ISOKINETIC DYNAMOMETRY 03

8/4/2019 ISOKINETIC DYNAMOMETRY 03

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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

ISOKINETIC DYNAMOMETRY 03

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