CASE STUDIES

Isokinetic Testing and Training with the Cybex 11+ Dynamometer ALPHONSO R A ONUOHA PhD MCSP DipTP Ch;iirnian. Physical Therapy Department. Faculty of Allied Health Sciences and Nursing. Kuwait University

Key words: Assessment, isotonics, isokinetics, resistive exercises, peak torque, training, rehabilitation.

SUInInary: A brief review of the strengthening programmes in physiotherapy is presented. The advantages of the isokinetic dynamometer over isotonic and manually resisted exercises are outlined. Two case studies are presented with full details of the testing procedures. and the subsequent training. The results ofthe testing and the training programmes are presented and discussed along with the research implications.

Biography: Dr Alphonso Onuoha graduated from the RN School of Physiotherapy, Haslar, in 1966 and later as a teacher from the Queen Elizabeth Hospital School of Physiotherapy, Birmingham. in 1970. He has held teaching appointments in Birmingham, the University of British Columbia and the University of Alberta. and was the director of the Mohawk McMaster physical therapy prngmmme in Hamilton. Ontario. from 1975-1978. After his doctorate degree in 1980 he returned to Nigeria. and taught for one year at the University of Ife. before being appointed the chief physiotherapist for the Nigerian Federal Ministry of Health and pioneer principal of the Federal School of Physiotherapy in Kano until 1986, when he joined the Kuwait University and has been chairman of the physical therapy department.

STRENGTHENING exercises of various sorts have been used by physiotherapists in rehabilitation of their patients. One of the most sensitive methods of applying graduated resistance to a working muscle is by manual resistance. The therapist is able to adjust his resistance to suit or match the amount of force generated by the muscle. This form of resistance is labour-intensive: it is a one-to-one contact and therefore ties the therapist to one patient for the duration of the contact. It is also tiring for the therapist. Furthermore, it is difficult to monitor, quantify and document.

The Isotonic Principle

On the other hand we are familiar with the problems of the use of progressive resisted exercises such as springs and weights, in which the resistance offered to the working muscle remains the same at all the points in the range of motion, from the extremes where the leverage is most inefficient, to mid range where it is most effective. This method, however, has the advantage of being quantifiable, objectively progressed and documented. It could also be time saving.

The introduction of isokinetic machines has resolved the problems encountered in the principles of isotonic exercises, and freed the therapist from the demands of manual resistance.

The lsokinetic Principle

The isokinetic machine is one device which is as sensitive to the state of the muscle as manual muscle resistance.

The principles of isokinetic exercises allow the muscle to be worked at a constant speed quite unlike other resistance programmes. The resistance is variable depending on the

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ability of the muscle to generate force to keep pace with the selected speed.

The resistance encountered varies throughout to match the power of the muscle at any point in the range of motion. It also means that maximum tension is generated in the muscle throughout the entire range of motion. It is, therefore, of considerable benefit for strengthening muscles.

There are several advantages of isokinetic dynamometers.

1. They are capable of providing maximal load to a working muscle to its maximum possible level at all points throughout the range of motion. 2. They provide accommodating resistances, ie the force generated changes to suit the different situations within the muscle, such as pain, fatigue, change in leverage. 3. Various speeds are available for use in slow, fast and endurance workouts. 4. They are safe because of the accommodating resistances, since it is unlikely that a patient would meet more resistance than he could cope with, at any of the speeds selected. 5. The most recent versions of isokinetic machines have the added advantage that they can be used both as diagnostic, training, rehabilitation and research facilities. As a diagnostic tool, information can be provided on the peak torque, ie the highest point reached on a single action curve. The range of movement and the shape of the curve provide detailed valuable information. 6. Further information can be obtained through the Cybex Data Reduction Computer (CRDC) on the endurance ratio, the agonist/antagonist ratio, the peak torque at selected and pre-set angles, and bilateral comparisons. 7. As a training instrument the isokinetic machine may be used for obtaining normative data, providing objective com- parable serial data, giving instant feedback during training on the level of effort and progress. As a training facility it is a ready instrument for carrying out rehabilitation. 8. In the study of the pathomechanics of joints such as the knee, the shape of the torque curve produced becomes of diagnostic significance and can be correlated to such common pathologies common in the knee as anterior cruciate insufficiency, meniscal pinching or compression, and chondromalacia patellae. For example, in anterior cruciate insufficiency there is a mechanical dysfunction which produces a deformation of the peak torque curve usually at mid range in the curve of quadriceps femoris (fig 1).

