OPTIMUM SPORTS TECHNIQUE OF THE PUSH-OFF MOVEMENT IN DIFFICULT ARMSTAND DIVES
Keywords: diving, push-off, kinematography, dynamography, simulation, angular momentum
AbstractINTRODUCTION: In 1994 the FINA decided to abolish the table’s of degree of difficulties limitation and to incorporate armstand dives with a back somersault. This is the reason for a forced performance development, especially performing armstand dives with a back somersault. The possibilities for optimum performance of the push-off movement are not yet exhausted, however. That is indicated, for example, by comparisons with the push-off in artistic gymnastics flic-flac. Therefore an additional enhancement of difficulty can be expected. METHODS: Our study on armstand dives was performed using the example of armstand back three somersaults tucked (626c). We used video recordings from the four countries competition between the USA, China, Russia and Germany, held in 1996 in Leipzig, and analyzed them with a 2D-photogrammetric procedure. The push-off phase was examined additionally with a force platform (Kistler) at a pit filled with soft plastic foam. For our analysis we used the Alaska computer simulation system (1993). The angular momentum about the transversal axis, the flight height and the joint torques were monitored as main parameters. Angular momentum is related to unified body height and body mass values. RESULTS: The optimization of somersault angular momentum and driving height, a principal movement task during the take-off or push-off to a somersault, concentrates in armstand dives on the maximization of angular momentum. The driving height ranged only a little above zero. — At the moment the major portion of angular momentum is generated by flexing and extending the knee joint. However, it is to be expected that in the near future judges will punish divers for this knee bending with lower scores. An alternative sports technique could consist of a longer falling backward of the straight body around the wrist, a minor elbow bending and the utilization of the arched posture. This push-off technique provides greater angular momentum, but requires a higher level of strength abilities, as shown in the values of joint moments. CONCLUSIONS: A more complete utilization of the available joint angle amplitude, above all in the loins area, can increase angular momentum about the transversal axis. This push-off technique requires a higher conditional level. Thus even more difficult armstand dives with a back somersault, for example by the integration of twists or by piked-stretched executions, can be created and performed. REFERENCES: Alaska (1993). Software for Simulation of Multi Body Systems. User Manual. Institute of Electromechanics, Technical University of Chemnitz-Zwickau. Miller, D. I., Hennig, E., Pizzimenti, M. A. (1989). Kinetic and Kinematic Characteristics of 10-m Platform Performances of Elite Divers: I. Back Takeoffs. Int. J. of Sport Biomech. 1, 5, 60-88
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