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RELATIONSHIP BETWEEN STRENGTH OF KNEE
EXTENSOR AND FLEXOR AND YOYO
INTERMITTENT ENDURANCE TEST IN
ELITE JUNIOR HANDBALL PLAYERS
BY
LAM CHI HO
06000851
AN HONOURS PROJECT SUBMITTED IN PARTIAL FULFILMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
BACHELOR OF ARTS
IN
PHYSICAL EDUCATION AND RECREATION MANAGEMENT (HONOURS)
HONG KONG BAPTIST UNIVERSITY
APRIL 2008
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HONK KONG BAPTIST UNIVERSITY
25 th April, 2008
We hereby recommend that the Honors Project by Mr. Lam Chi
Ho entitled “Relationship between strength of knee extensor
and flexor and YoYo Intermittent Endurance Test in elite
junior handball players” be accepted in partial fulfillment
of the requirements for the Bachelor of Arts Honors Degree
in Physical Education and Recreation Management.
________________________ _______________________
Dr. Tong Kwok Keung Prof. Chow Bik Chu
Chief Adviser Second Reader
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ACKNOWLEDGEMENTS
I would like to express my gratefulness to my chief advisor,
Dr. Tong Kwok Keung, for his kind and professional suggestions
throughout the whole project period. I would also like to give
thanks to Miss Lu Kui from Dr. Stephen Hui Centre for Physical
Recreational and Wellness, for guiding me in the use of the
laboratory equipments. Lastly, thank you for the Hong Kong
Junior Team Handball Team players for their participation.
________________________________
Lam Chi Ho Department of Physical Education Hong Kong Baptist University
Date: 25 th April, 2008
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ABSTRACT
YoYo Intermittent Endurance Test was very popular in
assessing the performance and aerobic ability of athletes.
On the other hand, isokinetic dynamometry was more
accuracy to assess the ability of muscle strength of
athletes today due to technical improvement. However, the
contribution of the two different abilities of muscle
endurance and muscle strength were seldom reported. This
study was to examine the relationship between strength of
knee extensor and flexor and YoYo Intermittent Endurance
Test. Seven male Hong Kong Junior Team Handball Team
players were participated in this study with age, 15.43
± 1.40 years; weight, 68.36 ± 9.86 kg; height, 180.14 ± 7.71
cm. The knee extensor and flexor was assessed by isokinetic
dynamometry (Humac Norm). For the YoYo Intermittent
Endurance Test, the measurement of the total distance
covered was obtained in this study. It was found that there
was no significant correlation between the knee extensor
and flexor muscle strength and the performance of YoYo
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Intermittent Endurance Test [(r = 0.491, p > 0.05) and
(r = 0.401, p > 0.05)]. The contribution of knee extensor
and flexor muscle strength was 24.1% and 16.1% to the
performance of YoYo Intermittent Endurance Test (r 2 =
0.241) and (r 2 = 0.161) respectively. The findings suggest
that there was weak relation between knee extensor and
flexor muscle strength and the performance of YoYo
Intermittent Endurance Test.
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TABLE OF CONTENTS
CHAPTER Page
1. INTRODUCTION. . . . . . . . . . . . . . . . . . . 1
Statement of the Problem. . . . . . . . . . . 3
Hypothesis. . . . . . . . . . . . . . . . . . 3
Significance of the Study. . . . . . . . . . . 4
2. REVIEW OF LITERATURE. . . . . . . . . . . . . . . 5
The Importance of Muscular Strength. . . . . . 5
The Importance of Leg Strength
on Running Sports. . . . . . . . . . . . . 6
Factors that Affecting Muscle
Strength and Endurance. . . . . . . . . . . 7
Testing Methods of Strength. . . . . . . . . . 14
Isokinetic Systems. . . . . . . . . . . . . . . 15
YoYo Intermittent Endurance Test. . . . . . . 16
Definition of Terms. . . . . . . . . . . . . . 18
Summary. . . . . . . . . . . . . . . . . . . . 23
3. METHOD. . . . . . . . . . . . . . . . . . . . . . .24
Subjects. . . . . . . . . . . . . . . . . . . . 24
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Procedures. . . . . . . . . . . . . . . . . . . 25
Test Protocol. . . . . . . . . . . . . . . . . .26
Statistical Analysis. . . . . . . . . . . . . . .29
Delimitations. . . . . . . . . . . . . . . . . 29
Limitations. . . . . . . . . . . . . . . . . . .30
4. ANALYSIS OF DATA. . . . . . . . . . . . . . . . . 31
Results. . . . . . . . . . . . . . . . . . . .31
Discussion. . . . . . . . . . . . . . . . . . 37
4. SUMMARY AND CONCLUSION. . . . . . . . . . . . . .43
Summary of Results. . . . . . . . . . . . . . 43
Conclusion. . . . . . . . . . . . . . . . . . 44
Recommendation of Further Study. . . . . . . .45
REFERENCES. . . . . . . . . . . . . . . . . . . . . .47
APPENDIX. . . . . . . . . . . . . . . . . . . . . . 51
A. Borg Rate of Perceived Exertion (RPE) Scale. .51
B. YoYo Intermittent Endurance Test
Data Collection Form. . . . . . . . . . . . . 52
C. Parental Consent Letter. . . . . . . . . . . . 55
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LIST OF TABLES
TABLES Page
1. Physical Characteristics of Hong Kong
Junior Team Handball. . . . . . . . . . . . . 31
2. Peak torque mean score of knees extensors. . .32
3. Peak torque mean score of knees flexors. . . .33
4. Pearson product moment coefficient of
correlation test between the distance
covered in the Level 2 YoYo Intermittent
Endurance Test and the muscle strength
of knee extensor. . . . . . . . . . . . . . .34
5. Pearson product moment coefficient of
correlation test between the distances
covered in the Level 2 YoYo Intermittent
Endurance Test and the muscle strength
of knee flexor. . . . . . . . . . . . . . . . .34
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LIST OF FIGURES
FIGURES Page
1. The setting of YoYo Intermittent
Endurance Test. . . . . . . . . . . . . . . . . .27
2. The setting of Isokinetic Dynamometry. . . . .28
3. Scatter plots of the distance covered of
Level 2 YoYo Intermittent Endurance Test
and muscle strength of knee extensor. . . . . . 35
4. Scatter plots of the distance covered of
Level 2 YoYo Intermittent Endurance Test
and muscle strength of knee flexor. . . . . . . . . .36
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Chapter 1
Introduction
Team handball is a dynamic sport that includes natural
athletic skills such as running, jumping, throwing, and
catching provide the action for the game (Fronske, 2008). It
can also be classified as an interval sport. As the needs of
physical fitness are vary and huge.