Quadriceps Hamstrings Fig 1: (A) Sample normal torque curve compared to (B) torque curve in anterior cruciate insufficiency

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Quadriceps Hamstrings Fig 2: Sample torque curve in a meniscus lesion

As shown in figure 2, in the meniscal problems, the pinching or compression of the torn meniscus sets up an associated pain and the reflex inhibition causes a serrated deformation of the quadriceps femoris peak torque curve at its middle.

In chondromalacia patellae, however, the pain inhibition set up creates an irregularity which is spread throughout the curve of the peak torque of the quadriceps femoris as represented in figure 3. A pre-operative torque curve can

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Fig 3: Sample torque curve in chondromalacia patella (Davies, 1985)

therefore be used as an aid to diagnosis (Hall and Williams, 1989) on patients undergoing arthroscopic surgery with a view to following up with post-operative training and rehabilitation regimes. 9. The most recent application of isokinetics is in the athletic screening and training. The case studies that follow are intended to illustrate the application of isokinetic principles in testing and training sportspeople.

Case Histories Forty-four Islamic countries participated in the Peace and

Friendship Games organised in Kuwait from October 30 to November 12, 1989. It was an important demonstration of the ways of promoting world peace. During the preparation period the coaches of the different Kuwait national teams carried out a number of experiments using a large number of players in order to determine the players who would form the main teams for the soccer, volley ball and basket ball. A training camp was held for the selected players.

Two players aged 26 and 28 years respectively and presented below as A and B. were kept on the stand-by list in view of their identified weaknesses and knee instability. They were referred to our exercise laboratory for tests and training on Cybex I1 + dynamometer.

Patient A had an anterior cruciate ligament repair nine months earlier, having had a medial meniscectomy in the same knee one year before. Following what seemed like a successful rehabilitation programme, he was ready to return to active competition when the captain noticed that he had little strength in his right leg. No pain was present. He was referred for an assessment only. Physical assessment showed no major wasting. On testing him on the Cybex II+, a significant weakness of the quadriceps and hamstrings of the affected knee was present. The readings obtained are shown in the table. A rigorous training was necessary.

Patient B had complained of nagging pain in the knee with instability and some muscle wasting after undergoing a left medial meniscus removal a year earlier. Following an arthroscopic examination he was sent to us for further

evaluation. On physical assessment, there was a definite wasting of the quadriceps. The hamstrings seemed remarkably more developed compared to the unaffected right knee. A test on the Cybex 11+ confirmed a marked weakness of the affected quadriceps, and a hypertrophy of the hamstrings compared to the unaffected knee as shown in the table. The results obtained following the training programme on the Cybex 11+ are provided in parentheses in the table for comparison.

The two athletes were intially tested and then placed on regular training at the research laboratory in the Faculty of Allied Health Sciences and Nursing in Kuwait University. The Cybex 11+ isokinetic dynamometer was used. The knee flexors and extensors were the muscles under study.

Procedure

The pre-test procedures were established as follows: A f ive-minute general warm-up programme was given on the treadmill after a general stretching. The subjects were weighed using the standard clinical scale.

The Test Protocol

Three test speeds were selected - a slow speed at 60° per second, a fast speed of 180° per second and an endurance speed of 240° per second. Two torque tests of five repetitions each were performed at each of the three speeds, followed by a work test of 25 repetitions at 240° per second for endurance testing.

