CALIFORNIA STATE UNIVERSITY, NORTHRIDGE
THE EFFECTS OF ISOKINETIC TRAINING AT PEAK
INSTANTANEOUS POWER ON KNEE EXTENSOR
TORQUE IN THE SPASTIC CEREBRAL PALSIED
A thesis submitted in partial satisfaction of the
requirements for the degree of Master of Arts in
Physical Education
by
Peggy Marie Lasko
August, 1981
The Thesis of Peggy Marie Lasko is approved:
Nick Breit, Ph.D.
sam Britten, Ph.D., Chairman
California State University, Northridge
ii
ACKNOWLEDGMENTS
Sincere thanks is given to the members of my thesis
committee for their thoughtful criticisms and suggestions.
My deepest appreciation is extended to
Dr. Sam Britten, whose interest and patience helped
in the completion of this study.
Additional thanks
are expressed to James Perrine, who has contributed
substantially to my knowledge of isokinetic exercise.
Appreciation is given to Steve Brown for his assistance
in acquiring subjects for the study.
Special thanks
are offered to Maria "Frenchie" French, ·.vhose determination inspired this study.
To my parents, Norris
and Elaine Gaines, a "gigantic" thanks is extended for
their constant support throughout my life.
iii
TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS
iii
LIST OF TABLES .
vii
LIST OF FIGURES
viii
LIST OF ILLUSTRATIONS
viii
ix
ABSTRACT • .
Chapter
I
INTRODUCTION
1
THE PROBLEM .
6
Statement of the Problem
6
Statement of the Purpose
6
Null Hypothesis .
II
. .
.
. .
7
DEFINITION OF UNIQUE TERMS
7
LIMITATIONS AND SCOPE .
9
ASSUMPTIONS
10
IMPORTANCE OF THE STUDY •
10
REVIEW OF RELATED LITERATURE
Secondary Functional Consequences
of Spasticity . . . . . . . . . . .
Effects of Repetition .
12
12
13
Kinematics of Locomotion
14
Habilitation of the
Cerebral Palsied
15
Concept of Contractile Power
19
iv
III
Torque and Muscle Fiber
Composition . . . . .
23
Specificity of Speed in
Strength Training .
26
Summary
38
METHOD
40
Overview of Approach and Design .
40
Pilot Study .
40
Selection and Assignment
of Subjects
. . . .
41
Instrumentation .
45
Calibration .
48
The Experimental Protocol .
IV
Pretest .
49
Post Test .
50
Training Procedures .
51
Statistical Analysis
52
RESULTS .
.
.
53
Strength Prior to Training
Analysis of Data
v
49
DISCUSSION
53
54
58
Conclusions
59
Major Findings
60
Recowmendations for Further Study . .
61
REFERENCES CITED
64
BIBLIOGRAPHY .
69
.
v
APPENDICES
Subjects' Profile, Experimental
Group . . . . . . . . . . . . .
72
B
Subject's Profile, Control Group
73
c
Consent for Participation
74
D
Consent for Participation
of Minors . . . . . . .
75
Torque at Peak Instantaneous
Power, Raw Scores
Experimental Group . . • .
76
Torque at Peak Instantaneous
Power, Raw Scores
Control Group . . . . . . .
77
A
E
F
vi
LIST OF TABLES
Table
Page
1
Experimental Design
2
Summary of t-test for Pretest Means
3
Mean Knee Extensor Torque Scores .
4
Summary of Analysis of Covariance
55
5
Velocity Shifts in Peak I.P . . . . .
57
vii
.
.
• .
.
.
.
.
45
54
.
55
LIST OF FIGURES
Page
Figure
1
Force-Velocity Relationship .
42
2
Power-Velocity Relationship .
43
3
Peak Torque Increase
56
LIST OF ILLUSTRATIONS
Page
Illustration
1
Cybex II Isokinetic
Dynamometer . . .
viii
46
ABSTRACT
THE EFFECTS OF ISOKINETIC TRAINING AT PEAK
INSTANTANEOUS POWER ON KNEE EXTENSOR
TORQUE IN THE SPASTIC CEREBRAL PALSIED
by
Peggy Marie Lasko
Master of Arts in Physical Education
The purpose of this clinical investigation was to
ascertain if isokinetic training at a velocity determined by peak instantaneous power output would have an
effect upon knee extensor torque in individuals with
spastic Cerebral Palsy.
The sample consisted of 12 volunteer college and
high school students, ranging in age from 16 to 33
years
(Male = 9, Female = 3) who evidenced the spastic
condition in the lower extremeties.
Subjects were
assigned to either the Experimental Group, receiving
isokinetic exercise, or a Control Group, receiving
no exercise.
The subjects were tested pretraining and
ix
post training in the non-dominant limb for knee extensor
torque at six angular velocities, utilizing an isokinetic
dynamometer (Cybex II, Lumex, Inc., Bay Shore, New York).
The Experimental Group trained three times per week
for a period of six weeks.
The exercise bout consisted
of four sets of maximal knee extensions for a period of
20 seconds each.
exercised.
Both the right and left limbs were
The Control Group abstained from any exercise
of the knee extensors for the six week period.
Analysis of covariance (ANCOVA) was accepted as the
statistical design for the study in order to adjust for
significant pretest scores between the Experimental and
Control Groups.
The data indicated a final adjusted mean
difference in favor of the Experimental Group, significant
at the .01 level of confidence.
This represented a mean
strength increase of 32 percent for the Experimental
Group.
Within the limitations to the present study, the
null hypothesis regarding the effects of velocity-specific,
isokinetic training was rejected.
The data from this
study indicated that isokinetic training at a velocity
where peak instantaneous power occurred significantly
increased knee extensor torque in young adults with
spastic cerebral palsy when .compared to similar adults
receiving no exercise.
X
Chapter I
INTRODUCTION
It has been demonstrated that abnormal neural
activity, or spasticity, typically occurs in the knee
flexors of individuals with spastic Cerebral Palsy
(C.P.).
If left untreated, this repetitive spastic
activity leads to an imbalance about the affected joint.
The knee flexors, particularly the medial hamstrings,
undergo severe contracture, while the knee extensors
become lengthened and atrophied.
The resulting muscular
imbalance is a possible contributor to gait anomalies
and an impediment to efficient ambulation.
Sutherland
(1969) has stated that the typical spastic gait is a
functional
conseq~ence
of spastic hip and knee flexors,
hip adductors and internal rotators, and plantarflexors.
In
addition~
it involves reduced measurements for stride
length and increased measurements for time (Black, 1979).
A pilot study for the present investigation demonstrated the effects of these abnormal muscle qualities
on the power-velocity relationship of knee extensor
muscles in spastic C.P. individuals.
~~bulatory
C.P.
subjects produced a peak instantaneous power (I.P.)
output at a velocity of 120 degrees/second.
Perrine
(1978) has reported peak I.P. to occur at 240 degrees/
1
2
second in sedentary subjects.
the histochemical
staini~gs
These findings concur with
of Edstrom (1973}, who indi-
cated that tonic spasticity or continual inactivity
selectively atrophies muscle fibers responsible for
rapid tension development.
These figures are important since many functional
movements require limb speeds in excess of 120 degrees/
second.
For example, the velocity at the knee during
normal locomotion has been reported between 185-350
degrees/second, depending upon the cadence requested
of the subject (Winter, 1976} .
. Numerous forms of treatment for spastic C.P. exist,
yet the number of scientifically controlled studies
evaluating exercise programs, particularly strength
training programs, are few.
Wright and Nicholson {1973}
surveyed the literature between 1940-1971 and found only
16 papers dealing with physiotherapy for the spastic
child.
Three major inadequacies were evident in the
studies examined:
1.
control groups were lacking
2.
the efficacy of the therapeutic modality
studies was difficult to assess objectively
and lacked quantitative data
3.
correction of the muscle imbalance and
patterns of movement were seldom related
3
to everyday activities or fitness for
employment.
Based on these studies, the role and value of physiotherapy in the management of spastic C.P. may be
inaccurate or misleading.
The present investigation was initiated to determine
the value of a strength training regimen in habilitation
of spastic C.P.
This study also attempted to present
precise and objective quantification of strength gains,
provide a control group against which to compare results,
and provide training which would transfer to functional
velocities of limb movement.
The problem to be resolved
was to determine which training velocity was most appropriate for this population.
Researchers have suggested that the speed at which
an exercise is performed is an important factor in determining the quality of muscle development.
This concept
conforms to the specificity of training principle
(S.A.I.D. - Specific Adaptations to Imposed Demands)
i.e., that muscles adapt according to the specific
demands placed upon them, as opposed to any generalized
improvement.
Only recently have studies on strength training
examined the role of velocity upon strength and power
gains.
Two major trends have been observed in the
4
literature from the past 10 years in regards to velocity
in isokinetic muscle training.
In studies involving
isokinetic training at limb velocities of 180 degrees/
second or less, strength gains resulted at angular
velocities equal to or slower than the training velocity
(Moffroid and Whipple, 1970; Pipes and Wilmore, 1975;
Lesmes, Costill, Coyle, and Fink, 1978, 1979).
More
specifically, low power (low speed, high resistance)
exercise produced strength gains only at slow speeds,
while high power (high speed, low resistance) exercise
produced strength gains at the training speed and slower.
Insignificant strength gains were observed at velocities
higher than those at which training occurred.
This
implied that the benefits derived from an exercise
regime may be restricted to those speeds of movement
equal to or slower than the training speed.
Investigations which utilized isokinetic training
at limb velocities as high as 300 degrees/second observed
a velocity-specific training effect for strength improvements
(Coyle and Feiring, 1980; Parker et al., 1980;
Caizzo, Perrine, and Edgerton, 1980).
The greatest
percentage of strength gain occurred at the velocity at
which training occurred and decreased for velocities
above or below.
Based on these findings, it is apparent that the
5
specific speed at which a muscle is loaded influences
the type of effort or neuromuscular response required.
