The document discusses isokinetic exercise, describing its mechanics, benefits, and guidelines for use in rehabilitation and testing. It highlights contraindications, ways to quantify muscle performance through parameters like peak torque, and the significance of force-velocity relationships in assessing muscle strength. Additionally, it outlines warm-up, test protocols, and data interpretation for improving training effectiveness and injury assessment.

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2.  It is defined as a term in which the body
segments are accelerated to achieve a
preselected fixed speed against an
accommodating resistance.
 Maximum possible effect is put by patient,
the machine will put equal effort or force to
maintain the same speed.
 The concept was developed by JAMES
PERRINE in late 1960
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3.  Fixed speed and totally accommodating
resistance.
 Reduced chance of overuse injury because
resistance is equal to patients resistance.
 Accommodation to pain & fatigue.
 Full range of speed for testing & exercising
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4.  Decreased compressive force at faster
speed and have more shear force
 Physiological overflow of strength.
 Visual elimination of ballistic movement, i.e.
no jerky movement with isokinetic machine.
 Accurate quantification of result.
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5.  Absolute contraindication
› Non united fractures to limb
› Epilepsy
› Cardiac insufficiency (unless monitored)
› Severe peripheral vascular disease
› Aneurysms
› Anticoagulants
› Recent (< 3 months prev) X-ray/chemo therapy
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6. › Long term steroid use (> 3 months)
› Acute (< 7 days) muscle/ligament tear (>grade I)
› Pregnancy
› Any neurological condition (e.g. stroke,
Parkinson's disease) unless closely monitored
› Skin problems under load cell
› Severe osteoporosis
› Malignancy (in area to be tested)
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7.  Relative contraindication
› Pain
› Limited range of motion (severe)
› Soft tissue healing
› Bone healing
› Effusions
› Osteoporosis
› Anaemia
› Rheumatoid arthritis
› Recent surgery (discretion must be used)
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8.  Muscle strength, power and endurance
development
 Screening for functional deficit
 Effectively quantify such parameter like force
strength etc at 1st day to find prognosis.
 Systemic scientific approach to rehab
treatment.
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10.  The force applied about an axis of rotation
› Torque(ft-lbs)=force × distance
› Torque will usually decrease when angular
velocity is increases.
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11.  Maximum value of a torque, indicates
maximum muscle tension capability.
 the peak torque is the highest point on the
curve.
 This is considered to be the gold standard in
isokinetic measurement (Kannus 1994).
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12.  Torque is normalized according to body
weight ratio, at per kg body weight how
much torque is produced, no matter how
much body wt one have.
 Valuable tool for inter individual comparison.
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13.  It is the ratio between agonist & antagonist
torque.
 E.g. in all injury determine that when patient
have 30% of quad hams ratio can go for
walk, and 60% can go for jogging.
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14.  The average of the peak torque values of the
first three repetition of an endurance test.
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15.  The average of the peak torque value for the
last three repetition in the endurance test
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16.  The percentage of peak torque decline
during the endurance test.
 The amount of work performed over a set
number of repetitions is recorded. These
tests have been said to be absolute
endurance measures which should be used
in research settings (Kannus 1994).
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17.  W(ork) = torque x angular displacement
 Total work (TW) = Area under torque curve x
angular displacement (according to Hislop
and Perrine 1967)
 Peak power (PP) = work done during the
best repetition (often called best work
repetition BWR)
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18.  W(ork done) / T(ime taken) = P(ower)
 Usually measured in Watts
 Power relates to the average time rate of work.
Power does not decline with increasing velocity as
peak torque does during concentric contractions
instead it increases (Osternig 1986). The use of this
measurements is limited mainly because the results
can be obtained from the peak torque to time
figures. These measurements can highlight
differences between elite performers when peak
torque figures appear fruitless (Kannus 1994)
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19.  Used to determine a specific angle torque
relationship which may be of interest (for
instance when looking at agonist/antagonist
con/ecc ratios).
 It has been shown (Kannus and Kaplan
1991) to be most reliable in middle joint
ranges with decreasing reliability at the
extremes of motion.
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20.  As the name suggests (but often called angle of
occurrence) this is when peak torque reaches it’s
maximum level.
 It can be useful as an indicator of maximum torque
production if plotted against various velocities
(Osternig 1986).
 Weaker muscles (probably due to neuromuscular
facilitation) show peak torque later in range (as has
been demonstrated by Kannus and Jarvien (1990).
