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Abstract

As sprint swimming events can be decided by margins as small as .01 s, thus, an effective start is essential. This study reviews and discusses the ‘state of the art’ literature regarding backstroke start biomechanics from 23 documents. These included two swimming specific publications, eight peer-reviewed journal articles, three from the Biomechanics and Medicine in Swimming Congress series, eight from the International Society of Biomechanics in Sports Conference Proceedings, one from a Biomechanics Congress and one academic (PhD) thesis. The studies had diverse aims, including swimmers’ proficiency levels and data collection settings. There was no single consensus for defining phase descriptions; and kinematics, kinetics and EMG approaches were implemented in laboratory settings. However, researchers face great challenges in improving methods of quantifying valid, reliable and accurate data between laboratory and competition conditions. For example, starting time was defined from the starting signal to distances as disparate as ~5 m to 22.86 m in several studies. Due to recent rule changes, some of the research outcomes now refer to obsolete backstroke start techniques, and only a few studies considered the actual international rules. This literature review indicated that further research is required, in both laboratory and competition settings focusing on the combined influences of the current rules and block configuration on backstroke starting performances.
Journal of Human Kinetics volume 4 2/2014, 7-20 7
Section I Kinesiology
1 - Centre of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal.
2 - Porto Biomechanics Laboratory, University of Porto, Porto, Portugal.
3 - Centre for Aquatics Research and Education, Institute for Sport, Physical Education, and Health Sciences, The University of
Edinburgh, Edinburgh, UK.
4 - Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, Sydney, Australia.
.
Authors submitted their contribution of the article to the editorial board.
Accepted for printing in Journal of Human Kinetics vol. 42/2014 on September 2014.
The Backstroke Swimming Start: State of the Art
by
Karla de Jesus1, Kelly de Jesus1, Ricardo J. Fernandes1,2, João Paulo Vilas-Boas1,2,
Ross Sanders 3,4
As sprint swimming events can be decided by margins as small as .01 s, thus, an effective start is essential.
This study reviews and discusses the ‘state of the art’ literature regarding backstroke start biomechanics from 23
documents. These included two swimming specific publications, eight peer-reviewed journal articles, three from the
Biomechanics and Medicine in Swimming Congress series, eight from the International Society of Biomechanics in
Sports Conference Proceedings, one from a Biomechanics Congress and one academic (PhD) thesis. The studies had
diverse aims, including swimmers’ proficiency levels and data collection settings. There was no single consensus for
defining phase descriptions; and kinematics, kinetics and EMG approaches were implemented in laboratory settings.
However, researchers face great challenges in improving methods of quantifying valid, reliable and accurate data
between laboratory and competition conditions. For example, starting time was defined from the starting signal to
distances as disparate as ~5 m to 22.86 m in several studies. Due to recent rule changes, some of the research outcomes
now refer to obsolete backstroke start techniques, and only a few studies considered the actual international rules. This
literature review indicated that further research is required, in both laboratory and competition settings focusing on the
combined influences of the current rules and block configuration on backstroke starting performances.
Key words: Biomechanics, dorsal starts, starting technique, starting variant, literature review.
Introduction
The total swimming race time is the sum
of the starting, stroking and turning times
(Guimarães and Hay, 1985). The start is the
swimming race fastest part (Thow et al., 2012)
and, if performed effectively, can influence race
finishing position (Arellano et al., 2003; Cossor
and Mason, 2001; Girold et al., 2001; Thanopoulos
et al., 2012). In fact, nearly all the small temporal
differences in the short distance events (i.e., 50 m
and 100 m) might be explained by the starting
efficiency (Ikuta et al., 2001). For instance, at 15 m
after the start, the second-place finisher of men’s
100 m backstroke at Barcelona 2013 Swimming
World Championships was 0.20 s slower than the
eventual winner, and the final race time difference
was 0.19 s. The importance of the start is
emphasized further in that the time differences
between individual international level swimmers
at 15 m after the start can vary by 0.30 s in the
same race (Vantorre et al., 2010).
Backstroke is the only competitive
swimming technique in which the swimmer starts
in the water. In accordance with the backstroke
start rules at the Federation Internationale de
Natation (FINA) from earlier 1960s to 2005,
swimmers grasped the handgrips and placed their
entirely immersed feet on the wall. Gripping one’s
toes on the pool gutter was not allowed. FINA
8 The backstroke swimming start: state of the art
Journal of Human Kinetics - volume 42/2014 http://www.johk.pl
backstroke start rules for feet positioning were
modified by the National Collegiate Athletic
Association (NCAA) from the early 1960s to 1990
to allow swimmers to curl their toes over the
starting wall gutter. However, from 1991 to 2006
the feet positioning was restricted to underwater.
This modification was made to prevent injuries in
competitive swimming involving backstroke
starts (Cornett et al., 2011). From 2005, FINA
established that swimmers must position their
hands on the starting grips and their feet totally or
partially immersed or entirely out of the water
without using the gutter (SW 6.1, FINA, 2005-
2009). The alleged advantages of feet placed high
on the wall to generate greater horizontal take-off
velocity (de Jesus et al., 2011a; 2013; Nguyen et al.,
2014), vertical peak force (Nguyen et al., 2014),
and consequently faster start times (Nguyen et al.,
2014), might be considered the main reason for
the respective rule adaptation. After the 2008
Olympic Games, the FINA approved a new
designed starting block (OSB11, Corgémont,
Switzerland), which included a back plate and
three different backstroke start handgrips (i.e.,
two horizontal and one vertical) (FR 2.7, FINA
2009-2012). Recently, a non-slip wedge was
authorised by FINA for feet placement during
backstroke starts (FR 2.7, FINA, 2013-2017).
Despite the controversies between ruling
authorities, and considerable swimming and
facility backstroke start rule changes recently
authorized by FINA, researchers have mainly
attempted to analyse the ventral start
biomechanics (e.g. Takeda et al., 2012). The
greater quantity of ventral start studies is firstly
justified by the greater quantity of events that
begin from a starting block rather than in water
(Theut and Jensen, 2006). Also, prior to recent rule
changes, some controversies were possible with
the dorsal, in-water start positions performed
under the FINA rules (Vilas-Boas and Fernandes,
2003) and the difficulties concerning the
underwater experimental set-up arrangements.
Cornett et al. (2011) mentioned the non-existence
of documented catastrophic injuries in
competitive swimming backstroke starts as one
reason for the scarce research. The backstroke
start has been considered a more difficult and
complex movement than the ventral techniques
(de Jesus et al., 2011a; 2013; Nguyen et al., 2014;
Takeda et al., 2014). It involves different skills to
achieve the mechanical goals (de Jesus et al.,
2011a; 2013; Maglischo, 2003; Nguyen et al., 2014;
Takeda et al., 2014) and more scientific evidence is
required.
The importance of swimming starts for
enabling backstrokers to improve overall
performances due to swimming rule changes and
starting block modifications, makes it a valuable
process to synthesise the scientific knowledge
relating to backstroke starts. Literature reviews
published regarding ventral start techniques were
conducted by Vilas-Boas and Fernandes (2003)
and Vantorre et al. (2014). This paper reviews the
‘state of the art’ regarding the biomechanics of
backstroke starts. It underscores the gaps in and
limitations of existing knowledge, and presents
topics for future research to enable coaches and
swimmers to better refine backstroke start
training.
Material and Methods
Search strategy
The literature search was performed using
PubMed, SportDiscus™, Scopus and ISI Web of
Knowledge electronic databases, only for English
written documents published before March 2014.
Key words including “swimming”, “backstroke”
and “start” were used to locate documents.
Besides the electronic databases, the identified
reference lists in the articles were also used to
ensure, as far as practically possible, that all
appropriate studies were considered for inclusion.
Searches were carried out from the Proceedings of
the Scientific Conferences of Biomechanics and
Medicine in Swimming (BMS), the International
Society of Biomechanics in Sports (ISBS), and the
International Society of Biomechanics (ISB) from
1980 to 2013.