For the testing each subject was firmly strapped on to the knee system for the knee testing table, starting with the unaffected limb. The necessary accessories were firmly secured. The data regarding the subjects, weight, and side being tested, were keyed into the CRDC.

Five sample repetitions were performed at each of the selected speeds in order to allow the subject to get accustomed to the machine setting and also to continue the warming up. During the actual testing, five contractions were performed at 60° per second, followed by five contractions at 180° per second and at 240° per second. A work endurance test of 25 repetitions at 240° per second was the final test for each limb. Verbal encouragements were given throughout the training.

At the completion of the endurance testing the CRDC automatically calculated and displayed the peak torque at, each speed, the hamstringlquadriceps ratio, and the endurance ratio (% of total amount of work of the first five contractions compared to the last five).

Following a five minute rest, the sequence of procedure was carried out on the affected limb. At the completion of this sequence the CRDC automatically calculated the parameters for the limb and also carried out a bi-lateral comparison of the tested limbs.

Results

The table shows the results of the evaluations of the knees on both subjects referred for Cybex evaluation. The peak torque of the involved knees was weakened at 60° per second. The torque ratio between the quadriceps and hamstrings was high. The need for a strengthening programme was obvious. Surprisingly, the total work of the involved knee for patient A at 240° per second was greater than that of the uninjured knee.

The treatment consisted of quadriceps and hamstring training on the Cybex 11+ at fast and slow speeds, three times a week, augmented by practice sessions in the camp

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Percentage mean peak torque values of quadriceps and hamstrings with endurance and hamstrings:quadriceps ratios (figures in parentheses are post-training values)

6O0~second 180u/second ZdO*/second Extensors Flexors ,Extensors Flexors Extensors Flexors

Patient A Unaffected knee Peak torque to 234 186 203 123 176 116

body weight 12421 11861 12251 11471 12051 11081 61 -

1661 - 82 50

1691 1541 Affected knee Peak torque to 203 144 170 9 0 160 102

body weight 12191 11781 12091 11381 11961 11241 Hamstrings quadriceps 71 53 -

ratlo I811 1661 Endurance - - 95 62

rat80 1771 1721

Patient B Undfectad knw ?eak torque to 332 152 235 115 228 119

body weight 13401 11771 12401 11501 12321 11371 Hamstrings quadrmps 46

ratio 1521 Eudurance ~

rat40

49 -

~ 96 77 1821 1751

1631

Allected knee Peak torque to 302 183 223 159 183 135 body weight 13231 11841 12281 11601 12201 11381

for three weeks. Serial Cybex tests were carried out at weekly intervals using exactly the same protocol and the computer print-outs were compared. By the end of eight sessions the peak torques for the knees had shown remarkable improvements. Even the quadriceps and hamstring ratios and endurance values were good. A final decision was made that they were fit to participate in the tournaments.

Discussion

It is obvious that the isokinetic programme of exercise has provided another wide field in the regimen of exercise testing, training and rehabilitation. Therefore isokinetic apparatus can no longer be regarded as an essentially research instrument (Devries, 1982). It is now diagnostic, therapeutic and rehabilitative. The case studies presented show that it was easy to carry out a gross bi-lateral comparison (Onuoha, 1990) between the unaffected and affected muscle groups as well as the agonist and antagonist muscle groups. The initial physical assessment revealed a marked difference between the quadriceps and the hamstrings. The data provided enabled us t o plan the training and final rehabilitation programme. Once the subjects were advised on what to do and how to carry on with it, they were able to carry on with their programmes with minimal supervision except for further periodic assessments. The muscle imbalance and poor endurance found during the initial tests improved enough to get the t w o athletes to return t o their competition and to become winners in their tournaments wi th no complaint of pain or further injury.,

