Isokinetics and Exercise Science - Volume 4, issue 2
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Isokinetics and Exercise Science (IES) is an international journal devoted to the study of theoretical and applied aspects of human muscle performance. Since isokinetic dynamometry constitutes the major tool in this area, the journal takes a particular interest in exploring the considerable potential of this technology.
Isokinetics and Exercise Science publishes studies associated with the methodology of muscle performance especially with respect to the issues of reproducibility and validity of testing, description of normal and pathological mechanical parameters which are derivable from muscle testing, applications in basic research topics such as motor learning paradigms and electromyography. The journal also publishes studies on applications in clinical settings and technical aspects of the various measurement systems employed in human muscle performance research.
Isokinetics and Exercise Science welcomes submissions in the form of research papers, reviews, case studies and technical reports from professionals in the fields of sports medicine, orthopaedic and neurological rehabilitation and exercise physiology.
Abstract: The purpose of this investigation was to compare reliability coefficients and standard errors of measurement (SEM) for absolute (peak torque in newtonmeters) and ratio (concentric/eccentric (C/E)) and knee flexion/extension (KF/KE) ratios—as percentages) data. Forty healthy volunteers (20 men and 20 women) completed knee extension and flexion tests on two occasions within a 2-week period. On each occasion, two concentric and two eccentric muscle actions, with a 5-second rest between muscle actions, were completed from 90° to 5° flexion at 60 deg/sec angular velocity. For each gender, absolute scores were characterized by higher interrepetition, interoccasion, and overall intraclass correlation coefficients and…lower relative measurement error (SEM/SD) than were either C/E or KF/KE ratios. These results do not discount the utility of ratio data, but suggest that to maximize reliability, ratio data should be acquired using more repetitions and/or occasions than is the case when using absolute data.
Keywords: Reliability, muscle performance, tests and measurements
Abstract: The reproducibility of sagittal plane knee translation during isokinetic exercises was measured in 10 healthy subjects. At eight different test occasions including two examiners. sagittal plane knee translation of both knees was measured with the CA-4000 system (Orthopaedic System Inc., CA) during maximum muscle forces on the Biodex machine (Biodex Medical Systems Inc., Shirley, NY) at an angular velocity of 60 deg/sec. Moderate correlations were found between the majority of the test occasions. with no differences between knees or examiners, but a high variability of sagittal plane translation was found in the individual subject (coefficient of variation (CV), 6–22%). Higher…correlations were found for total translation values than for left-right knee differences. No significant within-day, day-to-day, week-to-week. and between-examiner differences were observed. but a significant change in sagittal plane translation was noted between two tests immediately following each other, the second showing an increase in sagittal plane knee translation despite a similar muscle work at both tests. The amount of total muscle work varied greatly (CV 33%) in the total group, but little in the individual subject (CV 4–10%). Consequently, a moderate positive correlation was found between the total muscle work and sagittal plane knee translation in the whole group, but only weak or no correlations in the individual subject.
Abstract: The purpose of this study was to establish the reliability of isometric and isokinetic torque measurements of the knee extensors in healthy volunteers assessed on the Quadriceps Dynamometer. The subjects (18 men, 16 women) were tested on three occasions, at 1-week intervals, with three different angular velocities (0, 45, and 90 deg/sec). The mean absolute torque values (range 103–206 Nm) and coefficients of variation (range 15–24%) of the knee extensors were comparable with data obtained by other investigators using a Cybex II. Interindividual variability was considerable (13–20%), as had been expected. The maximum intraindividual variability was 11%. An analysis of…variance showed substantial differences within the subjects on subsequent weeks and at the different testing speeds. These results suggest that a variability of about 10% is accounted for by individual changes in torque within healthy subjects. It is to be expected that intra individual variability will be greater for patients than for healthy subjects. These data can therefore be relevant for patients in determining the reliability of strength measurements in neuromuscular disorders or in strength training.
Abstract: The purpose of this study was to investigate concentric quadriceps peak torque value using the Cybex II (Cybex, Ronkonkoma, NY), Biodex B-2000 (Biodex, Shirley, Ny) and Kinetic Communicator (KinCom; Chattex, Hixson, TX) 500H. Fourteen subjects (average age 20.14±0.36 years) were tested on their dominant leg on each of the three devices. This study concentrated on two sets of data: (1) highest peak torque, comparing the highest concentric peak torque value produced on each machine; and (2) clinical peak torque comparing the highest peak torque values produced on the Cybex and Biodex with the mean peak torque for the given number…of repetitions performed on the KinCom. Subjects were randomly assigned to begin testing on one of the three machines. At least 72 hours of rest occurred between each of the three testing sessions. Subjects first warmed up on a stationary bike for 5 minutes. Subjects then warmed up on the isokinetic device at approximately 25% maximal effort. Three concentric maximal effort extensions were then performed (60 deg/sec). After a minute of rest, each subject was instructed to perform three more concentric maximal effort extensions which were used in the data collection. The speed was increased to 240 deg/sec and the same procedure was followed. Analysis of variance (AN OVA) and posthoc results comparing raw data showed a significant difference between all devices at 60 deg/sec. At 240 deg/sec a significant difference was only noted between the Cybex and Biodex. ANOVA and posthoc tests comparing clinical data at speeds of 60 and 240 deg/sec showed a significant difference when comparing the Biodex to either of the other two dynamometers. Pearson product-moment correlation coefficient ranged from 0.84 to 0.97. This result indicated a strong relationship between the three dynamometers. The authors concluded that caution should be used when comparing the results from one isokinetic dynamometer to the results of a different model dynamometer.
Keywords: Isokinetic dynamometers, correlation of torques
Abstract: This article illustrates a new computerized analysis of endurance during prolonged isokinetic flexor–extensor contraction of the knee and studies its reproducibility. Thirty men 20–30 years of age with no knee pathologies were studied. Each subject performed an endurance test three times, each test separated by 3 days. The evaluation consisted of a cycle of 1 minute of concentric knee flexion–extension actions at an angular velocity of 180 deg/sec. Appropriate computer software was used to process the following parameters: total work and number of repetitions necessary to obtain a 20–30–50% decrement from baseline work, baseline torque, and number and duration of…cycles necessary to obtain a 20–30–50% decrement of the peak torque compared with baseline values. The parameters obtained were statistically evaluated. The results showed that there was no difference between left and right sides, and the parameters with the best reproducibility were total work, baseline torque, and the 20–30–50% decrement of work compared with base values.
Abstract: The purpose of this study was to determine whether external compression would cause a decrease in the isokinetic muscular endurance of the quadriceps and hamstring muscle groups. Subjects were tested on the Cybex II dynamometer (Cybex, Ronkonkoma, NY) under two conditions: with external compression applied to the thigh and without external compression applied to the thigh. External compression was applied with a lower extremity blood pressure cuff inflated to a predetermined clinically standardized pressure. The subjects performed an isokinetic endurance test consisting of 30 maximal repetitions at 180 deg/sec under both conditions. A paired t test showed no statistical differences…(p > 0.05) between the mean total work, work over the first five repetitions, and work over the last five repetitions between the two conditions for the quadriceps and the hamstring muscle groups. Results indicated that external compression applied to the thigh at 30 mm Hg caused no significant decrease in the isokinetic muscular endurance of the quadriceps or hamstrings. Further research is indicated to determine whether external compression could influence other aspects of muscular performance.
Keywords: External compression, Isokinetic endurance, work