 The reliability of this measure is often very low
(Kannus 1994) and is made worse by repeated tests
(due to alignment problems, Chan and Maffulli 1996)
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22.  Warm up: An initial warm up, including stretching and
gentle cardiovascular work, should be performed for 15
minutes prior to the use of the isokinetic machine. The
only exception to this is in the case of research which
specifically targets sports which would not normally
involve a warm up period.
 Familiarization: Isokinetic exercise is not easy to
become familiar with. So it is vital that a detailed
description of what will be required of the subject is
given, this should be followed by a period of ‘test’ sub-
maximal contractions (assistance by the machine using
passive or active assisted modes is acceptable).
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23.  Familiarization cont..: If eccentric motions are to be used
then the subject should be comfortable with the motion
before testing and they should be warned to expect some
delayed onset of muscle soreness (DOMS) although my
subjects/patients rarely complain of this. For research
purposes familiarization should occur on a separate day to
testing.
 Type of Contraction :
› Reciprocal (con/con and ecc/ecc) or absolute (con/ecc).
› Reciprocal - good for patients (con/con)
› High correlation of power and work findings makes it good for
research.
› Absolute - good for average strength
› The effects of isometric pre-activation (plyometrics) will not
necessarily adversely affect results (Dvir 1995) and may be of
interest to researchers examining high level performers.
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24.  Test Velocities :
› Lower velocities show lower variation
› Higher velocities (above 180 degrees/second) show
higher variation.
› Starting low and working up gives better correlation.
› Starting high and working down is easier for
patients.
› Random velocities for research.
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25.  Warm up repetitions: Specific for type of activity.
› 4-10 generally
 Number of Repetitions: Specific for type of activity.
› 5-40 maximal reps lower for strength/power higher for endurance
› 1-18 sets lower for testing higher for training
 Number of Sets: Specific for type of activity.
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26.  Rest: Rest between individual repetitions
 A 20 second rest between each repetition has been shown to allow
increases which do not appear to plateau until fatigue (Dvir 1995). A 1
second pause between con/ecc contractions reduces the effects of the
isometric pre-activation (particularly at high speeds) but this may be of
interest to researchers
 Rest between individual sets - 30 - 60 seconds for peak torque and
over 1 minute for endurance
 Between speeds-1 minute
 Between sides - 3 - 5 minutes should be waited before testing the
contra lateral side
 Between joints-Chan and Maffulli (1996) recommend at least one days
rest before testing another joint in the same limb e.g. ankle and knee
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27.  Warm down : A 15 minute warm down should be undertaken
immediately following isokinetic exercise. This should include both
stretches and gentle cardiovascular work.
 Repeated Measures :
› Differences between sessions : Johnson and Siegel (1978)
examined the reproducibility of uni-directional movement in
40 normal women. They concluded that over 6 days each of
the subjects got better results. Chan and Maffulli (1996)
recommend an initial test followed by a subsequent test 2
days later with the second test used as the criterion for
improvement monitoring
› Differences between repetitions : Correlation of repeated
repetitions can be used to determine intra-subject motivation
e.g. compliance test for (often used for insurance
assesments)
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28. Strength Endurance Pathology
Training Assessmen
t
Research Training Assessmen
t
Researc
h
Training Assessment Research
Warm up reps
> 3 3 3 >3 3 3 >3 3 3
No of reps 8-14 2-6 5 max. >25 25-40
25
max.
10-15 10 5 max.
No of sets 6-18 3 1 Cont. 1 1 6-18 3 3
Rest
Between reps
Between sets
Between tests
0
2 min
3-4 days
0
2 min
6 days
1 sec
30-60 sec
1 hour
0
N/A
> 1 day
0
N/A
3-4 days
0
> 60 sec
1 hour
0
15-30 sec
30-60 sec
0
15 sec
>3 days
0
15 sec
6 Days
Contraction type
Con/con
Con/ecc
Con/con
Con/ecc
Con/con
Ecc/ecc
Con/con Con/con
Con/Con
Con/ecc
Con/con
con/ecc
Con/con
Con/ecc
Con/con
Con/ecc
Speed/velocity
Starting speed
Progress speeds
Low
Med/high
High
Low
Random
Medium/
low
Medium/ low
Medium/
low
High
Low
High
Low
High
Low
Pre-activation High Low Minimal Medium Medium Minimal Medium Medium Medium
Stabilisation Maximal Maximal Maximal Not req. Not req. Medium Minimal Minimal Minimal
Range of
motion
Specific Full Specific Full Full Full Specific Specific Specific
Gravity
correction
None Consistent Vital None Consistent Vital None Consistent Vital
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29. Strength Endurance Pathology
Training Assessment Researc
h
Training Assessm
ent
Researc
h
Training Assessme
nt
Research
Feedback
Visual
Verbal
Vital
Useful
Useful
Useful
None
None
Vital
Vital
Useful
Useful
None
None
Vital
Useful
None
None
None
None
Encouragement
Visual
Verbal
Vital
Useful
Useful
Consistent
None
None
Vital
Vital
Useful
Consist
ent
None
None
Vital
Useful
None
None
None
None
Results
required
PT
PTBW
PT
PTBW
TPT
PTAE
Raw
Data
PT
PTBW
TPT
PTAE
AO
W
P
Ft index
W
P
Ft index
AO
Raw
Data
W
P
Ft index
AO
TPT
PT
W
PTBW
PT
W
PTBW
MAP
Curve
Raw
Data
PT
W
PTBW
MAP
curve
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con = concentric ecc = eccentric PTAE = peak torque acceleration energy TPT = Time
to peak torque P = Power MAP = Moment angle position PT = peak torque P = Power
W = Work AO = Angle of occurrence PTBW = peak torque to body weight Ft = Fatigue

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31.  In the case of testing only one side then the
opposite side should be used as a reference
(this is not the case in athletes who use one
side preferentially over the other e.g. Javelin).