Thus, the selection of exercise protocol should reflect
the functional outcomes desired by the individual.
According to Hellebrandt (1958, p. 278):
. . . therapeutic exercise is administered to
enhance the ability to muster the physiological
mechanisms required to contract muscles repetitively through the range at a cadence adequate
for the performance of types of physical activity useful to the disabled individual.
This principle, specificity of speed, has important
applications in the habilitation of the individual with
spastic C.P.
In regards to isokinetic exercise, train-
ing velocity is specific to desired outcomes.
There-
fore, an individual would not receive much functional
improvement from isokinetic exercise administered at
slow velocities.
Training at a velocity where maximum
torque occurs would not reflect an optimal improvement
in performance, since the time constraints imposed during
functional movements prevent muscles from developing
their peak torque limits.
However, Hellebrandt (1958) has stated that training
at velocities in excess of where maximum power output
occurs overloads the neuromuscular system, causing
incoordination and possibly spasticity.
Thus, the velocity at which each individual manifests his/her peak I.P. appears to be an appropriate
6
velocity at which to begin training.
Although this
velocity may be well below the limb velocity stated
earlier for locomotion, this would be as high as is
practical for a spastic C.P. group.
No investigation has determined whether a relatively high speed, high power output training regimen
might improve knee extensor torque and power at more
functional velocities
(120-300
individuals with spastic C.P.
degrees/seco~d)
for
The present study was
designed to make that determination.
THE PROBLEM
Statement of the Problem
The problem considered in this study was that
literature is non-existent in regards to the effects of
isokinetic training at functional limb velocities in
spastic C.P.
This form of training deserved examination
in light of its potentials in habilitation.
Statement of the Purpose
The purpose of this clinical investigation was to
ascertain if isokinetic training at a velocity determined by peak power output would have an effect on knee
extensor torque in subjects with spastic cerebral palsy.
/
7
Null Hypothesis
The following hypothesis was tested in this investigation:
That there will be no difference in muscular
torque of the knee extensors bebveen a group of spastic
cerebral palsied individuals training isokinetically at
a velocity determined by .peak instantaneous power output
and a control group of spastic cerebral palsied individuals receiving no exercise.
DEFINITION OF UNIQUE TERMS
The following terms will be used throughout this
thesis and are defined specifically as they pertain to
the present investigation.
1.
Isokinetic:
This refers to loading a dynamically
contracting muscle with a speed controlled device
so that speed is fixed and resistance is proportional
(i.e., accommodating) to muscular capacity at every
point in the range of motion (Pipes, 1977}.
2.
Strength:
The amount of force or tension exerted
during a contraction.
This mechanism is dependent
upon the size and number of muscle fibers that are
active, in addition to their frequency of firing
(Chu, 1971).
8
3.
Torque:
A force perpendicular to a lever arm which
is acting about an axis of rotation.
Torque is
considered an index of muscular strength (Coplin,
1971) .
4.
Power:
Composed of strength and speed, power is the
rate of performing work (deVries, 1974).
5.
Instantaneous Power:
"Expresses the· rate at which
work is being accomplished at any instant and is
obtained by dividing the torque at any point by the
speed of the contraction in units of revolutions per
minute"
6.
(Moffroid, 1970, p. 6).
Spastic Cerebral Palsy:
A non-progressive movement
disorder resulting from the destruction of congenital
absence of upper motor neurons within the pyramidal
tract of the cerebral cortex (Bleck, 1979).
Its
central features include abnormal muscle tone due to
hypersensitive stretch receptors, resistance to
active and/or passive movement, increased tendon
jerks, and clonus.
The outward manifestations include
inefficient and uncoordinated movement which may
functionally incapacitate the individual.
In addi-
tion, muscle groups opposing the contractures weaken
and atrophy, creating a muscular imbalance about the
affected joint.
9
LIMITATIONS AND SCOPE
1.
The population under study was limited to those
persons with spastic cerebral palsy who attended
California State University at Northridge or
Joaquin Miller High School.
2.
As there exists a considerable overlap of the various
types of cerebral palsy within individuals, it may
have been possible for a subject to have a combination
of types but to display predominantly spastic
symptoms.
3.
Since all subjects trained the knee extensors of both
the right and left limbs, possible cross transfer
effects may have produced higher torque values than
would be expected for a single trained limb.
4.
The present investigation was staged in a clinical
environment.
Variables such as degree of involve-
ment, prior surgeries, medication or drugs, response
to climatic conditions, and motivation were difficult
to regulate and, therefore, were given consideration
when the data was interpreted.
5.
The presence of parents and/or others may have produced an "audience effect" and influenced performance
during the testing and training sessions.
10
ASSUMPTIONS
The following assumptions were accepted for this
investigation~
1.
The subjects were properly classified as spastic
cerebral palsy.
2.
. The subjects were motivated sufficiently to give a
maximal effort at every training session.
3.
The subjects had not participated in any other
strength training or therapy program involving
the knee extensor muscle group during the training
period.
4.
The subjects were not receiving medication which
would interfere with or influence their performance
during the testing or training sessions.
5.
Subjects had adequate intelligence to ascertain the
purpose of the investigation.
IMPORTANCE OF THE STUDY
The results of the present investigations are
clinically important to the adapted physical education
teacher, physical and corrective therapist, and any
other professional involved in physical rehabiliation
11
of the disabled.
First, the appropriateness of loading
muscles to their maximal contractile power during
strength training would be determined for adults with
spastic cerebral palsy.
Secondly, the specific strength
effects of velocity-specific, isokinetic training would
mandate a change in the protocol for physical rehabilitation; i.e., that strength programs should reflect
the performance requirements (in terms of loads and
velocities) of activities of daily living.
Chapter II
REVIEW OF RELATED LITERATURE
The review of the literature has been categorized
into the following subheadings:
Secondary functional
consequences of spasticity, habilitation in cerebral
palsy, kinematics of locomotion, concept of contractile
power1 torque and muscle fiber composition, and specificity of speed in strength training.
Secondary Functional Consequences
of Spasticity
In definining spasticity, Harris (1978) coined the
term "inapproprioception", referring to a malfunctioning
of the proprioceptive system.
Distorted signals, repre-
senting the position of the body parts to the central
nervous system, are believed to disturb postural stability and phasic movement control.
Hyperactivity in the gamma spindle loop is the
primary disturbance underlying spasticity in cerebral
palsy.
This manifestation is brought about by the
congenital absence of upper motor neurons, disrupting
the balance between the facilatory and suppressor areas
of the brain (Bleck & Nagel, 1975).
Gamma motor neurons.
(ventral horns of the spinal cord) provide information
12 .
13
to the central nervous system about the velocity of
stretch in the muscle.
This dynamic component is pro-
portional to the rate of change in the muscle fiber and
reflects an increased dynamic sensitivity of the primary
endings within the muscle spindle (Harris, 1978).
Exces-
sive activation of the gamma efferents ("gamma bias")
results in continual excitation of alpha motor neurons
via stretch reflex arcs.
The final result is the classic
triad of motor signs in spasticity:
1.
hyperactive phasic stretch reflexes
2.
hyperactive tonic stretch reflexes
3.
clonus (Bishop, 1979).
Spasticity will typically produce activity in the
muscles in the position of antagonists during a movement
which exceeds the critical velocity-threshold of the
primary endings within the muscle spindle.
Thus, the
"brake" imposed by the spastic antagonist during rapid
movement constitutes a major obstacle in the habilitation
of spastic individuals (Birkmayer, 1975).
The active
range of motion of an individual may differ considerably,
depending upon the rate of stretch.
Effects of Repetition
Movement patterns which occur repeatedly over a
period of time lead to permanent alterations in motor
14
performance.
This is readily demonstrated in the
cerebral palsied individual who "practices" unwantedmotor responses due to spasticity.
Imposed repetitive
neural activity may create relatively permanent
change~
in structure and synaptic transmission.
Structural changes include contracture of the
spastic muscle, ligaments and joint capsule, with a
concurrent atrophy and lengthening of the opposing
muscle.
Although the lesion does not degenerate further,
the contractures become greater, producing subsequent
deformities in the limbs, pelvis, and spine (Harris,
1978).
Kinematics of Locomotion
Winter and associates
(1974) utilized a T.V.
computer system for measurement and analysis of the
kinematics of normal locomotion, including direct calculation of limb velocities.
The following angular veloc-
ities of the knee during extension were determined for
various cadences:
82 steps/minute - 288 degrees/second
(SLOW)
93 steps/minute - 330 degrees/second
114 steps/minute - 395 degrees/second
(FAST)
These results are somewhat in agreement with La Moreux
(1971) who determined a velocity of 350 degrees/second
15
for knee extension during a normal cadence.
In addition to the velocity requirements during
locomotion, the development of enough force within the
time constraints provides another demand on the muscular
system.
Moffroid and associates (1975) have suggested that
approximately 54 newton-meters of torque may be required
of the knee extensors during 20 degrees of extension to
sustain heel strike successfully.
If this force is not
generated within the time constraints (tenths of a
second) between heel strike and foot flat, an abnormal
gait pattern will result or the knee will collapse.
Furthermore, Bleck (1979) has stated that a knee
flexion deformity greater than 15 degrees during stance
phase will dramatically increase the force requirement
of the quadricep group in order to keep the individual
erect.
Thus, a contracture of the hamstrings in the
spastic gait creates an extremely energy consuming and
less efficient pattern.
Habilitation of the Cerebral Palsied
The role and value of physiotherapy for the cerebral
palsied has received mixed reviews, depending upon the
age, intelligence, and severity of involvement of the
subjects and the form of treatment received.
16
Knutsson (1973) has described the most common techniques available in physical therapy to facilitate the
control of spasticity.
These include local cooling,
electrical stimulation, a preceding maximal volitional
contraction, and changes in posture.
Other researchers
have utilized biofeedback in the form of response contingent aversive tone or informational tactile feedback
(Spearing & Poppen, 1974).
However, this review will
not deal with these avenues of treatment as they do not
involve strength training per se, and are not comparable
to the present investigation.
