Isokinetics and Exercise Science - Volume 4, issue 1
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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 purposes of this investigation were to examine (a) the relationship between total quadriceps cross-sectional area (CSA) and isokinetic peak torque at contraction velocities of 60 to 300 deg/sec, and (b) the relative contributions of the (SA values of the individual muscles of the quadriceps to the models predicting peak torque at each contraction velocity. Forty-three men (mean age ± SD = 24 ± 5 yr) volunteered as subjects for this investigation. Peak torque values for leg extension (dominant leg) were determined at 60, 120, 180, 240, and 300 deglsec using a (ybex II isokinetic dynamometer (Lumex Inc., Ronkonkoma, NY).…The (SA values for the vastus intermedius, vastus lateralis, vastus medialis, and rectus femoris muscles were measured at mid-thigh using magnetic resonance imaging. Full model multiple regression analyses indicated that total quadriceps (SA significantly (p < 0.05) predicted peak torque at all contraction velocities (R = 0.61 to 0.73). Furthermore, the (SA of the vastus medialis was the most potent predictor of peak torque at each contraction velocity. Factors that may have contributed to these findings include fiber type distribution patterns, biomechanical considerations, and/or muscle architecture.
Keywords: Magnetic resonance imaging, quadriceps cross-sectional area, correlation to isokinetic torque, prediction of individual muscle contribution
Abstract: The purposes of this study were (a) to investigate blood lactate accumulation (BLA) during a standardized isokinetic test and (b) to compare the BLAs of middle-distance runners and “sedentaries.” Seventeen subjects (mean age of 28.6 ± 5.5 yr), including seven middle-distance runners (national level) and ten sedentaries practicing recreational sports were evaluated. Testing involved unilateral use of the flexor and extensor muscles of the thigh. Exercise involved 5-second isometric tests at 0, 30, and 60 degrees, isokinetic tests at 60 and 180 deg/sec, and a 30-movement endurance test at 180 deg/sec beginning with the dominant extremity. Blood samples were taken…at rest, after each exercise set, 6 minutes after the completion of the initial extremity test, and 3 minutes after definitive stop for lactate analysis. Mean BLA of all subjects increased during both isometric and isokinetic exercises. However, there was no significant increase after isometric exercises. BLA reached 4.8 ± 1.42 mmol/L after the end of the first isokinetic endurance test (significant at p < 0.001) to the seated rest value. Mean BLA values obtained for the second extremity are greater than those of the initial value at p < 0.001. At R3, BLA increased to 7.02 ± 2.62 mmol/L. The BLA values of “sedentaries” were higher than those of the middle-distance runners: 2.74 ± 0.67 versus 1.61 ± 0.84 mmol/L at 180 deg/sec or 8.22 ± 2.22 versus 5.3 ± 2.23 mmol/L (significant at p < 0.01) 3 minutes after definitive stop. This study demonstrates that short (6–10 sec) heavy isokinetic exercise and isokinetic endurance tests increase blood lactate concentration. These results indicate that metabolic conditions at the beginning of the second extremity test differ from those of the initial rest conditions.
Abstract: Exercise consisting of muscle actions performed against an accommodating resistance at a linear rate of acceleration is provided via the isoacceleration mode of the LIDO Active dynamometer. Theoretically, these controlled concentric accelerative movements and eccentric decelerative movements more accurately reflect real-life muscular conditions than conventional isokinetic movements. The purpose of this study was to determine the concentric and eccentric reliability of the isoacceleration mode of the LIDO Active dynamometer at two rates of acceleration: 180 and 500 deg/sec/sec. Thirty normal subjects (mean age = 28.8 ± 5.66 years) participated. The quadriceps muscle group of the dominant lower extremity was tested…on three occasions over a 3-week period, with at least 48 hours but no more than 7 days separating test sessions. After a 5-minute warm-up consisting of stationary cycling, five maximal effort concentric and eccentric quadriceps contractions were recorded at each rate of acceleration during the last two test sessions. The first session was used as a learning trial and data were not utilized. Total work performed was collected and divided by the number of repetitions to yield average work per repetition. An analyses of variance showed no significant differences between corresponding values obtained across the test sessions, indicating reliability. An intraclass correlation coefficient (ICC 1, 1) was then calculated to determine the level of reliability of measures. The ICC for concentric and eccentric contractions at 180 deg/sedsec was 0.96 and 0.89, respectively. The ICC for concentric and eccentric contractions at 500 deg/sec/sec was 0.92 and 0.86, respectively. These results indicate high reliability of the isoacceleration mode of the LIDO Active dynamometer in a test-retest situation at the acceleration rates investigated for the quadriceps femoris. The establishment of sufficiently high reliability allows for continued research into the efficacy of controlled isoaccelerative exercise.
