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EMG activity and voluntary activation during knee-extensor concentric torque generation.
Eur J Appl Physiol. 2002 Apr; 86(6):541-7.EJ

Abstract

This study was designed to re-examine and compare the neural drive of the knee extensors during isokinetic concentric muscular actions by means of the twitch interpolation technique (activation level, AL) and surface electromyographic (EMG) recordings (root mean square, RMS). Torque, AL and RMS amplitudes of three knee extensors and one knee flexor were measured in nine subjects during maximal and sub-maximal voluntary contractions, performed under concentric (60 degrees.s(-1) and 120 degrees.s(-1); Con60 and Con120, respectively) and isometric (Iso) conditions. Mean (SD) maximal voluntary torque was significantly lower (P<0.01) during concentric contractions [Con60: 208.6 (26.8) Nm and Con120: 184.7 (26.4) Nm] compared with isometric contractions [327.4 (52.0) Nm]. A significantly lower AL (P<0.05) was recorded during Con60 [80.9 (8.8)%] compared with Iso [87.9 (5.1)%] and Con120 [88.2 (6.6)%] maximal contractions. Simultaneously, a lower knee extensor average RMS amplitudes (av.RMS) was measured during Con60 maximal contractions compared with Iso and Con120 maximal contractions. The antagonist biceps femoris RMS values were not different between maximal Iso, Con60 and Con120 contractions. During sub-maximal voluntary contractions, the RMS/torque relationships were similar whatever the muscle considered (vastus lateralis, vastus medialis or rectus femoris) and the AL/av.RMS relationships did not reveal any noticeable differences between each contractile condition. The results of the present study indicate that av.RMS and AL describe similarly the neural drive during maximal and sub-maximal efforts and indicate that during maximal voluntary efforts, neural drive is dependent upon concentric angular velocity (up to 120 degrees.s(-1)). Thus, our results suggest that when applying different contractile conditions, the torque output is regulated via complex interactions between intrinsic muscular properties and the neural drive.

Authors+Show Affiliations

Groupe Analyse du Mouvement (GAM), Faculté des Sciences du Sport, Université de Bourgogne, BP 27877, 21078 Dijon Cedex, France. nicolas.babault@u-bourgogne.frNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

11944103

Citation

Babault, Nicolas, et al. "EMG Activity and Voluntary Activation During Knee-extensor Concentric Torque Generation." European Journal of Applied Physiology, vol. 86, no. 6, 2002, pp. 541-7.
Babault N, Pousson M, Michaut A, et al. EMG activity and voluntary activation during knee-extensor concentric torque generation. Eur J Appl Physiol. 2002;86(6):541-7.
Babault, N., Pousson, M., Michaut, A., Ballay, Y., & Hoecke, J. V. (2002). EMG activity and voluntary activation during knee-extensor concentric torque generation. European Journal of Applied Physiology, 86(6), 541-7.
Babault N, et al. EMG Activity and Voluntary Activation During Knee-extensor Concentric Torque Generation. Eur J Appl Physiol. 2002;86(6):541-7. PubMed PMID: 11944103.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - EMG activity and voluntary activation during knee-extensor concentric torque generation. AU - Babault,Nicolas, AU - Pousson,Michel, AU - Michaut,Anne, AU - Ballay,Yves, AU - Hoecke,Jacques Van, Y1 - 2002/03/07/ PY - 2001/12/17/accepted PY - 2002/4/11/pubmed PY - 2002/10/31/medline PY - 2002/4/11/entrez SP - 541 EP - 7 JF - European journal of applied physiology JO - Eur J Appl Physiol VL - 86 IS - 6 N2 - This study was designed to re-examine and compare the neural drive of the knee extensors during isokinetic concentric muscular actions by means of the twitch interpolation technique (activation level, AL) and surface electromyographic (EMG) recordings (root mean square, RMS). Torque, AL and RMS amplitudes of three knee extensors and one knee flexor were measured in nine subjects during maximal and sub-maximal voluntary contractions, performed under concentric (60 degrees.s(-1) and 120 degrees.s(-1); Con60 and Con120, respectively) and isometric (Iso) conditions. Mean (SD) maximal voluntary torque was significantly lower (P<0.01) during concentric contractions [Con60: 208.6 (26.8) Nm and Con120: 184.7 (26.4) Nm] compared with isometric contractions [327.4 (52.0) Nm]. A significantly lower AL (P<0.05) was recorded during Con60 [80.9 (8.8)%] compared with Iso [87.9 (5.1)%] and Con120 [88.2 (6.6)%] maximal contractions. Simultaneously, a lower knee extensor average RMS amplitudes (av.RMS) was measured during Con60 maximal contractions compared with Iso and Con120 maximal contractions. The antagonist biceps femoris RMS values were not different between maximal Iso, Con60 and Con120 contractions. During sub-maximal voluntary contractions, the RMS/torque relationships were similar whatever the muscle considered (vastus lateralis, vastus medialis or rectus femoris) and the AL/av.RMS relationships did not reveal any noticeable differences between each contractile condition. The results of the present study indicate that av.RMS and AL describe similarly the neural drive during maximal and sub-maximal efforts and indicate that during maximal voluntary efforts, neural drive is dependent upon concentric angular velocity (up to 120 degrees.s(-1)). Thus, our results suggest that when applying different contractile conditions, the torque output is regulated via complex interactions between intrinsic muscular properties and the neural drive. SN - 1439-6319 UR - https://www.unboundmedicine.com/medline/citation/11944103/EMG_activity_and_voluntary_activation_during_knee_extensor_concentric_torque_generation_ L2 - https://dx.doi.org/10.1007/s00421-002-0579-3 DB - PRIME DP - Unbound Medicine ER -