·Much has been written about the Bobaths' neurodeve1opmental approach to treatment which prescribes
inhibition of abnormal reflexive postures and facilitation of more normal patterns of movement (Reyes, 1971).
Wright and Nicholson (1973) assessed the effectiveness of a treatment program consisting of the Bobath
approach which included reducing spasm, assuming normal
postures, and improving the strength of weak and
hypotonic muscle groups.
Forty-seven spastic children
under six years of age received this therapy for a period
of six months.
The results offered no evidence that the
physiotherapy increased the range of motion at the ankle
or hip.
In addition, nothing indicated the loss of the
immature reflexes.
In fact, the control as well as the
17
experimental group improved overall in disappearance of
the primary automatic reflexes.
The authors concluded
that physiotherapy appeared to be of little value in the
treatment of spastic C.P.
Twenty-four C.P. children under 18 months of age
were observed by Scherzer and associates
(1976) for a
minimum of six months on either an experimental or
control physical therapy program.
Experimental physical
therapy was administered in a multidisciplinary setting
and was intended to stimulate motor milestones, as well
as inhibit abnormal reflexes.
Medical and therapy
evaluations indicated definite changes in motor, social,
and management areas for the experimental group.
Success
was found to be somewhat correlated with age of entry to
the program.
Berg (1970) measured the change in oxygen uptake and
other physiological parameters of cerebral palsy children
after training for a period of six weeks on a bicycle
ergometer.
All 43 subjects were over seven years of age.
Twenty-one of those studied used wheelchairs for locomotion, and all but one of the other 22 children walked
unaided.
After training, the majority of subjects showed
an increased oxygen uptake of between 10 and 25 percent,
with relative increases in blood lactate levels at the
end of the final test exercise.
Berg also noted a
18
significant increase in hemoglobin levels and blood
volume, together with increased walking speed and endurance.
Berg concluded that lack of physical training
played an important role in the motor inefficiency of
cerebral palsy children.
Harris (1978) conducted a treatment program for
21 subjects with cerebral palsy (ages 3-32 years).
The
therapeutic approach sought to decrease spasticity in
spasmatic muscles and facilitate volitional contraction
of atrophied muscle groups.
This was accomplished
through the following procedures:
1.
slow passive stretch of spastic muscles;
2.
facilitated voluntary contraction of weak
antagonists;
3.
voluntary contraction of antagonists against
a resistance;
4.
functional reciprocal voluntary contraction of
both sets of muscles acting at each affected
joint.
Harris noted improvement of all subjects in posture,
dynamic balance and ambulation.
The duration of the
treatment program was not indicated nor was the data
treated statistically.
However$ he suggested that work-
ing against resistance appeared to be extremely effective
in strengthening weak muscles of cerebral palsy children.
19
Though research is limited, available results suggest that physical training should be included to a
greater extent than previously encountered.
Some
individuals with C.P. may never achieve normal patterns
of movement, yet it is desirable to promote progress to
the point where they can perform reliably and with
increased endurance.
Robson has concluded that
. . . the motor inefficiency of children with
cerebral palsy is due in part to the basic
motor disorder and in part to the general
conditions of living in which exercise is
not encouraged {1972, p. 812).
The Concept of Contractile Power
Conventional strength tests and training programs
are based on the concept of progressive resistance which
permits the generation of peak tension without the
imposition of time limits.
These methods provide a
general assessment of strength, but without the consideration of time, do not examine the factor of power.
Tra-
ditionally, power has not received attention in determining specific loads and velocities for strength testing
and rehabilitation {Osternig, 1975).
Most functional movement involves producing a given
percentage of one's maximum force within a specified
period of time or at a given limb velocity.
This import-
ant time-based neuromuscular parameter is referred to as
20
the time-rate of force development (Perrine, 1969).
This
capability, like force production at high speeds, depends
upon a muscle's capacity to operate at a high contractile
intensity or power output.
It is this capability which
appears to relate most closely to performance and function (Perrine, 1973; Moffroid, 1975).
Perrine has stated
that,
. • • muscle contractile power limits, including relative peak intensities and endurance
potentials may be the operative factors in a
high percentage of human skeletal muscle
functions, rather than peak strength limits
(1973, p. 10).
Muscles are rarely required to generate their maximum
force, except within the testing session.
In reality,
the majority of muscular activities probably demand only
a certain portion of peak tension, due to time or velocity requirements.
For example, during ambulation, the
quadriceps need to produce a certain amount of torque
during the final degrees of extension at the knee to
execute a heel strike successfully (Moffroid, 1975;
Perrine, 1970).
If the required force is not developed
within the time period during heel strike and foot flat,
an inefficient pattern will result.
Thus, the time
required for a muscle to develop a portion of its maximal
force output is an important variable.
The majority of
functional human movement such as heel strikes, toe-offs,
and dynamic body-weight shifts demand specific contractile
21
time limits to produce mechanically efficient patterns
(Perrine, 1980).
Tucker (1971) investigated the problem of genu
recurvatum in hemiplegic patients who had sustained
cerebrovascular accidents.
Patients were required to
perform maximal knee flexions and extensions on a
Cybex II at various velocities.
He concluded that the
hamstring musculature lacked the necessary contractile
limit~,
power within various time
resulting in insta-
bility and genu recurvaturn of the knee.
In addition,
he noted that the available range of motion was a
function of the rate or speed at which movement around
a joint is introduced.
According to Perrine,
An apparent deficiency in muscular force that
becomes progressively worse with fatigue,
e.g., a limp, would currently tend to be
regarded (and treated) as a (peak) strength
and (peak) strength type of endurance problem,
rather than as a time-related contractile
power and contractile power specific endurance problem (1973, p. 8).
These capabilities cannot be assessed through conventional isotonic or isometric strength tests, which are
concerned only with the total amount of force produced.
Accordingly, progressive resistance strength training
is not inherently designed to facilitate rapid force
development in muscles.
For example, during progressive
resistive exercise, the limb may move at an angular
22
velocity of 60 degrees/second or slower (Perrine, 1973);
whereas athletic movements may require the limb to move
at velocities of several hundred or thousand degrees per
second.
Thus, the functional capacity of a muscle at
any given movement depends upon several factors:
1) the
imposed time-limit for tension development, and 2) the
muscle's contractile power.
Strength programs in rehabilitation which are functionally oriented should focus, therefore, on developing
the muscle to meet time related force demands.
A viable
means of loading muscles to their individual maximal
contractile power for testing and training is through
isokinetic, velocity-specific exercise (Perrine, 1968;
Tucker, 1970; Moffroid, 1975; Osternig, 1975; Chu, 1971).
Increased velocity forces an individual to work within
the confines of small amounts of time.
Thus, speed may
be considered the variable for power output as force at
higher velocities must be developed in a limited amount
of time.
Contractile power deserves closer examination in
regards to functional testing and training.
Hellebrandt
stated that, "the amount of work done per unit of time
(power) is the variable on which extension of the limits
of performance depends"
(1958, p. 322).
Chu (1971) and
Perrine (1973) have determined that isokinetic exercise
23
is suitable for training a muscle at the specific speed
on the force-velocity curve where it can develop its
highest power output.
Since greater demands are placed
on the contractile speed of the muscle at the higher
velocities, it would appear to be an appropriate method
of training for specific muscular activities.
Torgue and Muscle Fiber Composition
Coyle, Costill, and Lesmes
(1979) have attributed,
in part, the ability to develop power to muscle fiber
composition.
The high intrinsic speed of shortening and
the rapid rate at which the fiber develops tension have
been associated with high force production at fast limb
velocities.
They indicated that individuals possessing
a high percentage of fast contracting muscle fibers are
better adapted for activities requiring explosive power.
Thorstensson and associates
correlations (r
=
(1976) discovered that
.5) exist between the peak torque pro-
duced at the highest speed of limb velocity and the
percent as well as relative area of fast twitch muscle
fibers in the contracting muscle.
In addition, muscles
with a high percentage of fast twitch fibers had the
highest maximal contraction speeds.
They observed that
motor units with high tension outputs and quicker contraction times contained fibers that could be classified
24
as fast twitch.
It was concluded that a high percentage
of fast twitch muscle fibers is one prerequisite for
performing fast contractions with appreciable tension
outputs.
In another study conducted by Thorstensson and
associates (1977), fast twitch fibers were found to
possess metabolic properties favoring anaerobic production.
This accounted for the positive relationship found
between the percentage of fast twitch fibers and the
ability to produce force during a fast contraction or
velocity.
They further noted that training appeared to
affect the force-velocity relationship.
Coyle (1979) also attempted to relate muscle fiber
composition to the isokinetic measure of peak torque
production through a range of knee extension velocities.
To determine the percent distribution of fiber types
(fast and slow twitch) , biopsies were taken from the
vastus laterialis of ten male subjects.
Those individuals
displaying predominantly fast twitch fibers were able to
generate 11, 16, 23, and 47 percent greater relative peak
torque than predominantly slow twitch subjects at lever
arm velocities of 115, 200, 287, and 400 degrees/second.
The authors cautioned, however, that consideration be
given to the velocity of movement in assessing the
functional role of fast twitch fibers and that other
25
factors are involved in determining peak torque production.
They concluded that muscle fiber composition
became increasingly more related to power performance
as the limb velocity increased.
Edstrom (1973) examined the role of spasticity,
resulting from upper motor neuron lesions, in the
selective atrophy of certain muscle fiber types.
Through histochemical staining, the effect of spasticity
or voluntary inactivity on "red" and "white"
(slow and
fast twitch fibers, respectively) were observed.
The
examination revealed that paralytic muscles with a
weak tonic spasticity atrophied in an unspecific manner.
Atrophic fibers were found within both the red and white
group.
In paralytic muscles with strong tonic
spasticity, atrophy selectively affected the white
fibers, while red fibers were subject to hypertrophy.
In addition, the degree of atrophy of white fibers was
related to the degree and duration of voluntary inactivity.
