TURN VELOCITY IS INFLUENCED BY PUSH OFF THE WALL AND STREAMLINE

Zamparo, P., Vicentini, M., Zorzi, E., Scattolini, A., Rigamonti, A., & Bonifazi, M. (2010). The interplay between leg kick efficiency and pushing phase acceleration in determining the "turning speed" in front crawl swimming. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 1619, 2010.

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This study focused on the contribution of acceleration during the pushing phase and of the efficiency of the underwater undulatory movement in determining the time taken to cover the first five meters after the turn in a simulated 100 m race conducted in a 50 m swimming pool. Elite swimmers of the Italian National Swimming Team (M = 4; F = 1) and swimmers competing at local/national level (M = 3; F = 4) served as Ss. Ss swam the 100 m distance as fast as possible. During this simulated race, the velocity in the first five meters after the turn (v50-55) was measured. In other repetitions, the average acceleration during the push ("Apush", an index of the force exerted during the push) was calculated based on data from an underwater video camera. In these experiments, Ss were asked to only glide after the pushing phase. In other tasks, Ss were asked to swim underwater using undulatory kicking while passing in front of an underwater video camera in order to calculate the Froude efficiency of the leg kick (nF).

Average velocity in the first five meters after the turn was ~3.09 m/s. Average acceleration during the push (Apush) was ~2.80 m/s/s. The Froude efficiency of the dolphin kick (nF) was ~0.67. There was a significant relationship between v50-55 and nF (r = 0.704) as well as between v50-55 and Apush (r = 0.680). A multiple regression analysis indicated that these two factors explained 73% of the variability of v50-55 after a turn.

Implication. The explosive nature of the push off the wall (Apush) and the streamline position of the swimmer (nF) are related to turning velocity over the first five meters in sprint swimming. Both factors should be emphasized as part of training content.

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