isokinetic dynamometry 03
TRANSCRIPT
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ISOKINETIC DYNAMOMETRY
NOR SHAFIQAH BT MOHD
SHARKAWI
(2009345967)
RABIATUL ADAWIYAHAKASYAH
(2009121853)
NATALIA ASIAH BT ZAMERI
(2008402984) RINI BT ALIK
( 2008402964)
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Introduction
- Originally described by Hislop and Perrine (1967)
- Is a relatively recent tool used in rahabilitation
- It capable of providing objective and quantifiable
strength data in :
1) static (isometric)
2) dynamic muscle contraction
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Principle of isokinetic system
Consist of fixed axis with a rotating lever armattached to a moveable head.
The lever arm is driven either hydraulically or
electricity & accomodates the movt generated by thepatient contracting muscle in such a way that thedistal limb segment moves through the joint range ata constant angular velocity.
However, this does not take place until the patientslimb exceeds the preset angular velocity which hasbeen programmed into the machine by thephysiotherapist.
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Modes of operation
1)Passive mode
velocity remains constant
no voluntary force is required by the patient to
initiate movement
Useful mode to : - familiarize the pt with the
machine
- begin motor relearning
exp: anterior cruciate lig repair
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2) Isometric mode (static exs)
Muscle contract without shortening or lengthening.
Allow physio to programme a series of isometric holdangles throughout the patients available ROM
Exp : weak at 90 of knee flexion
- physio train the quadriceps at thesespecific angle by presenting these as
hold angle before starting the exercise.
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- Machine passively move patient limb to 90 on kn
flexion & instruct patient (via screen prompt) to
contract the quadriceps for a predertermined time
- Machine then instruct the patient to relax
- Limb is allowed to reposition or is moved to the next
hold angle in inner range and the process repeated
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3)Isokinetic mode
Involve training muscle strength under condition of
constant angular velocity.
To fix the speed of movt of the exercising muscle
throughout its exercising ROM.
The external load applied to the moving segmentremains consistent with the maximum capacity of
the muscle throughout the range of either concentric
or eccentric contractionj
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4) Isotonic mode
Exercise velocity is controlled by the patientand the muscle tension varies throughout the
available ROM
Maximum effect of the resistance will beconfined to the weakness point in range.
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Programme facilities of the
dynamometer
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Dynamometers allow the physiotherapist to
select several other parameters such as the
velocity at which the exercise should takeplace, the range of movement in which it
should be performed, the number of
repetitions required, and the moment/forcethreshold values and damp setting.
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VELOCITY
The exercise velocity is measured in degrees per second.Current dynamometer velocities range from 1 to 500persecond.
Angular velocities on current machines are classified into
three categories: slow (1 to 60 per second).
Intermediate (60 to 240 persecond)
Fast (over 240 persecond)
The most usual usual clinical testing and training velocitiesrange between 30 and 240 per second.
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RANGE OF MOTION
The exercising range of movement can be
controlled by programming the desired start
and stop angles into the dynamometer
computer.
Mechanical stops positioned slightly beyond
these programmed values are also an
additional safety features on some machines.
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EXERCISE REPETITION
The number of repetition can easily be programmed
to suit individual requirements. For example, it is
possible to design an exercise programmed which
consists of five isometric holds, each performed at adifferent joint angle, followed by a full-range is
kinetic contraction repeated concentrically and then
eccentrically three times: the whole sequence then
being repeated after a short rest.
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MOMENT/FORCE THRESHOLD VALUES.
All dynamometers have torque limits. Example
the maximum amount of resistance that they
can provide.
If exceeded, an error message and/or alarm is
activated.
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SOURCES OF ERROR IN ISOKINETIC
DYNAMOMETRY
Three main sources of error which lead to inaccurate
information are reported within the literature and
summarized as:
Failure to take into account the effect of gravity which mayassist or resist limb motion.
Torque overshoot.
Malailgnment of the biological and mechanical axes, and
failure to stabilise the patient on the dynamometer toensure localisation of the movement to the joint under-
going or treatment
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Advantages and Disadvantages
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Advantages Testing procedures
accurate test data methods-vital complement to more traditional
methods of physical exam, electromyography, andradiographic procedures in ass of pt with
neuromusculaskeletal disorders. Treatments effectiveness
produce significance gains in strength, power,endurance
positive carry over into increased concentric andeccentric functional muscle performance.
