SHOOTING TECHNIQUES IN ARCHERY SPORT BASED ON
BIOMECHANICS ENGINEERING: ARM VIBRATION ANALYSIS
SITI NURHIDAYAH BINTI DAUD
Report submitted in fulfillment of the requirements
for the awards of the degree of
Bachelor of Mechanical Engineering
Faculty of Mechanical Engineering
UNIVERSITI MALAYSIA PAHANG
JUNE 2013
vii
ABSTRACT
This thesis is mainly about the archery sports and focusing on the shooting techniques
that finally will be result in accuracy of the shots and performance of the athlete. There
are several steps that need to be followed to obtain the correct postural during the
archery session. This may influent the result of the arrow release later. The aim of this
study was to investigate the relationship between arm vibration during the shooting
process with the score and performance of the athlete and to investigate the
relationship between the time taken for the athlete to release the arrow with the score
and performance of the athlete. Suitable outdoor experiment setup will be
recommended inside this paper work. Accelerometer will be used in this experiment.
Other equipment involve including DAQ device, camera digital, cable, and target
board. Vibration rate data will be collected and analyze by using the DASYLab
software. Time taken for the archer to release the arrow also will be recorded to
investigate either it will give a significant to the performance of the athletes. From the
results, it shows that there are significant relationship between arm vibration and time
with the performance of the athletes. Statistical analysis that consists of regression and
ANOVA also conducted in this project to show the correlation between the variables
involves.
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ABSTRAK
Tesis ini membincangkan tentang sukan memanah yang menjurus kepada teknik-tenik
melepaskan mata memanah dengan cara yang betul untuk melihat kesannya ke atas
ketepatan serta kejayaan atlit tersebut. Beberapa cara dan langkah yang harus diikuti
untuk mendapatkan pergerakan ideal ketika memanah. Objektif tesis ini ialah untuk
menyiasat hubungan di antara gegaran tangan semasa proses memanah dengan skor dan
prestasi atlit serta untuk menyiasat hubungan di antara masa untuk atlit melepaskan
panahan dengan skor dan prestasi yang berjaya diperoleh. Kerangka eksperimen luar
yang sesuai telah direka untuk projek ini. Pengesan gegaran akan digunakan bagi
eksperimen ini. Peralatan lain yang turut digunakan adalah seperti DAQ, kamera digital,
kabel dan juga tempat sasaran panahan. Data bagi gegaran akan dianalisis menggunakan
DASYLab. Masa untuk atlit melepaskan panahan mereka turut akan direkod untuk
melihat sama ada ianya akan memberi kesan kepada skor atlit itu sendiri atau pun tidak.
Daripada keputusan eksperimen, data menunjukkan adanya hubung kait di antara
pembolehubah yang terlibat iaitu gegaran tangan dan masa yang diambil dengan
prestasi dan skor atlit. Analisa statistika yang terdiri daripada regrasi dan ANOVA turut
dilakukan dalam projek ini untuk menunjukkan korelasi dan hubungkait di antara
pembolehubah yang terlibat.
