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ISOKINETIC STRENGTH FOR
SPORTS PERFORMANCE
&
SHORT TERM MUSCULAR ENDURANCE
KINANTHROPOMETRY
Presented By: Chanan Ben-Ami
Student Number: 9831438
Module Title: Exercise Physiology
Module Number: BIO 3222
Module Leader: Dr. Willy Pieter
Middlesex University
Semester II
Enfield Campus
CONTENT
1. Isokinetic Strength
1.1 Abstract
1.2 Introduction
1.3 Method
1.4 Results
1.5 Discussion
1.6 Bibliography & References
Pg. 3
Pg. 3-4
Pg. 5
Pg. 6
Pg. 7-8
Pg. 9
2. Kinanthropometry
2.1 Purpose
2.2 Method
2.3 Results
2.4 Discussion
Pg.
Pg.
Pg.
Pg.
3. Short Term Muscular Endurance
3.1 Purpose
3.2 Method
3.3 Results
3.4 Discussion
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Pg. 12
Pg. 12
Pg. 12
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10
10
10
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ISOKINETIC STRENGTH
ABSTARCT
The different conclusions drawn about the relationship between isokinetic
strength and athletic performance indicates that continued research is needed
in this area. Researchers have demonstrated a need to test athletes in a
various points in the season to examine how these variables may affect the
relationship between isokinetic strength and athletic performance. Research is
needed to determine if isokinetic testing is a good indicator of the readiness of
an athlete to participate in competition. Results of research with this may be
used to improve the way athlete's train or how they are evaluated before
returning to competition after injury.
INTRODUCTION
This paperwork is based upon a laboratory experiment involving the
measurement of isokinetic strength using the Biodex 3 system. It is an
isolated joint isokinetic system, which allows one to measure the amount of
strength produced at different velocities. The joint covered was the knee.
Information regarding the application of isokinetic strength is given with
respect to athletic performance.
Isokinetic muscle loading consists of fixed speed of movement and resistance
that is variable accommodates to the muscle's ability to generate force. It is
characterized by constant velocity at a pre-selected rate. Resistance varies to
match the exact torque/force applied throughout the range of motion. Speed is
expressed in degrees of movement per second around an axis of rotation.
Speed was adjusted to 180 and 300 degrees of movement per second. If one
moves less than the pre-selected speed, resistance will immediately be
eliminated from the limb.
Isokinetic training (movement at a constant angular velocity) has primarily
been used in rehabilitation for the purpose of strengthening muscle groups
(Anderson, M 1991). This type of training is used infrequently in athletic
settings for various reasons: The most important reason is that there are
different views as to whether or not isokinetic training has a strong correlation
with athletic performance. Researchers, such as Anderson (1991) and
Greenberger (1995) have indicated that a relationship does not exist between
isokinetic strength and athletic performance; whereas others (Oberg et al
1986) have shown that a positive relationship does indeed exist.
Uses for Isokinetic Dynamometers
Study made by Kannus (1994) reviewed various aspects of isokinetic testing
to determine factors that affect the results and initiated a protocol for using a
dynamometer for testing or rehabilitation purposes. The author found that
isokinetic testing was useful in obtaining information about knee strength and
power as they related to insufficiencies of ligaments. Kannus concluded that
isokinetic devices are useful in documenting progress in rehabilitation.
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Relationships between Isokinetic Strength and Athletic Performance
Several studies found a link between isokinetic strength and a particular
athletic performance. Oberg et al (1986) indicated that stronger soccer
players have higher skill levels and that training at a higher level yields greater
strength measures. These results were attributed to the fact that the training
intensity typically increases as the player's increases the level in which they
are participating. Podolsky et al (1990) tested and found a relationship
between isokinetic strength in various muscle groups, especially those acting
on the knee, and jump height. The authors found that high correlation
between jump height and isokinetic strength took place at a joint speed of
240o/sec for knee extension. The researchers concluded that weight training
would be beneficial in shortening the time necessary to develop the needed
strength for higher jumps.
On the other hand, many researchers have found no significant relationships
between strength measured isokinetically and athletic performance. Kannus
(1994) found that a disadvantage to isokinetic training is that it does not
actually happen during normal human or athletic performance
Isokinetic training only has benefits for those movements that occur at a
constant angular velocity, and that this type of movement can place larger
loads on an injured joint, which may be dangerous for healing tissues.
