Isokinetic techniques - type of exercise

Isokinetic Exercise

1. Isokinetic Dr. Siddhartha Sen Dept. of Physiotherapy 30-Apr-24 6:28:49 PM

2. Definition 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 30-Apr-24 6:28:50 PM

3. Benefits of isokinetic exercises 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 30-Apr-24 6:28:50 PM

4. Cont… 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. 30-Apr-24 6:28:50 PM

5. Contraindications 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 30-Apr-24 6:28:50 PM

6. Cont… 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) 30-Apr-24 6:28:50 PM

7. Cont… Relative contraindication Pain Limited range of motion (severe) Soft tissue healing Bone healing Effusions Osteoporosis Anaemia Rheumatoid arthritis Recent surgery (discretion must be used) 30-Apr-24 6:28:50 PM

8. Application Muscle strength, power and endurance development Screening for functional deficit Effectively quantify such parameter like force strength etc at 1 st day to find prognosis. Systemic scientific approach to rehab treatment. 30-Apr-24 6:28:50 PM

9. Parameters of Isokinetic 30-Apr-24 6:28:50 PM

10. Torque The force applied about an axis of rotation Torque(ft-lbs)=force × distance Torque will usually decrease when angular velocity is increases. 30-Apr-24 6:28:50 PM

11. Peak torque 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) . 30-Apr-24 6:28:50 PM

12. Torque to body weight ratio 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. 30-Apr-24 6:28:50 PM

13. Agonist Antagonist Torque Ratio 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. 30-Apr-24 6:28:50 PM

14. Initial Peak Torque The average of the peak torque values of the first three repetition of an endurance test. 30-Apr-24 6:28:50 PM

15. Final Peak Torque The average of the peak torque value for the last three repetition in the endurance test 30-Apr-24 6:28:50 PM

16. Fatigue index 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). 30-Apr-24 6:28:50 PM

17. Work 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) 30-Apr-24 6:28:50 PM

18. Power 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) 30-Apr-24 6:28:50 PM

19. 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. 30-Apr-24 6:28:50 PM

20. 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 (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) 30-Apr-24 6:28:50 PM

21. Protocol 30-Apr-24 6:28:50 PM

22. Protocol for Isokinetic 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). 30-Apr-24 6:28:50 PM

23. Familiarization cont..: If eccentric motions are to be used then the subject should be comfortable with the motion before t esting 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. 30-Apr-24 6:28:50 PM

24. Protocol cont.. 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. 30-Apr-24 6:28:50 PM

25. Protocol cont.. 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. 30-Apr-24 6:28:50 PM

26. Protocol cont.. 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 30-Apr-24 6:28:50 PM

27. Protocol cont.. 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 ) 30-Apr-24 6:28:50 PM

28. Strength Endurance Pathology Training Assessment Research Training Assessment Research Training Assessment Research Warm up reps > 3 3 3 >3 3 3 >3 3 3 N o of reps 8-14 2-6 5 max. >25 25-40 25 max. 10-15 10 5 max. N o of sets 6-18 3 1 Cont. 1 1 6-18 3 3 Rest Between reps Between sets Between tests 2 min 3-4 days   2 min 6 days   1 sec 30-60 sec 1 hour   N/A > 1 day   N/A 3-4 days   > 60 sec 1 hour   15-30 sec 30-60 sec   15 sec >3 days   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 30-Apr-24 6:28:50 PM

29. Strength Endurance Pathology Training Assessment Research Training Assessment Research Training Assessment 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 Consistent   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 30-Apr-24 6:28:50 PM 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

30. Interpretation 30-Apr-24 6:28:50 PM

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).            30-Apr-24 6:28:50 PM

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). 30-Apr-24 6:28:50 PM

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. 30-Apr-24 6:28:50 PM

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 30-Apr-24 6:28:50 PM

35. Individual Variables 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). 30-Apr-24 6:28:50 PM

36. Individual Variables 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) 30-Apr-24 6:28:50 PM

37. Individual Variables 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) 30-Apr-24 6:28:50 PM

38. Individual Variables 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. 30-Apr-24 6:28:50 PM

39. Individual Variables 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). 30-Apr-24 6:28:50 PM

40. Individual Variables 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 30-Apr-24 6:28:50 PM

41. Individual Variables 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. 30-Apr-24 6:28:50 PM

42. Individual Variables 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. 30-Apr-24 6:28:50 PM

43. Individual Variables 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. 30-Apr-24 6:28:50 PM

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. 30-Apr-24 6:28:50 PM

45. Individual Variables 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) 30-Apr-24 6:28:50 PM

46. Cont.. 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. 30-Apr-24 6:28:50 PM

47. Individual Variables 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. 30-Apr-24 6:28:50 PM

48. Individual Variables 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) 30-Apr-24 6:28:50 PM

49. Individual Variables 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. 30-Apr-24 6:28:50 PM

50. Individual Variables 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. 30-Apr-24 6:28:50 PM

51. Individual Variables 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. 30-Apr-24 6:28:50 PM

52. Individual Variables 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. 30-Apr-24 6:28:50 PM

53. Individual Variables 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! 30-Apr-24 6:28:50 PM

54. Thanks 30-Apr-24 6:28:50 PM