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TABLE OF CONTENT
Page
EXAMINER APPROVAL DOCUMENT i
TITLE PAGE ii
SUPERVISOR’S DECLARATION iii
STUDENT’S DECLARATION iv
DEDICATION v
ACKNOWLEDGEMENTS vi
ABSTRACT vii
ABSTRAK viii
TABLE OF CONTENT ix
LIST OF TABLES xii
LIST OF FIGURES xiv
LIST OF SYMBOLS xvi
LIST OF ABBREVIATIONS xvii
CHAPTER 1 INTRODUCTION
1.1 Background of The Study 1
1.2 Problem Statement 3
1.3 Objective 3
1.4 Scope of Study 3
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction 4
2.2 Archery Sport 4
2.3 Design of Experiment 5
2.4 Vibration Effect during Arrow Releasing 6
2.5 Time Taken for Archers to Release the Arrow 12
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2.6 Conclusion 15
CHAPTER 3 METHODOLOGY
3.1 Introduction 16
3.2 Project Flow 17
3.3 Collecting Information/Findings 18
3.4 Design of Experiment 19
3.41 Subjects 19
3.42 Equipment 19
3.43 Data Processing 24
3.5 Outdoor Experimental Setup 24
3.6 Experiment Procedure 26
3.7 Analysis of Experimental Data 30
3.8 Conclusion 32
CHAPTER 4 RESULTS AND DISCUSSIONS
4.1 Introduction 33
4.2 Raw Data Analysis 33
4.3 Athlete Data Analysis 36
4.4 Beginner Level 36
4.4.1 Data Validation 43
4.5 Intermediate Level 48
4.5.1 Data Validation 55
4.6 Elite Level 60
4.6.1 Data Validation 66
4.7 ANOVA Analysis 71
4.8 Discussion 74
4.9 Conclusion 75
CHAPTER 5 CONCLUSION
5.1 Introduction 77
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5.2 Conclusion 77
5.3 Future Recommendations 78
REFERENCES 80
APPENDICES
A1 Data sheet of score and arm vibration in (m/s2) - 82
Beginner level
A2 Data sheet of score and arm vibration in (g) - 83
Beginner level
B1 Data sheet of score and arm vibration in (g) - 84
Intermediate level
B2 Data sheet of score and arm vibration in (m/s2) - 85
Intermediate level
C1 Data sheet of score and arm vibration in (g) - Elite level 86
C2 Data sheet of score and arm vibration in (m/s2) - Elite level 87
D Gantt Chart for Final Year Project 1 88
E Gantt Chart for Final Year Project 2 89
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LIST OF TABLES
Table No. Title Page
2.1 Suitable aiming time during shooting process in archery 14
3.1 Subject’s age, height and weight 19
3.2 Data sheet for the experiment 30
4.1 Subject’s age, height and weight 36
4.2 Regression statistics between score and arm vibration at 3 sec 43
4.3 ANOVA analysis results for 3 seconds data 44
4.4 Regression coefficient table for 3 seconds data 44
4.5 Regression statistics between score and arm vibration at 5 sec 45
4.6 ANOVA analysis results for 5 seconds data 46
4.7 Regression coefficient table for 5 seconds data 46
4.8 Regression statistics between score and arm vibration at 7 sec 47
4.9 ANOVA analysis results for 7 seconds data 47
4.10 Regression coefficient table for 7 seconds data 48
4.11 Subject’s age, height and weight 48
4.12 Regression statistics result between score and arm vibration at 55
3 sec
4.13 ANOVA analysis results for 3 seconds data 56
4.14 Regression coefficient table for 3 seconds data 56
4.15 Regression statistics between score and arm vibration at 5 sec 57
4.16 ANOVA analysis results for 5 seconds data 57
4.17 Regression coefficient table for 5 seconds data 58
4.18 Regression statistics between score and arm vibration at 7 sec 58
4.19 ANOVA analysis results for 7 seconds data 59
4.20 Regression coefficient table for 7 seconds data 59
4.21 Subjects age, height and weight 60
4.22 Regression statistics result between score and arm vibration at 66
3 sec
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4.23 ANOVA analysis results for 3 seconds data 67
4.24 Regression coefficient table for 3 seconds data 67
4.25 Regression statistics result between score and arm vibration at 68
5 sec
4.26 ANOVA analysis results for 5 seconds data 68
4.27 Regression coefficient table for 5 seconds data 69
4.28 Regression statistics result between score and arm vibration at 69
7 sec
4.29 ANOVA analysis results for 7 seconds data 70
4.30 Regression coefficient table for 7 seconds data 70
4.31 Score results for 3different levels of athlete at 3 different times 72
taken
4.32 ANOVA summary results 72
4.33 Athlete’s arm vibration for 3different levels of athlete at 3 73
different times taken
4.34 ANOVA summary results 73
4.35 Suitable aiming time during shooting process in archery 75
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LIST OF FIGURES
Figure No. Title Page
2.1 Experiment design 6
2.2 Process of drawing the bow 10
2.3 Bow and string structure during arrow releasing 11
2.4 Total drawing time (TDT) and full drawing time (FDT) data 13
with score achieved by the athlete
2.5 Chance of good shot according to the bow holding time 15