Therefore, maximal contractions did not occur
in paretic states due to continual inactivity.
Select-
ive atrophy of white fibers found in highly spastic
muscles reflected a selective disuse of certain motor
units, since white fibers are recruited during phasic
activity.
26
Specificity of Speed in Strength Training
As early as 1928, the rate of working (i.e., power)
was considered an important variable in exercise programs
desiring to facilitate muscular performance (Hellebrandt,
1958).
Since power equals force times velocity, the
amount of work done per unit of time may be increased by
systematically overloading the resistance, cadence, or
both simultaneously.
In the past, the emphasis has been placed on
progressive increase in resistance which the muscles are
made to contract against.
The purpose of resistive
exercise was to effect changes in the physiological
mechanisms through the contraction of the muscles
within the range of motion, using the principles of
overload.
It was assumed that these "changes" would
transfer to all velocities of limb movement.
Studies have emerged in recent years, questioning
the efficacy of strength training through traditional
Progressive Resistance Exercise {P.R.E.).
Consideration
has now been given to the role of limb velocity on
strength and power gains.
In regards to the quality of
muscle development, the speed at which exercise is
performed is an important consideration.
It is invalid
to assume that a muscle made stronger will also be
faster (Counsilman, 1976).
27
Pipes and Wilmore (1975) studied changes in selected
motor performance tasks as a result of training isokinetically (fast and slow) or isotonically.
Thirty-six adult
males were administered five motor performance tests:
1) standing long jump, 2) 40-yard dash, 3) softball throw
for distance, 4) vertical jump, and 5) two-handed sitting
shotput.
These tasks were chosen as they correlate with
explosive strength.
An eight-week weight training pro-
gram followed, focusing on the specific muscle groups
involved in the performance tests.
Results did not reveal
any significant changes in scores of the isotonic training
group for the five motor performance tasks.
Both the
slow (24 degrees/second) and fast (136 degrees/second)
isokinetic high speed group significantly increased its
performance socres in the two-handed sitting shotput.
They concluded that motor performance tasks requiring
explosive strength were not facilitated or altered by
isotonic training procedures.
Hellebrandt (1958) first introduced the concept of
systematic increase in speed of movement.
She referred
to this method of overloading the neuromuscular system
as pacing.
Six normal female adults were tested for
supinator strength of the forearm on a radio-ulnar
ergograph.
An optimal load was chosen for each subject
by determining the largest amount of resistance that
28
could be lifted for 25 repetitions at a natural, unhurried rhythm (determined by an audio-visual metronome) .
Maximal power output was determined by varying the speed
of exercise with the metronome.
The optimal load, number
of lifts per bout, and rest period were held constant.
A subsequent graph of power versus pace (metronome)
revealed the approximate cadence required to overload
the machine when using the previously established optimal
resistance.
Hellebrandt observed that training at speeds
below where maximum peak power occurred never strained
(i.e., overloaded) the functional capacity of the muscle
for .the given load.
Pacing beyond this point produced
fatigue or incoordination,· resulting in breakdown before
the exercise bout 1;.1as completed.
Subjects performed
10 bouts of 25 repetitions at the optimal load and rate
of movement determined individually.
Her results showed
that the power capacity of the supinators more than
doubled after 10 days of training.
preferred side reached 150 percent.
Improvement on the
These results sur-
passed those obtained by the same author from a previous
study involving progressive resistive exercise
(Hellebrandt, 1958).
The author concluded that cadence
training increased strength in significant amounts.
After training, the maximal load lifted was greater; thus,
pacing was as effective a method of muscle training as
29
progressive resistance exercise.
In addition,
Hellebrandt suggested that pacing facilitated the functional capacity of the neuromuscular system.
She postu-
lated that a large proportion of changes with systematic,
voluntary exercise were due to motor learning.
Each time
new combinations of strength, speed, skill and endurance
are needed, the training process should be repeated.
Repetition, specificity, and experience are variables
upon which motor learning depends.
She further suggested
that changes in the central nervous system due to motor
learning play a much greater role in training programs
designed to increase muscle performance than previously
thought.
Moffroid and Whipple (1970) investigated the effects
of two different isokinetic training speeds on muscular
force and endurance.
The training programs consisted of
either 1) low power output (high load, slow speed) at
36 degrees per second, or 2) high power output (low load,
fast speed) at 108 degrees per second.
Thirty-six adult
subjects were measured for peak torque of the quadricep
muscle group at different limb velocities (0, 36, 54, 72,
90, and 108 degrees per second).
Subjects trained for a
period of two minutes, three times per week for seven
weeks.
Results showed no gains in strength at zero
degrees per second.
Strength increases were not uniform
30
across all velocities for the low power exercise group.
Significant gains occurred only at 36 degrees per second
and 48 degrees per second for this group.
Gains made by
the high power exercise group were uniform across all
speeds tested; however, increases at the training velocity
were smaller than the increase of the low power exercise
group at its own training velocity.
They concluded that
strength gains were speed-specific in the following ways:
1)
Low power, isokinetic exercise (36 degrees per
second) significantly increased peak torque
(strength) at the velocity at which training
took place, and
2)
High power, isokinetic exercise (108 degrees
per second) improved strength at limb
velocities at and below the training speed.
Van Oteghen (1975) compared maximum leg strength and
performance in the vertical jump between female collegiate
volleyball players training at two speeds of isokinetic
exercise.
The slow speed group executed leg press move-
ments of four second durations on a "compensator Leg
Press"
(Robar Mini-Gym Inc.) while the fast speed group
executed the same movement for two second durations.
Both groups trained three days per week for a total of
eight weeks.
Each subject performed three sets of
10 repetitions during the exercise session.
The analysis
31
of results revealed that both the slow and fast speed
treatment groups were significantly superior to the
control group in vertical jump performance.
The mean
socres for the two trained groups did not differ significantly from one another.
However, the training speeds
selected for this study may not have been qualitatively
different enough to affect the scores.
Pipes and Wilmore (1975) studied the differences in
strength between groups which trained isotonically or
isokinetically.
In addition, differences were assessed
between isokinetic training at slow and fast•velocities.
All three groups performed the bench press, bicep curl,
leg press, and bent rowing.
The training sessions were
carried out three days per week for eight weeks.
The
slow and fast speed isokinetic groups trained at 24 and
36 degrees of limb movement per second, respectively.
The results showed the following trends:
1)
increases in static strength for both the low
and high speed isokinetic groups were significantly greater than for the isotonic group,
2)
all training groups increased their relative
isotonic strength over the control group for
all movements; the isokinetic high speed
group had significantly greater increases
than the isotonic group in leg press, bicep
32
curl, and bent rowing;
3)
both isokinetic groups significantly increased
their strength at low limb speed when tested
isokinetically; the isotonic group did not;
with the exception of the leg press, the fast
speed isokinetic group gained significantly
more strength than the low speed isokinetic
group;
4)
both isokinetic groups made significantly
greater increases than the isotonic group
when assessed isokinetically at the fast
limb speed; the latter group made no significant gains in strength; the fast speed
isokinetic group demonstrated the largest
gains overall at this test velocity.
Pipes and Wilmore concluded that isokinetic training at
slow and fast speeds demonstrated superiority over
isotonic training, whether this improvement was measured
statically, isotonically, or isokinetically.
Further-
more, the fast speed isokinetic group made greater gains
than the slow speed isokinetic group for the velocities
tested.
Lesmes, Costill, Coyle, and Fink (1978) examined
the effects of short duration, high intensity training
on the development of torque in skeletal muscle.
Peak
33
torque of the knee extensors and flexors were measured at
velocities ranging from zero degrees per second to 300
degrees per second through a distance of 90 degrees.
Six
male subjects trained at a constant velocity of 180
degrees per second, four times per week for a duration
of seven weeks.
One leg was trained with repeated (10)
six second exercise bouts, while the opposite leg was
tr.ained using repeated (2)
30 second bouts.
Their
.results indicated that isokinetic training programs of
six and 30 seconds duration significantly increased
(P<.OS) muscular torque.
More specifically, they found
that the increases occurred only at the test velocities
of zero, 60, 120, and 180 degrees per second.
No signif-
icant gains were obtained at the test velocities of 240
and 300 degrees per second.
These findings imply that
strength training benefits may be restricted to velocities used during training and/or at slower speeds.
Thus,
for achievement of maximal results, the training speed
used during exercise should approximate the functional
movement speeds.
In a similar study, Costill, Coyle, Fink, Lesmes,
and Witzmann (1979) studied five men before and after
seven weeks of isokinetic strength training.
The legs
were trained in the same manner as described for the
study of Lesmes, Costill, and Fink (1978).
Results
34
were the same as previously cited.
Significant gains
were shown for both legs at the training velocity and
at slower speeds.
Improvements in peak torque ranged
from 14 percent at zero degrees per second to four
percent at 180 degrees per second.
No significant
differences in torque were observed at the velocities
of 240 and 300 degrees per second nor were there any
differences in knee extensor torque between the two
training schedules.
In a study conducted by Coyle and Feiring (1980),
the effects of slow and fast isokinetic knee extension
training on peak torque measured isometrically and at
isokinetic velocities of 60 and 300 degrees per second
were compared.
In addition, it was determined whether
these improvements were significantly greater than what
can be attributed to placebo effects.
(n
=
Male subjects
22) volunteered to train the knee extensors three
times per week for six weeks in one of the following
groups:
1) Slow = 60 degrees per second,
2) Fast = 300 degrees per second,
3) Mixed = 60 and 300 degrees per second, and
4) Placebo = low level electrical muscle
stimulation.
The results demonstrated that all groups significantly
improved peak isometric torque (8 -
26 percent), with
35
the placebo group achieving the largest improvement.
Peak torque at 60 degrees per second improved significantly in the Slow (+32 percent) , Mixed (+24 percent) and
Fast (+16 percent) groups; yet, only the groups training
at 60 degrees per second (Slow and Mixed) improved significantly more than the Placebo group.
