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Quadriceps femoris electromyogram during concentric, isometric and eccentric phases of fatiguing dynamic knee extensions.
J Biomech. 2006; 39(2):246-54.JB

Abstract

The objective of this study was to examine the superficial quadriceps femoris (QF) muscle electromyogram (EMG) during fatiguing knee extensions. Thirty young adults were evaluated for their one-repetition maximum (1RM) during a seated, right-leg, inertial knee extension. All subjects then completed a single set of repeated knee extensions at 50% 1RM, to failure. Subjects performed a knee extension (concentric phase), held the weight with the knee extended for 2s (isometric phase), and lowered the weight in a controlled manner (eccentric phase). Raw EMG of the vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF) muscles were full-wave rectified, integrated and normalized to the 1RM EMG, for each respective phase and repetition. The EMG median frequency (f(med)) was computed during the isometric phase. An increase in QF muscle EMG was observed during the concentric phase across the exercise duration. VL EMG was greater than the VM and RF muscles during the isometric phase, in which no significant changes occurred in any of the muscles across the exercise duration. A significant decrease in EMG across the exercise duration was observed during the eccentric phase, with the VL EMG greater than the VM and RF muscles. A greater decrease in VL and RF muscle f(med) during the isometric phase, than the VM muscle, was observed with no gender differences. The findings demonstrated differential recruitment of the superficial QF muscle, depending on the contraction mode during dynamic knee extension exercise, where VL muscle dominance appears to manifest across the concentric-isometric-eccentric transition.

Authors+Show Affiliations

Human Performance and Fatigue Laboratory, Department of Kinesiology, The University of Toledo, Mail Stop 119, OH 43606, USA. danny.pincivero@utoledo.eduNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16321626

Citation

Pincivero, Danny M., et al. "Quadriceps Femoris Electromyogram During Concentric, Isometric and Eccentric Phases of Fatiguing Dynamic Knee Extensions." Journal of Biomechanics, vol. 39, no. 2, 2006, pp. 246-54.
Pincivero DM, Gandhi V, Timmons MK, et al. Quadriceps femoris electromyogram during concentric, isometric and eccentric phases of fatiguing dynamic knee extensions. J Biomech. 2006;39(2):246-54.
Pincivero, D. M., Gandhi, V., Timmons, M. K., & Coelho, A. J. (2006). Quadriceps femoris electromyogram during concentric, isometric and eccentric phases of fatiguing dynamic knee extensions. Journal of Biomechanics, 39(2), 246-54.
Pincivero DM, et al. Quadriceps Femoris Electromyogram During Concentric, Isometric and Eccentric Phases of Fatiguing Dynamic Knee Extensions. J Biomech. 2006;39(2):246-54. PubMed PMID: 16321626.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Quadriceps femoris electromyogram during concentric, isometric and eccentric phases of fatiguing dynamic knee extensions. AU - Pincivero,Danny M, AU - Gandhi,Varsha, AU - Timmons,Mark K, AU - Coelho,Alan J, PY - 2004/07/12/received PY - 2004/11/24/accepted PY - 2005/12/3/pubmed PY - 2006/1/24/medline PY - 2005/12/3/entrez SP - 246 EP - 54 JF - Journal of biomechanics JO - J Biomech VL - 39 IS - 2 N2 - The objective of this study was to examine the superficial quadriceps femoris (QF) muscle electromyogram (EMG) during fatiguing knee extensions. Thirty young adults were evaluated for their one-repetition maximum (1RM) during a seated, right-leg, inertial knee extension. All subjects then completed a single set of repeated knee extensions at 50% 1RM, to failure. Subjects performed a knee extension (concentric phase), held the weight with the knee extended for 2s (isometric phase), and lowered the weight in a controlled manner (eccentric phase). Raw EMG of the vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF) muscles were full-wave rectified, integrated and normalized to the 1RM EMG, for each respective phase and repetition. The EMG median frequency (f(med)) was computed during the isometric phase. An increase in QF muscle EMG was observed during the concentric phase across the exercise duration. VL EMG was greater than the VM and RF muscles during the isometric phase, in which no significant changes occurred in any of the muscles across the exercise duration. A significant decrease in EMG across the exercise duration was observed during the eccentric phase, with the VL EMG greater than the VM and RF muscles. A greater decrease in VL and RF muscle f(med) during the isometric phase, than the VM muscle, was observed with no gender differences. The findings demonstrated differential recruitment of the superficial QF muscle, depending on the contraction mode during dynamic knee extension exercise, where VL muscle dominance appears to manifest across the concentric-isometric-eccentric transition. SN - 0021-9290 UR - https://www.unboundmedicine.com/medline/citation/16321626/Quadriceps_femoris_electromyogram_during_concentric_isometric_and_eccentric_phases_of_fatiguing_dynamic_knee_extensions_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9290(04)00590-1 DB - PRIME DP - Unbound Medicine ER -