Isokinetic System Research Articles

The Role of Ankle Strength in Functional Ankle Instability

The purpose of this study was to determine if there were any differences in ankle range of motion, strength, or work between persons with normal ankles (Normal,n= 14), those with functional ankle instability (FAI,n= 15), and those with a history of FAI who have been through formal proprioceptive rehabilitation (Rehab,n= 14). A second puipose was to determine normative values for ankle strength and work measurements using the Biodex® isokinetic system. There were no significant differences between groups for ankle range of motion or for any strength or work measurements. The overall strength/work averages were 11.75/3.42 for plantar flexion, 339/1.48 for dorsiflexion, 3.30/2.40 for inversion, and 2.62/1.79 for eversion. Dorsiflexion torque overall was 31.43% of plantar flexion, and the evertors produced 75.42% of the torque produced by the invertors. It is recommended that clinicians continue to rehabilitate ankles with strength and proprioceptive exercises but do not rely on ankle strength/work testing as the only criteria for determining an athlete's readiness to return to full activity.

NON-SURGICAL TREATMENT OF ACHILLES TENDON: SCOPE OF ISOKINETIC SYSTEMS IN EARLY FUNCTIONAL REHABILITATION 1211

Method: n=31 Mean age: 43 years (range: 18-73 years) Inclusion criteria for non-surgical treatment • Sonographically verified diastasis of the ruptured ends of the tendon, size of the diastasis <0.5 cm at 20° plantar flexion; • consent of the patient, • below-knee plaster, 20° plantar flexion for one week; • wearing a vario stabil shoe for 6 weeks, with an instep raiser for elevation of the heel; elevation of the heel should be as follows: 3 cm up to the 4th week (during the first four weeks the shoe should be worn at night too) and thereafter 2 cm up to the 6th week and 1 cm up to the 8th week (only during the day); • continuous passive movement of the isokinetic system (Biodex Joint System II) beginning in the 3rd post-traumatic week, consisting of free plantar flexion, limited dorsal extension and successive distension to 0° in 2 weeks, 2 × daily for 25 minutes; • active concentric eccentric training from the fourth week onward with a gradual increase in resistance, 2 × daily for 30 minutes; • using further rehabilitation measures from the 5th week onward - riding a bicycle with the vario stabil, underwater therapeutic exercise and proprioceptive training up to the 12th week. Results: Isokinetic tests performed 3 months after injury Difference between sides: 60°/s eccentric - 13.1 ± 11.5%, 60°/s concentric 22.4 ± 8.6%, 180°/s concentric 41.0 ± 13.3% Follow-up period: 1,5 years after injury Holz score: good result - 80%, satisfactory result - 20%, unsatisfactory result - 0% Achilles tendon reflex: of same quality on both sides - 60%, not obtainable- 13% Isokinetic systems offer various possibilities of application in early functional rehabilitation, and the subsequent results of treatment can be objectified by using isokinetic tests.

COMPARISON OF ISOKINETIC TEST AND LYSHOLM SCORE IN PATIENTS WITH ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION 1399

The purpose of this study was to examine the relationship between an isokinetic knee-flexion-extension strength ratio and Lysholm score in subjects with anterior cruciate ligament (ACL) reconstruction who were professional athletes. Fifteen subjects, three females and twelve males (age mean=24.13 years-old) between 24-52 weeks postoperative ACL reconstruction. Concentric isokinetic knee-flexion-extension strength ratio was evaluated using a Cybex isokinetic system at a speed of 180 degree/sec. Subjects were given one minute rest followed by five maximal efforts extension. The identical protocol was also repeated on the contralateral limb. On the day of functional testing, subjects were given instructions and day reply Lysholm test form. Flexion-extension work ratio value means were 91.8±6.25 for the involved limb and 83.4±4.4.78 for the uninvolved limb. Mean score for Lysholm test were 89.2±3.45 for patients with ACL reconstruction. Pearson-product moment correlation coefficients values between Lysholm Score and flexion-extension ratio were.54 and.61 for the involved and uninvolved limb respectively. This suggests a moderate correlation and that isokinetic testing alone may be sufficient to clinically assess a patient's readiness to return a dynamic functional level.