3.1 Flow chart of the research project 17
3.2 Accelerometer 20
3.3 Front view (a) and back view (b) of the cDAQ-9171 21
3.4 Sensor cable 21
3.5 Nikon D90 22
3.6 Panasonic Lumix DMC-S2 23
3.7 Archery target board 23
3.8 Schematic diagram of the experiment setup 24
3.9 Outdoor 30m field 25
3.10 New location for outdoor 30m archery experiment 26
3.11 Warming up session before the experiment 27
3.12 Training session 27
3.13 Setting up the accelerometer for athlete 28
3.14 One of the athletes during the experiment 29
3.15 Athlete’s score 29
3.16 Schematic of the computer based acquisition and control 31
system
4.1 Raw data from DASYLab signal process 34
4.2 Reading of acceleration during shooting 35
4.3 Subject 2’s score vs. arm vibration graph 37
4.4 Subject 5’s score vs. arm vibration graph 38
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4.5 Subject 7’s score vs. arm vibration graph 38
4.6 Subject 8’s score vs. arm vibration graph 39
4.7 Graph score vs. maximum arm vibration-comparison between 40
the 4 athletes at 3 seconds
4.8 Graph score vs. maximum arm vibration-comparison between 40
the 4 athletes at 5 seconds
4.9 Graph score vs. maximum arm vibration-comparison between 41
the 4 athletes at 7 seconds
4.10 Graph of maximum arm vibration vs. number of trials between 42
the 4 athletes
4.11 Subject 3’s score vs. arm vibration graph 49
4.12 Subject 4’s score vs. arm vibration graph 50
4.13 Subject 10’s score vs. arm vibration graph 50
4.14 Subject 12’s score vs. arm vibration graph 51
4.15 Graph score vs. maximum arm vibration-comparison between 52
the 4 athletes at 3 seconds
4.16 Graph score vs. maximum arm vibration-comparison between 52
the 4 athletes at 5 seconds
4.17 Graph score vs. maximum arm vibration-comparison between 53
the 4 athletes at 7 seconds
4.18 Graph of maximum arm vibration vs. number of trials between 54
the 4 athletes
4.19 Subject 1’s score vs. arm vibration graph 61
4.20 Subject 6’s score vs. arm vibration graph 61
4.21 Subject 9’s score vs. arm vibration graph 62
4.22 Graph score vs. maximum arm vibration-comparison between 63
the 3 athletes at 3 seconds
4.23 Graph score vs. maximum arm vibration-comparison between 63
the 3 athletes at 5 seconds
4.24 Graph score vs. maximum arm vibration-comparison between 64
the 3 athletes at 5 seconds
4.25 Graph of maximum arm vibration vs. number of trials between 65
the 3 athletes
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LIST OF SYMBOLS
g Gravitational acceleration
Acceleration
α Statistical significance level
Dependent variable: score
Independent variable: arm vibration
m meter
p-value Probability value
xvii
LIST OF ABBREVIATIONS
FITA International Archery Federation
TDT Total Drawing Time
FDT Full Drawing Time
SD Standard Deviation
DAQ Data acquisition
RTD Resistance Temperature Detector
ASCII American Standard Code for Information Interchange
df Degree of freedom
SS Sum of Square
MS Mean Square
ANOVA Analysis of Variance
FYP1 Final Year Project 1
MSNT Majlis Sukan Negeri Terengganu
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Humans have used archery since the dawn of history, first for hunting, warfare,
and in modern times for sport. Archery is a sport that has been around for a very long
time and is rich in history. The first archers were hunters looking for an easier, and
safer, way of getting their dinner. A bow allowed them to shoot an arrow much further
and with more accuracy than throwing a spear. In approx. 2500BC, the first bow was
produced by the Egyptians. It was made from wood, tipped with animal horn and held
together with animal sinew and glue. Unstrung, it resembled a "C" shape and would
have required 2 people to string it. The bowstring was made from "catgut" (sheep
intestines). The arrows used were extremely light, could be shot 400 yards using the
composite bow and would easily penetrate the armor of that time period. Since the
beginnings, archery has been taken up by different people for different reasons. Archery
competitions have been around almost as long as the invention of the bow and still are
very popular. Even with modern equipment, however, the principle is still the same and
the same qualities are that were required hundreds of years ago are still necessary to be
a good shot with a bow and arrow. In archery, the shooter needs to able to concentrate
and focus on single goal and still be able to relax and control their actions. Like most
other sports some participants will find this easy to do while it will be more challenging
to others. For every shooter however, the key to success is practice.
Nowadays, archery game becomes one of the favorite games around the world.
