Biomechanics of Body Movements During Competitive Swimming

BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
Name of the Student
Name of the University
Author’s Note

1BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
Summary
Swimming involves several variables of biomechanics which determines the performance of
the swimmer. The kinematics variables namely the stroke length, the stroke frequency, the
limbs’ kinematics along with the kinetics variables namely the propulsive drag, the lift force,
the drag force in addition to the neuromuscular variables and the joint movements play
fundamental roles in swimming. The systemic literature review attempts in associating all the
factors and variables to evaluate and understand the biomechanics of the body movement
during swimming and specifics that enhance the performance of the swimmer. The kinetics of
swimming in addition to the kinematics along with biomechanics of joint movements has
been highlighted in the study.

2BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
Table of Contents
Summary....................................................................................................................................1
List of Symbols and Abbreviations............................................................................................4
1. Introduction............................................................................................................................5
2. Hypothesis..............................................................................................................................6
3. Methodology..........................................................................................................................6
Search strategy.......................................................................................................................6
Selection criteria.....................................................................................................................7
4. Systematic literature review...................................................................................................7
4.1. The kinetics of swimming...............................................................................................8
4.1.1 Propulsive force........................................................................................................8
4.1.2 Drag force..................................................................................................................9
4.2. The kinematics of swimming........................................................................................13
4.2.1. Stroke cycle kinematics..........................................................................................13
4.2.2 Limbs kinematics....................................................................................................15
4.2.3. Hip and centre of mass kinematics.........................................................................15
4.3 Biomechanics of joint movements.................................................................................17
4.3.1 Biomechanics of gleno humeral joint.....................................................................18
4.3.2 Biomechanics of scapula-thoracic joint..................................................................19
5. Summarized model...............................................................................................................20
6. Conclusion............................................................................................................................22

3BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
References................................................................................................................................23
Appendices...............................................................................................................................28
Appendix 1: Hand movement during the strokes.................................................................28
Appendix 2: Forces that act on the body during swimming................................................29

4BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
List of Symbols and Abbreviations
V= Swimming velocity
SL= Stroke length
SF= Stroke frequency
Hz= Hertz
SI= Stroke index
ηp= Propulsive efficiency
CV= critical velocity

5BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
1. Introduction
Swimming is a physical activity which requires synchronized movement and action of
a significant number of muscles, joints and bones in order to balance the body and maintain
buoyancy on water whilst defying the gravitational drag together with propelling the body
forward (Kamata et al. 2016). On a regular basis, analysis of human movement encompasses
the movement made in the aquatic environments are evaluated with numerical and
experimental methods. The experimental methods generally quantify the measurements by
the attachment of bio-sensors on the participating subjects who are being analyzed followed
by the collection of bio-signals and its processing. The numerical methods have been
characterized by selection of relevant input data followed by processing of the selected data
based on mechanical equations and then collecting output data.
Swimming is composed of four phases: (i) starting phase; (ii) swimming phase; (iii)
turning phase in addition to (iv) finishing phase. A swimmer, during competitive swimming,
spends maximum time in swimming phase making the swimming phase the most determinant
moment of swimming performance of the swimmer (Sanders 2019). Therefore, majority of
the biomechanical analysis of the swimming is contributed to four common swimming
strokes: (i) freestyle; (ii) backstroke; (iii) breaststroke (iv) butterfly stroke.
The aim of this research report has is to perform biomechanical characterization of the
competitive swimming strokes including freestyle, backstroke, butterfly and breaststroke
along with assessing the biomechanical features of the strokes through kinetic study.

6BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
2. Hypothesis
H1: The stroke length (SL), swimming velocity (v), stroke frequency (SF), propulsive
efficiency (ηp), critical velocity (CV), stroke index (SI) all together affect the performance of
a swimmer.
H0: The stroke length (SL), swimming velocity (v), stroke frequency (SF), propulsive
efficiency (ηp), critical velocity (CV), stroke index (SI) do not affect the performance of the
swimmer.
3. Methodology
Search strategy
The formulation of the search terms was an indispensable aspect of the systematic
review as these search aided in the extraction of the articles which were pertinent to this
study. The framework that was published by Centre for Reviews and Dissemination (CRD
2009) was considered during the development of the search methodology. The use of this
model framework gave the scheme of basing the search based on the research aim (Zeng et
al. 2015). Taking reference and suggestions from the given guideline, the acronyms along
with the modification in spelling in addition with use of alternative words were taken into
consideration.
The articles were searched from three electronic databases namely, Scientific
Information Database (SID), WorldWideScience (WWS) in addition with PubMed. The
reference lists and bibliographies of the relevant articles were also searched manually to
retrieve appropriate articles which were not reflected during the search. The search terms
utilised during extraction of the articles were “swimming”, “biomechanics of swimming”,
“swimming kinetics”, “kinetics of swimming”, “kinematics of swimming”, “swimming

7BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
kinematics”, “biomechanics of joints”, “swimming joints”, “joints in swimming”, “swimming
biomechanics”, “swimming physics”, “swimming strokes”, “swimming strokes physics”, and
“physics of swimming”. The search terms were also combined with the aid of the boolean
operators namely ‘AND’ and ‘OR’ which helped the narrowing along with broadening of the
search results as per requirement (McGowan et al. 2016).
Selection criteria
The exclusion and inclusion criteria were also formulated to establish the attention
and priority for the articles reviewed in this systematic research based study. To maximise the
emphasis of the topic chosen for the systemic literature review, certain exclusion and
inclusion criteria were developed based on the guidelines set by Stern, Jordan and McArthur
(2014).
Table 1- Inclusion and exclusion criteria for the proposed literature review
Inclusion criteria Exclusion criteria
Articles selected were only in English Foreign language articles were excluded
Articles that highlighted swimming and the
biomechanics involved
Articles that focussed on biomechanics of
other sports were excluded
Peer reviewed articles were only selected Case studies were excluded
Only research articles were selected Manuscripts and blog contents were rejected
4. Systematic literature review
Kinetic assessment is usually done by the adoption of research designs from various
experiment based protocols. Since early 20th century, researches have been conducted for the
estimation of drag force and propelling force required for successful swimming. The pioneers
of such research are Houssay along with Cureton, Karpovich and Pestrecov from 1939
(Lewillie 2013). Techniques based on computer simulation (Bixler and Riewald 2012; Bixler

8BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
et al. 2017; Marinho et al. 2018) to calculate the forces applicable in swimming was
introduced in the 21st century along with protocols based on measuring the velocimetry of
virtual images (Kamata et al. 2016).
4.1. The kinetics of swimming
The kinetics of swimming attempts to resolve fundamental queries in the propulsive
force that is generated by the movement of the different parts of the body to overcome the
drag force of the water resisting the forward movement of the swimmer during swimming.
4.1.1 Propulsive force
The performance of the swimmer is limited to their ability in producing effective
propulsive force which is the main component of total propulsive force which acts in the
forward movement. The propulsive force measurement generated by the swimmer is of major
interest in the field of competitive sports. However, the job of calculating the propulsive
forces of a freely swimming individual is almost practically impossible. Hollander et al.
(1986) structured a research design to measure the active drag called the MAD system which
determines propulsive force applicable underwater on the push-off pads during freestyle
swimming. On the other hand, the ecological validity of the MAD system is exponentially
reduced in normal environment which lack lacks the intrusion of the MAD system implanted
on the push off pads (Payton and Bartlett 2015). Following this, non-intrusive way of
propulsive hand forces estimation was developed by Schleihauf (2019) during free swimming
which was the basis of multiple researches ( Berger et al. 2015).
The method formulated by Schleihauf (1979) attempted to estimate instantaneous
propulsive force on the basis of the combination of the vectorial forces acting on the model
hands in the open-water while recording the pulling action of underwater channel. Schleihauf
used resin plastic model of a human adult hand to measure the forces which are co-ordinated