Peak torque at
300 degrees per second improved only in groups training
at 300 degrees per second (Fast, +18 percent; Mixed, +16
percent).
The results suggest that placebo effects can
facilitate post training isometric performance.
Signifi-
cant improvements (>Placebo) at slower velocities were
acquired only through slow isokinetic exercise while
improvements at faster velocities were developed only
through fast isokinetic exercise.
Parker et al.
(1980) assessed the effects of a
short-duration, high-intensity aerobic training program
on the force-velocity (F-V) relationship and the instantaneous power (I.P.) output of the knee extensors.
Male
subjects (n - 12) trained three days per week for four
weeks on motor driven tread mill at a heart rate of 150160 beats per minute (75-80 percent of heart rate
maximum) for a period of 10 minutes.
cated that subjects improved their V0
The findings indi2
Maximum by 12-15
percent (P<.05) without concomitant fluctuations in the
F-V curve.
However, subjects demonstrated a velocity
36
specific training effect for I.P. at a limb velocity of
162 degrees per second during weeks two, three, and four
(P<.OS).
The F-V curves of the knee extensors for the
control and experimental group did not differ significantly (P<.OS) from the theoretical F-V relationship
described by Hill.
An explanation for the phenomenon of specificity
has been postulated by Perrine and Edgerton (1978) .
They
compared the in vivo force-velocity relationship of the
knee extensors of man to the force-velocity relationship
established by Hill (1970) for isolated, maximally stimulated animal muscle.
Fifteen males and females
(18 to
38 years old) of various activity levels executed
maximal knee extensions on an isokinetic dynamometer
at seven loading velocities.
At the four lowest test
velocities (0, 48, 96, and 144 degrees per second), all
subjects evidenced less than a 15 percent deviation from
their maximum torque established on the force-velocity
curve.
Furthermore, the maximum torque attainable by
each subject occurred most frequently at 96 degrees per
second, rather than at zero degrees per second as postulated by Hill.
Maximal instantaneous power output
occurred over the three highest test velocities (192,
240, and 300 degrees per second) and remained fairly
constant there.
The results indicated that the in vivo
37
force-velocity relationship followed a curve similar to
Hill until about 192 degrees per second.
Here it de-
parted and showed a diminishing rate of rise in force as
the velocities continued to decrease.
It was hypothe-
sized that the high tension region of Hill's curve (low
velocity end) deviates for in vivo muscle due to some
neural regulatory mechanism, providing the intact system
with a safe tension level to prevent a limb from exceeding its anatomical range of movement.
In contrast, the
low tension region (high velocity end) was hypothetically
limited by the contractile power capacity of the muscle.
In an investigation conducted by Caizzo, Perrine,
and Edgerton (1980) , the effects of two velocity-specific
training programs on the in vivo force-velocity relationship were compared.
Seventeen subjects were tested for
maximum knee extension torque at seven angular velocities.
Subjects then trained at either 96 or 240 degrees
per second.
These velocities were selected as they rep-
resent approximately optimal peak force output (within
the area of severe neurologic inhibition) and optimal
peak power output, respectively.
The training schedule
consisted of eight second bouts, three times per week for
a period of four weeks.
Significant strength increases
were obtained for both groups.
Subjects who trained at
96 degrees per second achieved a mean improvement of
38
14.7 percent at zero degrees per second but improved
only .5 percent at 288 degrees per second.
Subjects
who trained at 240 degrees per second demonstrated a
similar but opposite trend.
They concluded that
specific alterations were possible in the in vivo forcevelocity relationship through velocity-specific strength
training programs.
Summary
Current research demonstrates that response to
strength training relies on the principle of specificity.
Muscles specifically adapt according to the demands
placed upon them.
The practical application of this
principle would be to impose similar muscular demands
in training as is found in the desired activity.
Accord-
ing to Perrine (1968), the energy requirements of many
functional activities occur at the higher shortening
speeds on the force-velocity curve when tension is
limited by contractile power capacity and not neurologic
inhibitory mechanisms.
It may be possible to improve contractile power
through non-specific progressive resistance training.
However, higher levels of performance in functional
activities may be possible for the disabled through
contractile power-specific training techniques.
Matching
39
the speed of training to the speed of performance may
be critical in,view of the current research pertaining
to the specificity of training.
Chapter III
METHOD
Overview of Approach and Design
The intent of this investigation was to ascertain
the clinical value of isokinetic training at a velocity
determined by peak I.P. output of the knee extensors for
individuals with spastic cerebral palsy.
A two group
before-and-after design was employed to make that
determination.
_This chapter includes descriptions of the following:
pilot study, selection and assignment of subjects, instrumentation~
variables, training procedures, and statisti-
cal analysis.
Pilot Study
The purpose of the preliminary investigation was to
determine if significant differences existed in the forcevelocity and power-velocity relationship of the knee
extensors between cerebral palsy and normal subjects of
similar age and sex.
In addition, the velocity at which
peak I.P. occurred was noted for each group.
Ten subjects participated in the pilot study (n
for the C.P·. group, n
=
=
5
5 for the untrained Normal group).
40
41
Each subject was measured for knee extensor torque at
six angular velocities using a Cybex II dynamometer
(Lumex, Inc., Bay Shore, New York).
illustrated in Figures 1 and 2.
The results are
The C.P. group scored
well below the Normal group on knee extensor torque at
all six velocities tested (Figure 1).
Although peak
torque occurred at 60 degrees/second for both groups,
the C.P. group dropped off dramatically in strength
(60%) at 300 degrees per second as compared to the
Normal group (34%).
When comparing the power-velocity relationship
(Figure 2) , large differences were also evident at all
velocities tested.
The velocity where peak I.P. occurred
was considerably slower for C.P. subjects (120 degrees/
second) than the untrained Normal subjects (300 degrees/
second) .
From the data gathered in this pilot study, it is
apparent that ambulatory spastic C.P. subjects have
considerably lower indexes of strength and power,
especially at velocities above 60 degrees/second.
Selection and Assignment of Subjects
The sample consisted of twelve volunteer college
and high school students from either California State
University at Northridge or Joaquin Miller High School,
42
• •
-
-
• Normal
• Cerebral Palsy (Spastic)
90
•
I
80
I
I
70
' '•
I
'
I
Cl)
~
60
H
' ·-
I
-·
\
E-i
Ii-I
50
rz.:l.
0
0
p::;
40
5
\
I
........
=
N
\
•
\
•
0
E-i
30
20
•
./ ""'.
'---
.""·--N
10
30
60
120
180
240
VELOCITY (DEG/SEC)
Figure 1
FORCE-VELOCITY RELATIONSHIP
Pilot Study
=
•
300
5
43
••
-
• Normal
• Cerebral Palsy
•6
•5
./
•
....... • /
~
.4.
=
N
5
3:
0
p..
ILl
•
.3
/
l
Cf.l
I
~
0
::c:
........
/
ILl
I
.2
.1
/
•
I
N
=
5
.--· ---·--·--·--.
•
30
/
60
120
180
240
VELOCITY (DEG/SEC)
Figure 2
POWER-VELOCITY RELATIONSHIP
Pilot Study
300
44
Reseda, ranging in age from 16-33 years.
were male and three were female.
Nine subjects
With all subjects;
spastic C.P. was the primary medical diagnosis, although
the degree of involvement varied.
The criteria for
acceptance into the study included the following:
1.
evidence of the spastic condition in at least
one of the lower extremeties
2.
evidence of a knee flexion contracture as
measured by an electrogoniometer (Cybex II,
Division of Lumex,. Inc., Bay Shore, New York)
3.
the ability to ambulate either with or without
supports (e.g., canes, crutches, walkers)
4.
the ability to•produce some amount of knee
extensor torque at all of the test velocities
(i.e., 0-60-120-180-240-300 degrees/second)
5.
no participation in an exercise or therapy
program, specifically isolating the knee
extensor muscle group, for three months
prior to the present study.
A summary of information on the subjects is provided in
Appendix A and B.
Consent was obtained from all subjects participating
in the project (Appendix C).
In those subjects under 18
years of age, parental consent requested (Appendix D).
Subjects were then placed in the design described in
Table 1.
The Experimental Group received isokinetic
exercise at a velocity determined for each individual by
their respective peak I.P. output (ranged from 120-240
degrees/second.
The Control group abstained from exer-
but were administered identical pre and post tests.
45
Table 1
EXPERIMENTAL DESIGN
Group
Pretest
Post
Test
Training
Experimental
Yes
Isokinetic at a velocity
determined individually
by peak I. p. output
Yes
Control
Yes
No training
Yes
Instrumentation
To obtain objective and precise measurements of
torque at the six velocities of knee extension, an
electro-mechanical isokinetic dynamometer was utilized
(Cybex II, Lumex, Inc., Bay Shore, New York)
tion I).
(Illustra-
It consisted of a lever arm which could be
attached to a part of the body and carried through the
range of motion.
In this
study~
the lever arm was
attached to the tibia below the bulk of the calf
musculature.
The joint line of the knee was used as
the anatomical landmark for alignment with the lever
arm's axis of rotation.
The lever arm was prevented
from exceeding a preset and constant velocity and the
offered resistance was proportional to the dynamic
46
Illustration
CYBEX II
ISOKINETIC DYNAMOMETER
47
tension produced in the muscle at every point in the
range of motion.
A load cell inside the dynamometer
continuously monitored the force output of the subjects
and delivered this information to the recorder.
The
velocity range of the apparatus was 0-300 degrees/second.
To standardize the protocol and isolate the knee
extensor muscle group 1 the subjects were seated in an
upright position with support for the back.
A velcro
strap was placed across the thigh to check any lifting of
the pelvis during a knee extension.
In addition, subjects
were asked to grasp the handles at the base of the seat
and maintain contact with the back support of the chair.
A· strip chart recorder with dual channels was used
for measuring velocity-specific torque and the position
angle of the knee at any given point in the range of
motion.
Moffroid and associates (1969) have confirmed the
validity of the Cybex dynamometer as a velocity-specific,
torque measuring apparatus.