Isokinetic sampling probe and image processing system for droplet size measurement in two-phase flow

Isokinetic sampling probe and image processing system for droplet size measurement in two-phase flow

Pitfalls in isokinetics

A review is given of the possible sources of error to be found when using isokinetic measurement systems. These errors are associated with the subject on whom the measurements are being taken, the person conducting the measurement i.e. the therapist, and the machine itself. Examples of each are given as drawn from the authors own work.

Does Cybex testing increase knee laxity after anterior cruciate ligament reconstructions?

Long-term stability of the knee after anterior cruciate ligament reconstruction is imperative. Testing protocols that use isokinetic systems are commonly performed despite controversies as to their safety. The purpose of this study was to test whether one episode of isokinetic testing would cause an increase in anterior tibial translation. Twenty-four subjects who had anterior cruciate ligament reconstructions 153 to 300 days earlier volunteered for the study. Initially, subjects walked on a treadmill at 5 km/hr for 10 minutes to test the effect of exercise on displacement measurements. One week later, subjects performed a maximal knee flexion-extension test on the Cybex dynamometer at 60, 150, and 240 deg/sec. Anterior tibial displacement at 133.5 N was obtained from force-displacement curves produced by KT-2000 arthrometer testing at nine intervals: before exercise on the treadmill, at four intervals after treadmill exercise, and at four intervals after Cybex testing. Repeated measures analysis of variance did not show a significant exercise effect, interaction between type of exercise and time interval, or change after Cybex testing for the reconstructed knee displacement, the contralateral knee displacement, or side-to-side difference. The average difference before and after Cybex testing was 0.1 mm for the reconstructed knee. In conclusion, a single Cybex test, performed at least 6 months after surgery, did not affect anterior tibial displacement in this study sample.

Concentric and Eccentric Isokinetic Rotator Cuff Ratios in Skilled Tennis Players

Kevin Kennedy, PT, ATC* • David W. Altchek, MDt Irving V. Glick, MD=I= Hospital for Special Surgery, New York --------------------. -------------------The purpose of this study was to compare the concentric and eccentric strength of the internal and external rotators in skilled tennis players. Isokinetic testing of 62 male and female tennis players (Volvo levels 4-5 through 6-0) was performed on a LIDO Active Isokinetic System. Tests were conducted bilaterally for concentric internal and external rotation at 60 deg/sec, and for concentric and eccentric external rotators at 150 deg/sec. The concentric isokinetic testing of the dominant side at 60 deg/sec showed an external rotation to internal rotation ratio of 0.67 for average work per repetition. On the nondominant side, the ratio was 0.77. This difference represents a statistically significant difference in the work of the internal rotators in the playing arm. When tested at 150 deg/sec concentrically and eccentrically for the external rotators, it was found that the eccentric to concentric ratio was 1.46 for the average work per repetition on the dominant side. On the nondominant side, the ratio was 1.19. This difference represents a statistically significant difference in the work performed by the external rotators eccentrically. It was also determined that on the playing arm the external rotators' torque ratio, eccentric to concentric, was 1.43. From our data it was concluded that when measured eccentrically, the external rotators of the dominant arm were significantly stronger than those on the nondominant arm.

The Effects of Isokinetic Fatigue on Recovery of Maximal Isokinetic Concentric and Eccentric Strength in Women

This investigation examined the effects of different types of isokinetic eccentric and concentric exercise on subsequent isokinetic maximal concentric and eccentric muscle strength performances at 30° · s–1 and 120° · s–1 during the acute 10-min recovery period. Tests were administered at 2.5, 5, and 10 minutes into recovery. Sixteen physically active women were randomly assigned to either a control group (n = 6) or an experimental group (n = 10). Each subject in the control group was asked to attend two testing sessions consisting of randomly assigned concentric and eccentric modes of testing without any fatigue tasks. A LIDO™ Active Isokinetic System was used for the fatigue tasks and for measuring concentric and eccentric peak torque values at 30° · s–1 and 120° · s–1 velocities of movement during the preexercise and following the fatigue task. Fatigue tasks (Concentric fatigue, Eccentric fatigue, and Concentric/Eccentric fatigue) consisted of each subject performing three sets of 30 repetitions at 120° · s–1 with maximal effort. During the recovery period following the last set of repetitions, each subject was tested for concentric and eccentric strength at 30° · s–1 and 120° · s–1. Only with the concentric/eccentric fatigue task was there a significant decrease in concentric strength (30° · s–1) observed 5 min postexercise. No other differences were observed during recovery following any of the fatigue tasks. The major finding is that concentric and eccentric muscle activity recovers quickly from an isokinetic fatigue task. From a practical perspective, exercise protocols can utilize shorter rest periods between sets without fear of compromising the force production and concentric and eccentric isokinetic testing protocols, or can utilize a rest period of 2.5 minutes and be assured that recovery has been completed.

