Isokinetics and Exercise Science - Volume 9, issue 2-3

Authors: Mayer, F. | Baur, H. | Hirschmüller, A. | Heitkamp, H.C. | Horstmann, T. | Dickhuth, H.H.

Article Type: Research Article

Abstract: Muscular balance appears to be decisive for dynamic shoulder stability, since passive stabilizers do not take effect until the end of range of motion in order to not limit joint mobility. Changes in strength relationships are frequently viewed as one of the causes of shoulder pathologies. However, objective quantification of reciprocal strength relationships is difficult. In particular, the influence of movement velocity on the strength ratios during the test has not been clarified. Determination …of the strength relationships of reciprocal muscle groups (quotient of maximum torques) was performed on a total of 166 untrained men (M) and 83 untrained women (F) for extension/flexion, abduction/adduction and rotation movements of the shoulder. Moreover, differentiation was made by various working modes and movement velocities (isometric at various angle positions, concentric at 60°/s and 180°/s, eccentric at 60°/s and 120°/s). The results show a decreasing order of strength relationships: Abduction/Adduction > Flexion/Extension > External/Internal rotation. In spite of marked differences in absolute values, no differences were noted among the contraction modes (isometric, concentric, eccentric) or movement velocities (p>0.05). A slightly reduced ratio of rotational movements in concentric mode was the only conspicuous finding. Unlike isokinetically-determined absolute torque values, a relevant velocity-dependence must not be expected with respect to reciprocal strength relationships of the shoulder muscles. A different (neuro)-muscular structure of the muscle groups involved with a corresponding effect on the strength-performance ratio thus does not appear to be present or cannot be detected in isokinetic tests. However, further research is warranted regarding the effect of the various associated factors (e.g. stabilization) on the reliability and validity of isokinetic findings relating to this specific joint-muscles system. Show more

Keywords: Isokinetics, shoulder, strength ratio, velocity

DOI: 10.3233/IES-2001-0068

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 73-77, 2001

Authors: Gulick, Dawn T. | Dustman, Chrisa S. | Ossowski, Laura L. | Outslay, M. Duncan | Thomas, Christine P. | Trucano, Sean

Article Type: Research Article

Abstract: {\it Purpose:} To examine the normal strength relationship between eccentric external rotation (EccER) and concentric internal rotation (ConIR) strength ratios of the shoulder in the dominant and non-dominant extremities of healthy subjects. {\it Methods:} Fourteen men and sixteen women were tested in the scapular plane using two angular velocities: 90 and 120°/s. The dependent variables were: peak torque (PT), work per repetition (W/rep), and total work (TW) ratios. {\it Results:} The EccER: …ConIR ratio in a non-athletic population was significantly greater (p < 0.05) for the dominant than the non-dominant extremities for PT, W/rep, and TW. There was no significant difference in torque production between the two-isokinetic velocities. W/rep and TW ratios were significantly higher in females than in males. Although PT was not statistically significant, a similar relationship existed (p=0.069). {\it Conclusion:} In a healthy, non-athletic population, when tested at 90 or 120°/s, the EccER is just slight greater than its ConIR counterpart in women and men alike. Show more

Keywords: Isokinetic, torque ratios, shoulder strength

DOI: 10.3233/IES-2001-0070

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 79-84, 2001

Authors: Gajdosik, Richard L. | Leslie, Chad M. | Thorne-Thomsen, Aric A.