Inclusion and exclusion criteria
Included studies were experimental
biomechanical approaches in the laboratory or
during competitions with able-bodied swimmers.
The documents that were available only as
abstracts and duplicated studies from original
investigations were excluded.
Results and Discussion
General Findings
Eighty-seven references were obtained
from the preliminary search. Ultimately, 23
studies met the inclusion criteria: (i) two from
by Karla de Jesus et al. 9
© Editorial Committee of Journal of Human Kinetics
swimming specific journals; (ii) eight peer-review
journal articles; (iii) three from the proceedings of
the BMS conferences; (iv) eight from proceedings
of the ISBS conferences; (v) one from proceedings
of an ISB Biomechanics Conference, and (vi) one
doctoral thesis (Table 1).
Table 1 reveals a large variation in
experimental designs that were used. Most of the
studies analysed the different backstroke start
variations performed under FINA rules (86.5%).
Overall, studies included Olympic, International
and National backstroke swimmers, who were
able to master the aspects of the already tested
backstroke starting techniques. The research
settings included laboratory and competition
analyses performed in the Commonwealth Games
(Miller et al., 1984), Olympic Games (Arellano et
al., 2001; Cossor and Mason, 2001; Chatard et al.,
2003; Girold et al., 2001; Ikuta et al., 2001), Youth
Olympics (Arellano et al., 2003), Age Group Swim
Meeting (Cornett et al., 2011), and European
Championships (Siljeg et al., 2011). The
biomechanical settings in high calibre events
might be more advantageous than the laboratorial
conditions to obtain valid performance outcomes
(Toubekis et al., 2013; Schwameder, 2008).
Otherwise, the competition rules often hamper
the use of biomechanical methodology, thereby
narrowing the possibility of obtaining accurate
and reliable data (Schwameder, 2008).
The above mentioned factors, along with
a limited number of existing studies, restrict
quantitative assessments of the backstroke start
variables. Therefore, a qualitative description was
developed on relevant backstroke start evidence.
This included the separate features of the starting
phases, the biomechanical approaches used, and
the start techniques and variations for which the
main findings have been reported.
Backstroke starting phases
Aerial
The hands-off, take-off and flight are the
most common aerial starting phases studied
(Figure 1). However, the respective descriptions
vary in the literature, with disparities that hamper
communication among biomechanists, coaches
and swimmers. In fact, breaking down a swim-
start into its component parts can be challenging
as each phase is not always clear cut (Vantorre et
al., 2014). The hands-off and take-off phases are
characterised by actions performed when
swimmers are in contact with the starting wall.
The beginning of the hands-off phase is
determined by the starting signal (Figure 1) (de
Jesus et al., 2011a; 2013; Green, 1987; Hohmann et
al., 2008; Miller et al., 1984) and the swimmer’s
first observable movement (Hohmann et al., 2008).
Considering the take-off phase, authors
determined the starting signal (Cossor and
Mason, 2001; Hohmann et al., 2008; Miller et al.,
1984; Nguyen et al., 2014; Stratten, 1970; Takeda et
al., 2014), and the hands-off (de Jesus et al., 2010;
2011a; 2011b; 2013; Green, 1987; Hohmann et al.,
2008) (Figure 1) as the instant of the beginning
phase. This was also observed in ventral start
studies (Takeda et al., 2012; Thanopoulos et al.,
2012; Vantorre et al., 2010), where the hands-off
was less analysed than the take-off in backstroke
start studies.
The beginning of the flight phase was
unanimously described as the instant of take-off
by the feet (Cossor and Mason, 2001; de Jesus et
al., 2011a; 2013; Green, 1987; Hohmann et al.,
2008; Miller et al., 1984; Nguyen et al., 2014;
Takeda et al., 2014) (Figure 1). However, authors
differed regarding the conclusions for flight.
These included: the instant that the head
contacted the water (Cossor and Mason, 2001;
Nguyen et al., 2014), the instant of the hip entry
(Hohmann et al., 2008) and fingertip water contact
(de Jesus et al., 2010; 2011a; 2013; Green, 1987;
Miller et al., 1984; Takeda et al., 2014) (Figure 1).
According to Maglischo (2003), the fingertip water
contact is widely used to determine the end of the
flight phase (Vantorre et al., 2014). The head
and/or fingertip water contact could be a more
appropriate reference point than the hip entry,
since swimmers could immerse the hips before
the hands/head contact the water (Takeda et al.,
2014).
Aerial/In water and underwater phases
The entry and glide are the commonly
studied aerial/in-water and underwater phases,
respectively (Figure 1). As previously reported in
ventral start studies, these phases have been less
analysed than the aerial phases, even though they
contribute to reaching a considerable distance
from the wall at the beginning of a race (Vantorre
et al., 2014). Further, contradictory definitions
were found for some specific points of
measurement.
10 The backstroke swimming start: state of the art
Journal of Human Kinetics - volume 42/2014 http://www.johk.pl
Table 1
Descriptive analysis of the 22 included studies with the authors,
main aim, swimmer’s sample proficiency and data collection setting
Figure 1
The most common starting phases and respective initial and final instants
reported in the included studies, the starting signal, swimmer’s hands-off, swimmer’s feet take-off,
swimmer’s fingertip water contact, swimmer’s full body immersion
and beginning of lower limbs propulsive movements
Author (s)
Main aim
Proficiency
Setting
Rea and Soth (1967)
Comparison of two NCAA variations
Olympic
Experimental
Stratten (1970)
Comparison of FINA and NCAA techniques
Recreational to
Olympic
Experimental
Wilson and Howard (1983)
FINA backstroke start clusters
State to Olympic
Experimental
Miller et al. (1984)
Comparison of FINA technique
International
Competition
Green (1987)
Comparison of NCAA variations
National
Experimental
Green et al. (1987)
Comparison of NCAA variations
State
Experimental
Arellano et al. (2001)
Determinant swimming event factors
Olympic
Competition
Cossor and Mason (2001)
Correlation of FINA phases and starting time
Olympic
Competition
Girold et al. (2001)
Comparison among 200 m proficiency levels
Olympic
Competition
Ikuta et al. (2001)
Comparison between Japanese and other
nations
Olympic
Competition
Arellano et al. (2003)
Correlation of FINA start and 100 m event
time
International
Competition
Chatard et al. (2003)
Comparison among 200 m proficiency levels
Olympic
Competition
Theut and Jensen (2006)
Comparison of two FINA variations
Not clearly defined
Experimental
Hohmann et al. (2008)
FINA inter and intra-individual variability
International
Experimental
de Jesus et al. (2010)
Comparison of two FINA variations
National
Experimental
de Jesus et al. (2011a)
Performance prediction for two FINA
variations
National
Experimental
de Jesus et al.(2011b)
Comparison of two FINA starting phases
National
Experimental
Siljeg et al. (2011)
Comparison of 100 m starting performance
International
Competition
Cornett et al. (2011)
Racing start safety analysis
Not clearly defined
Competition
de Jesus et al. (2012)
Comparison of two FINA variations
National
Experimental
de Jesus et al. (2013)
Comparison of two FINA variations
National
Experimental
Takeda et al. (2014)
Comparison between specialists and non-
specialists
National
Experimental
Nguyen et al. (2014)
Comparison of two FINA variations
National
Experimental
by Karla de Jesus et al. 13
© Editorial Committee of Journal of Human Kinetics
Table 2
The kinematic parameters studied at the overall starting
and during the hands-off, take-off and flight phases.