 Imbalance of strength of up to 10%
can be considered normal.
 Imbalance between 10 and 20% is
possibly abnormal (with Injury this is
considered probably abnormal).

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32.  Imbalance of 20% or greater is probably
abnormal (in injury this is definitely abnormal).
 As a criterion measure for return to activity
following injury the following is considered
true.
 A maximum of 20% deficit for any
individual muscle
 A maximum of 10% deficit for any
involved limb (i.e. closed chain testing).
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33.  No figures exist that are validated for light
activities, but a decrease of 30% for one muscle
and 20% for one limb are considered acceptable
(bear this in mind when returning patients to
driving you could be asked why you did!).
 Imbalance of muscle ratios can be used e.g.
shoulder internal rotators against external
rotators. Try to use the ratios in a meaningful
way i.e. the concentric activity of the agonist to
the eccentric activity of the antagonist.
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34.  In the presence of pathology it is advisable to
compare the MAP curve to that of the
unaffected side. Care should be taken when
using this practice as MAP curve shape is
very variable. The separate sections relate
specifically to various pathologies and are
described best in Chan and Maffulli (1996).
 If both limbs are affected or the subject would
just like to know how strong they are then
comparison to normal values is acceptable
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35.  Peak Torque : This is considered to be the gold
standard in isokinetic measurement (Kannus
1994). When using peak torque to asses a subject
it is appropriate to compare the left side to the right
side and look for discrepancies of aver 5% Sapega
(1990).
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36.  If comparing concentric to eccentric figures (at
medium joint speeds) in the same muscle (e.g.
Concentric biceps to eccentric biceps) then the
eccentric figures should be 30% higher than the
concentric figures (Brown 2000), however, this varies
from joint to joint and can be as low as 20% or as
high as 147% (Brown 2000), and is obviously related
to speed (explained below in the force velocity
relationship). Individual ratios can be seen in the
normal values section. Generally low eccentric figures
indicate pathology (Dvir 1995) whilst high eccentric
figures can indicate connective tissue disorders (Dvir
1995)
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37.  Peak Torque : Figures may also be
analysed across joints (e.g. Concentric
quads to eccentric hamstrings could be
important in anterior cruciate ligament
deficient subjects as the eccentric
hamstrings could in theory resist anterior
tibial translation during the concentric pull of
the quads) in this situation the closer the
eccentric figure to the concentric figure the
better (as eccentric muscle action is required
to stop a joint motion at the end of range)
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38.  this comparison is very important in unstable joints
like the shoulder (but be aware that the figures can
sometimes be misleading as the angle of peak
torque will often be different, to accommodate for
this the same angles should be used e.g.
Torque@angle).
 Peak torque can be used to asses the differences
in strength between individuals e.g. A 150kg person
should be able to produce a higher peak torque
than a 80kg person.
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39.  The force velocity relationship: Peak
concentric force will decrease with increasing
speeds (as long as you start slow and work up
in speed), whilst, peak eccentric force will rise
initially with increasing speed then plateau and
eventually decrease. Using this knowledge it is
possible to work out how strong a subject is
related to speed and plot this on a graph
(known as a force velocity curve).
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40.  Force velocity curves are used mainly to
determine whether an athlete is able to maintain
their strength with increasing speed. With this
information it is possible to determine whether
they need to develop their speed of movement
or their strength.
