Isokinetics and Exercise Science - Volume 4, issue 4
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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 quantify the effect of a single Feldenkrais Awareness through Movement (ATM) intervention on a functional reach task on symptomatic subjects. Twenty-three subjects with upper back, neck, or shoulder discomfort were randomly assigned to the Feldenkrais ATM treatment (12 subjects) or sham Feldenkrais treatment (11 subjects) groups. The Feldenkrais ATM group followed the audiotape instructions of a lesson titled “Shoulder Clock”. The sham Feldenkrais group followed the taped instructions of a series of general upper body exercises. Subjects received a single application of the respective treatment. A hook-lying, functional reach task was measured after…4 warm-up reaches before and after the treatment. Subjects were asked to notice and remember the level of exertion it took to perform the reaching tasks. They rated the level of perceived exertion for the pre- and posttreatment reaching tasks on a visual analog scale. A one-way analysis of variance was used for data analysis, and the p level was set at 0.05. A reduction in perceived exertion after the intervention was significant for the Feldenkrais ATM group (p < 0.05). No significant difference in perceived exertion occurred with the sham treatment group (p > 0.05). No significant difference existed between the pre- and posttreatment functional reach measurements in the Feldenkrais or sham treatment groups (p > 0.05). Based on the results of our study, we conclude that a single Feldenkrais intervention (“Shoulder Clock”) was effective in reducing perceived exertion in subjects with upper back, neck, and/or shoulder discomfort.
Abstract: The purpose of this study was to investigate the reliability and validity of inexperienced trained and inexperienced untrained testers in the use of skinfold calipers. The subjects consisted of five testers. One tester was experienced, having performed skinfold assessments for 17 years. Two testers were inexperienced with a skinfold caliper but were trained by the experienced tester in one half-hour session, whereas the remaining two testers were inexperienced and untrained, having read instructions only. Testers took skinfold measurements at three sites on 57 volunteers. Twenty-eight volunteers were tested twice to provide intratester reliability estimates. Intraclass correlations were used to evaluate…intratester reliability of all testers, as well as intertester reliability between the trained testers and untrained testers to the experienced tester at each measurement site. Intratester reliability was greater with the experienced and trained testers than with the untrained testers. Intertester reliability of trained testers correlated more highly with the experienced tester (0.86–0.97) than did the untrained testers with the experienced tester (0.27–0.78). The results of this study indicate a substantial benefit of training to the clinician striving to become proficient in the use of skinfold calipers.
Keywords: Skinfold measurements, trained and untrained testers, reliability
Abstract: The present study was conducted to determine and correlate the various hamstrings/quadriceps (HQ) ratios given in knee testing by use of the numeric reports of modern computerized isokinetic equipment. The HQ ratios are based on the following parameters: peak torque, total work, and average power. Fifty-three sport students with an activity level of three training sessions a week were tested 8 weeks apart by five repetitions of 60 deg/sec and 30 repetitions of 240 deg/sec. The test-retest correlation ranged from 0.60 to 0.83 and showed a relatively strong association between the two tests for all HQ ratio parameters at either…side and for both speeds. On the nondominant side the difference between test and retest ratio values was significant at both speeds for all but one parameter. The reason was shown to be a selective improvement of the hamstring muscles. Reliability measured as the average coefficient of variation was found to be 6.0% for all ratio parameters. This indicates that for a group of 53 subjects and for an individual test, a minimum change in the HQ ratios of at least 2.3 and 16.6%, respectively, must occur to be statistically significant within 95% confidence limits.
Keywords: Knee muscles, ratios in isokinetics, reproducibility
Abstract: The purpose of this study was to quantify the errors associated with multiple regression equations that use gender, age, height, and weight for estimating peak torque (PT) for leg extension and flexion. Forty-three men (mean age ± SO 24.4 ± 4.7 years) volunteered as subjects. Peak torque values for extension and flexion of the dominant leg at 60 and 180 deg/sec were determined using a Cybex II dynamometer (Cybex, Ronkonkoma, NY). The results of the cross-validation analyses indicated that the total error (TE) values for the equations ranged from 21.4 to 24.6 ft-lbs (14.8 to 18.9% of mean) for leg…extension and 20.6 to 32.8 ft-lbs (31.0 to 52.0% of the mean) for leg flexion. The magnitude of the TE values indicate that these equations should be used only in situations where a gross estimation of PT may be helpful.
Abstract: The purpose of this study was to determine the relationship between average force, average torque, peak force, and peak torque produced by the knee musculature. Twenty women were assessed for isokinetic concentric and eccentric knee extensor and flexor muscular strength at a velocity of 90 deglsec. Correlational analyses showed relationships ranging from r = 0.89 to r = 0.94 for concentric extension, r = 0.92 to r = 0.99 for eccentric extension, r = 0.81 to r = 0.95 for concentric flexion, and r = 0.90 to r = 0.96 for eccentric flexion. The strong relationship between the tested variables…suggests that any of these variables are appropriate when reporting isokinetic strength data. However, because average values are dependent on the preload and range of motion through which a joint is assessed, it is imperative that these variables remain consistent between and among subjects. If this is not possible, the use of peak measures is recommended.