Authors
Overall
Take-off
Flight
Rea and Soth (1967)
Temporal, velocity
/
/
Stratten (1970)
Temporal
Temporal
/
Wilson and Howard
(1983)
/
Segmental length,
angle
Segmental length,
angle
Miller et.al. (1984)
Temporal and distance
Temporal, distance
Temporal
Green (1987)
Centre of mass
displacement
Joint angles, centre
of mass velocity,
acceleration,
angular velocity
Joint angles, centre
of mass velocity,
acceleration,
angular velocity
Green et al. (1987)
Temporal
/
/
Arellano et al. (2001)
Temporal
Cossor and Mason (2001)
Temporal
Temporal
Temporal,
distance
Girold et al.(2001)
Temporal, velocity
/
/
Ikuta et al.(2001)
Temporal
/
/
Arellano et al.(2003)
Temporal, velocity
/
/
Chatard et al. (2003)
Velocity
/
/
Theut and Jensen (2006)
Velocity, distance
/
/
Hohmann et al.(2008)
Temporal
Temporal, velocity
Temporal
de Jesus et al.(2010)
Temporal
Angular displacement
and velocity
Temporal,
centre of mass
displacement
Temporal, centre
of mass
displacement,
de Jesus et al. (2011a)
Temporal
Centre of mass
displacement,
velocity, angle
velocity
de Jesus et al. (2011b)
/
/
/
de Jesus et al. (2012)
/
/
/
Cornett et al. (2011)
/
/
/
Siljeg et al.(2011)
Temporal
/
/
de Jesus et al. (2013)
Temporal
Centre of mass
velocity, angle
Centre of mass
velocity, angle
Takeda et al., (2014)
Temporal
Temporal, Centre of
mass velocity, joint
angles, angular
velocity
/
Nguyen et al. (2014)
Temporal
Temporal,
displacement,
velocity
/
14 The backstroke swimming start: state of the art
Journal of Human Kinetics - volume 42/2014 http://www.johk.pl
Figure 2
Mean lower limbs horizontal force-time curves for backstroke start
with feet immerged (continuous line) and emerged (dashed line) (de Jesus et al., 2013)
Table 3
The set distance for the backstroke start variations performance assessment
Authors
Backstroke start variations
(feet positioning)
Distance
(m)
Start time
(s)
Take-off
Velocity (m.s-
1)
Rea and Soth (1967)
Entirely emerged, toes over the gutter
6.09
2.69
-
Rea and Soth (1967)
Entirely emerged, toes over the gutter, trunk leaned on block
6.09
2.51
-
Stratten (1970)
Entirely immersed
6.09
2.48
-
Stratten (1970)
Entirely emerged, toes curled over the pool gutter
6.09
2.26
-
Stratten (1970)
Entirely emerged, toes over the gutter, trunk leaned on block
6.09
2.49
-
Miller et al. (1984)
Entirely immersed
-
3.58
Green et al. (1987)
Entirely emerged, toes over the gutter
22.86
16.62
4.70
Green et al. (1987)
Entirely emerged, toes over the gutter, parabolic flight
trajectory
22.86
17.0
3.62
Arellano et al.
(2003)
Entirely immersed
15
8.27
-
Hohmann et al.
(2008)
Entirely immersed
7.5
3.29
3.45
de Jesus et al. (2010)
Entirely immersed
-
0.93
-
de Jesus et al. (2010)
Entirely emerged
-
0.98
-
Siljeg et al. (2011)
Entirely immersed
15
8.30
-
Siljeg et al. (2011)
-
15
7.72
-
de Jesus et al. (2013)
Entirely immersed
5
1.96
3.29
de Jesus et al. (2013)
Entirely emerged
5
2.11
3.80
Takeda et al. (2014)
Partially immersed
5
1.89
3.76
Nguyen et al. (2014)
Entirely immersed
5/ 15
1.86 / 7.59
3.51
Nguyen et al. (2014)
Entirely emerged
5/ 15
1.72 / 7.51
3.65
by Karla de Jesus et al. 15
© Editorial Committee of Journal of Human Kinetics
The beginning of the entry phase
corresponds to the final instant of the flight; and,
for which, definitions differ among authors (de
Jesus et al., 2011a; Green, 1987; Hohmann et al.,
2008). The end of the entry phase is defined as the
maximum feet depth from the first downward
underwater kicking by Hohmann et al. (2008) but
the full body immersion by de Jesus et al. (2011a)
and Green (1987). Full body immersion is
considered to be the end of the entry phase in
ventral start studies (Vantorre et al., 2010)
(Figure 1).
Authors have defined the glide phase as
beginning at the instant entry ends until the
maximum feet depth of the second downward
underwater kick is reached (Hohmann et al.,
2008), the hands reach the 5 m mark (de Jesus et
al., 2011a; 2013), and/or the instant before
underwater kicking commences (Green, 1987). In
competition, Miller et al. (1984) defined the glide
phase as being from when the fingertips made
first water contact, until the first hand which came
out of the water at the end of the glide, re-enters
the water. Cossor and Mason (2001) considered
the entry, glide and undulatory underwater
movements as one combined parameter.
In previous ventral start studies, authors
divided the underwater phase into two parts: the
glide (Guimarães and Hay, 1985; Thow et al.,
2012; Vantorre et al., 2010) and the undulatory
underwater swimming (Vantorre et al., 2010). This
convention was adopted by de Jesus et al. (2012)
for the backstroke start. The glide phase does not
include lower limb propulsive movements
(Guimarães and Hay, 1985; Thow et al., 2012;
Vantorre et al., 2014) (Figure 1). Hence, future
studies should examine if the underwater kicking
observed by Hohmann et al. (2008) as soon as the
feet entered the water, provides any advantage
over a period of motionless gliding during the
start.
Biomechanical approaches and parameters
assessed
Kinematics
Despite some authors using immediate
feedback devices such as stopwatches (Green et
al., 1987; Stratten, 1970) and velocimeters (de Jesus
et al., 2012), 82.6% of the studies assessed
backstroke start kinematics using video-based
techniques (Arellano et al., 2001; Arellano et al.,
2003; Chatard et al., 2003; Cornett et al., 2011;
Cossor and Mason, 2001; de Jesus et al., 2010;
2011a; 2013; Girold et al., 2001; Green, 1987;
Hohmann et al., 2008; Ikuta et al., 2001; Miller et
al., 1984; Nguyen et al., 2014; Rea and Soth, 1967;
Siljeg et al., 2011; Takeda et al., 2014; Theut and
Jensen, 2006; Wilson and Howard, 1983). Only
Green (1987) used a three-dimensional (3D) dual-
media setting via cinematographic cameras.
Most studies used digital cameras to
provide independent aerial, underwater or
combined dual-media analysis. In competition
settings, cameras were positioned 18 m above the
swimming pool (Arellano et al., 2001; Cossor and
Mason, 2001; Girold et al., 2001; Ikuta et al., 2001)
and along the side of the pool, 15 m from the
starting block wall (Arellano et al., 2003); or
underwater at 6.5 m from the starting block wall
(Cornett et al., 2011). Studies conducted under
laboratory conditions, used aerial and underwater
cameras positioned at 6.78 m (de Jesus et al., 2010;
2011a; 2013) and 7.5 m (Takeda et al., 2014), both
from the primary swimmer’s plane of motion, and
30 cm above- and below-water surface (de Jesus et
al., 2010; 2011a; 2013). Takeda et al. (2014) also
described the dual-media cameras as positioned
above the pool side deck and 1 m below the water
surface; while Theut and Jensen (2006)
implemented the same above-water camera
position but the underwater camera in the corner
of the swimming pool. Hohmann et al. (2008) and
Nguyen et al. (2014) did not provide further
details about the dual-media camera positions.
Quantitative data processing from digital
cameras usually requires a coordinate scale and
prevents immediate results due to the need for
manual digitising (de Jesus et al., 2011a; 2013;
Hohmann et al., 2008; Nguyen et al., 2014; Takeda
et al., 2014; Theut and Jensen, 2006). Furthermore,
the digitisation and reconstruction errors
associated with this procedure require authors to
measure the errors. However, only de Jesus et al.
