Isokinetics and Exercise Science - Volume 1, 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 paper is to present a reproducible, sport-specific, and functional method for isokinetic evaluation of the throwing shoulder. Fifteen guidelines for standardization of isokinetic shoulder testing are identified and discussed, including: (1) planes of motion to evaluate, (2) testing positions and stabilization, (3) axis of joint motion, (4) client education, (5) active warm-up, (6) gravity compensation, (7) rest intervals, (8) initial contralateral extremity testing, (9) standard of verbal commands, (10) standard visual feedback, (11) testing velocities utilized, (12) test repetitions to perform, (13) proper system calibration, (14) insuring that the system is level and stabilized, and (15)…the use of windowed data and a semi-hard (firm) end stop during testing. This Throwers' Series testing protocol outlines isokinetic testing at 180, 300, and 450 deg/sec in two planes: (1) internal rotation/external rotation (tR/ER) in 90 deg of shoulder abduction and 90 deg of elbow flexion, and (2) seated abduction/adduction. Following an active warmup, athletes perform 10 repetitions at 180 deg/sec, 15 repetitions at 300 deg/sec, and 10 repetitions at 450 deg/sec. IR/ER and the nondominant extremity are always evaluated first to standardize testing order. Fifteen parameters for interpretation of isokinetic test results of the throwing shoulder are outlined, with emphasis placed on the use of windowed data and a firm end stop to minimize endpoint oscillation torque spikes and misinterpretation of data. This paper offers clinical relevance by outlining an objective, reproducible, and standard method to evaluate the muscular performance of the throwing shoulder. These methods are designed to minimize variability and enhance interclinician communication regarding isokinetic shoulder test data and interpretation.
Keywords: Isokinetic testing, standardization, objective test data, shoulder abduction/adduction and internal/external rotation, throwers
Abstract: Isokinetic tests of seven patients presenting with symptomatic posterior shoulder subluxation were studied. Patients were tested over a velocity spectrum from. 100–400 deg/sec in two diagonal shoulder motions and internal/external rotation at 45 deg abduction. Torque curve abnormalities were seen from approximately 70–110 deg with the flexion/abduction/external rotation diagonal and 85 deg with the extension/adduction/internal rotation diagonal. These defects were present both while the patient was symptomatic and asymptomatic. In conclusion, posterior rotator cuff insufficiency at the specific position of torque suppression was responsible for the abnormal finding in flexion. Posterior labral tearing with an associated clunk test created the…positive finding on the extension curve.
Keywords: Shoulder cuff, rotator strength, posterior subluxation, isokinetic data
Abstract: The purpose of this study was to compare the force required to lift a given weight throughout the range of knee extension on the N-K Table, Nautilus, and Universal knee extension machines. A static measurement was taken with a force gauge and chart recorder at every 5 deg throughout the machine's range of motion using a 20-lb weight. Results revealed significant differences between the forces on each machine at each angle that was measured (p < 0.0001). The Nautilus machine's force curve ascended throughout the range from 9.7 to 20.2 lbs. The Universal machine's force curve descended from 41.1 to…27.9 lbs. The force curve of the N-K Table ascended from 8.8 to 27.5 lbs and then descended to 15.4 lbs, with an offset angle of 64 deg. Clinicians are advised to consider the differences in these machines in order to optimize the efficiency of available equipment and minimize the risk of injury.
Keywords: Force production, efficiency, isotonic extension, force curve
Abstract: The purpose of the study was to compare fatigue development in concentric vs. eccentric muscular activation in the quadriceps of 15 healthy human subjects, controlling as many of the dynamic variables as possible. An isokinetic testing protocol was used, with knee joint angular velocity limited to 180 deg/sec, and with 40 repetitions through a range of motion of 75 deg constituting the fatigue-developing exercise. Quadriceps torque was measured via a robotic dynamometer, IEMG of the rectus femoris muscle was recorded, and a subjective pain rating scale was used to assess delayed muscle soreness following fatiguing exercise for concentric and eccentric…tests. Eccentric peak torque to body weight ratio was greater than the concentric ratio (1.25 vs. 0.66, p < .001), significant torque fatigue developed in both eccentric and concentric tests (30.3% and 13.7%), and significant decline in IEMG occurred in both eccentric and concentric tests (17.0% and 15.1%). The eccentric declines in torque and IEMG were not significantly different than the concentric declines. There was no clear difference in the pain reports associated with the two different exercise modes. Delayed onset muscle soreness was rated as mild (3 on scale of 10) at most during the 72-h surveillance period. It is concluded that the development of fatigue through eccentric muscular activation may stress the contractile mechanism less than that associated with concentric muscular contraction, and that standard clinical fatigue protocols may have to be modified to better distinguish the role of active neuromotor vs. musculotendinous contributions to performance test results.