Article Type: Research Article

Abstract: The purpose of this study was to examine the influence of short hamstring muscles (hamstrings) on gravitational torque of the leg (GT) and on knee extension and knee flexion concentric isokinetic torque. Fifteen non-disabled men (ages: 18 to 37 years) with clinically short hamstrings (passive straight-leg-raising ≤ 65°) were measured for the GT in two positions: 1) seated position that included a passive stretch of the hamstrings, and 2) supine position that did not include a …passive stretch of the hamstrings. Subjects performed three trials of maximal concentric knee extension and flexion in the seated position under four randomly ordered conditions (60°·s^{-1} with seated GT, 60°·s^{-1} with supine GT, 180°·s^{-1} with seated GT, and 180°·s^{-1} with supine GT). One-way ANOVA analysis showed that the GT measured while seated (36.00 ± 9.58 Nm) was greater than the GT measured while supine (21.00 ± 3.90 Nm) (P < 0.001). The greater GT while seated was explained by the sum of the passive hamstring torque and the true GT. Knee flexion peak torque, knee flexion average torque, and the hamstring/quadriceps average torque ratios were decreased at 60°·s^{-1} (P ≤ 0.023) using the seated GT compared to using the supine GT. The same torque characteristics did not differ significantly for knee flexion at 180°·s^{-1} , or for knee extension at either isokinetic speed. We concluded that hamstring passive torque contributed to greater GT in the seated position, which caused invalid knee flexion torque measurements when tested at 60°·s^{-1} . This evidence supports weighing the leg supine in order to remove hamstring passive torque and to ensure valid knee concentric isokinetic torque measurements when testing at 60°·s^{-1} . Show more

Keywords: Isokinetic testing, knee muscles, short hamstring muscles

DOI: 10.3233/IES-2001-0071

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 85-90, 2001

Authors: Mandalidis, D.G. | Florides, P. | O'Brien, M.

Article Type: Research Article

Abstract: During isokinetic shoulder elevation in the coronal and sagittal planes, the centre of rotation of the glenohumeral joint was displaced 8-cm vertically relative to the centre of rotation of the dynamometer's actuator arm. It was suggested that in order to account for this displacement, the recorded maximum moment values should be reduced by 12.5%. displacement of the glenohumeral centre of rotation (DGCR) during isokinetic shoulder elevation in the scapular plane and to conduct an error analysis …of the dynamometer's moment recordings. The DGCR was assessed in twenty healthy volunteers, during isokinetic concentric elevation of the left shoulder, in the scapular plane, using a two-dimension motion analysis system. Measurements were performed at 30, 60 and 120°·s^{-1} , between 30--90° of shoulder elevation and were analysed every 12°. The glenohumeral centre of rotation was superomedially displaced relative to the centre of rotation of the actuator arm, throughout shoulder elevation (P < 0.001). The effect of isokinetic velocity on the DGCR was not significant. The DGCR resulted also in changes of humeral lever arm orientation and length relative to the pre-set orientation and length of lever arm. As a result of these changes, dynamometer's recordings underestimated corrected angle-based maximum moments by ≤ 6.2%. isokinetic elevation of the shoulder in the scapular plane was probably attributed to normal kinematics of shoulder elevation that requires synchronous function of both the scapulothoracic and glenohumeral joints. The cutaneous markers and the 2-D kinematic analysis system used for the assessment of a 3-D shoulder motion may effect the precision in detecting movements of the shoulder under the skin. The present findings are also limited to the position, stabilisation method and range of motion tested. Show more

Keywords: Isokinetic, shoulder elevation, centre of rotation, alignment, scapular plane

DOI: 10.3233/IES-2001-0072

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 91-99, 2001

Authors: Mandalidis, D.G. | Donne, B. | O'Regan, M. | O'Brien, M.

Article Type: Research Article

Abstract: The reliability of gravity corrected average and peak isokinetic moment of the shoulder elevators in the scapular plane, was assessed in 22 male college students without shoulder or neck pathology. Measurements were performed on two occasions, 7 days apart, by the same examiner. Both dominant and non-dominant sides were examined at 60 and 120°·s^{-1} , using Kin Com II dynamometer. Each volunteer was assessed in the seated position, elevating the shoulder …between 30--90° with the elbow in extension and the forearm in pronation. Reliability of both non-free and free of transient moment-oscillations (TMO) peak and average moment data (data selected from the entire range and the range of motion where isokinetic velocity was constant and equal to the pre-selected angular velocity, respectively) was determined using the intraclass correlation coefficient (ICC 3,1). The variability of isokinetic moment data associated with normal fluctuations of strength performance over repeated measurements (inter-session variability) was determined using the standard error of measurement (SEM) and the limits of agreement (LOA). The ICC (3,1) values ranged between 0.86--0.95. Inter-sessions variability of isokinetic moment data calculated using 95% Both SEM and LOA revealed lower variability for average compared to peak moment data, non-free compared to free of TMO average moment and for free compared to non-free of TMO peak moment data. Higher ICC values and lower variability was also obtained for peak moment data at the isokinetic velocity of 60 compared to 120°·s^{-1} and for most of the moment data recorded on the dominant compared to the non-dominant side. The present findings suggest that strength changes observed over repeated isokinetic measurements of the shoulder elevators in the scapular plane, may be better identified under certain conditions but they should only be considered as significant changes if they are lower or greater than inter-session variability of isokinetic moment data. Show more

