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Effect of ankle position fixation on peak torque and electromyographic activity of the knee flexors and extensors.
Electromyogr Clin Neurophysiol. 2000 Sep; 40(6):365-73.EC

Abstract

The purpose of this study was to examine the effect of ankle position fixation on peak torque (PT) and electromyographic (EMG) activity of knee-joint muscles during isokinetic testing. Twelve female athletes performed isokinetic knee flexion and extension at 60 degrees and 180 degrees/s under two conditions: with the ankle fixed in a position of plantarflexion and with the ankle fixed in a position of dorsiflexion. Bipolar surface electrodes were placed on the vastus lateralis, vastus medialis, biceps femoris, medial hamstrings, and the lateral head of the gastrocnemius for determination of the root mean square of the EMG (rmsEMG) and the median frequency of the EMG (mfEMG). No significant differences in knee extensor PT were noted in either ankle position for each velocity tested. Significant differences were noted, however, in knee flexor PT (p < 0.05) at both 60 degrees and 180 degrees/s, with the greatest PT observed with the ankle fixed in dorsiflexion. Neither quadriceps, hamstrings, nor gastrocnemius rmsEMG activity was affected by ankle position; however, there was a significant difference in mfEMG for the gastrocnemius, with higher frequencies observed with the ankle fixed in plantarflexion (p < 0.01). These results suggest that ankle position effects knee flexor PT during open chain isokinetic movements. The reason for decreased knee flexor PT with the ankle fixed in plantarflexion is probably due to the gastrocnemius muscle being in a too shortened position, thereby preventing it from effectively producing force at the knee joint.

Authors+Show Affiliations

University of New Hampshire, Durham, USA. rvc@christa.unh.eduNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

11039121

Citation

Croce, R V., et al. "Effect of Ankle Position Fixation On Peak Torque and Electromyographic Activity of the Knee Flexors and Extensors." Electromyography and Clinical Neurophysiology, vol. 40, no. 6, 2000, pp. 365-73.
Croce RV, Miller JP, St Pierre P. Effect of ankle position fixation on peak torque and electromyographic activity of the knee flexors and extensors. Electromyogr Clin Neurophysiol. 2000;40(6):365-73.
Croce, R. V., Miller, J. P., & St Pierre, P. (2000). Effect of ankle position fixation on peak torque and electromyographic activity of the knee flexors and extensors. Electromyography and Clinical Neurophysiology, 40(6), 365-73.
Croce RV, Miller JP, St Pierre P. Effect of Ankle Position Fixation On Peak Torque and Electromyographic Activity of the Knee Flexors and Extensors. Electromyogr Clin Neurophysiol. 2000;40(6):365-73. PubMed PMID: 11039121.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of ankle position fixation on peak torque and electromyographic activity of the knee flexors and extensors. AU - Croce,R V, AU - Miller,J P, AU - St Pierre,P, PY - 2000/10/20/pubmed PY - 2001/3/3/medline PY - 2000/10/20/entrez SP - 365 EP - 73 JF - Electromyography and clinical neurophysiology JO - Electromyogr Clin Neurophysiol VL - 40 IS - 6 N2 - The purpose of this study was to examine the effect of ankle position fixation on peak torque (PT) and electromyographic (EMG) activity of knee-joint muscles during isokinetic testing. Twelve female athletes performed isokinetic knee flexion and extension at 60 degrees and 180 degrees/s under two conditions: with the ankle fixed in a position of plantarflexion and with the ankle fixed in a position of dorsiflexion. Bipolar surface electrodes were placed on the vastus lateralis, vastus medialis, biceps femoris, medial hamstrings, and the lateral head of the gastrocnemius for determination of the root mean square of the EMG (rmsEMG) and the median frequency of the EMG (mfEMG). No significant differences in knee extensor PT were noted in either ankle position for each velocity tested. Significant differences were noted, however, in knee flexor PT (p < 0.05) at both 60 degrees and 180 degrees/s, with the greatest PT observed with the ankle fixed in dorsiflexion. Neither quadriceps, hamstrings, nor gastrocnemius rmsEMG activity was affected by ankle position; however, there was a significant difference in mfEMG for the gastrocnemius, with higher frequencies observed with the ankle fixed in plantarflexion (p < 0.01). These results suggest that ankle position effects knee flexor PT during open chain isokinetic movements. The reason for decreased knee flexor PT with the ankle fixed in plantarflexion is probably due to the gastrocnemius muscle being in a too shortened position, thereby preventing it from effectively producing force at the knee joint. SN - 0301-150X UR - https://www.unboundmedicine.com/medline/citation/11039121/Effect_of_ankle_position_fixation_on_peak_torque_and_electromyographic_activity_of_the_knee_flexors_and_extensors_ DB - PRIME DP - Unbound Medicine ER -