Muscular strength and endurance are the basic elements of
playing team handball. Strength and power are critical to the
performance of many athletic tasks. However, their assessment
is currently problematic because of the enormity of the area
and the limited work that has been completed within the field
to date (Gore, 2000).
On the other hand, technical and tactical skills in
handball are highly dependent on the player’s physical
capacity. In between the exchange of offense and defense,
players need aerobic endurance to perform a series of
movements and running in the handball court throughout the
match.
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The YoYo tests are a number of tests which in an easy way
evaluates various aspects of performance. The tests contain
running activities that are relevant for many sports. Using
the YoYo tests, it is possible to obtain information about
a large number of athletes within a short time, and the tests
have higher performance validity during competition than
laboratory tests. There are three YoYo tests. They are YoYo
endurance test, YoYo intermittent endurance test and YoYo
Intermittent recovery test. For the YoYo intermittent
endurance test, it is to evaluate an individual’s ability to
repeatedly perform running intervals over a prolonged period
of time. The test is especially useful for the athletes who
perform interval sports such as tennis, team handball,
basketball, and soccer (Bangsbo et al., 2006).
Some Sport like ball games, in which the ball is used in
the fitness training, the exercise intensity for an athlete
varies continuously, and some overlap exists between aerobic
and anaerobic training (Bangsbo, 2005). The team handball
players need both anaerobic and aerobic ability for this
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interval sport, quadriceps and hamstrings bear a great
workload of running, sprinting and jumping during the
competition.
Yoyo test is commonly used to assess individual’s
anaerobic capacity (ATPPCr) which is an essential energy
system utilized during handball competition. Since the test
requires individual to sprint repeatedly. I wonder if the
testing result was also determined by individual’s leg
strength.
Statement of Problem
The purpose of this study was to identify the contribution
of strength of knee extensor and flexor to the performance
of YoYo intermittent endurance test.
Hypothesis
The following hypotheses were tested in this study:
Research Hypothesis
There would be a significant relationship between the
muscles strength of knee extensor and flexor and the
performance of YoYo intermittent endurance test.
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Null Hypothesis
The correlation between muscles strength of knee extensor
and flexor and the performance of YoYo intermittent endurance
test was not significant in participants.
Significance of the Study
As the player’s ability of muscular strengths and
endurances can be assessed and train at the same time, the
planning and pointed specific training can be established in
a diversity way. In order to have a better improvement and
performance on team handball players, it is worth to find out
the relationship between the performance of YoYo
intermittent endurance test and the strength power of the
quadriceps and hamstrings of the players.
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Chapter 2
REVIEW OF LITERATURES
Muscular strength and endurance were important in most of
the sports. In this study, the purpose of this study was to
examine the contribution of strength of knee extensor and
flexor and the performance of YoYo intermittent endurance
test.
The review of literature was divided into six main
sections. The first section contained the importance of
muscular strength. Then the second section describes the
factors that would affect muscle strength. Third section shows
the testing method of strength. The information of YoYo
Intermittent Endurance Test and Isokinetic Systems would be
focused in the fourth and fifth section respectively. And the
summary was included in the last section.
The Importance of Muscular Strength
Strength is an important component of success in most
athletics events, and therefore should be an essential part
of most training programs. The time spent in training for
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strength should be proportional to the requirement for these
components in your event, and your deficiencies in this area
(Heyward, 2006).
Nowadays, there are lots of physiological assessments and
methods for people to measure the muscles strength. Isokinetic
dynamometry is one of the assessments. It has been used to
assess elite athletes since its inception in the late 1960s,
for the different purposes. For two decades it has been the
standard research tool used by physiologists to investigate
dynamic muscle function of single muscle groups. Isokinetic
dynamometry can be performed under a range of conditions –
of angular velocity, positioning, range of motion,
contraction mode, movement sequence, and so on – from which
a wide range of measurement parameters can be derived (Gore,
2000). Especially for the jumping and shooting of team
handball, it requires the muscular strength of different body
parts such as arm, shoulder, wrist and leg.
