Neural compensation within the human triceps surae during prolonged walking

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Title Neural compensation within the human triceps surae during prolonged walking
Author Cronin, Neil; Peltonen, Jussi; Sinkjaer, Thomas; Avela, Janne
Journal Name Journal of Neurophysiology
Year Published 2011
Place of publication USA
Publisher American Physiological Society
Abstract During human walking, muscle activation strategies are approximately constant across consecutive steps over a short time, but it is unknown whether they are maintained over a longer duration. Prolonged walking may increase tendinous tissue (TT) compliance, which can influence neural activation, but the neural responses of individual muscles have not been investigated. This study investigated the hypothesis that muscle activity is up- or down-regulated in individual triceps surae muscles during prolonged walking. Thirteen healthy subjects walked on a treadmill for 60 min at 4.5 km/h, while triceps surae muscle activity, maximal muscle compound action potentials, and kinematics were recorded every 5 min, and fascicle lengths were estimated at the beginning and end of the protocol using ultrasound. After 1 h of walking, soleus activity increased by 9.3 ± 0.2% (P < 0.05) and medial gastrocnemius activity decreased by 9.3 ± 0.3% (P < 0.01). Gastrocnemius fascicle length at ground contact shortened by 4.45 ± 0.99% (P < 0.001), whereas soleus fascicle length was unchanged (P = 0.988). Throughout the stance phase, medial gastrocnemius fascicle lengthening decreased by 44 ± 13% (P < 0.001), whereas soleus fascicle lengthening amplitude was unchanged (P = 0.650). The data suggest that a compensatory neural strategy exists between triceps surae muscles and that changes in muscle activation are generally mirrored by changes in muscle fascicle length. These findings also support the notion of muscle-specific changes in TT compliance after prolonged walking and highlight the ability of the CNS to maintain relatively constant movement patterns in spite of neuromechanical changes in individual muscles.
Peer Reviewed Yes
Published Yes
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Copyright Statement Self-archiving of the author-manuscript version is not yet supported by this journal. Please refer to the journal link for access to the definitive, published version or contact the author[s] for more information.
Volume 105
Issue Number 2
Page from 548
Page to 553
ISSN 1522-1598
Date Accessioned 2011-03-09
Language en_AU
Faculty Griffith Health Faculty
Subject Motor Control; Sensory Systems
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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