Muscle activation during maximal voluntary eccentric and concentric knee extension

Westing S.H., Cresswell A.G. and Thorstensson A. (1991) Muscle activation during maximal voluntary eccentric and concentric knee extension. European Journal of Applied Physiology and Occupational Physiology, 62 2: 104-108. doi:10.1007/BF00626764


Author Westing S.H.
Cresswell A.G.
Thorstensson A.
Title Muscle activation during maximal voluntary eccentric and concentric knee extension
Journal name European Journal of Applied Physiology and Occupational Physiology   Check publisher's open access policy
ISSN 0301-5548
Publication date 1991-02-01
Year available 1991
Sub-type Article (original research)
DOI 10.1007/BF00626764
Open Access Status Not yet assessed
Volume 62
Issue 2
Start page 104
End page 108
Total pages 5
Place of publication NEW YORK
Publisher Springer-Verlag
Language eng
Abstract The aim of this investigation was to study the relationships among movement velocity, torque output and electromyographic (EMG) activity of the knee extensor muscles under eccentric and concentric loading. Fourteen male subjects performed maximal voluntary eccentric and concentric constant-velocity knee extensions at 45, 90, 180 and 360-degrees .s-1. Myoelectric signals were recorded, using surface electrodes, from the vastus medialis, vastus lateralis and rectus femoris muscles. For comparison, torque and full-wave rectified EMG signals were amplitude-averaged through the central half (30-degrees-70-degrees) of the range of motion. For each test velocity, eccentric torque was greater than concentric torque (range of mean differences: 20%-146%, P < 0.05). In contrast, EMG activity for all muscles was lower under eccentric loading than velocity-matched concentric loading (7%-31%, P < 0.05). Neither torque output nor EMG activity for the three muscles changed across eccentric test velocities (P > 0.05). While concentric torque increased with decreasing velocity, EMG activity for all muscles decreased with decreasing velocity (P < 0.05). These data suggest that under certain high-tension loading conditions (especially during eccentric muscle actions), the neural drive to the agonist muscles was reduced, despite maximal voluntary effort. This may protect the musculoskeletal system from an injury that could result if the muscle was to become fully activated under these conditions.
Keyword Electromyography
Man
Tension regulation
Torque-velocity characteristics
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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Created: Tue, 14 Feb 2017, 15:20:45 EST by Sandrine Ducrot