(2011a; 2013) and Takeda et al. (2014) displayed
these values. In competition settings, challenges
increase because the competition regulations
make it difficult to use the most accurate
biomechanical methodology (Schwameder, 2008)
which requires researchers to use parts of the
swimming pool to create a digitising scale (Miller
et al., 1984). The automatic tracking motion
analysis systems have been considered highly
by Karla de Jesus et al. 15
© Editorial Committee of Journal of Human Kinetics
reliable for 3D underwater analysis (Kudo and
Lee, 2010). However, further validation and
reliability testing is required to establish its
viability for studying dual-media backstroke
starts.
Most of the kinematics approaches
mentioned in the backstroke start studies above
provide biomechanical performance indicators
instead of specifying how swimmers should
organize body segments movements to optimise
their performance. Performance indicators are less
time-consuming for coaching feedback and hinder
technique analysis method to be wide-used in
backstroke start studies. Table 2 outlines the
kinematic variables measured at the most
common backstroke starting phases and for the
overall start. In fact, 69.5% of the studies
measured the starting time, which ranged from
the signal to the first fingertip contact with the
water (de Jesus et al., 2011a; 2013) and the time to
22.86 m (Green et al., 1987). Following Guimarães
and Hay (1985), starting time has been often
measured for ventral start studies (Vantorre et al.,
2010), but, there is no clear consensus as to what
distances are best for assessing the most effective
start, yet.
Table 2 indicates that most backstroke
start studies have measured only linear
displacement and velocity parameters, despite
swimming starts not being exclusively rectilinear
motions (Bartlett, 2007). Authors have considered
the swimmer as a rigid body to calculate the
horizontal distance (Cornett et al., 2011; Cossor
and Mason, 2001; Miller et al., 1984; Theut and
Jensen, 2006) and the velocity during a backstroke
start (Arellano et al., 2003; Chatard et al., 2003;
Giroldi et al., 2001; Theut and Jensen, 2006).
Although these variables provide important
information in training and competition
environments, the curvilinear motions in the
backstroke start need to be quantified. Some
authors have studied translational kinematic
parameters of the centre of mass or hip vectors
during the overall backstroke start (Green, 1987)
and during starting phases (de Jesus et al., 2010;
2011a; 2013; Green, 1987; Nguyen et al., 2014;
Takeda et al., 2014), as have been conducted for
ventral starts (Guimarães and Hay, 1985; Takeda
et al., 2012).
As humans do not have rigid bodies and
display combinations of rotational and linear
motions (Bartlett, 2007), multi-segmental models
have been used to analyse segmental positions
(Nguyen et al., 2014; Takeda et al., 2014); and joint
angles from upper (Green et al., 1987; Wilson and
Howard, 1983) and lower limbs (de Jesus et al.,
2010; de Jesus et al., 2011a; Green et al., 1987;
Nguyen et al., 2014; Takeda et al., 2014; Wilson
and Howard, 1983); and trunks (de Jesus et al.,
2013; Wilson and Howard, 1983) at different
starting phases (Table 2). The study of the
coupling relationship between segments is
required to provide insight into the optimal
movement strategies underlying backstroke starts.
There is a paucity of evidence concerning
the parameters in the aerial/in-water and
underwater phases. In fact, research usually has
highlighted the importance of assessing entry
(Vantorre et al., 2010; Vantorre et al., 2014) and
underwater phase kinematics (de Jesus et al.,
2011a; Vantorre et al., 2010; Vantorre et al., 2014;
Thow et al., 2012) for ventral starts. Only Green
(1987) and de Jesus et al. (2011a) have calculated
the centre of mass displacement and velocity,
during the entry and glide phases; and the time
and frequency of some undulatory underwater
swimming cycles of the backstroke start (de Jesus
et al., 2012). In competitions, authors have
measured the combined time from the entry until
the swimmer’s head resurfaced (Cossor and
Mason, 2001) and the beginning of the first arm
stroking cycle (Miller et al., 1984).
Kinetics
Despite several studies having used
kinematics, few studies of backstroke starts have
included kinetic data. Kinetics requires higher
costs than image based systems and presents
technical difficulties when attaching the kinetic
devices to the starting block and pool wall.
However, de Jesus et al. (2010; 2011a; 2013)
successfully lowered, then elevated pool water
levels so as to position a strain gauge force plate
at two heights on the pool wall. Also, they
instrumented the handgrips with a strain gauge
load cell which was sequentially repositioned to
remain at the same distance above the water
surface. The dynamics between the lower limbs
and the pool wall were studied using a 3D
piezoelectric force plate (Hohmann et al., 2008;
Nguyen et al., 2014). The strain gauges are more
commonly used due to their lower costs and
highly accurate static and transient load
16 The backstroke swimming start: state of the art
Journal of Human Kinetics - volume 42/2014 http://www.johk.pl
measurement capabilities than via a 3D
piezoelectric force plate.
The instrumentation of starting blocks for
analysing backstroke starts has helped to verify
how the respective movements are generated (de
Jesus et al., 2013; Hohmann et al., 2008; Nguyen et
al., 2014). The horizontal force exerted by
swimmers’ lower limbs on the pool wall is the
main research topic of backstroke start kinetics
(de Jesus et al., 2013; Hohmann et al., 2008;
Nguyen et al., 2014). The horizontal swimmers’
lower limbs force-time curve profiles (Figure 2)
registered during backstroke start performances
were similar among these three studies reporting
two distinguished peak forces. Researchers stated
that swimmers should optimise the force-time
distribution during the take-off phase (de Jesus et
al., 2011a; 2013; Guimarães and Hay, 1985;
Hohmann et al., 2008; Nguyen et al., 2014;
Vantorre et al., 2014). To obtain further insight
into the mechanics of the backstroke start, de
Jesus et al. (2011a; 2013) analysed the horizontal
forces exerted on the handgrips and noted that the
role played by the upper limbs was to drive the
centre of mass above the water surface.
Despite the understanding about the
horizontal force profile generated by backstroke
swimmers to propel themselves off the wall (de
Jesus et al., 2011a; 2013), coaches also
recommended that swimmers endeavour to
accelerate the centre of mass upwards to clear the
water surface because the air presents less
resistance than water (de Jesus et al., 2013;
Nguyen et al., 2014; Takeda et al., 2014). In fact,
the external kinetics involved in backstroke starts
should be analysed and interpreted, to consider
the magnitude and timing of horizontal and
vertical propulsive force vectors applied by the
swimmer’s muscular actions to the handgrips and
pool wall. Hohmann et al. (2008) and Nguyen et
al. (2014) have assessed 3D resultant forces on
swimmers’ lower limbs; but only Nguyen et al.
(2014) measured the vertical force component.
These authors found that altering feet positions at
the start resulted in a significant change in peak
horizontal and vertical forces. In 2013, FINA
approved the use of a new starting platform to
prevent the backstroke swimmers sliding down
the wall at the start; previously a reasonably
common mishap, with disastrous results for the
competitor. Therefore, future research analyses
are required to ascertain and confirm any
advantages that could result from the increased
vertical forces backstroke swimmers might
achieve and could be translated into a faster
racing start.
The instrumented starting blocks used in
the previous research referred to the above are
few and are now obsolete following the recent
FINA facility rule changes approved in 2008 and
2013. The new hand and foot grips now available
for backstroke starts have not been instrumented
and used in research studies to date. Hence, sport
biomechanists and engineers are urged to develop
a 3D kinetic system in the new block
configuration. Then, one could identify
independently how the right and left, upper and
lower, limbs contribute to propelling backstroke
swimmers during the start.
Beyond the linear kinetics, Green (1987)
and Takeda et al. (2014) used angular kinetics
principles to study the resistance of the
swimmers’ bodies and separated segments to
change angular motion during backstroke starts.
In previous ventral start studies, swimmers were
advised to generate enough angular momentum
to make a clean entry into the water (Vantorre et
al., 2010). Despite the unique and valid attempt to
assess the swimmers’ reluctance to generate
angular motion during backstroke start, a number
of kinetic and kinematic variables also are
required to explain how much rotation is
occurring in the sequential starting phases.
Takeda et al. (2012) and Takeda et al. (2014)
suggested that a combination of kinetic and
kinematic measurements are needed for greater
clarification of important swimming start
components.
