Isokinetics and Exercise Science - Volume 3, 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 determine whether there was a difference in the amount of soreness and creatine kinase (CK) produced between isokinetic eccentric knee flexion and extension exercise. The subjects included 24 female college students with a mean age of 21.6 ± 2.0 yr. Two groups of eight subjects performed three sets of 35 isokinetic unidirectional eccentric contractions at 120 deg/sec on a Biodex isokinetic dynamometer. Group 1 performed eccentric contractions of the knee extensors (quadriceps femoris muscle) and group 2, knee flexors (hamstring muscle). Group 3 served as a control. Subjects in the exercise groups attempted…to maintain the intensity of the contractions at 80% of their respective isokinetic concentric 120 deg/sec peak torque, and each set was separated by a 2-min rest period. Blood samples were collected for CK, an indicator of muscle damage, at the following intervals: pre-exercise, and 1, 24, 48, and 72 h postexercise. Perceived soreness of the quadriceps femoris muscle and hamstring muscles was assessed by a 0–10 point scale, concurrently. The highest postexercise CK and soreness values were 261, 6,037, and 87 IU/L and 0.9, 4.1, and 0 pain scale units for groups 1, 2, and 3, respectively. Analyses of variance using a split plot factorial design found significant log CK (F = 25.0, P < 0.01) and soreness (F = 41.7, p < 0.01) differences between the three groups. Contrast-contrast testing found significantly higher elevations of log CK and soreness 48 and 72 h postexercise in group 2 when compared with group 1 (p < 0.01) and group 3(p < 0.01). This study demonstrates that after isokinetic eccentric exercise of this type the hamstring muscle is markedly more vulnerable to delayed muscle soreness and muscle damage than the quadriceps femoris muscle.
Abstract: The purposes of this study were to (1) determine and compare the cardiovascular (CV) responses (i.e., exercise and recovery heart rate and recovery blood pressure) to weight training (WT) exercise and a graded exercise test (GXT) on a cycle ergometer, and (2) to determine and compare the exercise and recovery heart rate (HR) and recovery blood pressure characteristics to several intensities of WT exercise. Nineteen weight-trained men (mean age = 24.5 ± 2.9 yr) performed the squat WT exercise for sets of 10 repetitions at 50%, 60%, 70%, 80%, 90%, and 100% of their 10 repetition maximum (RM). HR was…continuously monitored, and systolic (SBP) and diastolic (DBP) blood pressures, and rate pressure product (RPP; HR × SBP × 0.01) were recorded at T1 (15–30 sec postexercise), T2 (1 min postexercise), T3 (2 min postexercise), and T4 (3 min postexercise). Maximal mean CV responses at T1 during WT were: HR = 154.1 ± 20.8 bpm (during 100% 10 RM), SBP = 172.8 ± 19.2 mmHg (90% 10 RM), DBP = 88.8 ± 8.2 mmHg (60% 10 RM), and RPP = 259.3 ± 44.5 (100% 10 RM). On a separate day, all subjects performed a discontinuous GXT while the same CV variables were recorded at T1. Mean maximal exercise responses at T1 during the GXT were: HR = 161.5 ± 15.6 bpm, SBP = 190.6 ± 25.6 mmHg, DBP = 82.9 ± 8.9 mmHg, and RPP = 307.4 ± 51.4. For WT, HR, SBP, and RPP were always significantly less (p ≤ 0.05) than the values for the GXT, except for HR at T1 of 100% 10 RM intensity, which was similar to the GXT T1 values. WT DBP at T1 was always significantly greater than GXT DBP, but the differences appeared to be of little physiological importance. Recovery WT responses (T1 – T4) showed consistent decreases across time for HR and RPP. WT DBP increased slightly, but significantly after all WT intensities. It was determined that, in response to WT, the HR responses during exercise and recovery, and the SBP and RPP responses during recovery were generally less than or equal to the respective responses to a discontinuous GXT. Although the DBP responses to WT were greater than the responses to the GXT, it was determined that the differences were small enough to be of little physiological importance.