The Importance of Leg Strength on Running Sports
Maximal power is demonstrated in athletic performances by
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the ability to project an object or one’s body through apace.
Power produces momentum, which is the striking force when
contact is made. Thus power has many applications in a variety
of athletic events. In projecting an object, the object might
be thrown, kicked or struck, and the power is determined by
the combination of force and speed. For example, sprint
running is dependent largely upon power because it involves
a series of body projections, alternating from the two legs.
The rate of these projections is dependent upon the
combination of the force and speed of muscle contractions.
Power plays an even more prominent role in sprinting during
the acceleration phase than during the remainder of the sprint.
With consideration of the prevalence of sprinting,
acceleration, throwing, kicking, and impact in athletic
performances, the significance of power becomes apparent
(Fisher & Jensen, 1990).
Factors that Affecting Muscle Strength and Endurance
Muscle Length
According to Fisher & Jensen, the initial length of the
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muscle is important because stretched fibers exert more force.
Apparently, in the stretched state, crossbridges are more
effectively aligned with active sites and maximal force can
be generated. Muscle fibers stretched beyond 120% of resting
length begin to decrease their tension. This condition seldom
exists in the human body, however, because muscle length is
limited by joint movement, and many fibers are about 120% of
resting length when joints reach their full extension. When
fibers are less than fully extended, there begins to be an
overlap of action filaments which interferes with the coupling
potential of the cross bridges (1990).
Angle of Pull
As the elbow joint moves through its range of motion, the
mechanical advantage increases and the force the muscle needs
to apply decreases yielding a rather stable “strength curve”
for the particular joint and muscle group. During elbow
flexion the greatest force is exerted between 80 and 140
degrees (180 degrees is full extension). At its strongest
point in terms of length, the force at the hand was only 74%
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of maximum. In reality, the heaviest resistance that can be
moved through a full range of motion is not the load that can
be lifted at the optimal angle but the much smaller load at
the point of mechanical disadvantage when the muscle is
contracting maximally. Manufacturers have tried to compensate
for this effect by developing machines which provide variable
resistance so that maximal tension is being developed
throughout the range of motion (Fisher & Jensen, 1990).
Speed of Shortening
The relationship between muscular force and speed of
shortening is important to athletes, especially in limb
movements such as kicking and throwing. The faster a muscle
is contracted, the less time there is for crossbridge
coupling. The force generated by a muscle is greatest at the
slowest speeds of movement and decreases as the speed of
movement increases. Likewise, for any given force, the greater
the contribution of fast twitch fibers, the greater the
velocity of movement. Physiologically, fast twitch fibers
have a greater capacity for calcium release and uptake from
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the sarcoplasmic reticulum which allows for faster tension
development. This information has pratical application in the
sense that athletes with a high genetic distribution of fast
twitch fibers will probably perform better in power type
events compared to those with predominantly slow twitch fibers
(Fisher & Jensen, 1990).
Coordination of Accessory Muscles
Strength is also related to the coordination of the
antagonistic muscles and the action of the neutralizer and
stabilizer muscles. These factors can be improved through
appropriate training which allows more efficient application
of muscular force (Fisher & Jensen, 1990).
Muscle Size
According to Fisher and Jensen, the contractile force of
a muscle is related to the muscle’s crosssectional
measurement (4 to 6 kg/cm 2 ). As strength increases, the size
of the individual muscle fibers increase, resulting in a
greater crosssectional area of the muscle. The increase in
size relates fairly well with the increase in strength. Other
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factors may influence this relationship, such as the fat
around muscle, the proportion of active fibers, and the
efficiency of contraction. And muscle size and strength are
closely related and an increase in muscle size will result
in a significant increase in strength (1990).
Muscle Type
Fast and slow fibers are recruited selectively depending
on the force required. Training programs for strength
emphasize high resistance/low repetition movements to
stimulate recruitment of fast twitch fibers. For muscle
endurance, the resistance is decreased and the number of
repetitions are increased to allow slow twitch fibers to be
recruited. There may also be selective hypertrophy in fast
and slow fibers. Fast twitch fibers are much larger in power
athletes than in cross country runners (Fisher & Jensen,
1990).
Relationship of Strength to Age
Research, combined with practical experience, indicates
that under normal conditions boys increase in strength rather
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consistently until the age of 25. After this age, strength
increase at a slower rate. Maximal strength is attained at
the age of 25. Soon after the maximal strength is attained,
strength begins to diminish. After the age 25, it is speculated
that a person loses 1% of his strength each year. At age 65
most persons are 65 to 70% as strong as they were at age 20
to 30. The rate of strength loss is influenced considerably
by one’s activity level throughout life (Fisher & Jensen,
1990).
According to Bassey, Bendall and Pearson (1988), the
decline in muscle strength associated with aging carries with
it significant consequences related to functional capacity.
A significant correlation between muscle strength and
preferred walking speed has been reported for both sexes. Also,
there is strong relationship between quadriceps strength and
habitual gait speed in frail institutionalized men and women
above the age of 86 yr supports this concept from the study
of Fiatarone et al. (1990).
Relationship of Strength to Sex
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Women are about twothirds as strong as men and have about
twothirds as much muscle mass as men. They are about 80% as
strong as men in hip flexors and extensors, and about 55% as
strong in the forearm flexors and extensors. The difference
in upper and lower body strength between the sexes is probably
due to the difference in typical daily activity patterns,
although differences are diminishing. There is no evidence
to suggest differences in muscle quality between men and women
(Fisher & Jensen, 1990).
