Isokinetics and Exercise Science - Volume 3, 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 relationship between the electromyographic signal and local muscle fatigue is reviewed with focus on the electromyographic power spectrum analysis. The effect of neurogenic factors and peripheral factors, including muscle fiber composition, muscle force level, type of muscle activation, mechanical vascular compromise, muscle architecture and length-tension relationship, and posture on the electromyographic power spectrum signal are discussed. Clinical applications are also discussed.
Keywords: Electromyographic signal, local muscle fatigue, spectral parameters
Abstract: Many workers have jobs that require the physical capacity to lift on a regular basis. When preparing for these jobs or retraining for these jobs after a back injury, the question is whether it is necessary to retrain the knee extensors, the trunk, or both. The purpose of this study was to determine whether an 8-wk isotonic training program designed to increase knee extensor strength could result in increased lifting ability. Fifteen physical therapy students, ranging in age from 23 to 28 years, volunteered for the study and were randomly assigned to either a treatment or a control group. Both…groups were pretested for strength using the Cybex 340 (Cybex Inc., Ronkonkoma, NY) extremity unit to test concentric knee extensor torque (at 60, 90, and 120 deg/sec), the Cybex Liftask to measure isometric and concentric isokinetic lifting (18 inches/sec), and a modified milk crate to measure maximal functional lifting. The treatment group participated in an 8-week strength and flexibility training program, whereas the control group participated in only the flexibility program. At the end of 8 wk all subjects were retested. At baseline, no significant correlations were found between knee extensor peak torque production and isometric or isokinetic lifting ability for either group. The treatment group showed a significant increase in knee extensor peak torque production at 60 deg/sec (p < 0.01), 90 deg/sec (p < 0.01), and 120 deg/sec (p < 0.02). However, a significant correlation was found between the change in knee extensor peak torque production at 60 deg/sec and the change in functional lifting ability for the treatment group (r = 0.5125, p < 0.05). These results suggest that it may be helpful to increase functional lifting ability by isotonically training the knee extensors.
Keywords: Back lifting ability, knee extensor strength, isokinetic assessment
Abstract: The aim of this study was to investigate the response of heart rate during functional isokinetic testing of muscle. Testing involved unilateral use of the flexor and extensor muscles of the thigh (knee test). After a 10-min warm-up on a cycle ergometer, one leg was tested after the other, starting with the dominant limb. Exercise involved 5-sec isometric tests with extension, and then flexion at 0, 30 and 60 deg, isokinetic tests at 60 and 180 deg/sec, and a 30-movement endurance test at 180 deg/sec. Heart rate was recorded on average over 5 sec and was analyzed at the start…and end of exercise. Mean values were determined for 25 regular participants in sporting activities: distance running (n = 6), rugby (n = 11), and diverse recreational sports (n = 8). Respective increases in heart rate during exercise for the first and second legs were 50 and 67% in isometry, 87 and 102% at 60 deg/sec, 67 and 83% at 180 deg/sec, and 135.5 and 142.5% in endurance. Maximal values were reached in endurance testing, with respective means of 156.3 ± 16 bpm and 160.9 ± 17 bpm for the first and the second leg. Analysis of the individual curves for each subject showed maximal values of 181 and 188 bpm, i.e., 93 and 96.5% of the maximum theoretical heart rate (220 – age). Three minutes after testing the heart rate was 93.3 ± 16.8 bpm, i.e., 41.3% above the pretest resting rate. The results demonstrate the importance of the heart work rate imposed by these tests, which only brings into play a relatively limited muscle mass. The endurance test, which is more strenuous, should only be used with subjects free of cardiac risks. This study confirms that an isokinetic test must be performed under the supervision of an appropriate clinician, who should judge the value and feasibility of the endurance test.
Abstract: This study examined the reliability and interrelationships among isometric and isokinetic measurements of forearm pronation and supination strength. Twenty-one healthy men and 22 healthy women were tested at 0, 60, and 120 deg/sec angular velocities using a Cybex 340 dynamometer. Averaging scores over two test occasions was required to produce acceptable reliability coefficients for each gender (intraclass correlation coefficient > 0.75). Overall, men and women demonstrated similar correlations. Isometric torques were modestly related to isokinetic torques during pronation (r = 0.48–0.72; p < 0.05), but highly related during supination (r = 0.81–0.93; p < 0.01). Torques produced by the dominant…arm tended to be highly related to those produced using the nondominant arm (r = 0.68–0.83 during pronation and r = 0.79–0.92 during supination; p < 0.01). The predictive utility of these data should be interpreted with the objective of predicting a range of possible scores rather than a single precise score.
Keywords: Isometric, isokinetic, reliability, forearm, pronation and supination strength
Abstract: The purpose of this study was to describe the reliabilities and determinants of isometric pronation and supination forces obtained with a hand-held dynamometer. Healthy volunteers (12 women, 12 men) were tested twice on each side on two nonconsecutive days by each of two testers. Reliabilities of pronation and supination forces between trials. testers, and days were described separately by mean percentage differences. Values ranged from 0.4 to 6.8%. Intraclass correlation coefficients (Ices) were derived using the mean square value of repeated measures analysis of variance (ANOVA) procedures and the ICC equation (3.1). All ICC values were 0.904 or above, indicating…a high degree of reliability. The extent to which gender, muscle action, and side of dominance influenced force measurements were summarized descriptively and examined by multifactorial ANOVA procedures. The results indicated female subjects generated forces that were 52.0% of those generated by male subjects. The dominant side pronation forces were 15.8% greater than those on the nondominant side, whereas supination forces were 4.3% greater on the dominant side. Overall supination forces were 6.2% greater than pronation forces. The ANOVA showed significant differences between genders and between actions, but not between sides. The results of this study of healthy subjects provide evidence of the reliability of hand-held dynamometer measurements of forearm pronation and supination farces, When used clinically. such forces should be interpreted tn regard to gender and action.
Abstract: A single subject design was used to determine the biomechanical relationship of treadmill and water running. Literature review allowed electromyographic data of treadmill running to be a comparison point with video analysis of water running. Relatively large differences exist that bring into question how closely water running can substitute for land/treadmill activity. The authors discuss multiple implications and differences.
Keywords: Video analysis, water running, treadmill running
Abstract: The purpose of this study was to examine whether there is a significant difference in isokinetic concentric knee extensor torque measured by the nonpowered mode versus the powered mode of the Cybex 6000. The non powered mode allows free acceleration, whereas the powered mode controls acceleration. The impact of this difference on measurements of work and peak torque has not previously been investigated. Thirty female volunteers with a mean age of 24.8 were sequentially assigned to groups that began testing on the powered mode while the alternates began on the non powered mode. All subjects were then tested on each…mode of the Cybex 6000 at 180 deg/sec of maximal knee extension. The computer software of the Cybex 6000 calculated the mean of the peak torque and work values by averaging the last three of five test repetitions. Both the mean peak torque and the mean work values obtained in these two modes were then compared. The results of paired t tests indicated that there is no significant difference between mean peak torque values as measured during the non powered mode and the powered mode, nor was there a significant difference in mean work values found between these two modes. These results indicate that values of peak torque and work obtained from testing in these two modes may be accurately compared in the clinical setting. Clinicians should note that this study documents only that this equivalence exists at 180 deg/sec for concentric knee extension using the preprogrammed controlled acceleration rate of the Cybex 6000.