BACK-PLATE STARTING PLATFORM HAS ADVANTAGES OVER THE CONVENTIONAL PLATFORM
Nomura, T., Takeda, T., & Takagi, H. (2010). Influences of the back plate on competitive swimming starting motion in particular projection skill. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.
This study identified the influences of the back plate on the swimming starting motion and in particular, the projection skill. Male college swimmers (N = 10) performed the track start from the conventional platform and the platform with a back plate. A video camera was used to record the performance of each trial from the side view. The projection motion was divided into the set position, acceleration phase, take-off, and flight phase. Fifteen variables were analyzed
At the set position, the back-plate position of the center of mass was significantly more forward than the conventional position. The back-plate rear-leg knee angle was significantly smaller than on the conventional platform. The back-plate projection angle while still in contact with the platform was significantly more horizontal than the conventional projection angle. At take-off, the projection angles of the centers of mass were ~-8.2° for the back-plate and ~ -10.5° for the conventional platform. The vertical velocity components of the center of mass at the take-off were ~ -0.65 m/s for the back-plate platform and ~ -0.81 m/s for the conventional platform. Other items for the take-off and for flight were not significantly different.
At the set position, the center of mass of the back-plate position displaced forward. That is in agreement with a study of the squatting-to-standing movement where heel elevation primarily influenced postural adjustment as anterior displacement of the hip. In the back-plate position, the rear knee angle was about 90°. The isometric force-angle relationship of knee extension produces largest forces were between 105°-120°. Therefore, the rear knee of the back-plate position should possibly be more extended.
Implication. The back-plate starting position produces a more horizontal flight angle and initially positions the swimmer slightly more forward than that exhibited with the conventional flat-angled starting platform.
Return to Table of Contents for Biomechanics of Swimming.