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in constant water flow so as to determine the drag force along with the coefficients of arm lift
in specific orientations. The data generated were then digitized to estimate the kinematic
force of the hand in addition with the lift force, the drag force and the vectors of the resultant
force which is produced by the swimmers’ stroke cycles (Sanders 2019).
The contribution of the relative drag forces and the lift forces leading to overall
propulsion is a topic highly scrutinized and evaluated in the hydrodynamics research.
Schleihauf (2019) analysed water channel forces and reported lift coefficient values which
was noted to increase to attack angle at approximately 40º and was found to decrease as
sweepback angle was reduced. The values of drag coefficient were found to increase as the
attack angle was increased and was less sensitive to the changes of the sweepback angle.
Bixler and Riewald (2012) analysed it further to evaluate the steady flow around the hand of
the swimmer along with various attack angles and sweep back angles of the forearm of the
swimmer. The coefficients of force were measured as the function of the attack angle which
reflected that drag force of the forearm was generally constant and the forearm lift almost
zero. The hand drag represented minimum values when the angles of attack was at 0º or at
180º and maximum value was noted when the angle of attack was near 90º and the model
was almost perpendicular to flow. The hand lift was close to zero around 95º and maximum
around 60º along with 150º.
4.1.2 Drag force
The drag force in hydrodynamics is defined as the external force which acts on the
parallel body of the swimmer however is opposite in direction to the direction of movement.
The drag force is essentially a resistive force which depends on the anthropometric features
of the swimmer along with the specifics of any equipment utilized by swimmers in addition
to the medium’s physical characteristics and the technique used for swimming (Kjendlie and
Stallman 2018).

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The hydrodynamic drag force (D) resisting the forward motion could be expressed
below by the Newton’s equation:
D = ½ CD ρ S v2E1
In which ρ is the fluid density, drag coefficient is represented by CD, projection surface of
swimmer is represented by S and swimming velocity is represented by v.
The intensity of hydrodynamic drag force is evaluated in swimming and highlighted
in swimming biomechanics. The drag force by towing a non-swimming subject in water
which is known as passive drag had been studied previously; however the analysis of the
passive drag force does not illustrate the active drag force that the swimmer has to overcome
during actual swimming (Karpovich 2013). Therefore, it is vital to calculate the actual drag
force in swimming which is active drag force and studies have also shown that passive drag
force is actually lower when compared to the active drag force of the same individual
(Kjendlie and Stallman 2018).
In order to accomplish the goal, techniques must be directed to evaluate the active
drag which was first developed by the research groups Clarys and Jiskoot (1975) along with
Prampero et al. (1974) who formulated various interpolation techniques to analyse the active
drag force. The methods involve indirect calculations which are based on the changes in the
oxygen consumption when extra load was placed on swimmer (Marrinho et al., 2010).
Hollander et al. (1986) later developed MAD or Measurement of Active Drag system, which
is based measuring the direct push off force at the beginning of freestyle.
A new method was developed by Kolmogorov and Duplishcheva in the year 1992
which was designed to regulate active the drag force called velocity perturbation method or
small perturbations method (Kjendlie and Stallman 2018). This method comprised of the

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subject to swim two laps with the maximal effort in two scenarios which include firstly free
swimming followed by swimming with a hydrodynamic body which creates known added
active drag force. The mean velocities for both trials are calculated with the conjecture that
both the swims are with maximal power output which is required to overcome the drag, and
then the drag force could be calculated with the difference between the swimming velocities
(Toussaint 2016).
In comparison to interpolation procedures along with the MAD structure of
calculation which required heavyweight arrangements in addition with costly experimental
techniques, velocity perturbation process just mandated the utilization of hydrodynamic body
stratagem along with chronometer to evaluate the active drag. In addition, this method could
be applied in measuring the active drag for all the four types of competitive strokes. The
other approaches could be applied only to Front Crawl or free style technique of swimming.
In the MAD technique, the swimmer also presents few segmental constrains as the legs are
kept out of calculations as they are held by the pull buoy (Kjendlie and Stallman 2018). With
this approach numerous researches has been piloted to estimate the active drag in the various
techniques of swimming.
The active drag was found to be significantly higher in the adults in comparison with
children. The difference between the active force of an adult and a child was customarily due
to altered sizes along with velocity while swimming. Studies highlighting the active drag
force between the boys and the girls reported no significant difference between the two
(Marinho et al. 2011). The possible clarification might be associated to similar body mass
along with the height of the boys and the girls who participated in the experimental study.
However, later studies have shown that the girls generally have lower drag force as well as
lower velocity when compared to body which is attributed to the physical structure and body
mass difference between the boys and the girls.