In their study it was
determined that velocity remained constant with the
application of various torques
and observed speed) .
(r
=
.99 between predicted
Using a known control speed,
measurements of torque and work-rate also proved to be
highly .accurate (r
=
.99).
According to Thorstensson and associates (1976), no
48
variance was evident in the accuracy of the preset speed
throughout the range of motion in the lower range of the
angular speeds.
At a velocity of 180 degrees/second and
higher, an increase of speed was observed in the initial
.05 seconds of the movement.
Inherent in the construc-
tion of the machine was an acceleration phase before
the correct test speed was reached.
This lag in test
speed occurred in the initial five to ten degrees of
motion (i.e., approximately .03-.06 seconds).
After
this small acceleration, the velocity remained constant
throughout the remainder of the range of motion.
Calibration
The Cybex II dynamometer was factory calibrated
prior to the experiment and was rechecked daily by
adjusting the "zero null" screw until no movement
occurred on the stylus pen between the 30-180-360
torque scales at 60 degrees/second and a "damping" of
"2".
The following figures were accepted as possible
torque measurement errors inherent in Cybex systems
(Lurnex, Inc., 1980):
Accuracy
360 ft.lbs. scale
Accuracy
180 ft.lbs. scale
Accuracy
30 ft.lbs. scale
=±
=±
=±
2.0 ft.lbs.
1.0 ft.lbs.
1.0 ft.
lbs.
49
The accuracy of the speed control (using the tachometer
on the speed selector as a visual reference) was determined to be the following (Lumex, Inc., 1980):
± 0.25 RPM at 25 RPM
± 1.25 RPM at 50 RPM.
Speed control variability, depending upon the force
applied and the velocity performed at, was computed at
the following value (Lumex, Inc., 1980):
± RPM at 25 RPM and 240 ft.lbs. applied.
As no. subject produced torque greater than 100 ft.lbs.
at 150 degrees/second (25 RPM), it was assumed that the
variability was negligible across all testing sessions.
The Experimental Protocol
The independent variable in this study was the
velocity-specific, isokinetic training of the knee
extensors.
The dependent variable was the torque
obtained at six different velocities of limb movement.
In order to determine the effects of the independent
variable on the dependent variable, the study was conducted in the manner described below.
Pretest:
Following orientation, each subject was
asked to perform maximal contractions of the knee
extensors at six different velocities through a range
50
of approximately 100 degrees.
A protocol which consisted
of three submaximal trials followed by three maximal
warm-up efforts was essential before stable measures
could be achieved (Johnson & Siegel, 1978).
correlation coefficient was .94.
The expected
The test velocities
were 0-60-120-180-240-300 degrees/second.
These veloc-
ities were chosen as a significant difference in peak
torque occur between velocities which vary by 36 degrees/
second or more (Moffroid, 1970).
Five maximal efforts
were requested at each velocity, except for zero and
60 degrees/second, where one and three efforts were
requested respectively.
Subjects became unduly fatigued
if they performed more than the number of repetitions as
specified above.
A three minute rest was allowed between
each test velocity bout.
selected for testing.
The non-dominant leg was
The data collected at all six
velocities consisted of:
1.
torque at 30 degrees of extension
2.
active range of motion.
Torque at 30 degrees of extension was selected as the
specific angle for measurement as this enabled all
torque measurements to be taken after the subject's
muscle had reached its peak tension and provided a
standardized point of measurement for the pretest and
post test.
Instantaneous power outputs were computed in
51
Watts by multiplying the 30 degree torque values in
newton-meters by the velocity in degrees/second and the
appropriate constant, 0.0175 (equals a torque of one
newton-meter acting over 1 degree of arc =
2~/360,
0.0175 Joules of work; 1 Watt= 1 Joule/second).
or
This
formula was provided by Perrine (1978).
Post test:
The post test was conducted in the same
manner as the pretest.
The time of the post test was not
allowed to vary by more than one hour from the time of the
pretest because of the diurnal effects on strength
observed by Hislop (1963).
Training Procedures
The subjects who participated in the experimental
group exercised either Monday-Wednesday-Friday or
Tuesday-Thursday-Friday for a period of six weeks.
The
exercise bout consisted of four sets of maximal knee
extensions for a period of 20 seconds each.
Time,
rather than repetitions, was held constant within each
set as Moffroid and associates
(1969) have demonstrated
that subjects pretested at different velocities, but for
the same bout duration, yield practically equal starting
energy values (average power) •
allowed between each set.
One minute of rest was
A window on the dynamometer
provided the subjects with immediate knowledge of results.
52
Both the right and left limbs were exercised.
The
prescribed exercise velocities were calculated from
the pretest scores and are provided below:
1.
120 degrees/second
(two subjects)
2.
180 degrees/second
(three subjects)
3.
240 degrees/second
(one subject).
Statistical Analysis
In order to ascertain if significant pretraining
differences in mean torque scores existed between groups
prior to training, a two-tailed t-test was performed
using the pretest scores.
A significant difference did
exist in favor of the experimental group (P<.05).
The
mean torque scores of the experimental and control groups,
equalled 36 and 26.5 newton-meters, respectively.
Therefore, analysis of covariance (ANCOVA) was accepted
as the statistical design for this study, with post
test scores as dependent and pretest scores as covariates.
Chapter IV
RESULTS
The purpose of this investigation was to assess
the value of isokinetic training in eliciting strength
gains in the spastic cerebral palsied.
More specifi-
cally, this study examined the effects of training at
a velocity determined by peak instantaneous power
output upon knee extensor torque.
Subjects in the experimental group exercised three
times per week for a period of six \veeks.
The exercise
bouts consisted of four sets of maximal knee extensions
for 20 seconds each.
The control group did not exercise
during the experimental six week period.
Pretests and
post tests were taken of knee extensor torque at six
angular velocities of the non-dominant leg for all
subjects.
Analysis of covariance was utilized to
interpret the data.
Strength Prior to Training
A t-test (two-tailed) of pretest torque scores
revealed that significant differences in knee extensor
strength existed between the groups at the training
velocity (P<.OS).
Table 2 provides the mean torque
scores for Groups 1 and 2 on the pretest.
53
54
Table 2
Summary of t-test on Pretest Means
M
Experimental Group
36
(J
()M
23.7
10.6
6"d
4.1
Control Group
26.5
15.9
t
Sig.
2.3
• OS
7.1
It was concluded that the experimental and the
control group were not similar in regards to strength of
the knee extensor muscle group prior to the training
session.
Therefore, it was necessary to use ANCOVA to
account for significant pretest differences.
Analysis of Data
The mean torque scores for the experimental and
control groups before and after adjustment are presented
in Table 3.
The pretest scores were adjusted to a common
mean of 31.25 newton-meters.
Figure 3 illustrates the .
pretraining and post training difference between groups
as analyzed by the UCLA BioMed Computer Program BMD04V.
The final adjusted mean difference of 13.74 newtonmeters, in favor of the Experimental Group, was significant at the .01 level of confidence.
This represented
55
a mean strength increase of 32 percent for the experimental group.
The results of ANCOVA are provided in
Table 4 and reported an F ratio of 13.86.
Table 3
Mean Knee Extensor Torque Scores
(newton-meters)
Pretest
GROUP 1
EXPERIMENTAL
\
Post test
36
;
GROUP 2
CONTROL
Pretest
Adjusted
Post test
Adjusted
50.5
45.12
26.0
31.38
31.25
26.5
Table 4
Summary of Analysis of Covariance
Main Effects
SOURCE
Between
df
SSy
MSy
SSy X
1 1800.75 1800.75 530.548
Within
10 5579.5
Total
11 7380.25
5579.5
344.52
DFy X
1
9
MSy x
F
SIG.
530.548 13.86 .01
38.28
56
•
•-
• Experimental
• Experimental - Adjusted
* Control - Adjusted
* Control
*
*
60
-:z:
•
50
~
-
40
::::>
0:
p:::
0
8
30
•
I'Ll
~
..:t:
*• -:: :
---
-
-
-
- -*
---
?<
*
20
I'Ll
t:lo
10
1
2
3
4
PRE
5
6
7
POST
WEEKS
Figure 3
PEAK TORQUE INCREASE
57
The velocity at which peak I.P. occurred changed
in four out of six experimental subjects (see Table 5) .
In all four subjects, peak I.P. shifted from the training
velocity to the next highest velocity tested.
That meant
that for two subjects, peak I.P. shifted from 120 degrees/
second to 180 degrees/second.
In the other two subjects,
peak I.P. shifted from 180 degrees/second to 240 degrees/
second.
Peak I.P. remained at the same pretraining
velocity in the other two experimental subjects.
Table 5
Velocity Shifts in Peak Instantaneous Power
Subiect
Velocity-Degrees/Second
Pretest
Velocity-Degrees/Second
Post test
1
180
240
2
120
180
3
180
180
4
180
240
5
120
180
6
240
240
Active range of motion did not increase for any
subjects in either the experimental or control group.
Chapter V
DISCUSSION
The value of isokinetic strength training has
received little attention in regards to management of
spastic cerebral palsy.
The present study attempted to
assess the value of a program which utilized isokinetic
training at relatively higher velocities.
The data from this study suggests that isokinetic
training at peak I.P. may provide a protocol for achieving functional strength gains.
variables of
cross-transfer~
However, the uncontrolled
spasticity, and audience
warrant caution when interpreting the results.
Since both limbs were trained, the effects of crosstransfer may have produced higher torque scores than
would have been obtained with training only one limb.
Furthermore, it becomes difficult to discern the
amount of strength gain when the mechanism of spasticity
is involved.
As described earlier, the "brake" imposed
by spasticity creates a major obstacle in the facilitation of reciprocal movement.
This brake is the stretch
reflex and its rate of firing depends upon the rate of
stretch.
Therefore, in the spastic individual, strength
training must inherently include learning reflexinhibiting signals in addition to contraction of the
58
59
agonists {Perrine, 1968).