Keywords: reliability, isokinetic, shoulder elevation, scapular plane

DOI: 10.3233/IES-2001-0073

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 101-109, 2001

Authors: Mandalidis, D.G. | O'Brien, M.

Article Type: Research Article

Abstract: Peak and average moment of concentric elbow flexion was assessed in 30 males without previous elbow or shoulder injuries. Isokinetic assessment was performed with the forearm in supination and in the neutral position, at isokinetic velocities of 30, 60 and 120°·s^{-1} for both dominant and non-dominant sides. Eight volunteers were examined twice to determine test-retest reliability and estimate the variability of isokinetic moment data associated with normal fluctuations of strength …performance over repeated measurements (inter-session variability) using the intraclass correlation coefficient (ICC 3,1) and the 95% (95% 3.3--16.2 Nm, respectively. Our findings revealed higher reliability and lower inter-session variability for average compared to peak moment data, the dominant compared to the non-dominant side and at the angular velocity of 120 compared to 30 or 60°·s^{-1} . Isokinetic moment of elbow flexors was significantly greater with the forearm in supination compared to the neutral position (p < 0.001) regardless of the side or the isokinetic velocity used. Isokinetic strength of elbow flexion was significantly decreased, as the velocity increased p < 0.001). The dominant side was also stronger compared to the non-dominant side (p < 0.05). The results of our study suggest that elbow flexors can be reliably assessed with an isokinetic dynamometer. Consistent positioning of the forearm is necessary when isokinetic elbow flexion is monitored in longitudinal studies. A bilateral difference of less than 5% when the contra-lateral is used for comparison in pre and post-injury or rehabilitation situations. Show more

Keywords: Isokinetic, elbow flexion, supination, neutral position

DOI: 10.3233/IES-2001-0074

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 111-117, 2001

Authors: Smith, Jay | Padgett, Denny J. | Kotajarvi, Brian R. | Eischen, Joseph J.

Article Type: Research Article

Abstract: Scapular position has been hypothesized to influence rotator cuff function, but no current methods exist to reliably measure shoulder rotation strength in different scapular positions. The purpose of this study was to develop a reliable technique to measure isokinetic (ISOK) and isometric (ISOM) shoulder rotation strength with the scapula protracted. Ten healthy volunteers (5 male, 5 female, ages 20--41) completed two to three ISOM and five ISOK (90 degrees/second) internal rotation (IR) and external rotation (ER) …repetitions in a position of scapular protraction with the shoulder abducted 45 degrees in the scapular plane. Subjects returned 24--72 hours later to repeat testing. All torque measurements in the protracted position exhibited excellent intersession reliability (ICCs > 0.97). Shoulder rotational torque can be measured in the protracted scapula position with excellent reliability using the new technique described. Establishing the reliability of the protracted technique is a necessary prerequisite for the completion of future studies examining quantitative differences in rotational torque generation between the neutral and protracted scapula positions in the functional shoulder position of 45 degrees of scapular plane abduction. Show more