This can be regarded as a sort of a double single-subject study design with similar patients. As stated by Wood- Dauphinee (1988) it offered a suitable way to determine the efficiency of treatmentlintervention. A positive result from this study may not be intepreted as evidence of efficiency for all patients with the same or similar condition, hence the need for conducting multiple single-subject studies w i th similar patients, interventions and target outcomes before the matter of generalisation can be addressed as suggested by Guyatt et a/ (1986) and Barlow and Hensen (1984). Besides, the results presented here were obtained from the Cybex II + dynamometer which is just one type of isokinetic machine. Other versions available include the Lido, and

Kinetic-Communicator (Kin-Com), each of which has its own special characteristics. The only common feature between them all is that the speed of movement at a given setting remains constant, regardless of the force generating capacity of the muscle being tested. The attention of the reader is therefore drawn t o the advice of Hall and Williams (1989) t o the effect that any department considering buying these machines must take into consideration its own requirements and the various makes available with their individual capabilities and limitations.

The results presented here show that the concept of 100% recovery after surgery or trauma is, t o say the least, idealistic. The subjects here have shown, without doubt, that it is possible with some strength deficit between the affected and unaffected limbs t o obtain full recovery (Sherman eta / , 1983; Onuoha, 1990) and return t o full competitive sports.

This is especially the case when no pre-injury record is available regarding the two limbs. In such a situation it would not be ideal to set the final goal of rehabilitation as return to symmetry t o match the uninvolved leg, because the affected limb might have been weaker initially. These case histories have been used to make the point in the use of the isokinetic principles in rehabilitation. Ideally, even after the return t o full competitive sports, periodic practice sessions should be encouraged to maintain recovery or until no further gain is noticeable, provided similar relative dynamometer application arm lengths have been used in such strength assessments as outlined by Kramer e t a / (1989). Suffice it to say that these t w o subjects have continued t o play with no further pain or injury up to the time of this report.

Another remarkable outcome of the present study is that it promoted a much closer co-operation between the trainer, the therapist and the athletes during the training period than before this programme. Most sports therapists take for granted full co-operation between the trainer, the athlete and themselves. Indeed, the availability of this kind of objective measureable treatment method is a valuable adjunct in a stressed sports atmosphere, such as a professional football club or a top-level sports clinic, because the trainer and the athlete can see the effects of their rehabilitation programme.

REFERENCES Barlow, D H and Hensen, M (1984). Single Case Experimental

Design: Strategies for studying behaviour change, 2nd edn, Pergamon Press, New York.

Davies, T J (1985). A Compendium of lsokinetics in Clinical Usage and Rehabilitation Techniques, 2nd edn, S & S Publishers, OSPT, USA.

Devries, H A (1982). Physiology of .Exercise for Physical Education and Athletics, 3rd edn WMC, Brown Company Publishers, Dubuque, Iowa.

Guyatt, G, Sackett, D, Taylor, W, Chony, J, Roberts, R, and Pugsky, S (1986). 'Determining optimal therapy - Randomised trials in individual patients', New England Journal of Medicine, 314, 889-892.

Hall, Land Williams, J (1989). 'The use of isokinetics in rehabilitation - A case study', Physiotherapy, 75, 12, 737-740.

Kramer, J F, Hill, K, Jones, I C, Sandrin, M and Vyse, M L (1989). 'Effects of dynamometer application arm length on concentric and eccentric torques during isokinetic knee extension', Physiotherapy Canada, 41, 2, 100-106.

Onuoha, A R A (1990). 'Comparison of quadriceps and hamstrings in college age students', Physiotherapy, 76, 3, 172-176.

Sherman, W M, Plyley, M J, Pearson, D R, Habansky, A J, Vogelgesang, D A and Castill, D L (1983). 'Isokinetic rehabilitation after meniscectomy: A comparison of two methods of training', Physical and Sports Medicine, 11, 121-133.

Wood-Dauphinee, S (1988). 'Single subject research', Physiotherapy Canada, 40, 5, 274-276.

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