Electromyography (EMG)
As for kinetics, specific EMG studies of
swimming starts are few. To measure the muscle
activity of backstroke swimmers during the start,
a cable EMG system with surface electrodes was
used by Hohmann et al. (2008) and de Jesus et al.
(2011a; 2011b). This approach requires
methodological adaptations to record accurate
measurements (Clarys and Cabri, 1993) such as
immobilisation of cables and water proofing
electrodes. De Jesus et al. (2011a; 2011b) used a
complete swimming suit for electrode insulation
and cable immobilisation. The full body
swimming suit appeared to be suitable for
by Karla de Jesus et al. 17
© Editorial Committee of Journal of Human Kinetics
immobilising cables but these had to exit via holes
in the suit resulting in potential places for leaks.
Further, the use of full body swimming suits is no
longer allowed in competition. Insulation to cover
electrodes was provided by adhesive bandages
(de Jesus et al., 2011a; 2011b; Hohmann et al.,
2008). Knowledge of specific muscle activity is an
important factor in understanding neuromuscular
coordination and effective force production
during the different phases of the backstroke start.
Overcoming these challenges would greatly assist
in determining the most effective techniques and
optimise training drills.
The average and integrated EMGs, as
amplitude signals, were calculated by Hohmann
et al. (2008) and de Jesus et al. (2011a; 2011b),
respectively; to provide trunk, and upper and
lower limb muscle activation. Muscle intensity
data are only one element of motor activity; and
the sequential pattern in which the muscles are
engaged in a complex backstroke start movement
is a more important element (Clarys and Cabri,
1993). In fact, the EMG also provides information
on timing of muscle activities in human
movements (Bartlett, 2007); nevertheless, only
Hohmann et al. (2008) have been concerned about
the muscle activation sequence during the
backstroke start. According to these authors the
backstroke start is initiated by the Deltoideus
Anterior that had been very active fixing the body
in a high set starting position. Despite this initial
undertaking, Hohmann’s research group did not
provide detailed descriptions of the criteria used
to determine the muscles involvement along a
continuum from strongly active to an inactive
state. The lack of standard methodologies to
define the EMG activity makes comparisons
between studies difficult.
By studying the sequencing of muscle
activation, one can focus on several factors
relating to skill; including the timing and overlap
of agonist and antagonist activity (Bartlett, 2007).
The agonist and antagonist activation in
backstroke starts has not been studied yet, due to
the swim start acyclic pattern. Nevertheless,
Hohmann et al. (2008) mentioned that joint
stabilisation occurred during flight and entry
phases to overcome the high water resistance.
Therefore, simultaneous activation of muscles
surrounding joints should be investigated during
the backstroke start (Clarys and Cabri, 1993).
Seven muscles were commonly studied
(Hohmann et al., 2008; de Jesus et al., 2011a,
2011b); namely, the Biceps Brachii, Triceps Brachii,
Deltoideus Anterior, Erector Spinae Longissimus,
Rectus Femoris, Gluteus Maximus and
Gastrocnemius Medialis. Authors confirmed the
crucial function of the lower limbs to generate the
impulse during the take-off phase; however, they
disagreed about the main muscle activities of the
upper limbs. Studying the above-mentioned bi-
articular muscles (de Jesus et al., 2011a, 2011b;
Hohmann et al., 2008) has highlighted the need to
clarify how the mechanical functions vary,
depending on the different backstroke start
variations and phases (e.g. hip flexor and knee
extensor moments for the Rectus Femoris). As
backstrokers are required to coordinate multiple
muscles and joints to propel themselves
rigorously out of the pool wall, more studies
should couple EMG, kinetic and kinematic
approaches to dictate how better backstroke start
performance can be achieved.
Synchronisation methods
The selected studies used a voice
command (Stratten, 1970), starting pistol (Rea and
Soth, 1967; Miller et al., 1984; Wilson and Howard,
1983), or the official competition timing systems
for backstroke start synchronisation (Arellano et
al., 2001; Arellano et al., 2003; Chatard et al., 2003;
Cornett et al., 2011; Cossor and Mason, 2001; de
Jesus et al., 2011a, 2011b, 2013; de Jesus et al.,
2012; Girold et al., 2001; Green, 1987; Green et al.,
1987; Hohmann et al., 2008; Ikuta et al., 2001;
Nguyen et al., 2014; Siljeg et al., 2011; Takeda et
al., 2014; Theut and Jensen, 2006).
The competition timing systems were
used to simultaneously produce the starting
signal and export a light to the video images
(Arellano et al., 2001; Arellano et al., 2003;
Chatard et al., 2003; Cornett et al., 2011; Cossor
and Mason, 2001; de Jesus et al., 2011a; 2013;
Hohmann et al., 2008; Ikuta et al., 2001; Nguyen et
al., 2014; Siljeg, 2011; Takeda et al., 2014; Theut
and Jensen, 2006); and a trigger pulse for the
kinetics (de Jesus et al., 2011a; 2013; Hohmann et
al., 2008; Nguyen et al., 2014) and EMG
synchronisation (de Jesus et al., 2011a; 2011b).
Alternative synchronisation methods
have been implemented as the use of force
instants to record the swimmer’s handgrip release
(de Jesus et al., 2011a; 2013) and feet take-off (de
18 The backstroke swimming start: state of the art
Journal of Human Kinetics - volume 42/2014 http://www.johk.pl
Jesus et al., 2012) for the starting signal definition.
Considering that a small temporal and spatial
misalignment between different biomechanical
devices can lead to large errors in the variables
assessed, future studies should use a common
system with consistent low trigger delay.
The backstroke start techniques, variations and
main research findings
The main objective of swim-start research
has been to identify the most effective start
technique in terms of performance (Vantorre et
al., 2014). From the selected studies, 65% have
established comparisons using backstroke start
techniques and variations (Table 1). Researchers
have used different distances to assess the
effectiveness of each one (Table 3).
Considering the backstroke start studies
conducted with variations performed under the
NCAA rules, both had used the 6.09 m distance to
assess start time. According to Stratten (1970) the
most efficient variation was performed when the
swimmer’s trunk was positioned upright just in
front of the block, and hands holding the
horizontal hand-grips; and, the respective mean
start time seems to be shorter than the one
presented by Rea and Soth (1967). This finding
could be explained by the sample sizes and
proficiency levels. Rea and Soth (1967) studied
one specialist in backstroke start who performed
with the trunk inclined forward over the top of
the starting block and hands holding a bar
mounted over the block. Stratten (1970) included
13 swimmers of different proficiency levels who
completed a training period for
familiarisation purposes. Yet, it is quite likely that
previous experience with a technique may have
an impact on start variables and performance
(Vantorre et al., 2014). The feet positioned over the
pool gutter allowed swimmers to clear the water
from the starting position to the beginning of
entry by generating greater vertical reaction force;
and considered a crucial aspect for better
backstroke start performances (de Jesus et al.,
2013; Nguyen et al., 2014; Takeda et al., 2014).
These statements corroborate other findings
where the starts that were performed with shorter
horizontal take-off velocities, implied greater
aerial trajectory and shorter start time than the
variation with a flatter profile (Green et al., 1987)
(Table 3).
Most research considered backstroke
starts performed under FINA old rules and
measured the starting effectiveness using
distances from 5 to 15 m (Table 3). Miller et al.
(1984) and Arellano et al. (2003) assessed mean
start times; although, only the latter specified the
set distance. Siljeg et al. (2011) measured the 15 m
start time considering the pre and post period of
FINA rule changes for feet positioning (FINA
2005-2009, SW. 6.1), which explains the maximum
0.55 s mean difference from the Arellano et al.
