Biomechanics and Medicine in Swimming XI

The Swimming Speed Meter showed that swimming speeds increased from 2.5m·s for
2005 to 2.7m·s -1 in 2009 (during the second kick phase). Distance per stroke (DPS)
increased to 2.204m±0.131 for 2009, from 1.894m±0.062 in 2005 (m) Wicoxon.:
p=0.006061, 1 stroke (velocity) Wicoxon.: p=0.7748) (Figure 3.). Four phases of the
2009 and 2005’s velocity results were not significantly different (the first kick phase
Wilcoxon: p=0.64850, insweep phase Wilcoxon: p=0.16360, upsweep and second kick
phase Wilcoxon: p=0.00606, wave phase Wilcoxon: 0.10910.
Vel oci t y ( m/ sec)
1. 2 1. 4 1. 6 1. 8 2. 0 2. 2 2. 4
first kick phase insweep phase
upsweep and second
kick phase
| | | | | | | |
Figure 3. Four phase of velocity 2005 and 2009 using the Wilcoxon.
wave phase
2005 2008 2005 2008 2005 2008 2005 2008
Figure 3. Four phase of velocity 2005 and 2009 using the Wilcoxon.
Table 1. Knee-bend
2009 2005
Straight knee (+170 degrees) 55%(39/71) 39%(26/66)
Bent knee (-170 degrees) 45%(32/71) 61%(40/66)
In 2006, Kawamoto changed his stroke technique to a straighter knee
angle ,defined as 170 degrees to 180 degrees (+170 degrees) and 55% of
the stroke cycle was spent within this ‘degree of bend’ for 2009 whereas
it was only 39% in 2005 (Table 1.). Therefore, 2009’s stroke, with the
straight knee technique, decreased the resistance during his stroke and
as a result, increased his distance per stroke and maximum speed.
dIscussIon
Based on the above evidence it is clear the most preferred butterfly
technique is to use a straight knee kick. The men’s 100 butterfly world
record holder, Michael Phelps employed this stroke technique with the
straighter knee (+170 degrees) and 49.6% of the stroke cycle was spent
within these ‘degrees of bend’. Mike Cavic, 2nd in the men’s 100 butterfly
2008 Olympic Games, employed the straight knee kick and 55% of
his stroke cycle was at >170 degrees knee-bend. The men’s 100 butterfly
former world record holder, Ian Croker employed showed 48% of his
stroke cycle t be at >170 degrees knee-bend. Since 2006, we employed
a four step training plan in practice and in swimming competition
(Ide, 2009). In the first step, we imagined the straighter kick on land.
On land, we focused on the butterfly straight leg kick, stretching the
tendon of the tibialis anterior muscle rather than using the quadriceps
muscles (Huijing, 1992). When Kawamoto used this stretched tendon
in a similar way in the butterfly straight leg kick, the kick frequency was
much more rapid (Hosokawa, 2009). The second step was to utilize the
straight leg kick in the pool, and this involved slow speed drills during
training. We changed his technique during training, so these drills involved
swimming no more than 3500m. If he swam more than 3500m
he had a tendency to bend the knees and move the upper body too
much. Also, these sessions were performed just once a day. The third step
was to test the technique in a minor meet. After the race, we checked
these techniques by the video camera. Then we would check these techniques
from the minor meet and insure they are correct in preparation
for the next step. The fourth step was the major meet, which will be the
Olympic Trials, World Championship Trials, Japan Nationals, World
Championship, East Asian Games or Japan Open. His training partner
won and set a meet record at the 2009 US Junior Nationals men 100Fly.
chaPter4.trainingandPerformance
conclusIon
This study analyzed the butterfly stroke technique of Japan’s 100 meter
butterfly record holder. Kawamoto improved his performances, due
to three possible reasons: 1. increased maximum speed, from 2.5m·s -
1 to 2.7 m·s -1 . 2. increased distance per stroke, from 1.894m±0.062 to
2.204m±0.131 . 3. Use of the straight knee dolphin kick.
reFerences
Huijing P. A. (1992). Mechanical muscle models. In: Strength and power
in sport (Komi P. V. ed.). Blackwell Scientific Publications, Oxford.
Hosokawa K., Takise M., Kawakami T., Matsumoto K., Ito S., Koshiba
Y., Ide T., (2009). Effect of the Tendon Hold to Rat Rear Reg. The
64th Annual Meeting of the Japanese Society of Physical Fitness and
Sports Medicine, Niigata, Japan.
Ide T., Yoshimura Y., Kawamoto K., Takise M., Kawakami T., (2009).
How to Coach Butterfly. 2009 Japan Society of Sciences in Swimming
and Water Exercise, Kanagawa, Japan.
Japan Swimming Federation, Japan Swimming Club Association
(2006). Coaching Manual, Taishuukann sho-ten.
Loebbecke, A. V., Mittal, R., Fish, F., Mark, R. (2009) A Comparison
of the Kinematics of the Dolphin Kick in Humans and Cetaceans.
Human Movement Science 28, 99-112.
Maglischo EW (2003). Swimming Fastest. Champaign: Human Kinetics.
Yoshimura Y., Kosuge T. (2008). Science of Swimming. NHK books, 75-
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Yoshimura Y., Takahashi Y. (1996). Swimming. Ikeda-shoten, 60-61
Yoshimura Y., Tanaka T., Oishi K., Yasukawa M., Matsuo A. (2007).
Characteristics of Butterfly Stroking Skill in Elite Swimmers Detected
by Means of a Speed Meter. ACSM 54th annual meeting.
AcKnoWledGeMents
I would like to express my heartfelt appreciation to the many people who
supported this research. Thanks to the Tokyo Institute of Swimming
Science, who allowed us to use Kawamoto’s data since 2005. They had
control of the Swimming Speed Meter. Also Mr. Tetsuya Tanaka, who
was calculated Kawamoto’s data with the Wicoxon Signed Ranked Test.
And Hamamatsu Photonics K.K. (Hamamatsu Swim Stroke Watcher)
Mr. Takehiro Kurono, who had supported Kawamoto’s race data.
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