When strength is compared on an absolute score basis, men
are usually considerably stronger than women for all muscle
groups tested. These strength differences are particularly
apparent in comparisons of upper body strength, where women
are about 50% weaker than men; in lower body strength, women
are about 30% weaker (Heyward, JohannesEllis & Romer, 1986).
This sex characterization for strength is true regardless of
the device used to measure strength and is generally
attributed to the sexrelated difference in the distribution
of lean body mass (Castro & McCann, 1995). Exceptions are some
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strengthtrained female trackandfield athletes and body
builders who significantly increase the strength of specific
muscle groups through resistance exercises (McArdle, Katch
& Katch, 1996).
Testing Methods of Strength
There are only two basic ways to test strength – statically
or dynamically. Static strength is easier to measure, but the
measurements are less valuable to athletes and coaches because
dynamic strength is the kind of strength that is most used
in athletic performance. In fact, the relationship between
isometric and dynamic strength measures are relatively low
and one should not be predicted from the other. Results of
most strength tests are also influenced by motivation. This
factor should be controlled whenever possible (Fisher & Jensen,
1990).
Static Strength Tests
Static strength of different body parts has been measured
accurately using a cable tensiometer, a back and leg lift
dynamometer, or a hand grip dynamometer. More recent
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applications use a strain gauge and feed the information into
a personal computer. With either application, it must be
remembered that static strength varies at different points
through the range of motion. Therefore, if comparisons are
to be made, it is important that the strength be measured at
exactly the same angle each time (Fisher & Jensen, 1990).
Dynamic Strength Test
Maximal lifts with different kinds of weighttraining
equipment provide some of the best measures of dynamic
strength. A certain amount of experimentation is necessary
to determine the maximal weight that can be lifted for one
repetition, but when this is finally determined, it represents
the dynamic strength for that particular movement. Strength
can be measured by use of free lifting equipment,
weightlifting machines such as Nautillus or Universal gyms,
and isokinetic exercise devices such as the Cybex equipment
(Fisher & Jensen, 1990).
Isokinetic Systems
Isokinetic systems were conceived to analyse the muscular
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fitness of patients who are members of any population group.
During a standard session, patients must perform a set of
exercise, for example, ten seconds extending and flexing their
leg with the machine moving at a constant speed of 90 deg/s.
The number of exercises and speed at which they must be
performed are determined by the isokinetic protocol currently
in use (CaracaValente & LopezChavarrias, 2000). This
protocol defines the number of exercises to be performed and
at what speeds. Obviously, the protocol must always be the
same, if we are to be able to analyse some patients against
others, as differences in the number, order and speed of the
exercises would significantly alter the isokinetic curves
obtained. All of the exercises performed in a session are
called an isokinetic test (CaracaValente & LopezChavarrias,
2000).
YoYo Intermittent Endurance Test
YoYo Intermittent Endurance Test. The test was performed
according to the methods of (Krustrup et al., 2003) and
consisted of repeated 20m runs forward and back, keeping in
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time with a series of audio signals from a compact disc. After
completion of two 20m intervals, all subjects had 10 seconds
of active recovery, which consisted of 10 m of jogging around
a cone placed 5 m away from the starting point. The running
speed was progressively increased until the subjects reached
volitional exhaustion. The YoYo Intermittent Endurance Test
performance was taken as the total distance covered upon
volitional fatigue (Sirotic & Coutts, 2007).
Most team sports require athletes to regularly repeat short
highintensity bouts of exercise, interspersed with longer
intervals of submaximal exercise over a prolonged period of
time (i.e., > 30 minutes) (Reilly & Gilbourne, 2003). And this
test evaluates an individual’s ability to repeatedly perform
intervals over a prolonged period of time, particularly for
athletes from sports such as tennis, team handball, basketball
and soccer (Krustrup et al., 2003). YoYo Intermittent
Endurance Test was performed according to the methods of
Krustrup et al. (2003) and consisted of repeated 20m runs
forward and back, keeping in time with a series of audio signals
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from a compact disc. After completion of two 20m intervals,
all subjects had 10 seconds of active recovery, which
consisted of 10 m of jogging around a cone placed 5 m away
from the starting point. The running speed was progressively
increased until the subjects reached volitional exhaustion.
The YoYo Intermittent Endurance Test test performance was
taken as the total distance covered upon volitional fatigue.
This test has previously been reported to be both a reliable
and valid test of physical performance in team sports
(Krustrup et al., 2003).
Definition of Terms
Strength
Strength is the maximal force you can apply against a load,
and power is proportional to the speed at which you can apply
this maximal force. Training to improve in this area can
include lifting weights, throwing heavier implements, running
against a resistance, and plyometrics (depth jumping and
bouncing). Strength is also defined as “the peak force of
torque developed during a maximal voluntary contraction (MVC),
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under a given set of conditions (e.g. contraction type and
velocity)” (MacDougall, Wegner & Green, 1991). In more simple
terms, it is “the ability of a muscle group to exert maximum
contractile force against a resistance” (Heyward, 2006).
Muscular Strength
Muscular strength refers to the maximal force that can be
generated by a specific muscle or muscle group. Static or
isometric strength can be conveniently measured using a
variety of devices, including cable tensiometers and handgrip
dynamometers. Peak force development in such tests is commonly
referred to as the maximum voluntary contraction (MVC).
