Isokinetics and Exercise Science - Volume 6, issue 4

Authors: Weiss, Lawrence W. | Relyea, George E.

Article Type: Research Article

Abstract: Two force and two power variables were monitored during standardized multiple-joint, closed-chain, velocity-spectrum tests to ascertain if contiguous velocities produced discrete or redundant output. Measurements were obtained from 52 men and 50 women during squats performed at six velocities ranging from 0.51 to 2.04 m·s−1 . Main effects as well as the sex-by-main-effects interaction were significant (P<0.001) for all four variables. Therefore, post hoc tests were performed separately for men and women. Maximal squatting forces over the velocity spectrum produced force-velocity curves resembling classical single-joint ones. The highest force output occurred at the slowest test velocity as expected and signifcantly …decreased (P<0.05) for each increment in velocity for both men and women. Concurrently, maximal squatting power over the velocity spectrum produced power-velocity curves resembling classical single-joint ones. The highest power output ( $\overline{x}=1.26\mbox{ m}\cdot s^{-1}$ ) occurred as part of a plateau at intermediate velocities as expected and was signifcantly less at faster and slower velocities. However, maximal power output generally materialized at faster velocities for men ( $\overline{x}=1.54\mbox{ m}\cdot s^{-1}$ ) than for women ( $\overline{x}=0.97\mbox{ m}\cdot s^{-1}$ ). It appears the six squatting velocities used in this investigation elicit discrete force data for both men and women, and results for force and power resemble what would be expected for isolated single-joint testing protocols. However, it remains unclear why an apparent gender difference exists in the velocity at which the highest peak power is produced. Show more

Keywords: Accomodative resistance, Concentric contraction, Muscular force, Muscular power, Squat exercise

DOI: 10.3233/IES-1997-6401

Citation: Isokinetics and Exercise Science, vol. 6, no. 4, pp. 197-202, 1997

Authors: Jameson, Trevor D. | Knight, Kenneth L. | Ingersoll, Christopher D. | Edwards, Jeffery E.

Article Type: Research Article

Abstract: The purpose of this study was to determine the degree of correlation between isokinetic, isometric, and isotonic knee extension strength measurements and a one-leg vertical jump ground reaction force. Fifty-one volunteer students were put into three different groups (sedentary, partially trained, trained) depending upon their training level. All subjects performed an isokinetic, isometric, isotonic, and jump test as determined by a balanced latin square. One-leg vertical jump peak force was moderately correlated with isokinetic (r=0.57), isometric (r=0.54) and isotonic (r=0.68) peak force measurements. Partially trained subjects had the lowest correlations (r=0.26 to 0.56) to one-leg vertical jump peak force while …trained subjects had the highest correlations (r=0.81 to 0.85). Correlations among strength measurements were moderate (r=0.70 to 0.75). It is concluded that isokinetic, isometric, and isotonic peak force measurements are only moderately correlated to one-leg vertical jump, therefore they cannot be used independently to predict vertical jump ability. Show more

Keywords: Strength measurements, Functional skills, Correlation, Functional tasks

DOI: 10.3233/IES-1997-6402

Citation: Isokinetics and Exercise Science, vol. 6, no. 4, pp. 203-208, 1997

Authors: Kimura, Iris F. | Gulick, Dawn T. | Gasiewski, Edward

Article Type: Research Article

Abstract: The purpose of the study was to investigate the influence of visual feedback on concentric peak torque of the quadriceps and hamstrings muscles at 60 and 180°·s−1 . Testing was performed using the Biodex B-2000 isokinetic dynamometer. Fifteen male and 15 female asymptomatic subjects were each tested in the following randomly ordered conditions: (a) 60°·s−1 with visual feedback, (b) 60°·s−1 without visual feedback, (c) 180°·s−1 with visual feedback, (d) 180°·s−1 without visual feedback. Statistical analysis of two separate three-factor analyses of variance (ANOVA) with repeated measures (P<0.05) were used to examine the difference among test conditions. …Results indicated an increase in quadriceps concentric peak torque data due to the visual feedback in both genders, but visual feedback increased hamstrings peak torque for male subjects only. Both quadriceps and hamstrings concentric peak torque data decreased as velocity increased. Show more

Keywords: Isokinetics, Feedback, Muscle strength

DOI: 10.3233/IES-1997-6403

Citation: Isokinetics and Exercise Science, vol. 6, no. 4, pp. 209-214, 1997

Authors: Reimann, Uwe | Verdonck, Alexander J. | Wiek, Michael

Article Type: Research Article

Abstract: In this article the influence of a knee joint displacement in relation to the axis of the device on the results of torque, angle and angular velocity during an isokinetic test is theoretically investigated, using different tibial pads. In the case where the axis of rotation of the joint is not aligned with the axis of the device the test results become incorrect. However, due to the subjects activities during an isokinetic test the position of the joint changes all the time. The results of this theoretical investigation show that the errors of torque, angle and angular velocity …are in scale of the percentage displacement. This means for a lever arm of 40 cm and a displacement of 4 cm (this is a 10% shift) the error of torque and angular velocity is in scale of 10%, the error of the angle max. 10°. If a test is made with an instationary cuff, a torque correction will improve the results. The maximal error of torque for a shift of 10% can be reduced below 0,5%. A correct alignment of the subject on the isokinetic device in isokinetic testing is extremely important. If this adjustment is not made with special accuracy, errors can increase considerably. A comparison of both fixation types (stationary and instationary) does not show big differences concerning the error of measurement. This article describes some theoretical considerations and gives some theoretical explanations. Show more