From the beginning of the history that tell us about the main function of bow and arrow
that actually used for hunting. Through the years, it has already been commercialized
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into official games around the world. Competitive archery involves shooting arrows at
a target for accuracy from a set distance or distances. This is the most popular form of
competitive archery worldwide and is called target archery. A form particularly
popular in Europe and America is field archery, shot at targets generally set at various
distances in a wooded setting.
Shooting technique in archery is crucial in order to achieve high accuracy results
at the end of the game. By the aid of biomechanics engineering concept, Malaysian
athlete performance in archery game can be enhanced for the future as for preparation
toward Olympic Game in 2016. The basic idea of this project is more on experimental
work. This research studied about the factors of arm vibration and time that will affect
the accuracy of shooting in archery games. Any motions that repeat itself after an
interval of time are called vibration or oscillation. The theory of vibrations deals with
the study of oscillatory motions of bodies and the forces associated with them. A
vibratory system, in general includes a means for storing potential energy (spring or
elasticity), a means for storing kinetic energy (mass or inertia), and a means by which
energy is gradually lost (damper) (S.S.Rao, 2011). After releasing the arrow to the
target board, vibration will occur to the athlete. Some archers sway more than the
others while targeting or focusing on the correct score (C.Tinazci, 2011). Eventually
this action will affect the movement of the athlete thus can influence their score. Time
taken for the athlete to release the arrow also need to be consider. Subjects with the
quicker arrow release would have better performance than subjects with a slow release;
also subjects with more consistent release would have better performance than subjects
with an inconsistent release (M.Q.Wang, 1987). Arm vibration and time can also affect
each other. The more time taken for the athlete to hold and aim, the more vigorously
movement of the arm happens. This action will lead to the vibration factor and finally
resulting in their score target. In order to get the correlations between these two
variables, statistical analysis method will also be conducted. These two variables will
be further discussed in this research paper.
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1.2 Problem Statement
Archery in Malaysia is still developing. Malaysia is still far behind the top
performers in archery such as South Korea. In previous Olympic Game in London,
Malaysian athlete has just achieved the maximum score up until the quarter final round
where we lose to Japan. In order to improve their performance for the next world stage
game, a wide range of shooting technique that leads to the tournament success need to
be developed. There are some factors that contribute to the high accuracy of the shoot
in archery game. Based on the journals that I have read, the outcome issues that related
to this factor are arm vibration and time. By conducting this experiment, 2 variables
will be focus on that are vibration and time. Based on the results, relationship between
the variables can be analyze either it will give significant to the score and performance
of the athlete or not.
1.3 Objective
The objectives of this research are:
i. To investigate the relationship between arm vibration during the shooting
process with the performance of the athlete.
ii. To investigate the relationship between the time taken for the athlete to
release the arrow with the performance of the athlete.
1.4 Scope of Study
Based on this research, mainly will be focusing on young athletes from the
Majlis Sukan Negeri Terengganu (MSNT) that consist of three different levels;
beginner, intermediate and elite. Outdoor experimental setup will be run to collect all
the data that focus on vibration and time. All the recorded data then will be analyzed to
see either there is a correlation between them. Statistical analysis will then be
conducted to all the data that have been recorded to see the relationship between them
and also to validate the results.
CHAPTER 2
LITERATURE REVIEW
2.1 INTRODUCTION
The purpose of this chapter is to provide a review of past research regarding to
archery sports and how to improve the performance of it. This chapter will be focus on
the literature review of factors that will contribute to the performance of archery that are
arm vibration and also time taken to release the arrow. A review of other relevant
research studies is also provided. The review is detailed so that the present research
effort can be properly tailored to add to the present body of literature. Related literature
has been studied on archery sports, fundamental steps of shooting the arrow, body
movement, aiming time and also human arm vibration
2.2 ARCHERY SPORTS
Archery is the skilled sports that use bow and arrow as the equipment involve.
Nowadays, archery is one of the professional sports that has been commercialize into a
major sport’s tournament. Previously, main purpose of archery is for hunting while now
it turns out to be one of the famous sports around the world. There are two types of bow
in archery field that is recurve bow and compound bow. A Compound Bow is a type of
equipment used for archery that is composed of pulleys and cables. But unfortunately
even the compound type is famous though, what is commonly used in the Olympics is a
recurved bow. It's not only used for Olympics, but it's also the most highly used bow by
modern archers. It's basically made for high precision and quality.