Isokinetic testing involves the assessment of muscle tension
generated throughout a range of joint motion at a constant
angular velocity. Equipment which allows control of speed of
joint rotation (degrees/sec) as well as physical
adjustability to test movement around various joints (e.g.,
knee, hip, shoulder, elbow) is available from several
commercial sources. Such device measure peak rotational force
or torque, defined as ‘the measured ability of a rotation
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element to overcome turning resistance’ (Mahler et al., 1995).
Muscular Endurance
Muscular endurance is the ability of a muscle group to
execute repeated contractions over a period of sufficient time
duration to cause muscular fatigue, or to sufficient time
duration to cause muscular fatigue, or to statically maintain
a specific percentage of MVC for a prolonged period of time.
Simple field tests such as the 60second situp test or the
maximum number of pushups that can be performed without rest
may be used to evaluate the endurance of the abdominal muscle
groups and upper body muscles, respectively (Mahler et al.,
1995).
Torque
A torque is a vector that measures the tendency of a force
to rotate an object about some axis (Serway, 1996). The
magnitude of a torque is defined as force times its lever arm
(Tipler, 2004). Just as a force is a push or pull, a torque
can be thought of as a twist.
Peak Torque
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Peak torque is simply equal to force, it was generated by
a muscle decreases with increasing velocities of movement.
The greatest torque is produced at the slowest speeds of
movement (Mathews & Fox, 1976).
Power
Power is the rate at which work is done – which is equivalent
to the product of torque and angular velocity (or force and
linear velocity). Average or instantaneous power can be
calculated (Gore, 2000).
Average Power
Average power (watt, W) is derived by dividing work (J)
by the time (duration) of the contraction (watt = joules/s).
This is equivalent to taking the mean of the product of
instantaneous torque (N.m) and instantaneous velocity (in
radians/s) at every time interval throughout the movement
(dimensionless radians are dropped, and the resultant N.m/s
= watts) (Gore, 2000).
Instantaneous Power
Instantaneous power (watts) is the product of torque and
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the angular velocity (Gore, 2000).
Isokinetic Dynamometer
Isokinetic Dynamometer was used for the measurement of
resistance to passive movement of the knee joint (Supraja &
Singh, 2003).
Knee extensor and flexor
The recommended test position is seated, with hip flexion
angle of 80 degree. The knee extensionflexion axis is
approximated by aligning the dynamometer rotational axis with
the lateral femoral condyle. Restraint straps are applied for
the distal thigh, pelvis, and upper torso. The shin pad is
attached just above the lateral malleolus (Gore, 2000).
Isolated testing of the knee extensors may also sometimes
be performed in supine, with the hip in neutral (0 degree).
This position may be used for eccentric and concentric testing
of this muscle group. Axis alignment and stabilization are
often easier than in reciprocal concentricconcentric testing
of agonist and antagonist muscle groups; the direction for
the torque application is the same, and it bends to force the
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thigh against the testing bench, thus providing efficient
stabilization (Gore, 2000).
Conversely, isolated testing of knee flexors may be
conducted in the prone position, also with the hip in neutral.
The consistent direction of torque application for eccentric
and concentric testing of this muscle group again aids in
stabilization (Gore, 2000).
Summary
For the team handball players, jumping, sprinting, agility
and repeatedly running ability were the determined skills with
their performance. So the test of muscles (knee
extension/flexion) strength can be a prediction index of their
performance in team handball. The present study was to access
the contribution of the performance of YoYo Intermittent
Endurance Test and the strength power of the quadriceps and
hamstrings of the players.
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Chapter 3
METHOD
The purpose of this study was to examine the contribution
of strength of knee extensor and flexor to the performance
of YoYo intermittent endurance test. This chapter was divided
into the following parts: (a) subjects; (b) procedures; and
(c) method of analysis.
Subjects
The study included a total of 7 male elite youth team
handball subjects aged between 14 and 18 years. Participants
were fully informed of all possible risks and stresses
associated with the project and signed consent forms prior
to participation. They had to participate in the Isokinetic
Dynamometry Muscle Strength Test and YoYo Intermittent
Endurance Test. The study was conducted according to the Dr.
Stephen Hui Research Centre for Physical Recreation and
Wellness and was approved by Handball Association of Hong Kong,
China responsible. All subjects have been trained by the same
head coach and represent Hong Kong Junior Handball Team.
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Procedures
In this study, level 2 YoYo Intermittent Endurance Test
and Isokinetic Dynamometry were used to measure the
performance of YoYo test and the muscle strength of knee
extensor and flexor respectively to assess the correlation
of strength of knee extensor and flexor and the performance
of YoYo intermittent endurance test. The YoYo Intermittent
Endurance Test was conducted at Dr. Stephen Hui Sports Hall
and the laboratory of Dr. Stephen Hui Research Centre for
Physical Recreation and Wellness was used to conduct the peak
torque of knee extensor and flexor by using Isokinetic
Dynamometry (Humac Norm Testing & Rehabilitation System) with
22 degree temperature and 70% relative humidity respectively.
YoYo Intermittent Endurance Test
YoYo Intermittent Endurance Test is to evaluate an
individual’s ability to repeatedly perform intervals over a
prolonged period of time. In this study, level 2 YoYo
Intermittent Endurance Test and Isokinetic Dynamometry were
tested in two days apart. All of the subjects were given a
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trial before this study, to eliminate the learning effect.
