Isokinetics and Exercise Science - Volume 6, issue 2

Authors: Antonopoulos, J. | Gillquist, J.

Article Type: Research Article

Abstract: Sagittal translation of the tibia was examined in a static test with 90 N force at 20° of knee flexion and dynamically during knee extension in a Biodex machine using increasing quadriceps torque in six healthy volunteers. The translation increased in a non-linear fashion with increasing torque. Similar relative increases in quadriceps torque caused similar relative increases in translation in the different individuals. The dynamic translation at the individual maximum quadriceps torque was equal to the static 90-N translation. There was a negative correlation between the maximum quadriceps torque and the static 90-N translation. The results indicate that the quadriceps …torque is related to the amount of translation in the knee joint possibly by some feed back mechanism from the ligaments preventing abnormal translation. The findings also imply that a limitation of quadriceps torque around 80% of maximum would limit the strain in an injured ligament to a level not higher than what is caused by normal laxity measurements. Show more

Keywords: Knee kinematics, Sagittal plane translation, Isokinetic testing, Concentric quadriceps contraction

DOI: 10.3233/IES-1996-6211

Citation: Isokinetics and Exercise Science, vol. 6, no. 2, pp. 145-151, 1996

Authors: Miller, John P. | Catlaw, Kerriann | Angelopoulas, Charles

Article Type: Research Article

Abstract: The purpose of this study was to examine the effect of ankle position on knee flexor and extensor torque at 60 and 180°/s. Twelve female athletes had their dominant and non-dominant limb tested on a Cybex II + dynamometer (Cybex, Ronkonkoma, NY) under two conditions: with the ankle plantarflexed and dorsiflexed. Paired t-tests showed no statistical differences in knee extensor torque. Significant differences were noted in knee flexor torque at both 60 (P < 0.05) and 180 (P < 0.01)°/s with the greatest torque being seen with the ankle in the dorsiflexed position. These results suggest that ankle position affects …knee flexor torque during open chain isokinetic movements. Show more

Keywords: Ankle, Plantarflexion, Dorsiflexion, Knee, Torque

DOI: 10.3233/IES-1996-6212

Citation: Isokinetics and Exercise Science, vol. 6, no. 2, pp. 153-155, 1996

Authors: Fiebert, Ira M. | Pahl, Craig H. | Applegate, E. Brooks | Spielholz, Neil I. | Beernik, Karen

Article Type: Research Article

Abstract: The purpose of this study was to investigate knee flexion torque and changes in electro myographic (EMG) activity of the medial and lateral hamstrings during isometric knee flexion at different angles. Thirty-four subjects, 17 female and 17 male, between 21 and 33 years of age, with no history of right knee pathology volunteered to participate. Subjects were positioned prone on the Cybex II with their right lower extremity secured in knee flexion. Surface electrodes were placed over the medial and lateral hamstring muscles. Each test session consisted of nine maximal isometric knee flexion contractions. Three contractions, of six seconds each, …were recorded at 30, 60, and 90 degrees of knee flexion. Recordings of maximum torque and averaged EMG were made by the Cybex II and the Bioscope, respectively. The results showed statistically significant findings: (1) decreased torque as knee flexion increased (P < 0.0005); (2) men demonstrated greater torque than women (P < 0.05); and (3) EMG activity for both the medial and lateral hamstrings decreased as knee flexion increased with differences between 90 and 30° , and 90 and 60° (P < 0.05). We concluded that the decrease in torque output with increased knee flexion is consistent with present knowledge. The coordinated pattern of declining EMG activity with increased knee flexion for both the medial and lateral hamstring muscles requires further investigation. Show more

Keywords: Hamstrings, Torque, Electromyographic (EMG) Activity, Isometric Contractions

DOI: 10.3233/IES-1996-6213

Citation: Isokinetics and Exercise Science, vol. 6, no. 2, pp. 157-162, 1996