Background: We focused out analysis on the straightness of the knee for the butterfly kick. Our analysis show that the butterfly kick is more efficient when the swimmers body
maintains the most horizontal position as possible during the arm stroke. When comparing former World record holders angle of butterfly kick, we found that the extent to the straightness of their
butterfly kick improved the performance. We changed this to a straightness knee butterfly kick with less knee-bend. The former World record holder improved 50 meter butterfly time from 2011 through
2013 in FINA (Federation Internationale de Natation Amateur) governing body swim meet. The subject swam 22.05 was, 1st in FINA World ranking 2013 Men’s 50 Butterfly. The subject had result 1st place
in 50 meter butterfly prelim in 2013 FINA World Championship in Barcelona, Spain. The results employed all straightness knee butterfly kick are less resistance equal to increase the distance per cycle
in the championship meet races.
Methods: The subjects, the Olympic champion, 4 time Olympian, former 50 meter butterfly World record holder, and former Men’s 50 meter butterfly World record holder volunteered to
participate in this study. The Race Analyzer analyzed time, split, cycles, tempo, DPC (distance per cycle), velocity, turn time, 15 meter start time, and 15 meter velocity. The subject strokes angle
of degree was analyzed with DartTrainer and Kinovea (0.8.15, 1GHz, 256Mo) in regards to the bending of the knee and upper body movement. A Swimming Speed Meter (Vine, VMS-003, AC100V, 1/500sec,
0.2mm/pulse) using a wire attached to the swimmer, exported the analogue signals via an RS232C post to a computer. To compare the mean values of the different variables assessed, Friedman test was
used as well as the Wilcoxon signed rank test to assess the differences between them. The level of statistical significance was set at P ≤0.05
Results: Race Analyzer shows the former World record holder distance per cycle improved from 1.79M/C for 2005 to 1.87M/C for 2013 and Asian record holder distance per cycle was
1.89M/C for 2005 to 2.20M/C for 2013 in championship meet. DartTrainer and Kinovea showed the straight knee considered when of >170 degrees knee-bending, former World record holder 57.9% use of
straight knee kick for 2013 and 42.6% for 2005, Wilcoxon/Mann-Whitney.: 1.999831, p=0.0455. Asian record holder 55% use of straight knee kick for 2009 and 39% for 2005, Wilcoxon/Mann-Whitney.:
0.919703, p=0.3577 in the one stroke.
Conclusions: The aim of this study was based on the above evidence it is clear the most preferred butterfly technique is to use a straight knee kick. In the championship meet, Asian
record holder, the distance pre stroke (DPS) results were different resulting in a, 2.204m±0.131 for 2009 and 1.894m±0.062 for 2005 (DPS (m) Wicoxon.: p=0.006061, 1 stroke (velocity) Wicoxon.:
p=0.7748). This study analyzed the butterfly kick technique of former world record holder and Asian record holder and found butterfly performance significantly improved to an increase in distance per
stroke and reducing resistance compared to a bending knee butterfly kick.