And all of them were familiarized with the testing procedures
before data collection. 10minutes warm up was required before
the test. It includes 5minutes running on the treadmill with
moderate speed and 5minutes stretching exercise.
Test Protocol
YoYo Intermittent Endurance Test
Use cones to mark out three lines as per the Figure 1 below;
20 meters and 5 meters apart. The subject starts on or behind
the middle line, and begins running 20 m when instructed by
the cd. This subject turns and returns to the starting point
when signaled by the recorded beep. There is a active recovery
period (10 seconds respectively for the endurance and recovery
versions of the test) interjected between every 20 meter (out
and back) shuttle, during which the subject must walk or jog
around the other cone and return to the starting point. Verbal
encouragement was given by instructors in order to motivate
the subjects to their maximal ability. A warning is given when
the subject does not complete a successful out and back shuttle
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in the allocated time, the subject is removed the next time
they do not complete a successful shuttle. The athlete’s score
is the total distance covered before they were unable to keep
up with the recording (Krustrup et al., 2003).
Figure 1.
The setting of YoYo Intermittent Endurance Test
Isokinetic Dynamometry
All the patients were informed about the experiment’s
procedure and positioned properly by adjusting the height of
the dynamometer persuing congruence between the dynamometer’s
axis and the axis of the knee joint. Subjects were stabilized
by restraining straps at the level of the chest, around the
abdomen and thigh. The force acceptance unit was attached 5
cm above the lateral malleolus. Test program is selected after
feeding in the general information about the subject, joint
-
tested, movements (flexion and extension) tested and side
tested. After setting the range of motion, the evaluation mode
is turned into passive mode (Supraja & Singh, 2003).
Resistance to passive movement of the knee joint during
flexion and extension, measured as eccentric torque is
recorded at speeds of 60 deg/s with resting period of 10 seconds
and 5 repetitions for each leg. Comparison of the relative
strengths of the different sides of the body, or agonists
versus antagonists (e.g. quads & hamstrings) can show specific
muscular limitations. Maximal torque value was measured in
this study (Figure 2).
Figure 2.
The setting of Isokinetic Dynamometry
-
Statistical Analysis
Ordinary statistical methods were used for the calculation
of mean, standard deviations and Pearson productmoment
correlation coefficients. Pearson Product Moment Coefficient
of Correlation (r) was used to examine the relationship
between the performance of the Level 2 YoYo Intermittent
Endurance Test and the knee muscle strength. Statistical
significance was set p
-
and Wellness.
4. The Isokinetic Dynamometry and YoYo Intermittent
Endurance Test were tested in two days apart.
Limitations
The following limitations were understood for the purpose
of interpreting this study:
1. The study could not control other variables that might have
affected the results of isokinetic dynamometry, such as
injury, daily life activities, dietary habit and sickness.
2. The performance of the subjects might vary due to their
different physical characteristics.
3. The performance of YoYo Intermittent Endurance Test and
Isokinetic Dynamometry might be influenced by the
uncontrolled motivation and effort by the subjects.
4. The results could only apply for the subjects who
participate in this study.
-
Chapter 4
ANALYSIS OF DATA
Results
Seven male Hong Kong junior team handball team players were
invited to participate in this study. The purpose of this study
was to examine the contribution of strength and endurance of
knee extensor and flexor and the performance of YoYo
intermittent endurance test. All the subjects participate in
two tests, level 2 YoYo intermittent endurance test and
Isokinetic dynamometry within the same week. The physical
characteristics of the subjects were summarized in Table 1.
Table 1
Physical Characteristics of Hong Kong Junior Team Handball
Team (N = 7)
Variables Minimum Maximum Mean ± SD
Age 14.00 18.00 15.43 ± 1.40
Weight(kg) 53.90 80.20 68.36 ± 9.86
Height(cm) 167.00 187.00 180.14 ± 7.71
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The total distance covered in YoYo Intermittent Test from
the subjects was ranged from 640m to 1840m. The mean and
standard deviation of the distance were 1131.43 ± 399.14.
The peak torque mean score of both knees extensors and
flexors were shown in Table 2 and Table 3 respectively.
Table 2
Peak torque mean score of knees extensors (N = 7)
Subject Right Extensor Left Extensor Sum of the
Torque Score
1 188.00 Nm 179.00 Nm 183.50 Nm
2 197.00 Nm 197.00 Nm 197.00 Nm
3 275.00 Nm 245.00 Nm 260.00 Nm
4 167.00 Nm 156.00 Nm 161.50 Nm
5 297.00 Nm 260.00 Nm 278.50 Nm
6 133.00 Nm 99.00 Nm 116.00 Nm
7 241.00 Nm 221.00 Nm 231.00 Nm
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Table 3
Peak torque mean score of knees flexors (N = 7)
Subject Right Flexor Left Flexor Sum of the
Torque score
1 142.00 Nm 114.00 Nm 128.00 Nm
2 127.00 Nm 121.00 Nm 124.00 Nm
3 176.00 Nm 148.00 Nm 162.00 Nm
4 104.00 Nm 73.00 Nm 88.50 Nm
5 183.00 Nm 167.00 Nm 175.00 Nm
6 87.00 Nm 87.00 Nm 87.00 Nm
7 164.00 Nm 132.00 Nm 148.00 Nm
The Pearson Product Moment Coefficient of Correlation
between the distance covered in level 2 YoYo Intermittent
Endurance Test and the muscle strength of knee extensor and
flexor was computed. The Pearson correlation coefficient and
the coefficient of determination were shown in Table 4 and
Table 5 respectively.
