Isokinetics and Exercise Science - Volume 7, issue 3

Authors: Burkett, Lee N. | Phillips, Wayne T. | Alvar, Brent | Bartelt, Lyle | Stone, William

Article Type: Research Article

Abstract: Since the early 1960's interest has risen for using electrical stimulation (ES) as a supplement to voluntary effort in strength training programs. The purpose of this study was to evaluate the effectiveness of ES combined with simultaneous maximum dynamic contraction. An experimental, randomized control group was used. The independent variables were three methods of training, (a) isotonic weight training, (b) isokinetic resistance, and (c) isokinetic with ES. The dependent variables measured were, (a) peak torque at …36^0 sec, (b) height in the vertical jump, and (c) time in the 50-yard sprint. Results were analyzed using a 3 times 6 split-plot design. No significant differences were found among groups for the design (F_{2,12} = 1.045, P 0.3816). It was concluded that in groups of healthy individuals, ES combined with dynamic contraction in a training program does not develop strength and/or functional capacity more effectively than isokinetic or isotonic contractions without ES. Show more

Keywords: electrical stimulation, strength, dynamic strength, speed, vertical jump

DOI: 10.3233/IES-1998-0024

Citation: Isokinetics and Exercise Science, vol. 7, no. 3, pp. 101-106, 1998

Authors: Keating, Jennifer L. | Matyas, Thomas A.

Article Type: Research Article

Abstract: This research investigated factors influencing unpredictable variability in dynamometric measurements. The criterion for inclusion in this review was that the standard error of measurement (SEM) associated with test procedures could be estimated. SEMs were determined using reported retest correlations and standard deviations of measurements. Subject factors found to influence variability were impairment and gender. Test factors implicated were movement direction and test speed. A strong relationship was indicated between score magnitude and …variability. SEMs derived from measurements of low scoring subjects do not appear appropriate for interpreting measurements of higher scoring subjects. Measurements of subjects who achieve higher dynamometry scores appear more variable than measurements of lower scoring subjects. Similarly, as test conditions facilitate higher scores eg lower test speeds, variability in measurements increases. SEMs employed by clinicians to interpret test results should be derived from a population with a mean measurement that is representative of the subject being tested. Show more

Keywords: dynamometry scores, measurement variability, SEM, subject factors, test conditions

DOI: 10.3233/IES-1998-0026

Citation: Isokinetics and Exercise Science, vol. 7, no. 3, pp. 107-121, 1998

Authors: Evetovich, Tammy K. | Housh, Terry J. | Johnson, Glen O. | Housh, Dona J. | Ebersole, Kyle T. | Smith, Douglas B.

Article Type: Research Article

Abstract: The purpose of the present investigation was to examine the effect of concentric isokinetic leg extension training on peak torque (PT) and mechanomyographic (MMG) responses. Twenty-one males were assigned into a training (TRN, n=12) or control (CTL, n=9) group. The training group performed six sets of ten leg extensions three days per week for twelve weeks at a velocity of 90\dgs. All subjects were tested every four weeks for PT and MMG responses at a velocity …of 90 dgs. The two-way mixed factorial ANOVA indicated a significant increase (p < 0.05) in PT over the twelve weeks for the TRN group but no significant change (p>0.05) in PT for the CTL group. For the MMG there was no significant (p>0.05) interaction, therefore, the TRN and CTL groups exhibited the same pattern of responses over the twelve-week training period. The reason for the increase in PT in the absence of a change in MMG may be due to hypertrophy and/or changes in other muscles involved in leg extension. Show more

DOI: 10.3233/IES-1998-0027

Citation: Isokinetics and Exercise Science, vol. 7, no. 3, pp. 123-128, 1998

Authors: Sorensen, H. | Zacho, M. | Simonsen, E.B. | Dyhre-Poulsen, P. | Klausen, K.

Article Type: Research Article

Abstract: During strength measurement using isokinetic dynamometers great care is usually taken to align the anatomical joint axis to the rotation axis of the machine's lever arm. This ensures agreement between joint angular position/velocity and the corresponding measurements from the machine's potentiometer. We examined the accuracy of this correspondence during concentric knee extension with subjects sitting upright and strapped to the machine's chair. Extensions were performed at 30 dg, 120 dg and 240 dg with …range of movement from 90 dgz knee flexion to full extension. We observed that due to compression of the soft tissue at the back of the thigh and elevation of the pelvis (despite strapping) the anatomical joint axis moved downward relative to the rotation axis of the lever arm. This caused discrepancies between joint angle measurements from the machine and from a knee-mounted goniometer of up to 33 dgz. These circumstances should be taken into account when muscle force-length-velocity relation studies are conducted using isokinetic machines. Show more

DOI: 10.3233/IES-1998-0028

Citation: Isokinetics and Exercise Science, vol. 7, no. 3, pp. 129-133, 1998