Biomechanics and Medicine in Swimming XI

BiomechanicsandmedicineinswimmingXi
A Biomechanical Comparison of Elite Swimmers
Start Performance Using the Traditional Track Start
and the New Kick Start
honda, K.e. 1, 2 , sinclair, P.J. 1 , Mason, B.r. 2 & Pease, d.l. 2
1 The University of Sydney, Australia
2 Australian Institute of Sport, Australia
The international governing body for swimming ‘FINA’ has approved
the development of a new starting block (Omega, OSB11) with an inclined
kick plate at the rear of the block. The purpose of this study was to
determine the effects of the new start platform on performance relative
to that of the traditional track start. Fourteen elite swimmers completed
three ‘dive and glide’ starts using the kick plate and three traditional
track starts. Results indicated the kick start to be a significantly faster
start than the track start. The kick start was significantly faster off the
block with a higher horizontal velocity at take off and an increased on
block horizontal force. This advantage was maintained through the time
to 5 m and 7.5 m. It is recommended coaches and athletes should spend
time adapting to the new block and this new starting technique.
Keywords: biomechanics, swimming start, track start, kick start,
osB11.
IntroductIon
The goal of a swimming race is to complete the required distance in the
least amount of time, with races being won or lost by a hundredth of a
second. A race is made up of a number of key components, the free swim
(where the athlete is stroking), starts, turns and finishes. The velocity
achieved by a swimmer is greatest during the starting phase, therefore
it is important for a swimmer to maintain the velocity achieved off the
start block for as long as possible before slowing to race pace (Welcher,
Hinrichs, & George, 2008). Although the time a swimmer spends starting
is less than in the free swim and turning phases, an effective start is
important for success (Miller, Hay, & Wilson, 1984).
Researchers have broken down the swimming start into three phases
(Guimaraes & Hay 1985; Schnabel & Kuchler 1998). Block time (start
signal until toes off block) flight time (time spent in the air), and underwater
or glide time (from water entry until first kick). Swimmers
can only attain maximum performances during the start phase if they
are able to skilfully execute all three phases (Schnabel & Kuchler 1998).
The performance measure of a start is usually set to time to 15 m
(Cossor & Mason 2001), incorporated in this is the block time, flight
time and the water time (Guimaraes & Hay 1985). Ruschel et al, (2007)
suggest that water phase is intimately connected to the individual characteristics
of each subject, like the streamline position and the underwater
stroke technique used, being influenced by several factors and actions
that happen from the instant of entry in the water to the beginning of
the first kicking and the first stroke movements. A study by Guimaraes
and Hay (1985) observed 94% of the variance in start time was attributed
to the water time.
The requirements for a superior start include a fast reaction time,
significant jumping power, a high take-off velocity and a decrease in
drag force during entry. A low resistance streamline position during underwater
gliding to minimize the loss of horizontal velocity as well as
an increase in propulsive efficiency during the transition stage can assist
in a superior start (Schnabel & Kuchler 1998; Breed & Young 2003).
Over the last 40 years, the swim start technique has continued to
evolve, from the conventional or arm swing start to the grab start and
the track start. In the late 1970’s the track start debuted and has gained
in popularity and proven successful in international competition. The
track start has one foot at the front edge of the block, the other placed
94
towards the back on the starting platform with hands grabbing the front
edge of the block. Due to these changes in the swimmers foot placement,
the track start employs a wider base of support than the grab start
resulting in greater stability for the swimmer (Shin & Groppel, 1986;
Breed & McElroy, 2000).
In 2009 a new starting technique has developed with the introduction
of an incline or ‘kick’ plate mounted to the start platform. This newly
designed start block by Omega (OSB11, Corgémont, Switzerland, Figure
1), has the international governing body for swimming ‘FINA’ approval
and has allowed the development of the kick start. The kick start
is essentially a modified track start that allows the rear foot to be raised
off the platform and placed upon a kick plate. The kick plate is angled
at 30 deg to the surface of the block and can be moved through five
different locations on the starting platform. Omega claims that “tests
undertaken by top level swimmers showed faster races versus a standard
block” however no data was provided to support this statement. To date,
no study has examined the biomechanical factors associated with a successful
start using the OSB11. Hence the purpose of this study was to
determine the effects of the new angled start platform on performance
relative to that of the traditional track start. This study hypothesized
that the kick start would increase the amount of horizontal force being
applied, enabling faster start times and greater horizontal velocity when
compared to the track start.
Methods
The subject cohort for this study consisted of fourteen elite swimming
subjects (9 male aged 20.8 ± 3.0 years, 5 female aged 21.4 ± 2.8 years)
all of which were members of the Australian Institute of Sport (AIS)
Swim Team. All participants had personal best times which attained a
minimum of 850 FINA points (http://www.fina.org/swimming/FINA
points/index.php). The experimental procedure was approved by the
AIS ethics committee.
The participants completed a warm up, based around their pre-race
routine which consisted of some sprint and dive drills to ensure the athlete
was ready to perform at their maximal capacity. Before the commencement
of the testing session their weight was obtained using the
force platform built into the start block. This was used to normalise the
force data.
Normal competitive starting procedures were used for each trail. The
participants were instructed to perform a maximal effort dive and glide
until their forward momentum ceased, while not kicking or swimming.
The participants completed three ‘dive and glide’ starts using the kick
plate in their preferred position and three traditional track starts, in a
randomised sequence.
‘Wetplate’ is the proprietary system used to analyse the starts. It is