5
In archery sport, there will be some steps that need to be followed through in
order to achieve the accuracy of the target. Here is the step and foundation of the shots
proposed by USA CDC:
i. static alignment, body stable
ii. the stance; foot position, leg alignment
iii. body position; orientation hips, rib cage
iv. archer’s center of gravity & maintaining stability
v. position bow & draw shoulder
vi. position bow arm
vii. hand position & grip on bow handle
Stability has been determined to be the most important factor in aiming at the target
(T.M. Hung et al, 2009). Thus, it can be seen that there were several important factors
that contribute to the better performance in archery sports. As stated by Min Qi Wang
(1987), more consistency in release time was associated with better shooting
performance. In this project there will be 2 factors that will be focusing with that are
arm vibration and also time taken for the archer to release the arrow.
2.3 DESIGN OF EXPERIMENT
As suggested by K.B. Lin et al (2005), the suitable experimental setup can be
described as the schematic diagram shown:
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Figure 2.1: Experiment design
Source: K.B. Lin et al (2005)
2.4 VIBRATION EFFECT DURING ARROW RELEASING
Any motions that repeat itself after an interval of time are called vibration or
oscillation. The theory of vibrations deals with the study of oscillatory motions of
bodies and the forces associated with them. A vibratory system, in general includes a
means for storing potential energy (spring or elasticity), a means for storing kinetic
energy (mass or inertia), and a means by which energy is gradually lost (damper)
(S.S.Rao, 2011). Vibration process will occur at point when the athletes release their
arrow string after anchor point is achieved. At this moment, rate of the vibration will be
different among the 3 categorize of archer. All data will be recorded and studied to
observe whether it will affect the accuracy of shooting or not. In archery, there is the
relationship between stability of the archer, adjustments made during the aiming
procedure and the targeting coordination (K.B. Lin et al, 2005). International team
especially South Korea has scientifically studied every aspect of the archery shot
process with the goal of improving biomechanical efficiency (USA CDC). Most of the
shooting technique studied paper was about the proper method and how to get the
correct position for the archer to achieve better result. As we know, during the arrow
releasing there will be vibration processes occur at the arm and shoulder part of the
athlete. Vibration transmitted to different segments of the hand-arm system such as the
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nail, finger, wrist, elbow and shoulder (S.A. Adewusi et al, 2010). This condition will
eventually affect the motion of the archer hence resulted to the low accuracy of the
shots. As stated by T.M.Hung et al (2009), stability has been determined to be the most
important factor in aiming at the target. By the aid of high speed camera and an
accelerometer, I can actually observe the movement and frequency of that activity. The
condition before and after releasing of the arrow can be studied.
According to Ruth Rowe (2007), align the body so that it is the most stable by
aligning the shoulder and arm bones to carry the draw weight, it also produces greater
accuracy on the target and lessen the chance of injury. In archery, it is crucial to get the
right alignment and perfect body posture to help maintains the stability, hence can
ensure the accuracy of shooting. All the forces in the body at full draw must remain
after release, the forces should not change just because you have released (J.Larven et
al, 2007). But it is hard for the archer to maintain and keep in the same position after a
few trial shots. Non-symmetrical load adopted during the draw is retained unchanged
during aiming, but body balanced is disturbed upon arrow release and load on both feet
was reduced for a brief instant (C.Tinazci, 2011). The modern technique in sport
archery is not to hold but to stretch a hand against the bow handle (I.Zanevsky, 2006).
Keeping a body in steady state after releasing the arrow might be difficult for an archer.
In this experiment, this effect is going to be observed whether it will give a significant
impact to the accuracy. Sports archers stretch a bow in the common motion of a string
and an arrow with a fixed hand, whilst trying to keep a steady body pose, body mass is
significantly greater than bow mass (I.Zanevsky, 2006). It is ideal that the hand be as
vertical as possible at full draw as this provides even tension on the fingers, relaxes the
wrist and forearm and does not cause side interference to the string upon release
(J.Larven et al, 2007). An archer should establish and maintain the accurate balancing of
the body during the time of release and completion of the shots. As stated in FITA
Coach’s Manual, if this balanced is not maintained it is likely that the pushing arm will
shake or the drawing hand becomes unsteady and the shot being performed will not be
fully efficient.