Abstract: This study examined the relationship between concentric and eccentric average force, peak force, average torque, and peak torque of the shoulder internal and external rotator muscle groups in 33 male subjects. Testing of the nondominant side was accomplished with the shoulder at 90 degrees of abduction and the arm in the frontal plane. Peak values for both force and torque were obtained from the highest point in the strength curves, whereas average values were obtained across the entire curve. Correlation matrices found a relationship between the isokinetic parameters of r = 0.86 to 0.97 for concentric external rotation, r =…0.94 to 0.99 for eccentric external rotation, r = 0.86 to 0.96 for concentric internal rotation, and r = 0.55 to 0.97 for eccentric internal rotation. The strong relationship between average and peak force and torque suggests any of these isokinetic parameters may be used for assessment of human muscular performance. Factors that potentially confound the interchangeable use of these parameters include damp, ramp, preload, and the range of motion through which isokinetic assessment occurs.
Keywords: Average force, peak force, average torque, peak torque, shoulder rotators
Abstract: This study assessed the test-retest reliability of a protocol designed to measure isokinetic average torque, peak torque, and peak torque angle. The measurements were obtained during concentric shoulder and elbow flexion and extension and concentric and eccentric shoulder adduction, at 60 and 120 deg/sec, using the Kin-Com (II) dynamometer. The test and retest of 30 (18 men and 12 women) healthy subjects (mean age = 25 yr) were separated by exactly 1 week. The results demonstrated that the protocol can be used to measure average torque [intraclass correlation coefficient (ICC) range 0.921–0.982] and peak torque (ICC range 0.916–0.980) with high…reliability at the two angular velocities. Peak torque angle reliability results (ICC range 0.019–0.754) were considered unacceptable, suggesting that angle of peak torque is not a reliable measure of muscle performance. This protocol has advantages for both clinical and research application in that it is time efficient, can be conducted by one examiner, and uses positioning methods suitable for both able-bodied and lower limb-disabled subjects.
Keywords: Reliability, average torque, peak torque, specific torque angle, upper extremity
Abstract: The purpose of this study was to examine the validity of the average and peak torque values of the knee extensor and flexor musculature obtained through the data extraction technique. Twenty women (age = 20.2 ± 1.01 yr; height = 169.0 ± 6.8 cm; weight = 60.8 ± 5.5 kg) were assessed for isokinetic peak and average torque of the knee musculature at a velocity of 90 deg/sec. Subjects were randomly assessed through a range of motion of 5–90 deg and 25–70 deg. Peak and average torque values within a range of motion of 25–70 deg were extracted from the…tested range of motion of 5–90 deg. Correlational analyses between the tested and extracted variables revealed relationships ranging from r = 0.79 to 0.95. Paired t tests found no significant differences (p < 0.006). These findings suggest that the data extraction techniques are valid.
Keywords: Data extraction, validity, knee flexors/extensors
Abstract: The purpose of this study was to examine the appropriateness of isokinetic assessment in patients with multiple sclerosis (MS). We tested a group of 15 patients with a value of 2 to 3 on the Kurtzke disability status scale (DSS) and we compared that group with a similar healthy age- and weight-matched control group. All the patients underwent a maximal isokinetic test of knee flexion and extension at the angular speeds of 120 deg/sec, 60 deg/sec, and an endurance and work recovery test at 180 deg/sec. Data were collected using a Cybex 350. Several muscular parameters relating to peak…torque, work, and power were assessed. There were significant differences of these group results on most of the measured parameters. There was a deficit of 46% in peak torque in flexion and 30% in extension, thought to be related to the deficit in motor unit recruitment. Moreover, in comparison with the control group, the total work at 180 deg/sec (−55%) and the average muscular power (−45%) were significantly impaired. The higher deficit of the flexors compared with the extensors may be related to both the hypertonicity rate of the quadriceps and disturbances of reciprocal inhibition time during the alternate movement. From a morphological point of view it appears as a deficit in the muscle tension development in the initial part of the flexion curve. Our results, in contrast, do not show significant differences between the two groups in relation to endurance ratio and work recovery. This is in contrast to the increased fatigability commonly reported by MS patients. The explanation could be that fatigue in this disease has a mainly central origin, due to the impairment in motor control, whereas by means of isokinetic methods we explore the peripheral muscle fatigue linked to the muscular energy exhaustion.
