The running forward springboard approaches of 20 divers on the U.S. senior national diving team were analyzed using planar video analysis and accelerometer output; the purpose was to investigate kinematic responses of the springboard tip and divers' lower extremities to alterations in fulcrum setting. Divers executed jump takeoffs from a 1-m springboard with the fulcrum at their preferred setting as well as 0.144 m (two fulcrum numbers) forward and 0.144 m back from that location. Potential advantages of setting the fulcrum back further from the tip (as opposed to closer) included greater downward board tip vertical velocity at the beginning of takeoff, more time to generate angular momentum, and increased vertical velocity going into flight. However, setting the fulcrum further back required the diver to achieve longer hurdle flight durations and to reverse downward motion from a more flexed knee position. Accelerometer output in the absence of video was not beneficial as a means of providing immediate performance feedback for coaching purposes.
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Influence of Fulcrum Position on Springboard Response and Takeoff Performance in the Running Approach
Ian C. Jones and Doris L. Miller
Kinetic and Kinematic Characteristics of 10-m Platform Performances of Elite Divers: I. Back Takeoffs
Doris I. Miller, Ewald Hennig, Marc A. Pizzimenti, Ian C. Jones, and Richard C. Nelson
Reaction forces elicited from the 10-m platform by the 29 male and 26 female competitors in the Fifth World Diving Championships during the takeoffs for dives from the back group were analyzed and related to their patterns of motion. Major changes in linear and angular momentum occurred during the final period of upward acceleration. During this “final weighting” phase, maximum vertical reactions of 3.0 to 4.0 times body weight (BW) and maximum horizontal reactions in the “propulsive” direction of 0.5 BW were recorded. Further, the moment of vertical platform reaction with respect to the center of gravity, which was dominant and promoted backward rotation, was opposed by the moment of the horizontal component. At final contact with the platform, higher vertical velocities were more evident for back dives than multiple back somersaults, and for dives performed in tuck than in pike, and in pike than in straight positions.
Kinetic and Kinematic Characteristics of 10-m Platform Performances of Elite Divers: II—Reverse Takeoffs
Doris I. Miller, Ian C. Jones, Marc A. Pizzimenti, Ewald Hennig, and Richard C. Nelson
Takeoffs for 10-m platform dives from the reverse group at the 1986 World Championships and 1989 FINA Cup were analyzed to provide insights into their kinetic and kinematic characteristics. As with back takeoffs, the major changes in both linear and angular momentum occurred during final weighting (i.e., upward acceleration). Vertical velocities at last contact were higher for reverse dives than reverse multiple somersaults, and different moment-of-force patterns were associated with increased rotational requirements. Last-contact vertical velocities were less for reverse rotating dives than corresponding dives from the back group. Although last-contact horizontal velocities for the two groups were not statistically different, the horizontal acceleration patterns of the three composite body segments were near mirror images of one another. Finally, implications of a resultant head velocity of 10 m/s when passing the leading edge of the platform in reverse multiple somersaulting dives were considered.