Biomechanics and Medicine in Swimming XI

An Analysis of the Underwater Gliding Motion in
Collegiate Competitive Swimmers
Wada, t. 1 , sato, t. 2 , ohishi, K. 2 , tago, t. 3 , Izumi, t. 1 , Matsumoto,
t. 1 , Yamamoto, n. 4 , Isaka, t. 5 , shimoyama, Y. 6
1 Kokushikan University, Tokyo, Japan
2 Nippon Sport Science University, Tokyo, Japan
3 Tokushima Bunri University, Sanuki, Japan
4 Japanese Red Cross Hokkaido College of Nursing, Kitami, Japan
5 Ritsumeikan University, Kusatsu, Japan
6 Niigata University of Health and Welfare, Niigata, Japan
The purpose of this study was to analyze the underwater gliding motion
in collegiate competitive swimmers. Twelve male collegiate swimmers
were monitored with a video camera (SK-2130, SONY, Japan) with a
sampling frequency of 60Hz in the sagittal plane to measure the angular
displacement of their different joints. A motion analysis system
(Frame-DIAS4, DKH, Japan) was used to digitize ten body landmarks.
The following results were obtained: the highest speed was maintained
during the gliding motion when the knee and the hip joint angles of 180
degrees were maintained from push off from the wall to 0.8sec (1.82m).
In addition, swimming speed slowed down when the involuntary movements
of flexion-extension in the knee and the hip joints were observed
during the gliding motion.
Key words: Motion analysis, underwater gliding motion, competitive
swimming
IntroductIon
In competitive swimming races, the improvement of swimming performance
is related not only to the effect of stroking but also to performance
of the start and the turn phase. Furthermore, it is important that
the momentum created by a swimmer in the forward swimming direction
is larger than in the opposite direction.
Passive drag is produced by measuring the force necessary to tow a
swimmer through the water at a constant speed with his body in a prone
position (Adrian and Cooper 1995). The underwater gliding motion
during the start and turn phases are important for the total race time
in modern swimming (Marinho et al. 2009). Recently, the development
of the swimsuit progressed rapidly. Previous studies suggested that this
new model swimsuit had an effect on the body compression and the
good streamlined posture (Chatard and Wilson 2008, Mollendorf et al.
2004, Roberts et al. 2003), and could reduce the passive drag during
the underwater gliding motion (Chatard and Wilson 2008, Mollendorf
et al. 2004). Furthermore, many companies have been developed new
product of fabrics. These swimsuits were called “high speed” swimsuits.
However, most research done by these companies, focusing on the effects
of new fabrics, is not published.
The “high speed” swimsuit were hypothesized to assist maintaining
the knee and hip joint angles of 180 degrees, consequently, swimmers
could keep a better body position and higher speed during the underwater
gliding motion.
The purpose of this study was to analyze the underwater gliding
motion in collegiate competitive swimmers and to investigate whether
wearing “high speed” swimsuit could maintain the knee and the hip
joint angles of 180 degree.
Methods
Subjects and experimental procedures: Twelve healthy male collegiate
swimmers (age 19.4±1.3yrs, height 170.0±5.0cm, body weight
67.0±4.8kg, BMI 23.2±1.5) volunteered to participate in this study. The
chaPter2.Biomechanics
subjects performed underwater gliding motion as fast as possible after
a pushoff from the pool wall. During the underwater phase of gliding
motion, the swimmer maintained streamline position (Elipot et al.
2009), and it was directed not to kick it. The head of the subjects were
completely submerged during gliding. For each subject, only the fastest
gliding motion was analyzed.
The subjects were monitored with an underwater video camera (SK-
2130, SONY, Japan, Figure 1) with a sampling frequency of 60Hz in
the sagittal plane to measure the angular displacement of their different
joints. The underwater area covered by the camera ranged from the start
wall to the 5-meter point.
Figure 1. The underwater video camera (SK-2130, SONY, Japan)
In this study, the subjects were asked to wear two different models of
swimsuits: one is made of the conventional fabrics; the other is a newly
developed, so-called “high speed” swimsuit (Figure 2 and 3, respectively).
All subjects received a written and verbal explanation of the study
and gave their written informed consent for participation. Approval was
granted from the institutional human ethics committee and the study
was conducted in conformity with the Declaration of Helsinki for medical
research involving human subjects.
Figure 2. A conventional fabric swimsuit.
The “high-speed” swimsuit: The Speedo Fastskin LZR racer (LZR) is a
fully bonded swimsuit (Figure 3). Its full-length bonded seams are ultrasonically
welded together to eliminate stitching, creating the most low
profile silhouette and reducing skin friction drag. The LZR is made from
Speedo’s own LZR Pulse material the world’s lightest woven swimsuit
fabric. It is highly compressive, water repellent, chlorine resistant and
fast drying. The LZR is equipped with original panels of ultra-thin
polyurethane membrane, precisely cut by laser, which are embedded
into the base LZR Pulse fabric. The LZR Pulse fabric was strategically
placed on important parts of the body to create a Hydro Form Compression
system that provides an optimum streamlined shape and drag
reduction for the swimmer. This system also provides a core stabilizer
built to support and hold the athlete (Speedo International Limited
2009). However, these objective data were not published.
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