 More recently peak torque has been used in 3D
muscle mapping along with angle of occurrence
and velocity. It has also been used as part of
‘isomap’ in the Biodex system
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41.  Peak torque to weight ratio : To compare
results between individuals peak moment is
calculated compared to body weight (either
kilos or pounds). Lower limb strength is
dependent on body weight and can be
expressed in this way. Upper body strength is
less dependent and is not usually described this
way.
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42.  Contractional Work : A measure of the
energy expended by the muscle/s under test
and considered by some authorities to reflect
endurance. However, difficulties in assessing
the importance of strength (or lack of) and
endurance during the interpretation of these
results makes their use questionable for
research purposes but good for rehabilitation
the higher the work the more the subject has
done during each repetition.
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43. Power : Power relates to the average
time rate of work. Power does not decline
with increasing velocity as peak torque
does during concentric contractions
instead it increases (Osternig 1986). The
use of this measurements is limited
mainly because the results can be
obtained from the peak torque to time
figures.
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44.  These measurements can highlight
differences between elite performers
when peak torque figures appear fruitless
(Kannus 1994). Power measurements are
becoming increasingly popular in the
research community to look at
performance in activities/sports that are
not limited fundamentally be strength.
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45.  Acceleration Time : The time it took the
machine to accelerate to the preset angular
velocity. This will increase with softer stops and
higher speeds. If you have tested at high speed
the acceleration time required to perform the
movement may mean the angle of peak torque
is missed (as the figures obtained during the
acceleration time are not included as this portion
of the movement is considered to be isotonic
and is usually damped)
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46.  so it is important to ensure the range of
motion is large enough to accommodate for
this. If tests are performed at many different
speeds then the angle of peak torque should
remain in the same place if the range of
motion is sufficient, if not the peak torque
figures may be worthless.
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47.  Angle specific torque : Used to
determine a specific angle torque relationship
which may be of interest (for instance when
looking at agonist/antagonist con/ecc ratios). It
has been shown (Kannus and Kaplan 1991) to be
most reliable in middle joint ranges with
decreasing reliability at the extremes of motion.
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48.  Angle of peak torque : As the name suggests (but
often called angle of occurrence) this is when
peak torque reaches it’s maximum level. It can be
useful as an indicator of maximum torque
production if plotted against various velocities
(Osternig 1986). Weaker muscles (probably due to
neuromuscular facilitation) show peak torque later
in range (for individual ranges see individual
joints) as has been demonstrated by Kannus and
Jarvien (1990). The reliability of this measure is
often very low (Kannus 1994) and is made worse
by repeated tests (due to alignment problems,
Chan and Maffulli 1996)
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49. Time to peak torque : Evaluates the
ability to produce force rapidly and can be used
to determine explosive power. A prolonged time
to peak torque can indicate reduced recruitment
of type II fibres (Kannus 1994). This has been
superseded by peak torque acceleration energy.
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50.  Peak torque acceleration energy : Amount of work
performed in the first 125 ms of a torque production
cycle. This is supposed to reflect explosive power as
it assesses the speed and rate of torque production.
As an accurate measure it is very variable at slow
speeds (Kannus 1994) and can be greatly affected
by exercise cycles i.e. if there is no pause between
con/ecc cycle then the results are usually useless.
Ecc/ecc and con/con exercises produce best results,
however, even these have been questioned as they
may not (according to Perrin et al 1989) have a basis
in Newtonian physics.
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51.  Contractional Impulse : Used in literature to
describe the difference in performance where the peak
torque reveals no differences.
 Coefficient of Variance : This describes the
consistency of the results obtained. At the moment this type
of testing has gained a lot of support. It is used in a lot of
back testing systems but it has NEVER been tested in
court. If the results are low then the repetitions are closely
matched to each other (in other worlds a COV of 0 would
mean each rep was the same). High results could suggest
the subject needs more practice. High results are often
used to diagnose psycho/musculskeletal problems. A High
figure is expected during an endurance test.
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52. Declined Work : The most widely used
endurance measure. The amount of work
performed over a set number of repetitions is
recorded. These tests have been said to be
absolute endurance measures which should be
used in research settings (Kannus 1994). The
trouble starts when subjects can not reach the
set number of repetitions required.
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53.  Endurance Ratio : The peak torque of the first X
number of repetitions (usually 5) divided by the peak
torque of the last X number of repetitions (usually 5)
multiplied by 100 to give a percentage.
 In reality the line of least squares fit is used for the
first 5 reps. This is divided by the line of least squares
fit for the last 5 reps X by 100.
 Any figure under 100 means the subject fatigued (the
lower the figure the more the fatigue e.g. a fatigue
ratio of 65% means the subject tired by 35% during
the test).
 A figure over 100 means the test went wrong!
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