EXERCISES FOR WINDSURFERS Nazim Ouadahi, Samir Chadli, Amina Ababou, Noureddine Ababou Abstract: A simulator consisting of a home-made training apparatus linked to a virtual reality system VRS has been developed in our laboratory. The training apparatus allows working out specific muscle groups. The mechanical part of the simulator followed the structure of a sailboard. A digital simulation consisting of high graphic quality video game was displayed on a screen located at the left of right side of the user. It represented a sailboard on water moving faster as the force applied by the athlete increased. In addition, an audio system and a fan were used to increase the presence. Two sets of measurements were carried out on nine participants (three windsurfers and six non-windsurfers), without and with the VRS in operation. The participants were first asked to perform a pumping exercise during 2mn without the virtual reality system. The force developed by each subject was measured and both heart rate and duration were recorded at the end of the pumping session. After a rest, the same exercise was accomplished with the virtual reality system in operation. The results showed an increase in motivation reflected by a enhancement of heart rate response and cadence of pumping for all the participants with virtual reality system operating when compared to the first case. All users felt more fun when using the training apparatus interfaced with the digital simulation than without. 11:50 20 mins KINETIC ANALYSIS OF INSTEP AND SIDE-FOOT KICK IN FEMALE AND MALE SOCCER PLAYERS Keiko Sakamoto, Naoki Numazu, Sungchan Hong, Takeshi Asai Abstract: The technical level of women’s soccer is rising every year. Consequently, there is great demand for improving kicking techniques to enable faster shooting and passing. However, most previous research on kicking techniques has focused on male soccer players (Levanon and Dapena, 1998, Nunome et al., 2002). The purpose of this research was to clarify the technical characteristics of the swinging motion performed by female players by comparing the instep and side-foot kicking movements of female and male soccer players, as well as to consider technical factors for increasing the ball velocity for female players. Twenty-six participants (6 female and 6 male players) were requested to perform instep kicks with maximum effort, and their kicking movements and the corresponding ground reaction forces were captured using a three-dimensional motion capturing system (250 Hz) and force plate (1000 Hz), respectively. In comparison, the average ball velocity for two types of kicks were lower for female players than for male players, and the differences were statistically significant (p < .05). One major reason for this finding may be the players’ average foot swing velocity, which was significantly lower for the females than for the males (p < .05). In addition, we examined technical factors that contribute to increasing foot velocity. 12:10 20 mins THE DEVELOPMENT OF A METHODOLOGY TO DETERMINE THE RELATIONSHIP IN GRIP SIZE AND PRESSURE TO RACKET HEAD SPEED IN A TENNIS FOREHAND Jonas Christensen, Ben Halkon, Sekiya Kioke, John Rasmussen Abstract: Research Question: Is it possible to develop a methodology to examine the effects of changing grip size and grip firmness on the kinematic contribution of angular velocity (-KCAV) to the generation of racket head speed during a topspin forehand? Research Method: One elite male tennis player (age 24, weight 63 kg, height 1.83 meters) was recruited in this study. Two Babolat Pure Storm GT rackets with gip size 2 and 4 were used. Tekscan 9811E pressure sensors were used to examine pressure distribution variation on racket handles. Upper body kinematic data was obtained by using a Vicon motion capture system. Right arm and trunk kinematic data were analyzed. The study was conducted in a controlled laboratory environment. 100 topspin forehands were performed, of which 9 topspin forehands were discarded. Results: A firm grip condition led to a general increase in average racket head speed across grip sizes compared to the average racket head speed using a normal grip. A trend in negative linear relationships were found between upper trunk and shoulder joint in KCAV across all conditions. Using the smaller grip, also led to a trend in negative linear relationship between shoulder joint and wrist joint in KCAV across grip conditions. Grip pressure for grip size 2 showed the same pattern from the start of the forward swing until the point of impact across all gripping conditions. From 50-75% of completion in forward swing, the pressure difference due to grip firmness decreased. The mean time integrated pressure resulted in an increase in pressure during the firm gripping condition compared to the normal gripping condition. Conclusion: This study managed to quantify the KCAV whilst performing a topspin forehand, with respect to changing of grip size and grip pressure in an elite male tennis player. General significance: Increase knowledge in grip effects on racket head speed and KCAV. Leading to a potential increase in racket player fit.