Isokinetics and Exercise Science - Volume 3, issue 3
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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 use magnetic resonance imaging (MRI) to examine the relationships between the cross-sectional area (CSA) of the flexors and extensors of the forearm and isokinetic peak torque at speeds of contraction from zero to 300 deg/sec. Ten men (mean ± SO = 23.9 ± 4.5 years) volunteered as subjects for this study. Peak torque values for flexion and extension of the forearm were determined at 0, 60, 120, 180, 240, and 300 deg/sec using a Cybex II isokinetic dynamometer. For the forearm flexors, the only significant (p < 0.05) correlations between muscle CSA and…peak torque were at zero (r = 0.73), 60 (r = 0.85), and 120 deg/sec (r = 0.76). There were no significant (p > 0.05) correlations for the forearm extensors. It is likely that these findings were most influenced by the contribution of primarily fast-twitch fibers to peak torque at fast speeds of contraction and the differences in architecture (parallel versus pennate fiber orientation) of the forearm flexors versus extensor muscles.
Keywords: Cross-sectional area, magnetic resonance imaging, correlation, forearm flexors and extensors, peak isokinetic torque
Abstract: There continues to be a need to establish the reliability of repeated measurements of muscle performance in order to compare client strength and endurance measurements with baseline performance and normative data. This study reports on the reliability of concentric isokinetic peak torque, average power, and best work measurements when repeated at three different facilities following the same protocols using the Cybex Liftask (LT), the Trunk Extension/Flexion (TEF), and the Trunk Rotation (TR) isokinetic dynamometers. Ten healthy volunteers 30–48 years of age were assigned a random testing order at each of three facilities after site order was randomly determined. Performance on…the LT was tested at the linear velocities of 18 inches/sec, 24 inches/sec, and 36 inches/sec; the TEF at angular velocities of 60 deg/sec, 90 deg/sec, and 120 deg/sec; and the TR at angular velocities of 60 deg/sec, 120 deg/sec, and 180 deg/sec. Lifting was assessed and test-retest reliability was calculated using the intraclass correlation coefficients (ICC) at each velocity with each ICC tested for significance using the paired Wilcoxon test for the LT data, and the Kruskall Wallis test for the TEF and the TR data. No statistically significant differences in peak forceitorque, average power, total work (LT), or best work (TEF and TR) were found between the three testing sites. The ICCs ranged from 0.91 to 0.98 for the LT, 0.88 to 0.93 for the TEF, and 0.94 to 0.98 for the TR. The reliability of the angle of peak force, total work, endurance ratio, and recovery ratio were more variable, ranging from 0.43 to 0.99. Given the consistency of the isokinetic measurements of peak torque, average power, and best work taken with the Cybex back systems, physical therapists could collaborate to generate normative data and conduct clinical research across mUltiple sites as long as the same test protocols were followed and the same model equipment was used.
Abstract: The purpose of this study was to examine the comparability of force measurements obtained with two different digital strain gauge dynamometers. Ten muscle groups of 13 subjects (51–79 years of age) were tested bilaterally during two sessions. An Ametek Accuforce II was used during the first session and a Chatillon Medical Force Gauge was used during the second session. Over 85% of the measurements obtained with the different devices did not differ significantly, were consistent with high reliability, and demonstrated good to high correlations. For most of the muscle groups tested, therefore, the devices may be used interchangeably. Moreover, normal…values obtained with either device may be appropriate as a reference for patients tested with one or the other.
Abstract: Cold (cryotherapy) is commonly applied to an athlete immediately before and/or after sports participation. The purpose of this study was to determine the effect of cold water submersion (CWS) on isokinetic strength of the plantar flexor muscle group. Eleven women and five men (mean age 22.1 years, height 170.8 cm, weight 64.5 kg) with no history of ankle joint pathology were tested for peak torque, average power, and total work of the dominant foot at 60 deg/sec with a Cybex II isokinetic dynamometer. Before isokinetic testing subjects were randomly assigned to either CWS or an inactive rest period (RP). Subjects…returned 1 week later to receive the opposite treatment and undergo isokinetic testing. The CWS consisted of placing the leg in a 15° C tub of water for 20 minutes. The RP consisted of remaining seated for a 20-minute period. Paired t tests were computed to determine if any differences existed in peak torque, average power, and total work between the CWS and RP conditions. Results indicated concentric isokinetic strength values were lower after CWS for peak torque, average power and total work of the plantar flexor muscle group. These findings indicate that concentric isokinetic torque, power, and work of the plantar flexor muscle group are reduced immediately after CWS. Further research should be undertaken to determine the length of time isokinetic output is reduced before returning to normal responses after CWS is present.
Keywords: Cold water (cryotherapy), plantar flexors, isokinetic concentric assessment
Abstract: 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.
Keywords: Rotator cuff, tennis players, concentric/eccentric isokinetic ratio
Abstract: The purpose of this study was to assess the test-retest reliability of the Biodex System 2 isokinetic dynamometer. Twenty subjects performed knee concentric reciprocal extension/flexion exercise on 2 consecutive days, separated by 24 hours. Peak torque (PT), total work (TW), average power (AP), and joint angle at peak torque (JA) were collected from three repetitions across a velocity spectrum of 60, 120, 180, 240, 360, and 450 deg/sec. Correlation values between days 1 and 2 for PT, TW, and AP for both extension and flexion ranged from 0.86 to 0.98. The JA correlations ranged from 0.22 to 0.69. Also, extension…and flexion mean values for PT, TW, AP, and JA on day 1 were not significantly different (p < 0.05) from the mean values derived from day 2, with the exception of flexion JA at 60 deg/sec. It was concluded that the Biodex System 2 isokinetic dynamometer is a highly reliable instrument for assessing reciprocal concentric isokinetic parameters of knee extension/flexion.
Keywords: Reliability, Biodex System 2, knee extension/flexion
Abstract: The purpose of this study was to assess the reliability of the Biodex B-2000 Isokinetic Dynamometer and to determine whether there exists a sports-specific angle at which concentric peak torque (PT) is generated during both right and left isokinetic knee extension exercises at 60 deg/sec and 450 deg/sec. Thirty college-aged men (soccer, n = 10; baseball, n = 10; and nonathlete controls, n = 10) were tested on the Biodex B-2000 isokinetic dynamometer. Five members of each group were retested on a 2nd day to determine reliability. Anthropometric measurements included leg lengths, thigh circumferences, and anterior and posterior thigh skinfolds.…Reliability measures found no significant differences between days concerning PT or the angle of PT for either leg; however, the reliability coefficients were generally higher for the athletic groups, as well as for the slower isokinetic speed. There were no significant differences between the three groups concerning PT and the angle of PT. Therefore, their data were combined to evaluate right versus left leg measures. Again, no significant differences were observed concerning PT and the angle of PT that both legs generated. In conclusion, generally reliable data can be obtained on the Biodex B-2000 at the slower speeds regardless of athletic ability. There also appeared to be a specific joint angle (17 deg at 60 deg/sec and 55 deg at 450 deg/sec) at which PT is generated independent of athletic ability or leg dominance. Deviations from these angles of PT may indicate injury or a predisposition for injury in the force-producing musculature of the upper leg. These results suggest that normative data could be established that would aid physicians, therapists, and trainers to determine if the angle of PT for a specific testing protocol is appropriate or if further evaluation is needed.
Keywords: Sport-specific and speed-specific angle of peak torque, knee extensors, concentric assessment