Keywords: Average force and torque, peak force and torque, relationships
Abstract: The bilateral deficit (BD) during force production may result from decreased activation of either slow-twitch or fast-twitch muscle fibers. The purpose of this study was to investigate the effect of velocity on the BD and estimate the relative contribution of muscle fiber type to the BD in untrained women. Twelve subjects performed three concentric reciprocal knee extension and flexion repetitions at isokinetic speeds of 60, 120, 180, 240 and 360 deg/sec using both unilateral limbs and bilateral limbs. Results showed that the extension peak torque BD decreased significantly (p < 0.05) at speeds of 60 to > 120 deg/sec, whereas…the flexion peak torque BD decreased significantly at speeds of 60 to > 180 deg/sec. These results appear to demonstrate that decreased activation of primarily slow-twitch muscle fibers may be responsible for the BD during dynamic knee extension and flexion exercise in women.
Abstract: The purpose of this study was to evaluate the reliability of two procedures that assess ankle dorsi/plantar flexion strength among adults 2:65 years of age. Twenty-two older (mean 72.8 years) volunteers completed two testing sessions in which isometric and isokinetic protocols measuring ankle dorsi/plantar flexion strength were performed. The inteNal between the two testing sessions was 1 week. Three maximum isometric trials for dorsi/plantar flexion were collected at each testing session using a hand-held dynamometer. Peak and average isokinetic eccentric and concentric strength were assessed at a test speed of 30 deg/sec using a Kin-Com 500H isokinetic dynamometer (Chattecx Corp.,…Chattanooga, TN). Intertrial reliability of the isometric measures was found to be high (r = 0.92 to 0.97) at both testing sessions. Test-retest reliability of the isometric procedures ranged from r = 0.76 to r = 0.85, and for isokinetic measures from r = 0.74 to r = 0.93. Both of these procedures yield reliable measures of ankle dorsi/ plantar flexion strength in older adults.
Abstract: Long space flights will require astronauts to perform progressive resistance exercise, which is difficult to achieve in microgravity, to maintain skeletal muscle strength and bone mineralization. We assessed changes in knee extensor strength in 10 healthy men in response to a 10-week ground-based training program of concentric and eccentric muscle contractions as well as plyometric movements. Isokinetic knee extensor strength and vertical jump were measured before and after the training period, which involved a progressive resistance protocol of horizontal jumps and squats using the Shuttle 2000-1 Cardiomuscular Conditioner (Contemporary Design Inc., Glacier, WA). This device provides resistance by use of…elastic cords attached to a movable sled positioned between two parallel runners on a fixed base. Both concentric and eccentric strength increased in the trained subjects relative to 10 untrained controls. Improvements in strength ranged from 21.5% for concentric contractions and 26.2% for eccentric contractions. We conclude that the Shuttle 2000-1 device effectively improved muscular strength.
Abstract: The purposes of this investigation were twofold: (1) to identify the repetition during which peak torque and maximum work occurred during isokinetic testing of the shoulder's internal/external rotators and (2) to determine if a significant difference existed between the test speeds and/or the dominant arm for both parameters. One hundred ninety-one healthy professional baseball pitchers participated in this study. Testing was performed using a Biodex isokinetic dynamometer (Biodex, Shirley, NY) at 180 and 300 deg/sec for both the throwing and nonthrowing shoulders. All testing procedures were standardized and followed established guidelines for each subject. Statistical analysis was performed using a…paired t test with a p≤0.01 level of significance. No statistically significant differences were demonstrated between or among matched pairs for test speed or arm dominance during isokinetic testing of the shoulder's internaVexternal rotators. Both peak torque repetition and maximum work repetition occurred most frequently between the second and fourth test repetitions for all parameters evaluated. This investigation offers clinical relevance for investigators using isokinetic testing of the shoulder internal/external rotators by demonstrating an optimal range of test repetitions to ensure the adequate assessment of peak torque and maximum work parameters.
Keywords: Isokinetics, shoulder testing, peak torque repetition, maximum work repetition
Abstract: The purpose of this investigation was to determine the effect of test protocol on concentric and eccentric torque production of the rotators of the shoulder. Twenty-eight female subjects were randomly assigned to participate in either a continuous (no pause between concentric and eccentric contractions) or interrupted (5-second pause between contractions) measurement protocol. A Kin-Com dynamometer (Chattecx Corp., Hixson, TN) was used to obtain average torque measurements at 60 and 180 deg/sec for the shoulder rotators. Analysis of variance determined that there were no significant (p > 0.05) differences in average torque between test protocols for either muscle group. Intraclass correlation…coefficients (ICCs) ranged from 0.57 to 0.88 for the continuous protocol and from 0.83 to 0.94 for the interrupted protocol. Standard error of measurement estimates ranged from 0.7 to 1.5 Nm for the continuous protocol and from 0.5 to 1.4 Nm for the interrupted protocol. The results of this investigation demonstrate no differences in torque production between continuous and interrupted test protocols, although the interrupted measurement protocol provides greater reliability and precision of measurement than the continuous protocol when assessing torque production of the rotators of the shoulder.
Keywords: Rest interval, shoulder internal/external rotation, test reliability