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The total drag comprises of frictional, wave and form components of the drag force
created. The frictional drag is based on viscosity of water along with shear stress that is
generated in boundary layer. Intensity of these components is mainly because of the
moistened body surface area, in addition to the surface characteristics along with the water
current situations inside the boundary layer. The final drag is resultant of the differential
pressure flanked by the front and the rear of the swimmer as well as depends on velocity
along with the compactness of water in addition to swimmers cross-sectional area. Owing to
difference of boundary between the two different liquids of the incomparable densities, the
swimmer is inhibited with the surface wave formation that leads in formation of the wave
drag that is close to the surface of the water (Toussaint and Truijens 2015).
The influence of the form, the wave drag and friction modules of the entire drag while
swimming will be stimulating in biomechanics study in sports. The information accessible
from several experimental researches indicates some problems in evaluating every drag
constituent's influence (Bixler et al. 2017). Often predictable that the lowest element is
frictional drag of complete drag, particularly at greater swimming speeds, although this drag
element should not be ignored in elite level swimmers. Using numerical simulation methods,
Bixler et al. (2017) discovered that friction drag, when the diver glides underwater, accounted
for about 25% of complete drag. Zaidi et al. (2018) also discovered a significant involvement
of resistance drag to the overall drag when swimmer glides underwater submissively. The
writers discovered that the dragging resistance accounted for around 20% of the complete
drag. According to these, problems such as sporting equipment, shaving plus decreasing body
surface of the immersed body should be regarded in aspect, as the drag element appears
towards affect efficiency particularly throughout slithering afterward starting and turning.
However, wave drag and shape are the vital constituent of the entire hydrodynamic
drag, so it is important for the swimmers to strain the most hydrodynamic positions while

13BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
swimming (Marinho et al. 2019). However, a gigantic part of complete swimming drag is
wave drag (Kjendlie and Stallman 2018); this drag element is tremendously reduced when
gliding underwater. For example, Lyttle et al. (2016) concluded, when a characteristic adult
swimmer is maximum 0.6 m below the water surface, there is no significant wave drag. In
addition, Vennell et al. (2018) found that for velocities of 0.9 m s-1 and 2.0 m s-1,
respectively, a swimmer must be lower than 1.8 and 2.8 chest depths below the surface to
avoid wave effects.
4.2. The kinematics of swimming
A major part of swimming technique exploration is committed to the kinematics of
the various swimming strokes. Biomechanics of the body movements in competitive
swimming comprises of (i) kinematics of the stroke cycle; (ii) kinematics of the limbs; (iii)
kinematics of the hip and the centre of the mass (iv) kinematics of various joint movements.
4.2.1. Stroke cycle kinematics
Velocity (v) is the utmost swimming results assessment adaptable. The freestyle
technique is regarded the fastest swimming stroke for a specified range. However, the
Butterfly stroke, the Backstroke and the Breaststroke cannot be neglected (Craig et al.
2015; Chengalur and Brown 2012).
Its autonomous variables can describe swimming speed: length of stroke (SL) and
frequency of stroke (SF).Length of the stroke can be defined as the range travelled by the
body horizontally in a complete strokes cycle. Stroke length can be demonstrated as the
complete number of cycles of strokes accomplished in a time unit (strokes.min-1) or Hertz
(Hz). Increases or reduces in v are determined in SF and SL respectively by combined
increases or reduces (Tousaint et al., 2016; Kjendlie et al. 2016). For all swimming strokes,
these are polynomial relationships (Pendergast et al. 2016). For Craig and Pendergast (2015)

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Freestyle has the largest SL and SF compared to the rest of the swimming methods. Authors
proposed comparable conduct for the Backstroke except that the SL and v were lower in a
specified SF than in the Freestyle (Craig et al. 2015). At the stroke of Butterfly, rises in v
were almost completely linked to rises in frequency of stroke, neglecting the highest. Increase
in velocity can also be correlated with an increase in frequency of stroke at Breaststroke,
however the stroke length decreased as compared to other strokes in the swimming (Craig
and Pendergast 2019).
During the course of swimming, the decreasing velocity is directly related to
reduction of the stroke length of most of the strokes in swimming chiefly due to exhaustion
(Hay and Guimarãe 2013). The “zig-zag” arrangement for the stroke frequency during the
inter-lap also alters leading to the lowering of velocity. At the final lap, the peak SF occurs
regularly (Letzelter and Freitag 2013). The decreasing trend of stroke frequency, velocity and
a minimal maintenance of stroke length with further development of ranges as compared to
swimming strokes by range (Craig et al. 2015). Swimmers should possess a prominent
change of stroke frequency (Craig and Pendergast 2019).
The stroke index (SI) is another variable is most often utilized to estimate the
kinematics of the process of stroke. SI is determined as a general swimming estimator of
effectiveness (Costill et al. 2015). This index assumes that the most efficient swimming
technique is available to the swimmer with greater SL at a given v (Sánchez and Arellando
2012). Freestyle is the one with the highest SI, of all the swimming strokes, followed by the
Backstroke, the Butterfly stroke and the Breaststroke. Analyzing it by distance, it is not
entirely consensual in literature. Sánchez and Arellano (2012) with the exception of
Breaststroke, recorded a trend for SI decline from 50 to 400 m occurrences. On the other side,
in the World Championship finals, The apparent reduction in SI from shorter to longer