Isokinetik in der Rehabilitation

Isokinetic has been proved to be one main component of a complex muscle training in the field of rehabilitation. With the help of the isokinetic system Cybex 340 objective and reproducible muscle tests can be carried out.

Validity and Reliability of the LIDO Active Isokinetic System

No grant monies were used for this research. When evaluating a strength testing method, reliability rather than validity, the most critical component, is most frequently addressed. The purpose of this study was to assess the validity and reliability of the LIDO Active system in the isokinetic mode. Velocity and torque were continuously monitored while torques of 10.4, 25.6, 30.6, and 89.6 ft-lb were applied to the actuator with the speed set at 5 degrees /sec. This was done through a 200 degrees arc of motion concentrically and eccentrically. The procedure was repeated one week later to determine reliability. Analysis of variance revealed no significant variance associated with the date of measurement regarding angular velocity. The maximum deviation of angular velocity from the selected speed was 0.02 degrees /sec. Pearson's r values for measured torque averaged r = 1.00 using paired data from the two test dates. The mean correlation coefficient relating observed to expected torques was Rho = 0.98. These results demonstrate that the LIDO Active system is both valid and reliable within the torque and velocity limitations described. J Orthop Sports Phys Ther 1992;15(1):32-36.

Effects of a Resistance Training Program on Adults with Mental Retardation

Very low levels of strength and muscular endurance have been reported in adults with mental retardation. A progressive resistance training program was developed for a group of adults with mental retardation (ages 23-49 yrs) using state-of-the-art equipment (Nautilus Isokinetic Systems). A MANCOVA analysis was employed to determine the differences between control and experimental groups. The analysis revealed a significant overall group effect. Subsequent univariate ANCOVA analyses were performed to isolate the significant dependent measures. Results indicated that a 2-day-a-week resistance training program was effective in improving the strength levels of this population. It was also revealed that the resistance training program was favorably received by the participants and could be performed with minimal assistance. Service providers for the mentally retarded should consider community based weight training facilities as a viable avenue for improving the strength levels of this population.

Comparison of tensor fascia lata+semitendinosus tendon and free patellar bone - tendon - bone graft reconstruction of the anterior cruciate ligament deficient knee

The reconstruction of anterior cruciate ligament deficient knee is now almost universall accepted in young and physically active patient. If left untreated the risk for funther injury seems unavoidable. Many procedures have been described in the reconstruction of the anterior crucrate ligament (ACL) deficrent knee as the long term follow-up studies of extraarticular procedures have been unsatisfactory intraarticular procedures or a combination of the two are now the treatment of choice. Two separate techniques of reconstruction have been compared in this study. 20 ACL deficirent knees had been operated by tensor fascia Iata+semitendinosus (TFL - ST) technique between 1983-1987. The second group is made up of 20 patients who were treated with free patellar bone-tendon-bone greft. First group's mean, age was 28, 15 years and mean follow-up was 71 months. The second groups, mean age was 24, 55 years and mean follow-up 19, 2 months. Clinical testing, arthrometric testing (GENU COM Fore Medical Technologies inc.), and isokinetic muscle testing (LIDO ACTlVE isokinetic System LOREDAN Biomedical Inc. Cal) were done. For the first group jerk test was positive in 3 of patients (15%). For the second group Jerks was positive in 3 of patients (15%). Isokinetric muscle testing results have shown a good control of knee in the second group of patients. The results of group II are superrorto TFL-ST but follow-up period are not the same in both groups. Thus Iong term results should be verified.