(Chan, Maffulli & Korkia, 1996)
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Cont
Properly used- effective means of improving musclestrength
Can performed variety of contractions speeds thatapproach velocity of jt movement occurred during ADL
Accommodation to length tension curve and maximumforce output at each point in ROM
Used to measure force production of various musclegroups and compare the force of production of injuredwith noninjured extremities or agonist with antagonist
(Baratz, Watson & Imbriglia, 1999)
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Disadvantages Does not afford diagnostic precision obtained through other
methods of exam (MRI, endoscopy) It is clinically based, not easily usable in pts environment of
function, such as football field/basketball court
Lack of definitive knowledge on how to apply isokinetic
science to clinical context(Chan, Maffulli & Korkia, 1996)
Increased joint compression
Movement does not approach velocity of motion occurs
during sports activities
Increased shear forces at low contraction velocity-harmful
following surgical procedures designed to provide joint
stability(Baratz, Watson & Imbriglia, 1999)
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Cont
Initially time consuming to learn how to use
Expertise need to be developed
Isokinetic movt is artificial constraint. Normalfunctional movt does not occur at fixed velo
Expensive Malalignment of axes of rotation of joints and
dynamometer will not provide a true reflection ofmuscle performance. Alignments can be difficult when
complex joints involved. Eccentric testing predisposes to the phenomenon of
DOMS(Jones & Barke, 1996)
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ISOKINETIC EVALUATION
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Isokinetic evaluation is an objective method that
allows for rapid and reliable comparison of the
relationship between the agonist/antagonist musclegroups musculature during dynamic exercise.
By using this evaluation we can measure and
determine muscular performance.
(Linde, Farrs, Oliete, Til & Turmo, 2010)
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PARAMETERS TO BE EVALUATED
For example in knee rehabilitation:
1) Type of load
2) Type of exercise
3) Range of motion applied
4) Maximal or submaximal effort
5) Angular speed of the exercise for agonistic and antagonistic
muscles
6) Number of repetitions and sets
7) Duration of pauses
8) Number of sessions per week9) Duration of the treatment
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ISOKINETIC LOWER LIMB EVALUATION
The evaluation methodology (Jones, 1996):
1. Assess the patient by both subjective and objective examination
2. Familiarize the patient with the isokinetic dynamometer.
3. Explain the test aims.
4. Ensure that the patient warms up without the dynamometer,eg:stretches, cycle ergometer
5. Position and stabilize the patient accurately on the dynamometer.
6. Test the contralateral limb first.
7. Align the joint and dynamometer axes of rotation as closely as possible.
8. Use gravity correction if testing in a gravity-dependent position.
9. Select the test type (concentric/eccentric for knee extensor)
10. Select the test velocity (eg: 30 degree per second)
(Tidswell, 1998)
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11. Warm up on the dynamometer using the warm up mode.
12. Perform the maximal test at the chosen velocity (eg: perform three
concentric/eccentric repetitions with overlay facility, with a 30 second or 1
minute rest between repetitions).
13. Record test details to ensure replication on retest.
14. Retest at the same time of day as the original evaluation was
performed.
(Tidswell, 1998)
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USES OF ISOKINETIC DYNAMOMETER IN CLINICAL
SETTING
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One of the most important features of isokinetic exercise:
- able to perform muscular contractions at a constant angularspeed along the full range of motion
Thus, the resistance produced by the dynamometer isproportional to the force exercised by the muscle and thismeans that a maximal load can be placed on any point ofthe ROM.
This load is recorded by the isokinetic equipment anddisplayed either in graphic form or by a series of numericalparameters for a clinical evaluation.
In this way the isokinetic dynamometer:
- provide a wide range of information on the dynamic
muscular contraction, which would otherwise be difficult toobtain.
(Osternig, 1986)
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EXERCISE PROTOCOL IN THE CLINICAL SETTING
Isokinetic dynamometer research tool forquantifiying static, concentric, eccentric musclecontraction.
Standard rehabilitation programme are nowbecoming available for the treatment of specificconditions.
The most popular condition for which programmeshave been designed invovles rehabilitation afterinjury and repair of the anterior cruciate ligament.
(Pua, Bryant, Steele, Newton &Wrigley, 2008)
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REFERENCES
Linde,X., Farrs,O., Oliete,F., Til, F. & Turmo,A.(2010).
Isokinetic comparison of shoulder internal-external
rotations between waterpolo and volley players.
INTERNATIONAL CONGRESS ON SPORTS REHABILITATION
AND TRAUMATOLOGY. Page 177-178.
Pua,Y., Bryant,A.L., Steele,J.R., Newton,R.U. &Wrigley, T.V.
(2008). Isokinetic Dynamometry in Anterior Cruciate
Ligament Injury and Reconstruction.Annals Academy of
Medicine. Page 330-340.
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cont
Baratz, M., Watson, A. D., & Imbriglia, J. E.,(1999). Orthopaedic surgery: the essentials,Thieme Medical Publisher, New York
Jones, K., & Barke, K., (1996). Human movementexplained, Butterworth-Heinemann, ElsevierLimited, UK.
Chan, K. M., Maffulli, N., & Korkia, P., (1996)
Principles and practice of isokinetics in sportsmedicine and rehabilitation, Williams & WalkinsAsia Pacific Limited, Hong Kong