A three-finger hook in archery is a unique example of isometric forearm
muscular activity in which a delicate pull and push balance should be established on the
8
bowstring (H.Ertan et al, 2003). If this balance can be kept throughout the shooting
process, accurate shots will be achieved. Based on C.Tinazci (2011) research, he
assumed that some archers sway more than the others while targeting or focusing on the
correct score. This factor actually will lead to the inaccurate target shots. When the
archers tend to sway more, their arm is experiencing vibration motion. As the bow
string is released, the force from the bow tending to flex the bow arm joints is removed
and the equilibrium established before release would be disturbed (C.Tinazci, 2011).
String and arrow united motion is accompanied by intensive oscillations, which are
caused by destruction of the static balance of forces at the point of string release
(I.Zanevsky, 2006). A major part to success in archery is learning the proper shooting
technique. With the proper shooting technique, your accuracy will greatly increase. Arm
vibration is one of the factors that will contribute to this technique. When the bow is
drawn, the sight level and the bow level must be aligned properly to achieve maximum
accuracy. Poor alignment could occur due to fatigue or possibly bad habit in practice.
To reduce this problem, beginners should rehearse the correct bow alignment and
choose the bow weight that best suits each individual. Small women should use a bow
around 25-30 pounds of draw weight. Men could use up to 35 pounds. Unsuitable bow
can also lead to the unbalanced body posture and archers will tend to sway more
vigorously.
Apart from that, vibration that happens at the archer’s arm during the shooting
process relevantly will influence the posture of the body where this situation will bring
to the instability of the athlete. This problem will then affect the results and
performance of the athlete. According to Tatsuya Kasai et al (2002), mechanical
vibration applied to muscle tendons is known to selectively activate muscle receptors,
especially the muscle spindle, in human subjects. Generally, archery sport is a static
sport that needs full concentration and focus in order to perform well. Good body
posture, balancing control and arm movement also become important factor that should
be consider. As stated by Tatsuya Kasai et al (2002), it is also well known that the effect
of muscle vibration increase with increasing frequency of vibration, the mechanical
characteristic of tendon vibration must be controlled. During the shooting process, there
will be steps that need to be followed precisely in order to shoot accurately. As stated by
A.R.Soylu et al (2006), in the full draw position, the archer has to perform many tasks
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simultaneously where they should both aim at the target and release the bowstring
without disturbing the aiming position and the lateral deflection of the string.
Unfortunately, most of the archer tends to sway vigorously during this state. Practically,
to reduce this problems athlete need to balance their posture in a proper way and
maintain the position until the releasing of arrow. According A.R.Soylu et al (2006), to
the release phase must be well balanced and highly reproducible to achieve
commendable results in an archery competition. Vibration is the movement of a body
about its reference position. Stability was determined by the movement of the locus of
the center of mass projected on the ground, which is caused by body sway (T.M.Hung et
al, 2009). Usually for elite archer, they do not have any specific time to shoot because it
will come naturally. As they come to the full drawing state, eventually they will release
the arrow automatically. According to T.M.Hung et al (2009), stabilization is a very
sophisticated system to balance and stabilize the bow before and during the shot.
Vibration occurs because of an excitation force that causes motion. In recent
times with compound scores reaching higher and higher standards the importance of
being able to hold steady and maintain strength for a full days shooting is becoming the
most important aspect (J.Larven et al, 2007). Based on USA CDC, during the release it
is important to minimize tension in any place; the bow arm should be strong and static
during the release and also follow through process. Vibration of postural muscles
caused involuntary postural responses of forward or backward inclination (T.Kasai et al,
2002). This statement can explain why accuracy of the shoots can be affected with the
vibration factor during the shooting process. During the releasing of an arrow, string
will contribute to the acceleration of the arrow toward the target board and transferred
potential energy in the elastic part of the bow as kinetic energy into the arrow. The bow
is held in its place and the archer feels the recoil force in the bow hand (B.W.Kooi,
1991). As the recoil movement happening to the archer, at some part it will slightly
affected the target point of the archer. At this moment, the stability and static
consistency of bow arm should be considered. Based on FITA Coach Manual, an archer
should establish and maintain an accurate balance during the time of the release and
completion of the shots. As what we can observe during this situation, if the archer can
maintain their consistency throughout the process, their performance manages to be well
and so do their score point. If the balance is not maintained it is likely that the pushing
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arm will shake or the drawing hand becomes unsteady and the shot being performed
will not be fully efficient (FITA Coach Manual).