The Reliability of Two Different Cybex Isokinetic Systems

The ability to accurately assess the strength of a variety of muscles is basic to professionals in a number of fields. The purposes of this study were to determine: 1) the intertest reliability of muscular strength utilizing two different Cybex II(R) isokinetic dynamometry systems and 2) reliability of peak torque values (PTV) obtained from two methods of data reduction [Cybex Data Reduction Computers (CDRC) and Cybex Strip Chart Recorders (SCR)]. Subjects (N = 50) were required to complete four knee extension/flexion cycles at two speeds (60 and 240 degrees /sec) on each of 2 test days which were separated by 1 day of rest. Correlation coefficients were used to determine the relationship between values obtained from two different Cybex systems and to determine the relationship of values obtained within each system from the CDRC and the SCR. ANOVA procedures were used to determine differences between values obtained using the two systems and between CDRC and SCR values obtained within a system. Correlation coefficients between CDRC and SCR PTVs indicated a strong relationship between values obtained within a system (r = 0.987 and r = 0.985 for Cybex A and B, respectively) and across systems (r = 0.983 and r = 0.982 for CDRC and SCR values, respectively). However, ANOVA results indicated that the Cybex II system (Cybex A) CDRC PTVs were higher (F = 5.64 and F = 23.90, p < 0.05 for extension and flexion, respectively) than those of the Cybex II+ system (Cybex B). No differences were noted between systems (F = 0.14 and F = 2.05, p > 0.05 for extension and flexion, respectively) for SCR PTVs. Clinicians should be aware that CDRC PTVs determined on different Cybex systems may not be comparable. However, SCR PTVs determined on different systems appear to be comparable. It should also be noted by clinicians that CDRCs and SCRs within the same system appear to be comparable. J Orthop Sports Phys Ther 1990;12(4):157-162.

A Comparative Study of Clinical Muscle Testing and Cybex Evaluation After Shoulder Operations

One hundred consecutive patients treated with shoulder surgery were studied to determine their functional recovery. Their average age was 47.3 years, and the average follow-up period was ten months. Clinical grading of muscle strength was compared pre- and postoperatively with objective testing using the Cybex II Isokinetic System, with subjective functional assessment by dictation, and with the ability of the patient to return to work. The clinical grade of muscle strength increased postoperatively by approximately one-half of a grade in both forward flexion and external rotation. However, various Cybex parameters did not significantly improve. The postoperative values were significantly less for the operated side than for the uninvolved side. Only weak statistical correlations were found between the clinical muscle grading and objective Cybex evaluation. Pain relief was obtained in 87% of the patients. Eighty-six percent of the patients returned to work, although 43% returned to light duty only. Thirty-two percent of patients reported full recovery, while 58% had decreased but satisfactory function. The study showed that although the clinical assessment of muscle strength improved early after shoulder surgery, the clinical grading of muscle power did not correlate well with objective parameters of strength, endurance, ability to work, or functional assessment. Strength did not recover to the level of the uninvolved opposite shoulder. Endurance, which is not measured by clinical grading, may decrease. Longer follow-up and rehabilitation periods are required to optimize results.

A Comparative Isokinetic Evaluation of a Functional Ankle Orthosis on Talocalcaneal Function

The purpose of this study was to determine the effectiveness of a semirigid orthosis in restricting ankle inversion-eversion range of motion (ROM), and evaluate its effect on subjects' ability to produce muscular torque, during pre- and post-exercise test conditions. Thirty healthy subjects, 15 males and 15 females, with no history of right ankle injury were evaluated. Active ankle inversion-eversion torque and angular displacement were measured on a LIDO(R) isokinetic system, with the subjects' right ankle positioned in 0 degrees of plantarflexion. T-tests for paired samples at the 0.001 confidence level revealed that the orthosis demonstrated significant inversion-eversion range restrictive capabilities; did not interfere with maximum inversion-eversion torque production; and retained its support effectiveness following 20 minutes of dynamic exercise. The results suggest that the tested orthosis may be an effective prophylactic in preventing ankle sprains and beneficial to individuals with chronic ligamentous instability. J Orthop Sports Phys Ther 1989;11(6):245-252.

A Noninvasive Technique for the Evaluation of Diversion Cross Flow at the Inlet of a Simulated Fuel Rod Bundle

Diversion cross flow was characterized from a two-subchannel simulation of a nuclear fuel assembly using a gamma camera. The gamma camera alllowed external monitoring over the length of the test assembly, thereby eliminating experimental problems associated with flow partitioning and an isokinetic withdrawal system, allowing the possibility of noninvasive measurement. The experiment was performed by providing fixed but different flow rates to each subchannel. The higher mass flow rate stream was traced with a gamma-emitting radionuclide, /sup 99m/Tc pertechnetate. Activity in each subchannel was measured by the camera. Diversion length was found to be relatively small and strongly dependent on gap spacing. Effective lateral velocity through the gap was also evaluated. With some exceptions, the results were in good agreement with the predictions of the subchannel analysis computer code COBRA IIIC. At a high inlet axial mass velocity ratio of 4, however, the agreement with the prediction was poor.

