Measuring the vibrations of a racket handle and the wrist joint in the tennis forehand drive

Abstract

s-International Society of Biomechanics XIII Congress 1991 719 MEASURING THE VIBRATIONS OF A RACKET HANDLE AND THE WRIST JOINT IN THE TENNIS FOREHAND DRIVE Ryoso Tomosue, Yoshiteru Mutoh, Keiko Yoshinari and Yoshihiko Kawaxoe Department of Sports Sciences, College of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, JAPAN. The present study was designed to measure the vibrations of a racket handle and the wrist joint simultaneously from the view point of inducing upper extremity injuries. Seven Dunlop tennis rackets with different frame body width, face area, flexibility and string tension were selected. All rackets have the same weight and grip size. A male tournament player stroked flat forehand drives. The amplitude magnitude was defined as the difference between the positive and negative peaks of the vibration immediately following impact. In the case of the center impact, the amplitude magnitudes of the wrist joint were so small as to be a one-tenths of that of the racket handle. The high frequency vibrations were evident only on the racket handle. In the case of the off-center impact, the amplitude magnitudes of the wrist joint and the racket handle showed 1.9-3.1 times and 1.3-1.6 times of those of the center impact, respectively. When comparing these seven rackets, there were no significant differences in their vibration responses for both a racket handle and the wrist joint. LONGITUDINAL STUDY ON SELECTED SPORTS PKRFORMANCE RELATED WITH THE PHYSICAL GROWTH AND DEVELOPMENT IN TWINS. T.Goya, YAmano, T.Hoshikawa and H.Matsui Department of Physical Education Aichi University of Education, Kariya, AICHI 448, JAPAN The purpose of this study was to evaluate the similarity and dlfferentia of the characteristics and selected sport performances (running, throwing and swimming) in MZ and DZ twins. Furthermore a significance of the heritability and trainability in determining the individual variation of those parameters by means of longitudinal design. The data for this experiments of motor patterns were obtained by cinematographic and video taped procedure. Comparison of the differences between MZ and DZ twins were made by intrapair difference (X) . Anthropometric parameters, except body weight, were significant differences between MZ and DZ twins in the series of the growth and development respectively. Aerobic power for physical working capacity might be relied on the difference of the usual physical activities. Kinematic variables in running were related with genetic factors based on the discussion of intrapair difference and motor patterns between MZ and DZ twins. However, Motor patterns and Kinematic variables in throwing and swimming performance seemed to be influenced by a total amount of individual activities and experiences, especially by learning and training. THE DETERMINATION OF THE SUBTALAR PRONATlON AXIS OF ELITE HIGH JUMPERS ATTOUCH-DOWN BEFORE TAKE-OFF: A THREEDIMENSIONAL CINEMATOGRAPHICAL APPROACH Van Gheluwe and E. Deporte Laboratory of Biomechanics, Vrije Universiteit Brussel, BrusselsBelgium Aithou determined a h the orientation and positition of the subtalar pronation axis has been ‘g undantly in literature, it has never been determined during a highly dynamic movement such as high jumping. As force plate data and high speed video pictures recorded during competition, est excessive loads on the lower extermities at take-off, it is assumed that the sug subta ar ? pronation axis during ground contact may shift consrderabiy from the conventlanai orientation andposition. Threedimensional high speed cinematography, at 500 frames a second, was used to reconstruct the movement of the lower leg of elite high jumpers in aotion. The results of this study show pronation axes oriented somewhat differently from what is usually found in literature. This will have to be taken in account when developing biomechanical models in order to evaluate joint forces and moments of the ankle joint.