AIMS and GOALS
The aims of this study are to analyze and note the relationship of mean peak
torque and its standard deviation between two groups of females and males
and to highlight and emphasis the muscular differences (Hamstring &
Quadriceps) which exist between the groups.
HYPOTHESES
There will be a difference in peak torque between females and males.
There will be differences of HQ, HH, QQ rations between the females and the
males.
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METHODS
As mentioned before, the aim of the study was to measure and evaluate
isokinetic strength for sports performance. Human subjects, isokinetic
dynamometer and computer software, were used in order to achieve this goal.
A mixed group of four males and four females were chosen to carry out this
study.
Procedure
Short and brief introduction to Biodex Pro 3 system and its software.
Setting of a test protocol
STANDARDIZED TEST PROTOCOLS
A standardized testing routine improves the operator's control of several
variables that influence tests.
• testing of uninvolved side first
• alignment of axis of rotation
• warm-ups
• subject stabilization
• verbal commands
• visual feedback
• test position
• system calibration
• angular velocity selection
• system stabilization
• skill, training of tester
• gravity compensation
• rest intervals
• test repetitions
Collection of data (print - out) for future analysis.
Analysis of data through the use of statistical software (SPSS)
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RESULTS
The data from this study was collected and analyzed by a use of statistical
software (SPSS) and thereby presented in two tables.
Table 1 indicates the mean and standard deviation measured among females
and males at different variables during Isokinetic Peak Torque.
Right Extension @ 180
Right Flexion @ 180
Left Extension @ 180
Left Flexion @ 180
Right Extension @ 300
Right Flexion @300
Left Extension @ 300
Left Flexion @ 300
Mean Female
91.44
62.68
82.7
61.94
95.94
71.5
100.56
67.16
Standard Female
8.48
10.54
6.43
10.34
25.29
9.49
16.13
10.38
Mean Males
146.66
107.74
158.5
97.44
113.54
87.94
117.16
96.7
Standard Males
29.79
11.73
20.5
11.48
18.7
14.9
29.86
22.31
Table 2 displays means and standard deviations for isokinetic strength ratios
(%) in university students.
(H) = Hamstrings (Q) = Quadriceps as measured at different velocities
Right HQ @ 180
Left HQ @ 180
Right HQ @ 300
Left HQ @ 300
QQ @ 180
QQ @ 300
HH @ 180
HH @ 300
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Mean Female
69.25
74.56
77.65
67.82
110.75
94.82
103.02
107.5
Standard Female
14.38
8.08
17.12
12.38
8.87
15.23
20.24
13.92
Mean Male
75.28
61.64
78.89
83.55
91.79
101.25
111.07
94.46
Standard Male
12.49
3.15
10.98
11.26
8.68
29.32
11.47
19.99
DISCUSSION
The aims of this chapter are to provide analysis and explanation of the results,
with support and reference of current literature, in order to evaluate the
implication to sports performance.
The form of analysis for this study was either bilateral or unilateral.
Researchers at the Biodex web site (http://www.biodex.com/rehab/isotest)
argues and explain the differences between the two. According the their point
of view:
"Bilateral method is quick and easy: Bilateral differences greater than 10% are
generally considered significant. Unfortunately, in the presence of a deficit in
the contra-lateral limb - used for a standard - this method of analysis is
inaccurate. Therefore, bilateral comparison is, in many cases, a poor method
of evaluating joint systems."
Another way of evaluating the integrity of a joint is by comparing the ratio of
the agonist to the antagonist muscles, is the unilateral method. Changes in
this ratio indicate weakness and are most easily identified during velocity
spectrum training.
Ratios for the normal knee are:
• 60 degrees per second - 60% to 69%.
• 180 degrees per second - 70% to 79%.
• 300 degrees per second - 80% to 95%.
• 450 degrees per second - 95% to 100%.
Peak Torque and HQ ratio
Peak torque is the highest point on a subject's extension/flexion curve,
regardless of where in the ROM it occurs. In contrast, mean peak torque is
the average of the peak torque values obtained during a series of repetitions
or within a group, thus mean peak torque may be considered a better
estimate of overall function than peak torque.