(2003) findings. Indeed, Nguyen et al. (2014)
noted that since the FINA rule changed for feet
positioning, many backstrokers have obtained
advantages from altering their starting technique
to place the feet completely out of the water. To
achieve a great start-time performance at 7.5 m,
elite backstrokers displayed considerable intra-
and inter-variability of the upper limbs trajectory
during the flight phase (Hohmann et al., 2008;
Wilson and Howard, 1983). The upper limb
pathways over the centre of mass and close to the
body allow the trunk to follow a greater parabolic
flight than using a lateral path (Bartlett, 2007;
Green, 1987; Maglischo, 2003). According to de
Jesus et al. (2013), Nguyen et al. (2014) and
Takeda et al. (2014), a greater parabolic flight path
assists in minimising drag and optimising
propulsion underwater. Since a clear water entry
depends on preceding actions performed during
the wall and flight phases (Thow et al., 2012),
Theut and Jensen (2006) identified the effects of
the feet submerged and positioned parallel to
each other or staggered (i.e., one above the other)
on backstroke start horizontal distance and
average velocity. Anecdotal evidence suggested
that the feet staggered position prevented
swimmers from slipping down the wall;
nevertheless, findings did not confirm that
difference between variations (Theut and Jensen,
2006). The backstroke start ledge (FINA FR. 2.7,
2013-2017) is pointed out to avoid the slippage;
however, further studies are needed to describe in
detail how technique must be changed to improve
backstroke start performance.
Backstroke starts are performed now
under the current FINA rule (adopted in 2005)
and only de Jesus et al. (2010; 2011a; 2011b; 2013)
and Nguyen et al. (2014) compared the variations
with the feet parallel, and entirely submerged and
out-of-water. Considering the 5 m start time
(Table 3) for both variations, shorter values seem
by Karla de Jesus et al. 19
© Editorial Committee of Journal of Human Kinetics
to be displayed by the latter research group,
which is mainly explained by the swimmers’
greater proficiency level. The variation with feet
entirely submerged seems to register lower
horizontal take-off mean values in both studies;
and the values presented by de Jesus et al. (2013)
seem lower than those of Nguyen et al. (2014).
Although this finding was not significant, the
trend might be explained by the use of a fixed
point to indicate the swimmer’s centre of mass.
Takeda et al. (2014) verified that backstroke
swimmers specialists used a feet-partial-out-of-
the-water start, and tended to register greater
mean 5 m start time than participants of Nguyen
et al. (2014). This might indicate superiority of the
variation performed with feet entirely out-of-the-
water over the method with partially emerged. De
Jesus et al. have not displayed performance
differences during above- (2013) and underwater
phases (2012), between the variation with feet
entirely out and under the water; thereby
disagreeing with the Nguyen et al.’s findings
(2014). These contradictions might be explained
by the larger sample size and greater swimmers’
preference for feet positioned out of the water
displayed by Nguyen et al. (2014). De Jesus et al.
(2011a; 2013) and Nguyen et al. (2014) stressed
that swimmers should generate greater horizontal
and vertical take-off velocities when the feet were
positioned out of the water to achieve the most
appropriate aerial trajectory (de Jesus et al., 2013).
The inclusion of the new device for backstroke
starts potentially improves the parabolic flight
trajectory due to minimised take-off friction force.
However, since greater vertical flight trajectory
implies deeper water entry, future research
should also examine underwater phase variables
which can indicate risk of injury, as previously
pointed out during youth competitions (Cornett et
al., 2011).
Summary and future directions
The main research findings can be
summarised as follows: (1) the phase definitions
used in analysing backstroke starts are
inconsistent and unclear. Hence, this makes it
difficult to determine how many changes over
time can be attributed to a real change, or mere
differences between definitions; (2) studies
conducted in laboratory settings have adopted
kinematics, kinetics and EMG; however, many
research challenges remain in both settings to
improve the methods of quantifying valid,
reliable and accurate data; (3) the temporal
variables, particularly the starting time, were most
studied; and backstroke start movements were
predominantly described using linear kinematics;
(4) most of the experimental and competition
research findings are now out of date since the
backstroke start rules have been recently changed,
and the studies were completed under swimming
rules which are now obsolete.
Future research would help coaches and
swimmers by exploring issues not yet fully
addressed in the literature. For example: (1)
determination of a consistent observational model
for categorisation and study of the backstroke
start technique; (2) development of appropriate
biomechanical measurements and research
methodologies as standard tools; for scientific
purposes and training support, competition
preparation and analysis; (3) reinforcement of
more holistic and process-oriented biomechanical
approaches in laboratory procedures: involving
interactions of kinematics, kinetics and EMG
variables; from aerial, aerial/in-water and
underwater phases; definitions for more detailed
parameters which better describe the overall
backstroke start in competitions, beyond the
starting time; (4) focusing on studies based on the
actual FINA rules and the new starting block
configurations.
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Corresponding author:
João Paulo Vilas-Boas
91 Dr. Plácido Costa st., 4200-450, Porto, Portugal,
Phone: +351220425236
Fax: +351225500687
E-mail: jpvb@fade.up.pt.
... As featured in literature (K. De Jesus, K. De Jesus K, Fernandes, Vilas-Boas, & Sanders, 2014;Tor et al., 2015;Vantorre et al., 2014), biomechanical factors influence the start performance in swimming events, e.g. take off horizontal velocity, entry angles, and underwater trajectories. ...
... biomechanical factors influence the start performance in swimming events, e.g. take off horizontal velocity, entry angles, and underwater trajectories. The start phase is the first and shortest in swimming events, and could be defined as the point between the start signal and the very beginning of the first stroke cycle breaking the water surface (K. De Jesus et al. 2014;Vantorre et al., 2010). In addition, the start phase is traditionally subdivided into five other sub phases: block; flight; entry; glide; and leg kicking (Vantorre et al., 2010). According to our best knowledge, no other start sub phase has received more scientific attention than the block phase, including several perspectives: biomechan ...
... Comparing strokes, the backstroke has presented a smaller BT in relation to others. In addition, backstroke classifications also have greater possibility to be influenced by the BT (CC=4.97%) than the OS strokes, emphasizing BT specific importance. In literature reviews, both starts, IS (K. De Jesus et al., 2014) and OS (Vantorre et al., 2014), were analyzed in order to achieve a better BT. Additionally, they suggest that it is necessary to have the shortest time as possible in contact with the block or wall, in order to minimize the block time (K. De Jesus et al., 2014;Vantorre et al., 2014). However, there is a need to remain at the block or w ...
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In high level championships small details are able to define the swimming medalists. Overall 0.01 s represents just a short piece of swimming final time, but between elite swimmers just 1.12% of the final time performance in 50 meters freestyle are improved annually. In this perspective greater block time differences over swimming final time differences could change the importance of block time to the swimmers classification. Thus the aim was to investigate the influence of block time in the final sprint events (50 and 100m) classification, including seven FINA World Championships (2003-2015). Thereunto, were calculated the frequency of possible Classification Changes (CC), based on differences between block times (BT) and final times (FT) in each swimming event. Public data was collected at the Omega Timing website. Totally, 112 events and 894 individual results (447 men and 447 women) were analyzed. The Chi-Square test was used to verify the Classification Changes occurrence between strokes (freestyle, backstroke, breaststroke and butterfly), event distances (50 and 100m), sex (male and female), block versions (traditional block used by FINA until 2007-OSB9; and new block used by FINA from 2009-OSB11), and years of championship (2003, 2005, 2007, 2009, 2011, 2013 and 2015). Between strokes and distances, the Classification Changes effect was shown more frequent in backstroke and 50m (4.97% CC and 4.24% CC; respectively). In addition, although the new block version has been shown to reduce the block times, it did not affect notably the Classification Changes. However, overall differences in block times were greater than differences in final time events (3.44% CC). These findings emphasize the importance of BT and recommend the block start technical training to achieve better swimming classifications.
... In sprint swimming, improving the start could make the difference between winning or not get a medal (García-Hermoso et al., 2017;Arellano et al., 2018;Sánchez et al., 2021). Therefore, several investigations have shown that swimmers should optimise the force-time distribution during the impulse phase (de Jesus et al., 2014;Vantorre et al., 2014;Cuenca-Fernández et al., 2015). Despite swimming start speed was not calculated, a good start is understood as an increase in speed since the swimmer leaves the block and reach the water could be achieved by either a combination of a reduction in execution time and an increase in distance of entry or a combination of both (Vantorre et al., 2014). ...