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distances has also been reported (Jesus et al. 2011).The effects was quite significant for the
distance for the SI to relate the swimmers who were female.
4.2.2 Limbs kinematics
Variables of stroke mechanics, together with SF and SL, depend on the kinematics of
the limb, which is why certain attempts must be made to comprehend the involvement of the
movements of the limbs during swimming. As for example, it was observed during Freestyle
stroke a significant relationship between velocity of movement of the hip along with the
vertical and horizontal motions of the upper limbs (Deschodt et al. 2016). As the velocity of
the upper limb increased, so did the swimmers ' horizontal speed. It can therefore be asserted
that the velocity of the upper limbs has a significant impact on the efficiency of swimming.
Indeed, during Freestyle stroke analysis, it was discovered that minute contributions from the
leg movements of about 10 percent was there during propulsion (Hollander et al. 2018).
Deschodt et al. (2019), however had recorded a comparative contribution of approximately
15%. No research is there on partial contribution of the lower and the upper limbs to the total
swimming speed of remaining strokes.
4.2.3. Hip and center of mass kinematics
The mass and the hip center are often taken as the manner of analyzing the kinematics
of the body however, the hip is not validated as a suitable estimator of the center of mass
kinematics (Psycharakis and Sanders 2019). The intra cyclic hip velocity has more
differences than the mass center (Mason et al. 2012). In addition, the peaks and troughs do
not interconnect temporarily during the process of the cycle of the stroke. Throughout the
process of stroke cycle, inter-limb activities continually alter the center of mass position
(Psycharakis and Sanders 2019). Such variations cannot be represented by the hip as it is an
anatomical milestone. Although the bias remains an alternative for some study organizations
to evaluate the anatomical landmark.

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The most frequently appraised adjustable related to the hip or center of mass is the
horizontal velocity (dV) intra-cyclic variation. Body's speed is not uniform throughout the
stroke cycle. The velocity of the body is increasing and decreasing due to the actions of the
limb. In fact, the dV was regarded one of the most significant biomechanical factors to be
evaluated in swimming to be more competitive (Komolgorov and Duplisheva 2012).
The dV is defined with non-linear features from a mathematical point of perspective.
However, coefficients determined from these replicas are mild, as different dV curves are
implemented for different swimmers. Discrete curve shows particular modifications
compared to mean curvatures of various topics, expressing the swimming method
interpretation (Barbosa et al. 2011).
The dV has a multi-model profile at Front Crawl (Barbosa et al. 2011). Higher peaks
are associated with actions of the arm and reduced peaks are associated with actions of the
leg. Two greater peaks with distinct speeds can be observed for some individual curve. These
peaks are associated with each arm's most propulsive stages. In addition, it appears that there
is an asymmetric application of propulsive power from both weapons for some topics. A
comparable trend for the Backstroke dV can be confirmed.
The dV has a bi-modal profile at Breaststroke (Barbosa et al. 2011). One peak is
linked to the behavior of the arm and the other to the action of the leg. Both peaks should be
more or less even, but followed by a greater value for the top of the leg. After this peak, a v
reduction occurs in the gliding stage. In fact, the gliding stage is another problem to consider
with regard to the dV of the Breaststroke. Subjects should understand the precise time to
begin a fresh stroke cycle, avoiding a significant decline in instantaneous v (Capitão et al.
2016).

17BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
The dV shows a tri-modal profile at Butterfly stroke (Barbosa et al. 2013). The initial
peak of the curvature is because of the first laidback of the leg, the next peak remaining to
insweep of the arm, the highest peak during the upsweep of the arm. The regaining of entire
arm is a phase when the immediate speed reduces quickly. There is a connection between dV
and v and the cost of swimming energy between dV and dV (Craig et al. 2015).
The four competitive swim strokes have a polynomial connection between dV and v
(Barbosa et al. 2016). With raising v, the dV rises to a specified point and then begins to
decline. So, a reduced dV seems to be imposed by elevated speeds. In addition, raising dV
will result in a rise in swimming energy costs, even controlling the v impact (Barbosa et al.
2016). In this sense, a small dV results in greater swimming effectiveness in all four
competitive strokes. For example, a more pronounced body wave at Breaststroke enforced a
reduced dV (Silva et al. 2012). A small velocity at Butterfly stroke during the entrance of the
hand, a top rapidity during the upsweep and an elevated additional downbeat velocity will
reduce the dV (Barbosa et al. 2018). Thus, the activities of some particular limbs in each
swim stroke can reduce the dV and thus boost the swimming effectiveness and thus improve
performance.
4.3 Biomechanics of joint movements
The basic joints needed for swimming are the scapula-thoracic joint, the radial-ulnar
joint and the gleno-humeral joint (Lawrence et al. 2014). Freestyle stroke is performed in
swimming activities for a big percentage of the moment. It is also the swimming races '
longest stroke and has produced the most studies. The scapula thoracic joint or the scapula
costal joint is the pectoral girdle's physiological joint where scapula is apprehended alongside
the thoracic wall with the help of several muscles (Reinold, Escamilla and Wilk 2019). The
gleno humeral joint (knee joint) is the ball and socket joint that links the scapula to the

18BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
humerus bone and joins the top of the primary body (Hik and Ackland 2019). The gleno
humeral joint is one of human body's most mobile joints and is essential for swimming arm
motion that helps propel the flesh forward.
4.3.1 Biomechanics of gleno humeral joint
Gleno-humeral joint is an extreme joint that is essential to the swimming arm motion
that helps to propel the body forward. Gleno humeral joint's multiple motions include
abduction, internal rotation, and flexion along with the gleno humeral joint's external rotation
(Xipoleas et al. 2016).
a. Abduction of Gleno humeral joint
The abduction motion occurs when the legs are kept sideways and parallel to the torso
and then raised in the frontal plane (Swimming Resource 2018). It includes two fundamental
motions the first in which the humerus is elevated from its parallel place with the sine to a
perpendicular location of the spine accompanied by the second motion involving the
elevation of the humerus above the knee. As for example, this movement generates an out
sweep action of arms in the freestyle swimming.
b. Flexion of Gleno humeral joint
The abduction of the flexion or limb is contrary to the abduction motion of the arm.
This also comprises of two fundamental gestures; first, the spinning backward motion of the
scapula by the gleno-humeral joint accompanied by continuing backward motion of the neck
toward the shoulder. As for example, this combined joint motion includes the swimmer
placing his hand on the water and pushing it in the water. (Hik and Ackland 2019).
c. Internal rotation of Gleno humeral joint

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The humerus rotates in this motion out of the torso plane to point forward. This
motion takes place in the sagittal plane while the weapons are fired from the body (Sahara et
al. 2019).
d. External rotation of Gleno humeral joint
The external rotation is the exact reverse of the gleno-humeral joint's internal rotation.
The arm is raised here as if to point at the roof. This movement is used to maintain
equilibrium while swimming on the back (Swimming resource 2018).
4.3.2 Biomechanics of scapula-thoracic joint
The scapula thoracic joint allows for complicated scapular motions related to the
thoracic cage, i.e. retraction and protraction along with depression and speed during
swimming.
a. Retraction (adduction) of the scapula-thoracic joint
Medially and later, the scapula in this motion is enthusiastic along the transverse
plane as the arm is relocated afterwards along with the shoulder joint. Both the shoulder
blades retraction provide a gripping feeling. This retraction motion of the scapula-thoracic
joint motion usually takes place throughout the rowing stage and is the swimming catch point
(Swimming Science 2019).
b. Protraction (abduction) scapula-thoracic joint
In comparison to scapular retraction, the protraction or removal of the scapula-
thoracic segment can be described as the competing motion (Seth et al. 2016). The motion of
the scapula is along the anterior and horizontal axis as the body moves along the anterior

20BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
plane and the shoulder joint. The shoulder blades are protracted allowing separation of the
scapulae while squeezing together the front of the neck consisting of the pectoral significant
tissues. The freestyle swimming entrance point shows the scapula-thoracic joint's protraction
motion (Swimming Science 2019).
c. Elevation of the scapula-thoracic joint
In a shrugging motion, raising the shoulder blades contributes to the scapula-thoracic
joint elevating movement. When the swimmer's neck reaches the water while swimming
freestyle, the thoracic joint of the scapula is raised. The joint moves along the Sagittal plane
as the arms travel in the water. (Swimming Science 2019).
d. Depression of the scapula-thoracic joint
Scapula is lowered from high to depressed level during the depression motion of the
scapula-thoracic joint. Slumped shouldered along with obtuse angle between throat and
shoulders are observed in this motion. This is observed between the strokes during the
soothing stage (Swimming Science 2019). As far as the concern of hydrodynamic drag, the
external force can be justified acting parallel to the body of the swimmer but in an alternative
direction of its direction of movement. This resistive force depends on the swimmers’
anthropometric features, the machinery features used by the swimmers, the water field's
physical features, and the swimming method.
5. Summarized model
The summarized model involves factors such as duration of stroke, frequency of
stroke, coefficient of stroke, and velocity of swimming. The confirmatory model described 79

21BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
percent of the results of 200-m freestyle and was appropriate for the submitted hypothesis
(Barbosa et al. 2010). Another research created an effective drag force structural equation
modeling centered on anthropometric, hydrodynamic (i.e. frontal surface region, drag
coefficient) and biomechanical factors (i.e., stroke length, stroke frequency and swim speed)
in teenage children (Barbosa et al. 2010). After removing the frontal ground region, the
confirmatory system described 95% of the effective force. The model's main restriction is
linked to the equation for estimating the facial surface area that does not fit in the model. All
chosen anthropometric factors, susceptible gliding experiment, stroke duration, stroke
frequency, and velocity were included in the confirmatory model. The vertical buoyancy
experiment was removed from the final model.
The good-of-fit confirmatory path-flow model was regarded to be very near to the
cut-off price, but not yet appropriate to the hypothesis. Vertical buoyancy and susceptible
gliding testing are simple and inexpensive methods to evaluate the kinetics of the swimmer.
Both methods, however, are not the finest methods respectively to evaluate the hydrostatic
and hydrodynamic profile of the swimmer. Hohmann and Seidel (2010) estimated 41 percent
of the 50-m freestyle output of teenagers based on psychological, technical (i.e., stroke
frequency, swimming speed, alignment of the limbs), physical training and anthropometric
factors.

22BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
6. Discussion
Drag force is well discussed here which is a force which acts parallel to the body of
the swimmer. Strokes cycle depends on the strokes length which determines the number of
stroke cycles completed in the allocated time. This strokes length is directly proportional to
the decrease in velocity of the swimmer. The higher the strokes length, the higher is the
velocity of the swimmer in water. The movement of the joints of the swimmers body is also
dependent on several biomechanical factors. It can be said that the scapula thoracic joints are
responsible for the movement of the joints. The summarised confirmatory model on the
various factors and relationship in biomechanics, swimming performance along with
kinematics is illustrated below. The stroke length (SL), swimming velocity (v), stroke
frequency (SF), propulsive efficiency (ηp), critical velocity (CV), stroke index (SI) in
relevance to performance have been incorporated into the model.
7. Conclusion
Therefore, in conclusion, it can be asserted that the stroke length (SL), swimming
velocity (v), stroke frequency (SF), propulsive efficiency (ηp), critical velocity (CV), stroke
index (SI) are interconnected and together assert the performance of a swimmer during any
swimming stroke. The activities of particular limbs in each swim stroke along with the
kinematics of the stroke cycle as well as the kinematics of the limbs along with kinematics of
the hip and the centre of the mass in addition to the kinematics of various joint movements
thus boost the swimming effectiveness and thus improve performance.

23BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
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Appendices
Appendix 1: Hand movement during the strokes
The hand’s underwater path at Front Crawl (panel A), Backstroke (panel B), Breaststroke
(panel C) and Butterfly stroke (panel D).

29BIOMECHANICS OF BODY MOVEMENTS DURING COMPETITIVE SWIMMING
Appendix 2: Forces that act on the body during swimming