Continual practice of a move-
ment should facilitate progressively more successful
repression of undesired neuromuscular activity.
Therefore, it is not clear as to whether an increase
in performance reflected an actual physiologic alteration
in strength or whether the agonist was released from the
confined range of motion imposed by an opposing spastic
muscle.
Further studies are necessary to discern the
contribution of isokinetic exercise in facilitating
reciprocal movement.
However, regardless of the underlying mechanisms,
a significant improvement in knee extensor torque occurred
at relatively functional velocities in spastic C.P.
subjects.
In addition, the age of the subjects in this
investigation discount the popular assumption that age
of entry into a therapy program largely determines the
individual's prognosis (Black,
1979~
Scherzer, Mike, &
Ilson, 1976; Wright & Nicholson, 1973).
Thus, individ-
uals up to 33 years of age can expect to benefit from an
isokinetic training program.
Conclusions
Based upon the available data and limitations of
this clinical investigation, the following conclusion
appears indicated:
Isokinetic training at a velocity
60
where peak instantaneous power occurred significantly
increased knee extensor torque in young adults with
spastic cerebral palsy.
The null hypothesis of this
study is therefore rejected.
Due to the many variables
influencing this study, further clinical research in the
area of velocity-specific, isokinetic training is warranted to determine the practical application of the
present results to functional movement patterns in the
spastic cerebral palsied.
Major Findings
The following list summarizes the major findings
of this clinical investigation:
1.
Significantly greater gains were achieved in
knee extensor torque when subjects with spastic
C.P. isokinetically trained at a velocity
sufficient to produce maximum power output,
as compared to spastic C.P. subjects who
received no exercise.
2.
Physiotherapy in the form of isokinetic
strength training benefitted spastic C.P.
individuals past the developmental years
(0-18).
Therefore, continued isokinetic
training is indicated for adult individuals.
61
3.
Peak instantaneous power output appeared
to be a satisfactory beginning point for
determining the initial training velocity
for each subject.
It appears then that isokinetic training may allow
a cerebral palsied individual to work at progressively
higher velocities, thereby achieving strength and power
within more functional limb velocity ranges.
The challenge for the therapist is to develop techniques in strength training at velocities which would be
near or identical to the velocity of functional skills.
The motor learning process would probably be more
effective and provide more positive transfer, as opposed
to being a simple muscle strengthening process.
Recommendations for Further Study
The following recommendations are offered for
future research:
1.
A similar investigation should be initiated
which omits the variables found in the
present study:
presence of an audience and
training of both the right and left limbs.
A research effort such as this would more
clearly delineate the role of isokinetic
strength training and would confirm the
62
results of the current study.
2.
Other studies are necessary which investigate other variations in the training
protocol (i.e., sets, repetitions, velocities) to determine the most effective
regimen for spastic cerebral palsy.
3.
An examination of the specificity of speed
principle in relation to the cerebral palsy
population is warranted.
4.
Electromyography needs to be utilized to
determine the role of spasticity in strength
training; i.e., is there a reduction in
abnormal neural activity with concurrent
strength gains at relatively high
velocities?
5.
Kinematic studies are needed which would
determine typical angular limb velocities
during activities of daily living.
These
velocity demands could then be imposed in
training programs.
6.
Biomechanical research is needed to assess
the force requirements of various muscles
during activities of daily living.
7.
Additional biomechanical research is necessary to demonstrate the effectiveness of
63
velocity-specific, isokinetic training on
improved performance in functional movement
patterns.
8.
Correlations should be determined between
peak instantaneous power output and the
time-rate of force development at various
velocities .. This would help assess the
role of contractile power in various
functional movements such as walking.
REFERENCES
1.
Berg, K. Adaptation in cerebral palsy of body
composition, nutrition and physical capacity
at school age. Effects of physical education
and improved nutrition. Acta Paediatrica
Scandinavica, 1970, Supplement 204.
2.
Birkmayer, W. (Ed.)
Spasticity: a topical survey,
Bern Stuttgart, Viena: Hans Huber, 1971.
3.
Bleck, E. E. Musculoskeletal examination of the
child with cerebral palsy. Pediatric Annals,
1979, ~, 606-613.
4.
Bleck, E. E., & Nagel, D. A. (Eds.)
Physically
handicapped children. A medical atlas for
teachers. New York: Grune & Stratton, 1975.
5.
Caizzo, V. J., Perrine, J. J., & Edgerton, v. R.
Training induced alterations of the in vivo
force-velocity relationship of human muscle.
Paper presented at the 1980 American College
of Sports Medicine Annual Meeting, Las Vegas,
Nevada, May 1980.
6.
Chu, D. A. Comparisons of selected electromyographic
data under isokinetic and isotonic stress loads.
Unpublished manuscript, Stanford University, 1974.
7.
Coplin, T. H.
Isokinetic exercise: Clinical usage.
Journal of the National Athletic Trainers Association, Fall 1971.
8.
Costill, D. L., Coyle, E. F., Fink, W. F., Lesmes,
G. R., & Witzmann, F. A. Adaptations in skeletal
muscle following strength training. Journal of
Applied Physiology, January 1979, 96-99.
9.
Counsilman, J. E. The importance of speed in
exercise. Scholastic Coach, October 1976, 94-99.
10.
Coyle, E. F., & Feiring, D. Muscular power improvements: specificity of training velocity. Paper
presented at the 1980 American College of Sports
Medicine Annual Meeting, Las Vegas, Nevada,
May 1980.
64
65
11.
Coyle, E. F., Costill, D. L., & Lesmes, G. R.
Leg extension power and muscle fiber composition.
Medicine and Science in Sports, 1979, 11 (1),
12-15.
12.
deVries, H. A. Physiology of exercise for physical
education and athletics. Dubuque: Wm. C. Brown
Co., 197 4.
13.
Edstrom, L. Relation between spasticity and muscle
atrophy pattern in upper motor neuron lesions.
Scandinavian Journal of Rehabilitative Medicine,
1973, ~' 170-171.
14.
Harris, F. A. Muscle stretch receptor hypersensitization in spasticity. American Journal of
Physical Medicine, 1978, 57 (1), 16-28.
15.
Hellebrandt, F. A. Methods of muscle training.
The influence of pacing. Physical Therapy Review,
1958, 1' 319-326.
16.
Isolated joint testing and exercise. Sports Medicine Department, Cybex, Division of Lumex, Inc.,
100 Spence Street, Bay Shore, New York, 1980.
17.
Johnson, J., & Siegel, D. Reliability of an
isokinetic movement of knee extensors. Research
Quarterly, March 1978, 88-90.
18.
Knutsson, E. Physical therapy techniques in the
control of spasticity. Scandinavian Journal of
Rehabilitative Medicine, 1973, ~' 167-169.
19.
Lesmes, G., Costill, D., Coyle, E., & Fink, W.
Muscle strength and power changes during maximal
isokinetic training. Medicine and Science in
Sports, 1978, lQ (4), 266-269.
20.
Moffroid, M. T., & Kusiak, E. T. The power struggle.
Definition and evaluation of power of muscular
performance. Physical Therapy, 1975, 22,
1098-1104.
21.
Moffroid, M. T., Whipple, R., Hofkosh, J., Lowman,
E., & Thistle, H. A study of isokinetic exercise. Physical Therapy, 1969, ~' 735-746.
66
22.
Moffroid, M. T., & Whipple, R. Specificity of
speed of exercise. Physical Therapy, 1970,
2Q, 1692-1700.
23.
Moffroid, M. T., Whipple, R., Hofkosh, J.,
Lowman, E., & Thistle, H. Guidelines for
clinical use of isokinetic exercise.
Rehabilitation Monograph XL, 1969, iQ, 1-27.
24.
Osternig, L. R. Optimal isokinetic loads and
velocities producing muscular power in human
subjects. Archives of Physical Medicine and
Rehabilitation, April 1975, 56, 152-155.
25.
Parker, M. G. Ruhling, R. 0., Bolen, T., Edwards,
S. W., &.Edge, R. Aerobic training effects on
force-velocity and instantaneous power relationships of human quadriceps femoris muscle. Paper
presented at the 1980 American College of Sports
Medicine Annual Meeting, Las Vegas, Nevada,
May 1980.
26.
Perrine, J. J.
Isokinetic exercise and the
mechanical energy potentials of muscle. Journal
of Health, Physical Education, Recreation, and
Dance, May 1968, 40-44.
27.
Perrine, J. J.
Isokinetic potentials in spasticity
treatment.
Unpublished monograph, Cybex, Division of Lumex, Inc., 100 Spence Street, Bay
Shore, New York, 11706.
28.
Perrine, J. J. When strength depends on power.
The IV International Seminar on Biomechanics,
Pennsylvania State University, August 26-31,
1973.
29.
Perrine, J. J. & Edgerton, v. R. Muscle forcevelocity and power-velocity relationships under
isokinetic loading. Medicine and Science in
Sports, 1978, lQ (3), 159-166.
30.
Pipes, T. V. Strength-training modes: what's the
difference? Scholastic Coach, 1977, ~' 120-124.
31.
Pipes, T. v. & Wilmore, J. H.
Isokinetic vs.
isotonic strength training in adult men.
Medicine and Science in Sports, 1975,
(4),
262-274.
z,
67
32.
Reye, c. Changing patterns in the treatment of
cerebral palsy. Medical Journal of Australia,
1971, 1, 1187-1188.
33.
Robson, P. Cerebral palsy and physical fitness.
Developmental Medicine and Child Neurology,
1972, li, 811-813.
34.
Rosentswieg, J., Hinson, M., & Ridgeway, M. An
electromyographic comparison of an isokinetic
bench press performed at three speeds. Research
Quarterly, 1975, ~' 470-475.
35.
Scherzer, A. L., Mike, V., & Ilson, J. Physical
therapy as a determinant of change in the
cerebral palsied infant. Pediatrics, 1976,
~ (1), 47-51.
36.