... In previous studies, the underwater phase has been divided into two parts: the glide and the undulatory swim, differentiated by the moment at which the movement of the lower limbs begins (de Jesus et al., 2014;Vantorre et al., 2014). However, a limitation of current methods of competition analysis is that the camera setup is limited to the above-water view only, which means that underwater kinematic information cannot be assessed in detail (Gonjo and Olstad, 2021). ...
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This study explored in the 50 m races of the four swimming strokes the performance parameters and/or technical variables that determined the differences between swimmers who reach the finals and those who do not. A total of 322 performances retrieved from the 2021 Budapest European championships were the focus of this study. The results of the performances achieved during the finals compared to the heats showed that the best swimmers did not excel during the heats, as a significant progression of performance was observed in most of the strokes as the competition progressed. Specifically, combining men and women, the swimmers had in freestyle a mean coefficient of variation (CV) of 0.6%, with a mean range of performance improvement (Δ%) of Δ =~0.7%; in breaststroke a mean CV of~0.5% and Δ = −0.2%; in backstroke a mean CV of 0.5% and Δ = −0.6%, and; in butterfly a mean CV of~0.7% and Δ = −0.9%. For all strokes, it was a reduction of the underwater phase with the aim of increasing its speed. However, this result was not always transferred to the final performance. In any case, most of the swimmers tried to make improvements from the start of the race up to 15 m. Furthermore, the swimmers generated an overall increase in stroke rate as the rounds progressed. However, a decrease in stroke length resulted and, this balance appeared to be of little benefit to performance.
... Different methods have been used to analyze muscle activation in backstroke starts, making direct comparisons difficult [34]. Both integrated [22] and average [35] EMG have been described during backstroke starts. ...
... Since increased wall contact time has a negative impact on backstroke starts [5], the integrated and average EMG data can be misleading. Furthermore, some research has identified that it is important to understand muscle activation sequence [34], although few studies have examined these data in backstroke starts [35]. To address the importance of muscle activation magnitude and timing, without the confounding factor of wall contact time, we chose to examine peak activation and time to peak activation. ...
... Since short distance swimming events can be decided by margins as small as .01 s, an effective start is essential (de Jesus et al., 2014), forcing coaches and competitors to search for and use newer and sometimes innovative solutions in the training process (Wiktorowicz et al., 2015). The application of predictive models has been a supporting solution to this process, being used in swimming starts analysis through the linear regression tool (e.g. ...
... and ANN val.) Currently, backstroke start is performed with different handgrips and a feet support, which might allow swimmers to position their CM as high out of the water as possible and, consequently, reduce drag, since they need to move through the take-off, flight and entry phases (de Jesus et al., 2013(de Jesus et al., , 2014. In fact, it has been previously mentioned that coaches should focus on strategies that would improve flight and entry phase biomechanics, guaranteeing a shorter backstroke start time (Takeda et al., 2014). ...
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Our aim was to compare non-linear and linear mathematical model responses for backstroke start performance prediction. Ten swimmers randomly completed eight 15 m backstroke starts with feet over the wedge, four with hands on the highest horizontal and four on the vertical handgrip. Swimmers were videotaped using a dual media camera set-up, with the starts being performed over an instrumented block with four force plates. Artificial neural networks were applied to predict 5 m start time using kinematic and kinetic variables and to determine the accuracy of the mean absolute percentage error. Artificial neural networks predicted start time more robustly than the linear model with respect to changing training to the validation dataset for the vertical handgrip (3.95 ± 1.67 vs. 5.92 ± 3.27%). Artificial neural networks obtained a smaller mean absolute percentage error than the linear model in the horizontal (0.43 ± 0.19 vs. 0.98 ± 0.19%) and vertical handgrip (0.45 ± 0.19 vs. 1.38 ± 0.30%) using all input data. The best artificial neural network validation revealed a smaller mean absolute error than the linear model for the horizontal (0.007 vs. 0.04 s) and vertical handgrip (0.01 vs. 0.03 s). Artificial neural networks should be used for backstroke 5 m start time prediction due to the quite small differences among the elite level performances.
... To our knowledge, no previous research has directly measured kinetic variables for backstroke starts performed using the OBL2. While hand and foot reaction forces have been measured in ventral starts and integrated to predict take-off velocities (Murrell & Dragunas, 2012;Slawson, Conway, Cossor, Chakravorti, & West, 2013), the situation is more complex in backstroke starts as vertical and horizontal forces are applied prior to the start signal (de Jesus, de Jesus, Abraldes, Mourao et al., 2016;de Jesus, de Jesus, Fernandes, Vilas-Boas, & Sanders, 2014). Nevertheless, this approach yields direct information about the vertical and horizontal forces during the backstroke start that directly relate to the start performance. ...
... Third, we chose to quantify the sequence of joint extension using the time of onset for hip and knee extension. This is somewhat similar to the timing of maximum knee and hip angular velocities reported in previous studies (Takeda et al., 2014) and is a step towards providing detailed information regarding their relative extension timing as recommended in a recent review paper (de Jesus et al., 2014). Furthermore, ankle extension was not measured as the foot segment could not be clearly visualised in our above-water video images for all of our swimmers, as some of them setup with their feet underwater. ...
Article
FINA recently approved the backstroke ledge (Omega OBL2) to improve backstroke start performance in competition, but its performance has not been thoroughly evaluated. The purpose of this study was to compare the mechanics of starts performed with and without the OBL2. Ten high-level backstroke swimmers performed three starts with, and three starts without, the OBL2. A wall-mounted force plate measured the lower limb horizontal impulse, vertical impulse, take-off velocity and take-off angle. Entry distance, time to 10 m and start of hip and knee extension were recorded using video cameras. Starts performed with the OBL2 had a 0.13 s lower time to 10 m, 2.5% less variability in time to 10 m and 0.14 m greater head entry distance. The OBL2 provides a performance advantage by allowing an increased head entry distance rather than larger horizontal impulse on the wall. This may be due to the swimmers assuming different body positions during the start manoeuvre. Additional studies are needed to evaluate factors that contribute to improved performance when using the OBL2. Swimmers should train with the OBL2 and use it in competition to ensure optimal start performance.
... As sprint swimming events classifications can be decided by very small margins (e.g. 0.01 s), sport engineers and biomechanists aimed optimizing instrumented starting blocks for more/multiconditions analysis purposes (de Jesus et al., 2014). The noticeable technological advances provided by these devices supply swimmers and coaches with new opportunities for assessment and training of technical elements of swimming race as starts and turns. ...
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Individual starts for ventral and dorsal swimming events have changed. After the introduction of back plate and wedge, some studies (mainly on ventral starts) have aimed to clarify their benefits and optimal application. This systematic review is aimed at a critical appraise of the literature on the main findings for back plate and wedge usage. We explored the databases of PubMed, Scopus and Web of Science and conducted a manual search on the reference list of papers. We based our search on the quality scale of the National Health Institutes and found 25 studies that met the eligibility criteria and that scored 7.75 ± 1.18 and 8.0 ± 0.71 on fair-quality studies addressing kick and backstroke starts. Kick start has shown faster start time comparing with grab and track starts by reducing block time and increasing horizontal take-off velocity. Backstroke start using the wedge improved performance through a greater centre of mass vertical position at take-off, horizontal and vertical position at entry and underwater velocity. Swimmers have adopted technical variants of kick and backstroke start by changing block set-up and stance, which should be monitored considering anthropometrics and strength abilities.