-
Table 4.
Pearson product moment coefficient of correlation test
between the distance covered in the Level 2 YoYo Intermittent
Endurance Test and the muscle strength of knee extensor (N
= 7)
Level 2 YoYo
Intermittent r r 2 p
Endurance Test
Distance Covered 0.491** 0.241 0.263
** Correlation is significant at the 0.01 level (2tailed).
Table 5.
Pearson product moment coefficient of correlation test
between the distance covered in the Level 2 YoYo Intermittent
Endurance Test and the muscle strength of knee flexor (N =
7)
Level 2 YoYo
Intermittent r r 2 p
Endurance Test
Distance Covered 0.401** 0.161 0.372
-
** Correlation is significant at the 0.01 level (2tailed).
Figure 3 showed the relationship between the distance
covered of Level 2 YoYo Intermittent Endurance Test and
muscle strength of knee extensor for all the subjects.
Figure 3.
Scatter plots of the distance covered of Level 2 YoYo
Intermittent Endurance Test and muscle strength of knee
extensor (N = 7)
Figure 4 showed the relationship between the distance
covered of Level 2 YoYo Intermittent Endurance Test and
-
muscle strength of knee flexor for all the subjects.
Figure 4.
Scatter plots of the distance covered of Level 2 YoYo
Intermittent Endurance Test and muscle strength of knee flexor
(N = 7)
By using the Pearson product moment coefficient of
correlation, the results shown that the contribution between
the distance covered of Level 2 YoYo Intermittent Endurance
Test and muscle strength of knee extensor and flexor was not
significant (r = 0.491, p > 0.05) and (r = 0.401, p > 0.05).
Hence there was null significant correlation between the
-
distance covered of Level 2 YoYo Intermittent Endurance Test
and muscle strength of knee extensor and flexor. According
to Figure 3 and 4, it shown that there was no significant
correlation between the distance covered of Level 2 YoYo
Intermittent Endurance Test and muscle strength of knee
extensor and flexor. Since the coefficient of determination
are 0.241 (r 2 = 0.241) and 0.161 (r 2 = 0.161) respectively, the
variance shared by or common to the variables are 24.1% and
16.1%. It shown that there are lack of contribution between
the distance covered of Level 2 YoYo Intermittent Endurance
Test and muscle strength of knee extensor and flexor.
Discussion
The purpose of this study was to examine the contribution
of strength of knee extensor and flexor to the performance
of YoYo intermittent endurance test. The following
discussion will be divided into two parts: a) Relationship
between the performance of Level 2 YoYo Intermittent
Endurance Test and muscle strength of knee extensor and flexor,
and b) Factors that affect the performance of the test.
-
Relationship between the performance of Level 2 YoYo
Intermittent Endurance Test and muscle strength of knee
extensor and flexor
As the previous study seldom use the power of muscular
strength to compare with muscular endurance performance due
to the different type of muscle ability. And there are lack
of data approve on Level 2 YoYo Intermittent Endurance Test
whether it have the positive relationship with muscle strength.
In this study, the finding shown that there are no relationship
between the performance of Level 2 YoYo Intermittent
Endurance Test and muscle strength of knee extensor and flexor
(r = 0.491, p > 0.05, n = 7) and (r = 0.401, p > 0.05, n
= 7). As the coefficient of determination are 0.241 (r 2 = 0.241)
and 0.161 (r 2 = 0.161) respectively, the variance shared by
or common to the variables are 24.1% and 16.1% only. It shown
the contribution of muscle strength of knee extensor and
flexor are just 24.1% and 16.1% to the performance of Level
2 YoYo Intermittent Endurance Test.
The objective of this study was to find out the relationship
-
between different types of ability of the subjects. Different
muscle fiber types may be one of the factors that cause the
result of no significance in this study. There were three
muscle fiber type, slow twitch fiber, type I fast twitch fiber
and type II fast twitch fiber. Although most of the sports
required both three types of muscle fibers, slow twitch fiber
was typically dominant in the endurance exercises, and two
fast twitch fibers were mainly in the strength exercises. For
muscle strength, it required mainly on the fast twitch fiber
in order to perform high intensity movements. So the
isokinetic dynamometry used to test the ability of muscle
strength with explosive power of the knee. It related to the
muscle length, high speed of energy production, muscle size
etc. On the other hand, muscle endurance was mainly required
the slow twitch fiber. The function of this slow twitch fiber
was totally different from the fast twitch fiber, it used to
perform a prolonged exercise with lower intensity. It mainly
referred to the ability of utilization of gas, gas exchange,
cardiovascular system, muscle tolerance and delivery of
-
oxygen to muscle through blood transfer etc. As this study
was to examine these two opposite types of ability of the body,
the correlation between the two tests may be weak.
Factors that affect the performance of the test
In this study, it requires subjects to pay their maximum
effort on the two tests. It was too difficult to ensure the
subjects perform their maximal effort during the test. Verbal
motivation can only push them to perform a better result, but
may not be the best result of them. Uncontrolled motivation
may be one of the factors that there was no significance in
the study.
