Studying water polo for kicks

Date:
August 25, 2020
Source:
University of Tsukuba
Summary:
Scientists measure the propulsive force of water polo players
executing highly efficient 'eggbeater' kicks, paving the way to
improved sports performance and new undersea transportation methods.



FULL STORY ========================================================================== Researchers at the University of Tsukuba used high-speed cameras
and pressure sensors to quantify the force created by water polo
players during kicking motions. They found that the high efficacy
of the "eggbeater" technique exceeds the predictions of conventional biomechanical theories, which may be due to turbulent water flow. This
research may help improve our understanding of both the biophysics of
sports, as well as lead to new ways to travel through the water more
easily.


========================================================================== While polo played with horses may seem genteel and relaxing, the same
cannot be said of water polo. It is a grueling competition in which
players must constantly expend energy just to stay in a position to
catch or throw the ball.

A common swimming technique that allows players to tread water while
upright is called an "eggbeater" kick, in which the legs make large
circles, just like the kitchen gadget. In fact, they spend about half
their time in the water performing this motion, which allows players to
elevate themselves from the surface without becoming exhausted.

To understand why this method is so efficient, researchers at the
University of Tsukuba studied six male water polo players.

"Sports are often a good place to look for highly optimized techniques,"
Senior author Professor Hideki Takagi says. "We captured the kicking
motions using three high-speed cameras, and we attached four pairs of
pressure sensors to the dorsal and plantar surfaces of each participant's
right foot." The video recording allowed the scientists to know the
position, velocity, and acceleration at each moment of time, and the
force could be calculated using the pressure sensors.

Surprisingly, the researchers found that the force created by the
eggbeater kick was greater than would be expected if one just applied
Newton's laws and hydrodynamics. "Our study hints that water polo players
are actually taking advantage of complex physics, including unstable
vortices, to achieve this increased efficiency," explains Professor
Takagi. "In addition to improving sports performance, the results of
this research may lead to optimized underwater propulsion."

========================================================================== Story Source: Materials provided by University_of_Tsukuba. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Eisuke Kawai, Takaaki Tsunokawa, Hiroyuki Sakaue, Hideki Takagi.

Propulsive forces on water polo players' feet from eggbeater kicking
estimated by pressure distribution analysis. Sports Biomechanics,
2020; 1 DOI: 10.1080/14763141.2020.1797152 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200825110735.htm

--- up 1 day, 6 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)