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This study investigated how the difference in the timing of the extension of the joints of the lower limbs during take-off affects the backstroke start performance. Eleven backstroke swimmers performed three lower-limb joint extension sequences of backstroke start: knee extension after hip extension (KAH), simultaneous hip and knee extension (SHK), and knee extension before hip extension (KBH). The shortest 5-m time was performed at KAH (1.90 ± 0.26 s), followed by a performance at SHK (2.12 ± 0.52 s) and KBH (2.47 ± 0.61 s). The greater trochanter (GT) vertical positions at toe-off were higher at KAH and SHK than at KBH. KAH had a shorter entry range, defined as the horizontal distance from the fingertip (FT) to the GT entry in the water, than KBH and SHK. A positive correlation was noted between the entry range and the 5-m time at KAH (r = 0.79). In addition, a negative correlation was observed between the GT vertical position at toe-off and the entry range at KAH (r = -0.65). The results suggested that KAH makes it easier to take the arched-back posture after toe-off, allowing the performance of a hole-entry technique that reduces the entry range and the 5-m time.
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Backstroke starts involve the athlete starting from a flexed position with their feet against the pool wall and then extending their ankles, knees, hips and back to push off; however, swimmers can start in different positions. The purpose of this study was to evaluate the performance impact of different knee extension angles in the setup position for a backstroke start. Ten backstroke swimmers completed maximum-effort starts in each of two setup positions: one with the knees maximally flexed, and one with the knees less flexed. The start handles and touchpad were instrumented with multi-axial force sensors. Activity of major hip and knee extensors was measured using surface electromyography. Body position in the sagittal plane was recorded using high-speed cameras. There was no overall difference in time to 10 m between the two conditions (p = 0.36, d z = 0.12), but some participants showed differences as large as 0.12 s in time to 10 m between start conditions. We observed that starts performed from a setup position with less knee flexion had an average 0.07 m greater head entry distance (p = 0.07, d z = 0.53), while starts from a setup position with maximal knee flexion had an average 0.2 m/s greater takeoff velocity (p = 0.02, d z = 0.78). Both head entry distance and takeoff velocity are related to start performance, suggesting each position may optimize different aspects of the backstroke start. Coaches should assess athletes individually to determine which position is optimal.
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The aim of our work was to analyze the partial shares of selected factors of explosive strength of lower limbs on the overall explanation of swimming performance to the 25 meters backstroke. 29 students of Physical Education took part in our research and completed 6 tests. These tests were realized on a dry-land and in the water and they consisted of swimming performance to 25 meters backstroke, swimming start speed to 4 meters, vertical jump with and without arm-swing, maximum and average velocity of take-off performance on dry land under the backstroke start conditions. The obtained data are described by descriptive statistics and all parameters were entered to the correlation analysis for their dependence evaluation. By the analysis, we found that all tests significantly correlated with each other (p < 0.01; p < 0.05) except for the start to 4 meters test and Tendo velocity average test. For the evaluation of factors that determine the swimming performance to 25 meters backstroke, we use the regression analysis of parameters where the regression model was reflected as statistically significant (R ² = 0.479 %; SEE = 3.396 %). Partial shares of individual tests, except for tests of maximal and average velocity on a dryland, showed up as statistically significant (p < 0.05; p < 0.01), with the highest share of swimming start to 4 meters performance (p < 0.01; r = 0.686). We used the regression step analysis in which we decrease the indicators to the three main factors of the strength of lower limbs model, which influence the swimming performance to the 25 meters backstroke significantly with large effect (R ² = 0.4787 %; f ² = 0.9183; F = 7.652; p < 0.01). Again, the highest and statistically significant (p < 0.01) share on the explanation of swimming performance had the start to 4 meters with 43.33 % percentage share. Besides the swimming start, the Countermovement Jump test was statistically significant too (p < 0.05) and statistically insignificant was test of maximum velocity on a dry-land. By this study we can evaluate how individual factors of strength of lower limbs influence the swimming performance and for the future it is necessary to complete them with the other factors for the better creation of the appropriate swimming training program.
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Research on competitive swim start safety has focused on starts involving a dive from above the water surface. The purpose of this study was to determine the depths, speeds, and distances attained when executing backstroke starts, which begin in the water, and to investigate whether or not these variables are a function of age. Backstroke starts (n = 122) performed in 1.22 m of water during competition were stratified according to age group (8&U, 9-10, 11-12, 13-14, and 15&O). Dependent measures were maximum depth of the center of the head (MHD), head speed at maximum head depth (SPD), and distance from the wall at maximum head depth (DIST). Main effects were shown for age group for MHD (F = 8.86, p < 0.05), SPD (F = 4.64, p < 0.05), and DIST (F = 17.21, p < 0.05). Because they performed starts that were deeper and faster than the younger swimmers, the older swimmers seem to be at a greater risk for injury when performing backstroke starts in shallow water.
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The purpose of this study was to identify the mechanical characteristics of the hands-between-the-feet grab starting technique which contribute to a faster start. Twenty-four high school swimmers performed four trials of a grab start followed by a glide to a distance of 9 m. The results suggested that to obtain a faster start, swimmers should (a) move the center of mass fast in the forward direction while the feet are in contact with the starting block, (b) maximize the force exerted through the feet in the backward direction, and (c) maximize the force exerted through the hands against the starting block in the forward and upward direction. In competitive swimming the goal is to cover a set distance in the least amount of time. This means that a swimmer must start, swim, and turn fast. Although the time spent starting is very small, the differences between winning and losing a race are often so small that this time can be decisive. A few investigations have been conducted on this subject. In most cases (Bloom, Hosier, & Disch, 1978; Bowers & Cavanagh, 1975; Hanauer, 1967, 1972; Michaels, 1973) the results suggest that the grab start is more effective than other starting techniques. In other cases, however, (Ayalon, Van Gheluwe, & Kanitz, 1975; Lowell, 1975) the results suggest the opposite. Finally, there are still other cases (Gibson & Holt, 1979; Lewis, 1980) in which the results suggest that there are no differences between the grab start and other starting techniques. Parts of this paper have been published previously in a modified form for the use of teachers, coaches and swimmers. Direct all correspondence to Dr. James G.
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This study aimed to determine if starting with the feet above the water (FAW) in male backstroke swimming resulted in faster start times (15-m time) than when the feet were underwater (FUW). It was hypothesised that setting higher on the wall would generate increased horizontal force and velocity, resulting in quicker starts. Twelve high-level male backstrokers performed three trials of the FAW and FUW techniques. A biomechanical swimming testing system comprising one force plate (1,000 Hz), four lateral-view (100 Hz), and five overhead (50 Hz) video cameras captured the swimmers' performance. Data for each participant's fastest trial for each technique were collated, grouped, and statistically analysed. Analysis included Wilcoxon, Spearman Rho correlation, and regression analysis. Wilcoxon results revealed a significantly faster start time for the FAW technique (p p = 0.02), while take-off horizontal velocity was significantly greater (p = 0.01). Regression analysis indicated take-off horizontal velocity to be a good predictor of start time for both techniques, and the horizontal displacement of the centre of mass for the FAW start.
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Abstract The purpose of this study was to clarify factors to perform the hole-entry technique in the backstroke start. A total of 16 well-trained Japanese competitive swimmers were divided into two groups (backstroke specialists and non-specialists) to compare their backstroke start motions. Their backstroke motions were videotaped, and two-dimensional co-ordinates for the swimmers were obtained from the video images using direct linear transformation methods. A non-paired t-test and Mann-Whitney U-test were used to analyse the statistical difference of the kinematic variables between the groups. Backstroke specialists showed a significantly shorter 5 m time (P = 0.009, effect size = -1.54), a significantly higher position of the toe (P = 0.010, effect size = 1.47) at signal and of the hip at toe-off (P = 0.002, effect size = 1.94), a significantly larger hip joint angle at toe-off (P = 0.007, effect size = 1.60) and a significantly higher angular velocities of the hip joints (45-85%; P < 0.05) for the normalised time as compared to that of non-specialists. An earlier initiation of the extension and the maintenance of a higher extension speed at the hip joints were important factors in achieving an arched-back posture, which facilitated and water entrance with a small entry range.