Abstract: The evaluation of strength and the development of methods to improve strength in the lower extremity are integral areas of interest in biomechanics and athletic training. Contemporary research has established that (1) the hip extensors and the hip flexors are the strongest muscle groups within the lower extremity, and (2) the extensors are the primary movers by acceleration of the body's center of gravity. Thus, the purpose of this study was to determine the relationship between sprint speed and hip flexor/extensor strength measured from a functional position. Forty-one intercollegiate athletes (mean age-19.4 yr, mean weight = 194.5 lbs) participated in…this study. Sprint speed (SS) was determined from the mean of three 40-yard sprints on artificial turf. Muscular assessment was performed using a Cybex II isokinetic testing device. Test speeds of 60 deg/sec and 240 deg/sec were selected for assessment of peak torque (PT), peak torque/body weight (PT/BW), torque acceleration energy (TAE), average power, flexion/extension ratios, and endurance ratios. Unlike previous research, this strength assessment was performed from a functional standing position (right leg testing). A reliability study established consistency of strength measures on different occasions. Absolute intraclass correlation coefficients (ICC) of 0.91, 0.96, 0.93, and 0.82 were established for flexion at 60 deg/sec, extension at 60 deg/sec, flexion at 240 deg/sec, and extension at 240 deg/sec, respectively. Results of regression analysis showed significant (p < 0.01) correlations between SS and flexion PT/BW at 60 deg/sec (r=−0.57), extension PT/BW at 60 deg/sec (r=−0.56), flexion PT/BW at 240 deg/sec (r=−0.42), and extension PT/BW at 240 deg/sec (r=−0.41). This study suggests that when tested functionally, there appears to be a strong relationship between hip flexion and extension strength relative to body weight and SS. Additionally, it suggests that a cause/effect relationship could exist between enhanced hip flexion/extension strength and sprint speed.
Keywords: Sprint speed, functional concentric assessment, hip flexor/extensor ratio
Abstract: We examined the interaction between velocity and progression order on average power and torque production during isokinetic velocity spectrum exercise (lVSE). Twenty-two subjects were assigned randomly to four exercise trials, each containing an isokinetic exercise session involving the dominant knee extensors. Each exercise trial consisted of two sets of 10 repetitions at velocities of 30, 90, 150, and 210 deg/sec (0.52, 1.57, 2.62, and 3.66 rad/sec). Before and after the exercise trials, peak torque (Nm) was assessed and showed no change (training effect) at any of the four velocities. Analysis of the experimental muscle function measurements showed a significant difference…for the main effects of protocol for average power (W) and torque (Nm), and for the main effects of velocity for average power and torque. In addition, a significant interaction was found for both average power and torque. Within the velocity spectrum studied, performance of faster velocity contractions before progressing to slower velocities during IVSE is recommended when power or torque production is important.
Keywords: Isokinetic exercise, average power, average torque, muscle fatigue
Abstract: We investigated the effects of different sequences of concentric isokinetic test speeds on knee extensor muscle peak torque production, and attempted to validate the findings of previous studies suggesting that slow test speeds should precede fast test speeds. Under a sequential repeated-measures paradigm, which included a test-multiple retest design, 72 subjects (39 males, 33 females; ages 17–28 yr) were randomly assigned to one of six groups for the testing of a randomly selected extremity on a Cybex 340 dynamometer system. Each test group was subjected to a different order of slow (60 deg/sec), intermediate (180 deg/sec), and fast (300 deg/sec)…speeds in a sequential manner. Testing occurred on six different days, each separated by 48 h, for each group and consisted of a standardized cardiovascular and isokinetic warm-up followed by peak torque data collection across five maximal efforts at each speed. Multifactorial analysis of variance showed significant differences (p < 0.001) between speeds, but not between sessions or the combined factors of speeds and sessions across the experiment. A post hoc Scheffe test confirmed the differences between speeds (p < 0.01). Results of intraclass correlation coefficient tests showed a high level of reliability (0.81) across both test speeds and sessions. It was concluded that isokinetic test speed order did not affect concentric peak torque measurements, that distinct differences existed between the individual test speeds, and that the procedures afforded a high degree of muscle performance measurement consistency.
Keywords: Concentric knee extensor torque, test speed sequence