Figure 2.2 show the step of drawing the bow in archery. Based on the figure,
archers need to maintain their position and avoid from vigorous movement at the bow
hand.
Figure 2.2: Process of drawing the bow
Source: J.Larven et al (2007)
At full draw the archer should be standing upright with body weight evenly
distributed on both feet and there should be between 60 % to 70 % of body weight
toward the front of each foot and only 40 % to 30 % on your heels (J.Larven et al,
2007). The modern technique in sport archery is not to hold but to stretch a hand against
the bow handle (I.Zanevsky, 2006). As stated by B.W.Kooi et al (1980), when drawing
a bow in general the force exerted by the archer on the string will increase. At this point,
it is the maximum energy of them pulling out the string of the bow. But somehow, this
value will not be fixed throughout all the athletes. Different athletes will have different
11
strength. So in order to keep the bow in fully drawn position the maximum force, called
the weight of the bow must be exerted by the archer while he aims at the target
(B.W.Kooi et al, 1980). This situation includes the value of vibration in the archer’s
arm. The value may vary to different athlete according to their level, age, and also
weight. It is not possible that all the deformation energy stored statically in the bow can
be transferred, during the dynamic process of shooting, as kinetic energy to the arrow
(B.W.Kooi et al, 1980). Based on the figure below by B.W.Kooi (1991), it shows the
steps and movement of the bow and string before releasing the arrow. As seen from the
figure, the maximum force happens at the third graph. This is where the full draw of the
bow happens. At this moment, most of the athlete will experience large amount of
vibration if they cannot control the movement and muscles. Indeed, they need to stay
naturally without any other force about their posture to minimize the movement and
sway. The maximal pull-out force is restricted by the physical strength of the archer
(M.Pagitz et al, 2004).
Figure 2.3: Bow and string structure during arrow releasing
Source: B.W.Kooi (1991)
Some archers have tremendous shaking problems. When they come to the full
draw, their bow arm shakes excessively or their drawing arm shakes almost
12
uncontrollably (S.Ruis et al, 2004). After releasing the arrow, an experience known as
jolt will be face by the archer. The jolt occurs only when the bows full energy is transfer
to the arrow. The residual effect causes the body to recoil from the instantaneous
transfer of energy, thus negatively affecting the shots (S.Ruis et al, 2004)
2.5 TIME TAKEN FOR ARCHERS TO RELEASE THE ARROW
The effect of reaction time on scoring points in archery can be one of the major
research topics where the main idea is to search for any relationship between the time of
reaction and the scored points on the target in archery (C.Tinazci, 2011). The exact
duration of time has been given to the athlete before they start releasing the arrow to the
target board. The aiming and expansion phase of the shot sequence should be a very
short interval of time and should be subconscious rather than conscious (USA CDC).
The more time used by the archer to aim after reaching the anchor point, the lower the
performance in shooting the target board. As stated by Cevdet Tinazci (2011),
performance of the group of archers has negative correlation with the total drawing time
because as the time increased the performance decreased. When shooting a recurve bow
the release must be a surprise and must be made immediately the clicker goes off
(J.Larven et al, 2007). It can be seen between the elite and beginner archers. Elite
archers take less time taken before releasing their arrow compare to beginner archers.
Subjects with quicker arrow release would have better performance than subjects with a
slow release, also subjects with more consistent release would have better performance
than subjects with an inconsistent release (M.Q.Wang, 1987). Moreover, intraindividual
smaller deviations of the aiming trajectory within the last second before the release of
the shot are more likely to result in a higher score compared to larger deviation
(N.Ganter et al, 2010). This time taken scope also related with the usage of clickers at
the riser. Clicker is a mechanical device which produces a clicking sound when the
archer reaches the correct draw length and it’s ready to release the arrow. As stated in
FITA Coach’s Manual, the relationship of time when the clicker falls from the arrow
point to the moment of the release is also very important. It is found that if there is a
delay this is the moment where most of the mistakes take place. From a biomechanical
point of view, the archer has to cope with the breakdown of the static balance of forces
between the external tension and their muscular forces at the time of shooting