Isokinetics and Exercise Science - Volume 2, 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 study was to delineate differences between the medial and lateral hamstrings by comparing both electromyographic (EMG) activity and force output in three positions of tibial rotation. Forty-two normal subjects were positioned prone with their right leg secured in 90 deg of knee flexion. Surface electrodes were placed over the medial and lateral hamstring muscles. Each test session consisted of nine maximal isometric knee flexion contractions. Three contractions were recorded in each position of tibial rotation: neutral, external, and internal. Recordings of averaged EMG and force output were made by the Bio-Prompt 3000 and FARO Axis Muscle…Tester, respectively. The results showed statistically significant differences: (1) lower force output when positioned in internal rotation (p < 0.01); (2) greater EMG activity of the medial hamstrings when positioned in neutral (p < 0.01); and (3) lower EMG activity of the lateral hamstrings when positioned in internal tibial rotation (p < 0.01). We concluded that these differences demonstrated the need to consider the hamstrings as separate muscles: medial and lateral.
Abstract: The purpose of this study was to determine the relationship between selected anaerobic power tests and isokinetic peak torque values and a criterion power measure established by the sum of several isokinetic power outputs. Forty college-age men participated in the study. The selected anaerobic power tests included the Margaria-Kalaman stair test, vertical jump, and leg and arm cranking power. Peak torque values were obtained from knee and elbow flexion and extension at 60 and 240 deg/sec. The results showed correlations (r) between the tests and the criterion ranged from r = 0.43 to r = 0.84 (p < 0.01). Multiple…regression analysis was used to determine the percent of variance in the criterion that could be explained by the selected tests. Three significant (p < 0.01) equations were developed with multiple correlations (R) ranging from R = 0.84 to R = 0.92. Up to 85% of the variation in the criterion can be explained by the following test performances (in order of influence): the Margaria-Kalaman, summed peak elbow torques at 240 deg/sec, and leg cranking power.
Abstract: Robotic isokinetic dynamometry has become a standard modality in orthopedic assessment and rehabilitation. The advent of computerized dynamometry has allowed the incorporation of visual feedback into the testing and training of isolated muscle groups. Visual feedback provides objective information, motivation, and behavior reinforcement regarding an individual's motor response. Research on the use and effect of visual feedback as an adjunct to muscle performance, rehabilitation, and isokinetics in particular has been limited. This study was designed to explore the effect of visual feedback on force production of the quadriceps muscles in both the dominant and nondominant extremity. Slow (30 deg/sec) and…moderate (120 deg/sec) speeds were compared as well as three versus five repetitions. Twenty-seven subjects (15 female and 12 male) were randomly assigned to vision and nonvision groups. Each subject participated in two tests at a 1-week interval with and without visual feedback from a computer monitor. Results demonstrated significantly higher (p < 0.01) force production when receiving visual feedback. Significance was achieved regardless of testing order. In conclusion, when seeking peak torque or peak average force production, visual feedback is facilitative. Similarly, when maximal effort is desired during rehabilitation, visual feedback could be an effective adjunct to usual clinical procedure.
Keywords: Visual feedback, quadriceps force production, concentric/eccentric peak, average peak torque
Abstract: The purpose of this study was to determine whether significant concentric strength and range of motion differences exist between the dominant and nondominant shoulders of highly skilled junior tennis players. Concentric isokinetic testing of 26 (12 male and 14 female, 11- to 14-year old) highly skilled tennis players was conducted using a Cybex 350 and UBXT. Tests were conducted bilaterally for shoulder internal and external rotation with 90 deg abduction at 60, 90, 210, and 300 deg/sec. Significantly greater (p < 0.005) dominant arm internal rotation strength was measured compared with the nondominant arm for boys at all four testing…speeds for peak torque and best work repetition. No significant difference was found in external rotation at any speed for peak torque and best work repetition for boys. Bilateral comparisons also showed significantly greater (p < 0.05) internal rotation strength on the dominant arm of the girls at 60, 90, and 210 deg/sec for peak torque and at 210 and 300 deg/sec for best work repetition. No significant difference was measured for external rotation at any testing speed for peak torque or best work repetition. Significantly less (p < 0.05) goniometrically assessed internal rotation range of motion and greater (p < 0.05) external rotation range of motion was found on the dominant arm of the boys when compared with the nondominant extremity. The girls also had less (p < 0.05) internal rotation range of motion on the dominant arm, but did not have a significant difference between extremities in external rotation. Selective development of the internal rotators of the shoulder relative to the external rotators was found in the dominant arm of highly skilled junior tennis players at a very young age. The imbalance of strength found in this study is important to physical therapists in rehabilitation and design of specific conditioning programs for the upper extremity athlete.
Keywords: Arm dominance, internal/external rotation strength, skilled junior tennis players
Abstract: Isokinetic torque measurements of the knee extensors have become increasingly popular, and in many instances are replacing isometric tests. The aim of this study was to determine whether isometric and isokinetic tests measure the same aspects of muscular output. The torque of the knee extensors of 34 healthy subjects was measured during three sessions at weekly intervals. Testing was performed using the Quadriceps Dynamometer (QD) for both isometric and isokinetic assessments. A significant positive correlation of 0.70 and 0.56 (p < 0.05) was found between the isometric torque and the isokinetic torque at angular velocities of 45 and 90 deg/sec,…respectively. However, the common variance was too low to enable a prediction of the result of an isometric test from that of an isokinetic test and vice versa. It was concluded that both methods appear to measure a different area of muscular performance.
Abstract: The purpose of this study was to determine test–retest reliability of knee extensor and flexor strength measurements in elderly patients after total knee replacement. Twenty men and 16 women (mean age 70 ± 4 years; mean postsurgical time 19 ± 11 months) were tested isometrically at 45 deg flexion with a hand-held dynamometer and isokinetically at 60 deg/sec angular velocity using a Kin-Com dynamometer during two test sessions within a 2-week period. All patients were independent in activities of daily living, ambulation, and stair activities, and none had previous experience with equipment-based isometric or isokinetic tests. Isometric torques at 45…deg flexion and isokinetic peak torques were reliable (intraclass correlation coefficients > 0.75) on a single test session, whereas averaging torques over two test sessions was required to produce reliable torques at 45 deg flexion during isokinetic movements. Reliability was greater during isometric than during isokinetic tests, greater during knee extension than during knee flexion, and, during the isokinetic tests, greater for peak torques than for torques at 45 deg flexion. Future studies should examine (1) reliability during the second and third test sessions when using the present and other tests protocols, and (2) means of familiarizing the patient with the test procedures in an effort to improve reliability.
Keywords: Total knee replacement, reliability, extensor/flexor strength
Abstract: Rehabilitation after anterior cruciate ligament (ACL) reconstructive surgery is designed to prevent the many complications once reported after this procedure. Today, the rehabilitation program emphasizes immediate motion, immediate weight bearing, and early strengthening exercises for the knee extensors and flexors. This study details the isokinetic muscular performance data of 250 male recreational athletes collected at 12 weeks postsurgery. The results demonstrated statistically significant differences (p < 0.001) for the knee extensors parameters of peak torque, torque to body weight, total work, and average power at 180 and 300 deg/sec. The knee flexors exhibited a significant difference at 180 deg/sec for…all isokinetic parameters and no significant difference at 300 deg/sec. The results indicate that at 12 weeks after ACL patellar tendon autograft reconstruction using an aggressive rehabilitation program, the knee flexors' muscular strength appears nearly equal to the contralateral knee, whereas the quadriceps exhibits a deficit of 24–31% in recreational athletes.