Keywords: Isokinetics, Angle, Torque, Angular velocity, Joint displacement, Measurement error

DOI: 10.3233/IES-1997-6404

Citation: Isokinetics and Exercise Science, vol. 6, no. 4, pp. 215-221, 1997

Authors: Verdonck, Alexander J. | Reimann, Uwe | Wiek, Michael

Article Type: Research Article

Abstract: In this article we investigated the influence of a displacement of the knee joint in relation to the axis of the isokinetic device on the measured torque, angle and angular velocity during isokinetic knee extension/flexion. We analysed the motion of the knee joint of four young men with the CCD-camera system KINEMETRIX (ORTHODATA GmbH, Lüdenscheid, Germany) at different isokinetic speed (60° /s and 180° /s), using a device with a stationary (CYBEX 6000, LUMEX Inc., Ronkonkoma, NY) and a device with an instationary (LIDO ACTIVE, LOREDAN Biomedical Inc., Davies, California) tibial pad. The results show that the displacement of …the knee joint in relation to the axis of the device using the instationary (sliding) input cuff is greater than using the stationary cuff. The torque errors range from 0% to −15% using the stationary pad and from +10% to −20% using the instationary cuff. While it is impossible to correct the torque values using the stationary pad (the displacement cannot be measured), the sliding cuff allows a mathematical correction of the torque values after the exercise. The max. torque error can be reduced below 2%. The largest deviations in angle occur at the higher speed (180° /s). At the moment the knee is in full extension, the max. error amounts approximately 20°. At lower speed (60° /s) the max. error amounts around 10°. The device with the stationary input cuff produces more accurate results. The measurement errors are below 10°. Using the instationary cuff, the selected isokinetic speed of 60° /s and 180° /s had been kept well. Considering the angular velocity of the knee joint during a test session, no real isokinetic state could be found. The device with the stationary input cuff has no real isokinetic state of the knee joint during the ROM too. In addition, the speed control during the motion is insufficient. Analysing the different factors which can influence the test results, it must be said that a comparison of test results, receiving from different isokinetic devices, is not possible resp. very questionable at today's state of the art. Show more

Keywords: Isokinetics, Angle, Torque, Angular velocity, Joint displacement, Measurement error

DOI: 10.3233/IES-1997-6405

Citation: Isokinetics and Exercise Science, vol. 6, no. 4, pp. 223-233, 1997

Authors: T'Jonck, L. | Lysens, R. | Witvrouw, E. | Hulens, M. | Delvaux, K. | Peers, K.

Article Type: Research Article

Abstract: In the last decade, more attention is drawn to the complex function of the ankle joint. Isokinetic devices provide an objective and standardised protocol to evaluate the functional plantar and dorsal flexors strength at the ankle. The purpose of this study is to document the effect of positioning, sex and leg dominance on the plantar and dorsal flexion strength. Forty-six subjects (26 females, 20 males) were participated in this study on voluntary base (age range 19–31 year). They were in no way engaged in sports competitions. Isokinetic data was collected using a cybex-II dynamometer at two speeds (60 and 120° …/s) and in two positions (prone with extended knee and supine with 90° flexion at the knee and 45° at the hip). Statistical analysis of the peak torque to body weight ratio has revealed significant differences for the plantar as well as the dorsal flexors at 60° /s and 120° /s, with higher values in the prone extended position. We have only found differences between sexes in dorsal flexion at 60° /s for both legs in both positions. No significant differences were obtained between extremities. These findings suggest that plantar and dorsal flexion strength depend on the test position. Sex was a significant factor for dorsal flexion strength at 60° /s. The lack of differences between both legs is an advantage in pathological situations. The non affected limb can be used as a control value. We prefer the prone position with extended knee. Factors that influenced our conclusion are higher strength, better standardisation and better patient comfort. Show more

Keywords: Cybex, Plantar flexor, Dorsal flexor, Dominance, Position, Sex

DOI: 10.3233/IES-1997-6406

Citation: Isokinetics and Exercise Science, vol. 6, no. 4, pp. 235-241, 1997

Article Type: Other

DOI: 10.3233/IES-1997-6407

Citation: Isokinetics and Exercise Science, vol. 6, no. 4, pp. 243-246, 1997

Article Type: Other

DOI: 10.3233/IES-1997-6408

Citation: Isokinetics and Exercise Science, vol. 6, no. 4, pp. 247-248, 1997