Running skills in YoYo test may also influence the results.
The performance of level 2 YoYo Intermittent Endurance Test
may affected by the various turning skills and inconsistent
speed. The variation of different turning skills may affect
the muscle endurance, because the ineffective turning
required more energy expenditure. And so as to the
inconsistent speed by failure to catch up with the “bip” sound
during the YoYo Intermittent Endurance Test. These problems
-
may affect the accuracy of the results.
On the other side, there was extremely different body size
between subjects. The range different of height was 20 cm,
it was a great deviation on assessing the ability of the
subjects. When two people with 20 cm height different within
a small group of subject, it may have a great ability
discrepancy. For instances, the distance of each running step,
the number and size of muscle, lung volume, loading of heart
and power output etc. Those factors may influence the results
of level 2 YoYo Intermittent Endurance test a lot. Also,
referred to the above results shown in Table 2 and 3, the
strength power had obviously different in performance. The
greatest extensor torque score was 278.50 Nm, compare with
the lowest score 116.00 Nm, it over twice of the lowest score.
It shown that the individual different within the subjects
was great, due to the different growth period.
The performance of YoYo Intermittent Endurance Test and
Isokinetic Dynamometry might be influenced by the daily
activities by the subjects. Daily activities include dietary,
-
sleeping habit, examination period in school, training
intensity on the day before the test, injury and sickness.
As most of the subjects were students and they participate
in the tests after school. Tiredness may occur due to the school
work and some of them were having examination during the
testing period, it may not ensure the performance would be
the best of them. Eating before the test also may affect the
result’s accuracy.
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Chapter 5
SUMMARY AND CONCLUSION
Summary of results
The purpose of this study was to examine the contribution
of strength of knee extensor and flexor and the performance
of YoYo intermittent endurance test.
7 male players of the Hong Kong Junior Team Handball Team
participated in this study. The muscle strength of knee
extensor and flexor, the Isokninetic Dynamometry was
conducted at the laboratory of Dr. Stephen Hui Research Centre
for Physical Recreation and Wellness. The performance results
of level 2 YoYo Intermittent Endurance Test was conducted
at the Dr. Stephen Hui indoor sports hall with recorded the
total distance covered of each subject. All the collected data
were analyzed by the Statistical Package for Social Science
(SPSS) version 16. Pearson Product Moment Coefficient of
Correlation (r) was used as well with the 0.05 level of
significance.
The results of this study were summarized as follows:
-
1. There was no significant relationship between the
muscle strength of knee extensor and flexor and the
performance of YoYo intermittent endurance test, at
the 0.01 level of significance (r = 0.491, p > 0.05)
and (r = 0.401, p > 0.05) respectively.
2. The contribution of muscle strength knee extensor and
flexor are 24.1% and 16.1% to the performance of level
2 YoYo Intermittent Endurance Test (r 2 = 0.241) and (r 2
= 0.161) respectively.
Conclusion
The finding shown that there are no relationship between
the performance of Level 2 YoYo Intermittent Endurance Test
and muscle strength of knee extensor and flexor. The
coefficient of determination are 0.241 (r 2 = 0.241) and 0.161
(r 2 = 0.161) respectively. As the contribution of muscle
strength of knee extensor and flexor are just 24.1% and 16.1%
only to the performance of Level 2 YoYo Intermittent
Endurance Test. The correlation between muscle strength of
knee extensor and flexor and the performance of Level 2 YoYo
-
Intermittent Endurance Test were weak.
Recommendation of Further Study
Based on the study, the following recommendations are
presented for the further study:
1. For the Isokinetic Dynamometry, it is better to use more
different speeds and force protocols (add 2 more speed which
are 180 deg/s with resting period of 10 seconds and 5
repetitions and 240 deg/s with resting period of 10 seconds
and 15 repetitions) to acquire different types of data.
Different speeds of the peak torque can show the different
ability (muscular strength and muscular endurance) of the
specific muscle group. So that it not just investigate the
relationship between muscular strength and the performance
of YoYo Intermittent Endurance Test.
2. It is better to measure the muscular strength and endurance
of calf.
3. Sample size should be enlarged in order to conduct a more
representative research.
4. The control of dietary, exercise and sleeping habit of the
-
subjects should be executed consistently.
-
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APPENDIX A
運動感覺測量表
6
7 非常, 非常輕鬆
8
9 非常輕鬆
10
11 尚算輕鬆
12
13 少許辛苦
14
15 辛苦
16
17 非常辛苦
18
19 非常, 非常辛苦
20
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APPENDIX B
YOYO INTERMITTENT ENDURANCE TEST DATA COLLECTION FORM
TEST SCHEME: YOYO INTERMITTENT ENDURANCE TEST – LEVEL 2
Date: Name:
Speed level: Intervals:
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1.______________________________________________________
2.______________________________________________________
3.______________________________________________________
4.______________________________________________________
5.______________________________________________________
6.______________________________________________________
7.______________________________________________________
8.______________________________________________________
9.______________________________________________________
10. _____________________________________________________
11. _____________________________________________________
12. _____________________________________________________
13. _____________________________________________________
14. _____________________________________________________
15. _____________________________________________________
16. _____________________________________________________
17. _____________________________________________________
18. _____________________________________________________
19. _____________________________________________________
20. _____________________________________________________