Keywords: rotator cuff, reliability, posture torque

DOI: 10.3233/IES-2001-0075

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 119-127, 2001

Authors: Dauty, Marc | Rochcongar, Pierre

Article Type: Research Article

Abstract: The aim of this study is to define the test-retest reproducibility for measuring the peak torque of the knee flexors according to the isokinetic concentric and eccentric muscle action. The tests were done in two sessions at a 21 day interval. Ten healthy national-level volleyball players, 24.3 years old ± 3.9 were included. Tests took place after the competition season. Evaluation was carried out with a Cybex 6000 dynamometer and the reliability was calculated according to …the intra-class correlation coefficient (ICC~2.1). The protocol consisted of 5 isokinetic concentric contractions at 180°/s followed by 5 isokinetic eccentric contractions at 30 and 60°/s. Results show an excellent reproducibility for isokinetic concentric peak torque at 180°/s. (ICC: 0.94) and very good reproducibility for isokinetic eccentric peak torque at 30 and 60°/s. (ICC: 0.86; 0.83). These results indicate that knee flexion strength at these velocities may be used to estimate the performance of volleyball players. Show more

Keywords: reliability, isokinetic, eccentric, hamstrings, volleyball

DOI: 10.3233/IES-2001-0076

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 129-132, 2001

Authors: Croisier, Jean-Louis | Forthomme, Bénédicte | Foidart-Dessalle, Marguerite | Godon, Bernard | Crielaard, Jean-Michel

Article Type: Research Article

Abstract: The purpose of this study was to determine the effectiveness of eccentric training models in treating various types of tendinitis and evaluate protection from re-injury when returning to causal activities. Isokinetic eccentric training was administered to 34 patients with chronic tendinitis (9 Achilles, 10 patellar and 15 epicondyllar) with a long duration of symptoms and failure of conventional treatment. Following training which consisted of 20 to 30 sessions of progressive increase of load and speed parameters, …a significant reduction of pain indicated by the visual analog scale (average initial value > 6.5, final score ≤ 2.5). Seventy four percent of the patients were completely relieved or presented marked decrease in symptoms when returning to sport and occupational activities, and only 12% state. At the end of treatment, isokinetic assessment revealed no significant concentric or eccentric peak torque asymmetries between involved and non-involved sides. In comparison with pretreatment ultrasound observations which showed systematic hypoechoic lesions and thickness, 14/34 patients recovered homogeneous tendon structure and normalization of the diameter and 15 presented improvement in echostructure. Our treatment model proposing isokinetic eccentric exercises presents a very satisfactory short-term effect on three different localizations of chronic tendinitis. Show more

DOI: 10.3233/IES-2001-0077

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 133-141, 2001

Authors: Micalos, P.S. | Marino, F.E. | Tarpenning, K. | Kay, D. | Gard, M.

Article Type: Research Article

Abstract: The purpose of this study was to examine the concentration of blood ammonia (NH_3 ) and lactate (La^- ) responses to separate isokinetic arm exercise (AE) and leg exercise (LE). Eleven healthy non-trained subjects (aged 18--22~yrs, 5 males, 6 females) completed 50 maximal effort concentric isokinetic contractions at 60°/sec for preferred arm (elbow joint) and leg (knee joint) on two separate occasions. Blood was drawn before exercise (Rest), immediately following …exercise (End-Ex) and 10 minutes post-exercise (Post-10) and analysed for NH_3 and La^- . The exercise intensity was assessed after exercise by presenting the mean (± SE) torque output as a percentage of the peak torque output following the 50 contractions for both AE and LE. The exercise intensity was 78.3 ± 1.4% AE respectively. The fatigue index is a ratio of beginning torque to end torque within the exercise period, which was 62.7 ± 3.7% 78.5 ± 2.8% statistically analysed by ANOVA with repeated measures. There was an increase in NH_3 following AE between Rest and End-Ex from 92.7 ± 7.6 μmol.l^{-1} to 115.3 ± 11.4 μmol.l^{-1} , p < 0.05. There was an increase in La^- following AE between Rest to End-Ex from 1.6 ± 0.10 mmol.l^{-1} to 2.8 ± 0.24 mmol.l^{-1} , p < 0.05. The La^- increased for LE between End-Ex and Post-10 from 2.4 ± 0.23 to 3.3 ±0.41 mmol.l^{-1} , p < 0.05. These data suggest a more severe metabolic stress during fatiguing concentric isokinetic AE compared with LE and are consistent with previous findings. Show more

DOI: 10.3233/IES-2001-0069

Citation: Isokinetics and Exercise Science, vol. 9, no. 2-3, pp. 143-149, 2001