As the results indicate, there was a great deal of difference in the values of
the females and the males in all the parameters. Higher values of mean peak
torque, supports the claim that greater force was generated through muscles
performance in the males. However, the standard deviation noted in the
males results (Right and left Extension @ 180, left extension @ 300 and left
flexion @ 300) was significantly higher. It may seem that although the males
scored higher values in left extension and flexion @ 300 degrees, their
standard deviation indicates that there was imbalance of muscular
performance among the group. To strengthen this point, QQ ratio (extensors)
measured among the males at 300 degrees shows high standard deviation
compare to the females, while the score was very similar. The same applies
to the HH ratio (flexors) at 300 degrees.
The scores of HQ ratio for the females and the males suggests that values
were over 60% to 70%. Holcomb & Kleiner (1994), researchers at the
University of North Florida investigated some of the reasons why hamstring
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strains are among the most common musculoskeletal injuries in sports.
Exercise physiologists and sport scientists recommend that the hamstring:
quadriceps strength ratio should be 60-70%. In other words, the hamstrings
should be 60-70% as strong as the quadriceps to prevent injury. Out of the
102 athletes that were tested, none showed a strength ratio exceeding 70%,
and only about 4% showed the minimum criteria of 60%. They recommended
that strength and conditioning coaches should be concerned with hamstring
strengthening to reduce the prevalence of hamstring injury.
A research project (1999) presented to the faculty of Springfield College
(department of physical therapy) dealt with the relationship between strength
and functional outcomes among collage level male and female gymnasts.
Analysis of the results for the isokinetic strength and functional tests, found
the male to produce significantly higher torque values during strength testing
at all speeds, except for knee flexors at 300o /sec. Male subjects also
demonstrated significantly higher vertical jump test heights, required less time
to complete the cocontraction test. There was no significant difference
between male and female subjects and their mean perception of readiness to
compete in gymnastics. Furthermore, the mean of the quadriceps peak torque
production and the hamstring peak torque production where higher among the
males.
CONCLUSION
Isokinetic strength training aims to improve muscular endurance and
performance. The use of dynamometer in isokinetic muscle evaluation and
exercise make it possible to keep a limb in motion at a constant,
predetermined velocity while applying accommodating resistance throughout
the range of motion (ROM).
This study aimed to measure and differentiates between the abilities of
females and males in isokinetic training, using a Biodex dynamometer.
Further research is needed in order to draw a link concerning the differences
arising from this study. The use of larger number of subjects and higher
number of repetitions per session can contribute to more accurate conclusion
regarding isokinetic strength between the genders.
The results of the study support the null hypothesis that there will change in
peak torque and HQ ratio between males and females scores.
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BIBLIOGRAPHY & REFERENCES
Anderson MA, Gieck JH, Perrin D, Weltman A, Rutt R, Denegar C.(1991) The
Relationship among Isometric, Isotonic, and Isokinetic Concentric and
Eccentric Quadriceps and Hamstring. Orthopedic Sports
Physiotherapy 14: 114-120.
Greenberger HB, Paterno MV (1995). Relationship of Knee Extensor Strength
and Hopping Test Performance in the Assessment of Lower Extremity
Function. Orthopedic Sports Physiother.22: 202-206.
Hamill J, Knutzen KM (1995) Biomechanical Basis of Human Movement.
Williams & Wilkins: USA
Kannus P. (1994) Isokinetic Evaluation of Muscular Performance: Implications
For Muscle Testing and Rehabilitation. International Sports Med.;
15:S11-S18.
McArdle, WD, Katch FI, Katch VL (1996) Exercise Physiology: Energy,
Nutrition and Human Performance. 4th ed.
Lippincott Williams & Wilkins
Oberg B, Moller M, Gillquist J, Ekstrand J (1986) Isokinetic Torque Levels for
Knee Extensors and Knee Flexors in Soccer Players. International
Sports Med.; 7:50-53.
Podolsky A, Kaufman KR. (1990) The Relationship of Strength and Jump
Height in Figure Skaters. American J Sports. 18:400-405.
http://www.biodex.com/rehab/isotest.htm
http://www.makaimedia.com/html/hamstring_strength.htm
http://www.chuckiii.com/Reports/strains_of_the_hamstring_and_groin.shtml
http://www.spfldcol.edu/homepage.nsf/
http://www.google.com
http://www.doctors.co.il
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KINANTHROPOMETRY
Purpose
The application of kinanthropometry as a sport performance related field,
deals with the aspects of body composition and anthropmetric measurements
and it’s contribution to sport.