Keywords: isoacceleration, reliability, concentric and eccentric patterns
Abstract: The reliability of the trunk Biodex unit (Shirley, NY) was assessed in asymptomatic men (n = 30) and women (n = 29) 20 to 35 years of age. Flexion peak torque (FPT) and extension peak torque (EPT) and maximal repetition work (MRW) were evaluated at 60, 120, and 150 deg/sec. Variables were measured on two occasions on each of 3 days. Data were analyzed using analysis of variance with repeated measures (p < 0.01). Reliability was estimated by intraclass correlation coefficients. For men, EPT at 60 deg/sec on day 1 was significantly lower than on days 2 and 3. For…women, values on day 1 were significantly lower than on days 2 and 3 for all parameters measured except EPT at 60 deg/sec, FPT at 60 and 150 deg/sec, and FMRW at 60 and 120 deg/sec. The occasion effect was nonsignificant for women. For men, values for FPT at 60 and 120 deg/sec were significantly lower on occasion 2, suggesting a fatigue effect. Reliability coefficients ranged from 0.81 to 0.98 for men and women, with the exception of EMRW at 150 deg/sec for men (R = 0.54) and 60 deg/sec for women (R = 0.57). Reliable Biodex trunk strength values can be obtained using 1 day of testing for men, except for EPT at 60 deg/sec, which requires 1 day of practice. Women require 1 day of practice for most of the parameters tested. It is not necessary to test men or women twice on the same day. Reliable EMRW at 150 deg/sec for men and 60 deg/sec for women was not achieved.
Abstract: The purpose of this study was to determine, for measurements of lateral trunk flexion strength obtained by hand-held dynamometry, the reliability and effects of side of dominance, gender, age, weight, and height. Twenty six subjects (19 women, seven men) 50 to 79 years of age participated. Lateral trunk flexion strength was measured bilaterally with a strain gauge dynamometer while subjects were seated and manually stabilized. Repeated measurements differed significantly, but intrasession values were reliable (intraclass correlation coefficients > 0.95) bilaterally. Measurements of the dominant and nondominant side were significantly different but highly correlated. Gender, weight, and height were, but age…was not, correlated significantly with strength. The multiple correlation of gender, weight, and height with strength was 0.906 on the dominant side and 0.883 on the nondominant side. The results suggest that side, gender, weight, and height should be considered when reporting normal values.
Abstract: The purpose of this study was to investigate, using the Biodex B2000 isokinetic dynamometer (Biodex Corp., Shirley, NY), differences between surgical and nonsurgical back-injured patients referred to a functional restoration facility by an orthopedic surgeon for physical therapy. Return-to-employment information and other pertinent therapeutic data were also tabulated. The subjects were 12 patients who had recently undergone back surgery and 44 nonsurgical patients presenting with a chief complaint of mechanical low-back pain. Data of the two groups were factored and compared using paired t tests with 0.05 chosen as the level of significance. Pretherapy and posttherapy isokinetic data for the…nonsurgical group were all found to be significant, with the exception of flexion variance (p = 0.159). The surgical group made substantial progress in all isokinetic parameters and significant progress with peak extension, total extension, and extension as a percentage of body weight (p < 0.0044). It was concluded that trunk force production strength can be increased through a highly structured, medically directed functional restoration program and a high level of return to work achieved.
Keywords: Trunk force production, functional restoration, surgical status
Abstract: Eccentric muscle activation has been found to play an important role in athletic pursuits. Interest in the biomechanics of performance has led increasingly to the examination of muscle action. The concentric/ eccentric ratio of a muscle may be altered by activity, which led to our purpose of determining if the ratio of concentric to eccentric activation of the quadriceps femoris differs between sprint-type athletes and individuals of normal activity level. Eight sprinters and 10 normal individuals were evaluated on a KinCom dynamometer at 180 deg/sec in both concentric and eccentric maximal efforts. We found no significant difference in the concentric/eccentric…ratio (0.78 sprinters versus 0.75 normals) of these two groups. Implications for the clinician and further research were discussed.