Spearing, D. L., & Poppen, R. The use of feedback
in the reduction of foot dragging in a cerebral
palsy client . . Journal of Nervous and Mental
Disease, 1974, 159 (8), 148-150.
37.
Sutherland, D. H.
Internal rotation gait. Journal
of Bone and Joint Surgery, 1969, 51-A (6),
1075-1082.
38.
Thistle, H., Hislop, H., Moffroid, M., & Lowman, E.
Isokinetic contraction: a new concept of resistive exercise. Archives of Physical Medicine and
Rehabilitation, June 1967, 279-282.
39.
Thorstensson, A., Grimby, G., Karlsson, J. Forcevelocity relations and fiber composition in human
knee extensor muscles. Journal of Applied
Physiology, 1976, iQ (1), 12-15.
40.
Thorstensson, A., Larsson, L., Tesch, P., &
Karlsson, J. Muscle strength and fiber composition in athletes and sedentary men. Medicine
and Science in Sports, 1977, ~ (1), 26-30.
41.
Tucker, J. Genu recurvatum in the hemiplegic
patient. Newsletter . . . Devoted to Isokinetics,
June 1971, Cybex, Division of Lumex, Inc.,
100 Spence Street, Bay Shore, New York, 11706.
68
42.
Van Oteghen, S. L. Two speeds of isokinetic exercise
as related to the vertical jump performance of
women. Research Quarterly, 1975, ~ (1), 78-84.
43.
Winter, D. A., Quanbury, A. 0., Hobson, D. A.,
Sidwall, H. G., Reimer, G. Trenholm, B. G.,
Steinke, T., & Shlosser, H. Kinematics of
normal locomotion--a statistical study based
on T.V. data. Journal of Biomechanics, 1974,
]_ 1
44.
4 7 9- 4 8 6 o
Wright, T., & Nicholson, J. Physiotherapy for the
spastic child: an evaluation. Developmental
Medicine and Child Neurology, 1973, 15 (2),
146-163.
BIBLIOGRAPHY
Basmajian, J. V. Neuromuscular control of voluntary
movement.
In A. A. Buerger, J. S. Tobis (Eds.),
Neurophysiologic aspects of rehabilitation medicine.
Springfield, Ill.: Thomas, 1976.
Bishop, B. Spasticity: its physiology and management.
Part I. Neurophysiology of spasticity: classical
concepts. Physical Therapy, 1977, 57 (4), 371-376.
Spasticity: its physiology and management.
Part II. Neurophysiology of spasticity: current
concepts. Physical Therapy, 1977, 57 (4), 3.77-384.
Spasticity: its physiology and management.
Part III.
Identifying and assessing the mechanisms
underlying spasticity. Physical Therapy, 1977, 57,
(4) 1 385-395.
Spasticity: its physiology and management.
Part IV. Current and projected treatment procedures
for spasticity. Physical Therapy, 1977, 57 (4),
396-401.
Brandell, B. R. Functional roles of the calf and
vastus muscles in locomotion. American Journal of
Physical Medicine, 1977, ~ (2), 59-73.
Capen, E. K. The effect of systematic weight training
on power, strength, and endurance. Research
Quarterly, 1950, 21I, 83-93.
Chui, E. The effect of systematic weight training on
athletic power. Research Quarterly, 1950, 21,
188-194.
DeLorme, T., Ferris, B., & Gallagher, J. Effect of
progressive resistive exercise on muscle contraction
time. Archives of Physical Medicine, February 1952,
33, 86-92.
Dintman, G. B. The effect of various training programs
on running speed. Research Quarterly, 1964, l2•
456-463.
69
70
Elliot, J. Assessing muscle strength isokinetically.
Journal of the American Medical Association, 1978,
240 (22)' 2408; 2410.
Grimby, G., & Hook, o. Physical training of different
patient groups. Scandinavian Journal of Rehabilitative Medicine, 1971, l (1), 15-25.
Hellebrandt, F. A. Application of the overload
principle to muscle training in man.
International
Review of Physical Medicine and Rehabilitation,
October 1958, 278-282.
Hinson, M., & Rosentswieg, J. Comparative electromyographic values of isometric isotonic, and
isokinetic contractions. Research Quarterly,
1973, !! (1)' 71-79.
Hinson, M., Smith, W. c., & Funk, s.
Isokinetics:
a clarification. Research Quarterly, 50 (1),
30-35.
Hislop, H. Quantitative changes in human muscular
strength. Journal of the American Physical Therapy
Association, 1963, !lr 21-38.
Katch, F. I., McArdle, W. D., Pechar, G. S., &
Perrine, J. J. Measuring leg force-output capacity
with an isokinetic dynamometer-bicycle ergometer.
Research Quarterly, i2 (1), 86-91.
Laird, c. E., & Rozier, C. K. Toward understanding
the terminology of exercise mechanics. Physical
Therapy, March 1979, 287-292.
Murray, P., Baldwin, J., Gardner, G., Sepic, S., &
Downs, W. Maximum isometric knee flexor and
extensor muscle contractions--normal patterns of
torque vs. time. Physical Therapy, June 1977,
637-643.
Osternig, L. R., Bates, B. T., & James, S. L.
Isokinetic and isometric torque force relationships. Archives of Physical Medicine and
Rehabilitation, June 1977, ~, 254-256.
Patton, R., Hinson, M., Arnold, B., & Lessard, B.
Fatigue curves of isokinetic contractions. Archives
of Physical Medicine and Rehabilitation, June 1977,
~1 254-256.
71
Rosentswieg, J., & Hinson, M. Comparison of isometric
isotonic, and isokinetic exercises by electromyography. Archives of Physical Medicine and
Rehabilitation, 1972, ~' 249-252.
Smith, L., & Whitley, J.
Influence of strengthening
exercises on speed of limb movement. Archives of
Physical Medicine, 1965, 446, 772-777.
Smith, L.
Influence of strength training on pre-tensed
and free arm speed. Research Quarterly, 1964, ~,
554-561.
Thorstensson, A. Observations on strength training
and detraining. Acta Physiologica Scandinavica,
1977, 100, 491-493.
Wilkie, D. R. The relation between force and velocity
in human muscle. Journal of Physiology, 1950, 110,
249-280.
72
Appendix A
SUBJECTS' PROFILE
EXPERIMENTAL GROUP
Subject
Age
Sex
Diagnosis
1
. .
F
.
28
. .
.
2
. . .
M
. . .
21
. . .
3
. . . .
M
. . .
21
. . .
4
. . . .
M
. .
.
21
. . .
5
. . . .
M
. . .
24
. . .
6
. . . .
M
. . .
16
. . .
Cerebral Palsy
Spastic Quadriplegia
Cerebral Palsy
Spastic Paraplegia
Multiple Congenital
Anomalies
Cerebral Palsy
Spastic Quadriplegia
Cerebral Palsy Acquired
Spastic Double Hemiplegia
Cerebal Palsy
Spastic Hemiplegia
Cerebral Palsy
Spastic Paraplegia
73
Appendix B
SUBJECTS' PROFILE
CONTROL GROUP
Subject
1 .
Sex
.
Age
M.
Diagnosis
14 .
. .
Cerebral Palsy
Spastic Paraplegia
2
. . . .
F
. . .
32
. . .
3
. . . .
M
. . .
16
. . .
4
. . . .
F
. . .
26
. . .
5
. . . .
M
. . .
25
. . .
Cerebral Palsy
Spastic Paraplegia
6
. . . .
M
.
..
16
. . .
Cerebral Palsy
Spastic Quadriplegia
Cerebral Palsy
Spastic Hemiplegia
Cerebral Palsy
Spastic Quadriplegia
Cerebral Palsy
Spastic Hemiplegia
74
Appendix C
CONSENT FOR PARTICIPATION
I,
, agree to participate in
the Master's study conducted by Peggy Lasko in the
Adapted Physical Education Lab under the supervision
of Dr. Sam Britten. This agreement pertains to the
following days and times:
Dates:
----------
Times:
----------
I have received and read a copy of the proposal.
I
understand the procedures, purpose, and possible
benefits.
I understand that I may withdraw from the
project at any time without jeopardy.
To my knowledge, I am physically able to participate
in the project, and I agree to hold Peggy Lasko and
California State University, Northridge harmless for
any illness or injury which I may incur as a result
of participation.
Subject's Signature
Date
If you have any questions, please feel free to call
me at 885-2182 or 993-6362.
You will receive a copy of the results.
Thank you,
Peggy Lasko
75
Appendix D
CONSENT FOR PARTICIPATION OF MINORS
IF SUBJECT IS UNDER 18 YEARS OF AGE:
has my permission to partie(Child's name)
ipate in the Master's study conducted by Peggy Lasko in
the Adapted Physical Education Lab under the supervision
of Dr. Sam Britten. This agreement pertains to the
following days and times:
Dates:·
Time: ----------
----------
I have received and read a copy of the proposal.
I
understand the purpose, procedures, and possible benefits.
I understand that I may withdraw my child at any
time without jeopardy. I understand that this project
is in no way connected to Miller High School or the Los
Angeles Unified School District. To my knowledge, my
child is physically able to participate in the project,
and I agree to hold Peggy Lasko and California State
University, Northridge harmless for any illness or
injury which my child may incur as a result of his/her
participation.
Parent or Guardian Signature
Date
You are welcome to observe any of the testing and training sessions.
If you have any questions, please feel
free to call me at 885-2182. You will receive a copy of
all results. Thank you.
Peggy Lasko
76
Appendix E
TORQUE AT PEAK INSTANTANEOUS POWER
(newton-meters)
RAW SCORES
EXPERIMENTAL GROUP
Subject
Pretest Torque
Post Test Torque
1
24
33
2
49
65
3
18
26
4
14
20
5
34
64
6
77
95
77
Appendix F
TORQUE AT PEAK INSTANTANEOUS Pm-vER
(newton-meters)
RAW SCORES
CONTROL GROUP
Subject
Pretest Torque
Post Test Torque
1
22
20
2
57
57
3
11
8
4
18
19
5
24
26
6
27
26