Variables such as skinfold thickness, weight and girths were chosen to stress
and highlight the differences between subjects of the group.
Method
Measurements were based on skinfold thickness and girths, while
proportional values were based on phantom height (170.18cm).
Calculation of skinfolds, girths, weight and height.
Calculation of mean and standard deviation to analyze differences between
groups.
Results
Table 1 shows the accumulative data collected from six subjects and divided
into two groups of males and females.
Table 1 - Accumulative Data of Subjects A-F
Subject A Subject B Subject C Subject D Subject E Subject F
Skinfold (mm)
Triceps
Subscapular
Supraspinale
Umbilical
Anterior thigh
Medial calf
10.2
10.2
8.2
12.4
13.5
8.8
9.2
13.3
13.8
23.1
13
7.4
7.8
10.2
10
10.5
9
5.1
19
11
11
15.5
18
9.5
24
24
22
23
18
19
12
14
5.5
12.5
20
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Total
63.3
79.8
52.6
84
130
75
65.233
13.702
96.3
29.5
193
155.4
173.7
159
183
10.9
162.7
9.69
87
54
105
54
86.75
6.78
71
29.44
35.5
39
28
33
36.5
45
27
36
Male/Female
Height (cm)
Male/Female
Weight (kg)
Male/Female
mean deviation
standard deviation
185.5
171.5
mean deviation
standard deviation
86.5
75
mean deviation
standard deviation
Girths (cm)
Tensed arm
Calf
10
35
37
33.5
35
Reciprocal Ponderal Index (RPI)
Male
Female
Body Mass Index (BMI)
Male =25.97
Female =27.09
Proportional Weight
Male
= 64.98
Female = 86.40
Discussion
As the results indicates, the females have more adipose tissues than the
males, and therefore, presumably, less lean tissues. In order to stress this
claim, their proportional weight is significantly higher than the males. On the
other hand, both groups have excess weight and fat, since they are over the
limit set to describe BMI (>24 for males and >25 for females).
However, another way to explain the differences between the males and the
females may be in the fact that the height of the males was greater than the
females, which contributes to a lower BMI
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WINGATE TEST
Purpose
Short-term muscular endurance was assessed using the Wingate anaerobic
test. Four university female subjects were chosen to take part in this study.
Assessment of anaerobic performance can provide the fitness trainer with
valuable information about the athlete's fitness and allow monitoring progress
through training.
Methods








Measurements of weight and height were taken.
Warm up – 4 minutes to allow heart rate of 150 bpm. Short sprints of
10 seconds each, every minute.
Rest interval – 3 minutes of rest prior to the test.
Test – based on the subjects’ weight, load (Kg) was applied according
to Wingate ratio of 7.5%.
Once the load applied, measurements of total pedal revolution begin
and continued for 30 seconds.
Pedal count was recorded every 5 seconds by the computer’s
software.
Cool down – continuance peddling for 3 min follows the completion of
the test, in order to minimize the risk of subject fainting.
Collection of data and results
Results
Data was collected from the four female subjects at the end of their test.
Analysis and presentation of the findings is given in figure 1.
Figure 1 – Total Data Collection
Subject
A
B
C
D
Weight
54
58
50
58
Height
155cm
158cm
160cm
161cm
Load (Kg) Peak power (W) Mean power (W)
4
4.5
3.75
4.5
733.8
836.9
642.9
517.1
191.8
240.4
228.7
165.6
Fatige index (%)
93.60%
74%
66.30%
81.10%
Discussion
The differences that exists between the subjects, refers to the ability of ATP
and CP breakdown by the body. Anaerobic capacity (mean power) represents
the force generated over total distance in 30 sec. Fatigue index represents the
systems total capacity to produce ATP via the immediate and short-term
energy systems by providing percentage decline in power output. Subjects B
& D shared the same load (relatively to their body weight) but it is noticeable
that subject B is in a higher fitness level. The reason being is that mean power
produced over 30 sec was higher and more efficient with respect to fatigue
index
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