The importance of isokinetic measurement of force in sports and rehabilitation

The musculature serves as motor of the human body and hence promotes our movement within our environment. Its organ-specific performance is the translation of force into movement. This force can be described by means of different qualities - maximal force, speed and endurance. These properties are essential for sports activities and also set limits for the achievement of athletic records. Muscular force can be evaluated by different means. Measurement of force via isokinetic systems enables quantitative measurement of effective muscular forces in various body positions which are frequently comparable under conditions specific to different types of sports. The relevance of these measurements in sports and rehabilitation is documented in this article. Two different groups of subjects (72 sportsmen and 73 patients after capsular ligament reconstruction in the knee joint) were examined. The measurement values: dynamic maximal force, energy of acceleration, average performance and the hamstring/quadriceps ratios (H/Q quotient) are measured at different speeds. The maximal force shows intraindividual differences depending on the speed. These differences are due to different conditions of training and different distribution of muscle fibre types. The acceleration energy enables assessment of differences in the ability to exercise force. Likewise, the different muscle performances can be described by means of the appropriate individual performance maximums. In rehabilitation, muscle atrophy caused by immobilization can be measured and described. Measurement of force by means of isokinetic systems enables the analysis of muscular forces with their different properties, and hence to give advice in training matters and to supervise and control popular recreational sports and competitive sports activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Case Studies: Use of the Cybex®Trunk Extension Flexion Unit in the Rehabilitation of Back Patients

This article presents the case histories of two back patients, one who had undergone three separate spinal surgeries and one who was status post-cerebrovascular accident, that were successfully rehabilitated using the Cybex® Trunk Extension/Flexion Isokinetic System.

Factors affecting selected reciprocal muscle group ratios in preadolescents.

This study examines the influence of limb velocity and lateral dominance on the relationship between the knee flexors and extensors. Thirty preadolescents, 18 male and 12 female, performed a series of reciprocal knee flexion-extension movements on the Cybex II isokinetic system. The tests were performed at a range of selected velocities and on both dominant and nondominant limbs. The agonist-antagonist ratios considered were the peak torque ratios, the torque ratio produced at specific angles, and the ratio comparing the total work performed by the hamstrings with that of the quadriceps. The results showed that an increased limb velocity produces a significant increase in the peak torque and work ratios (P less than 0.05), limb velocity has no significant effect on the torque ratio produced at 30 degrees and 60 degrees in the preadolescents, and lower limb lateral dominance has no significant effect on the three ratios examined.

Isokinetic Measurement in Preadolescent Males

Eighteen preadolescent males (mean age 11.4 +/- 0.59 years) performed 15 knee flexion-extension repetitions on both legs. Peak torque (T peak) and torque acceleration energy (TAE) were measured using the Cybex II Isokinetic system, which permitted a study of the effect of limb velocity on T peak, TAE, and reciprocal muscle group ratios. The effect of limb dominance was also assessed. The results indicated (Student's t test) that an increase in limb velocity from 1.05 rad/s to 4.2 rad/s produced a significant decrease in the T peak generated (P less than 0.001). A similar increase in limb velocity resulted in a significant increase in the TAE recorded (P less than 0.001). The limb velocity was also shown to influence the T peak and TAE ratios in reciprocal muscle groups. At a limb velocity 1.05 rad/s mean T peak ratios of 0.64 and 0.66 were recorded for the dominant and nondominant limbs, respectively. At 4.2 rad/s, ratios recorded for dominant and non-dominant limbs were 0.79 and 0.80, respectively. The limb velocity of 1.05 rad/s produced TAE ratios of 0.21 (dominant) and 0.14 (nondominant), and at 4.2 rad/s, ratios of 0.28 and 0.24 were recorded for dominant and non-dominant limbs, respectively. No significant difference (P less than 0.001) was observed between T peak and TAE values recorded for the dominant and non-dominant limbs under the same conditions. These results indicate that young boys show velocity-related isokinetic strength characteristics similar to adults. Although they have lower absolute levels, the children showed typical adult reciprocal muscle group ratios. Limb dominance at this age is not reflected in strength differences.