Abstract: Several authors have suggested that work or power might be a better representation than peak torque as a measure of muscle function. The purpose of this study was to analyze the relationship of peak torque to peak work and peak power of the quadriceps and hamstring muscles of normal subjects using an accomodating resistance isotonic device and to determine if peak torque alone provides sufficient information regarding muscle function. Forty-five subjects (27 females, 18 males) with a mean age of 23.5 years were tested on an Omnitron Total Power Unit at slow, medium, and fast speeds of contraction. All correlations…between peak torque and peak work and between peak torque and peak power at all speeds of contraction were greater than .95. Peak torque appears to provide information equal to peak work or peak power regarding the ability of the muscle to emit force throughout the range of motion as assessed via accommodating isotonic contraction.
Abstract: The aims of the present study were (1) to characterize the knee angles of hamstring and quadriceps peak torques at slow (60 deg/sec) and moderate (180 deg/sec) isokinetic speeds in patients with different knee ligament insufficiencies (n = 227); (2) to find out what (if any) quantitative effect the speed increase has on these peak torque angles; and (3) to determine if injury type or muscle strength has an effect on the results. For the measurements, the Cybex II dynamometer was used. In hamstrings, the mean peak torque angle was 35 deg of knee flexion, when the angular speed of…the dynamometer was 60 deg/sec. At 180 deg/sec, the angle appeared 8 deg later in the range of motion, at 43 deg (p < 0.001). In quadriceps, the average peak torque angle was 54 deg at 60 deg/sec. At 180 deg/sec, the angle occurred 10 deg later, at 44 deg of knee flexion (p < 0.001). Within each injury group, there were no significant differences between the injured and uninjured limb. The type of the knee ligament injury (grade II or III anterior cruciate, medial collateral or lateral collateral ligament injury, or grade I combination injury) also did not affect the results. However, the muscle strength of the weak muscle groups (that is, hamstrings in all the other injury groups except anterior cruciate ligament group) had a significant negative correlation with the angle of peak torque. This meant that in these hamstrings, the peak torque angle occurred later in the range of motion when muscle strength decreased, and vice versa.
Abstract: Previous investigations have examined the effect of gravity correction on hamstring and quadriceps force and reciprocal muscle group ratios when tested from a seated position. The effect of gravity correction on these values when knee extension is tested from supine and knee flexion from prone has not been determined. This study tested 48 females for concentric and eccentric average force of the quadriceps in the supine position and of the hamstring muscle group in the prone position with a Kin Com dynamometer. For the quadriceps and hamstring muscle groups, the gravity-corrected values were greater (p < .01) than gravity-uncorrected values…for concentric and eccentric force. The gravity-corrected flexion/extension reciprocal muscle group ratios were also greater (p < .01) than uncorrected ratios when determined from both concentric and eccentric average force values. These findings indicate gravity correction had a significant effect on both quadriceps and hamstring force production and reciprocal muscle group ratios, regardless of the fact that both muscle groups were assessed against the effects of gravity. Furthermore, the effect of gravity correction on the hamstring muscle group was approximately twice as great as on the quadriceps. These findings support the need to correct for the effect of gravity when assessing knee extension from supine and knee flexion from prone. Thus, it is very important for clinicians to report how testing and gravity correction were accomplished to allow proper interpretation and analysis of the presented values.
Keywords: Gravity correction, concentric/eccentric ratio of hamstring/quadriceps, prone/supine positioning
Abstract: The purpose of this study was to determine a relationship between hip abductor and adductor muscle force output measured isokinetically in normal adult subjects. Bilateral testing of 42 normal subjects ages 21−36(n=84) was performed isokinetically (MERAC) in a −5 deg to 35 deg range of motion (ROM) at 60 deg/sec. Subjects were positioned on the test bench lying on their side with test limb up, knee extended, and leg in neutral rotation. The mean peak abductor: adductor torque output ratio was 1 : 2.30 (0.44) for the total sample. As motion occurred in the coronal plane, a statistically significant change…in mean abductor: adductor torque ratio was determined in the test sample. A statistically significant positive correlation between hip abductor and adductor muscle force output existed through motion in the coronal plane between 0 to −30. Because two-thirds of the test sample was composed of females, these results may be less applicable to male clients and generalization may also be limited due to specific instrumentation.
Keywords: Lower kinetic chain, isokinetics, abductor, adductor, isokinetic torque ratio