QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online March 28, 2008
Journal of Experimental Biology 211, 1211-1220 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.013227

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JEB Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nelson, F. E. Articles by Roberts, T. J. Search for Related Content PubMed Articles by Nelson, F. E. Articles by Roberts, T. J. Social Bookmarking                         What's this?

Task-dependent force sharing between muscle synergists during locomotion in turkeys

Frank E. Nelson^* and Thomas J. Roberts

Ecology and Evolutionary Biology Department, Brown University, Box GB205, Providence, RI 02912, USA

^* Author for correspondence at present address: Institute of Integrative and Comparative Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK (e-mail: f.e.nelson{at}leeds.ac.uk)

Accepted 7 February 2008

At most joints, there is a redundancy of muscle function. For any given movement, there are a wide range of possible solutions to the problem of how force is shared among muscle synergists. A better understanding of how force is shared among muscle synergists can provide insight into the mechanics and control of movement. We examined force sharing in the gastrocnemius of wild turkeys (Meleagris gallopavo), using strain gauges bonded to bony tendons. Force was measured separately in the lateral (LG) and medial (MG) heads of the gastrocnemius, to evaluate force sharing. We also used inverse dynamics to determine the total force required during swing phase. To determine whether the pattern of force sharing varied depending on the mechanical task, we used running speed (1 to 3.5 m s^–1) and limb loading (30 and 60 g added tarsometatarsal mass) to vary the force required at the intertarsal joint. We found that the distribution of force between these two heads varied depending on the phase of the stride cycle. During stance, force was shared in near equal amounts between the two heads and this distribution was unaffected by changes in running speed or limb load. During swing phase, however, there was no force sharing. Force was produced only in the lateral head, and this force was not significantly different from the total force required, as calculated from inverse dynamics. Thus, the LG produced all of the force required for limb extension during swing. This change in the pattern of force sharing between stance and swing supports the theory that force sharing between muscle synergists is task-dependent.

Key words: force sharing, running, bird

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

Related articles in JEB:

SWINGERS DON'T SHARE FORCES

Kathryn Phillips
JEB 2008 211: ii. [Full Text]  

This article has been cited by other articles:

				G. A. Lichtwark, J. C. Watson, S. Mavrommatis, and A. M. Wilson Intensity of activation and timing of deactivation modulate elastic energy storage and release in a pennate muscle and account for gait-specific initiation of limb protraction in the horse J. Exp. Biol., August 1, 2009; 212(15): 2454 - 2463. [Abstract] [Full Text] [PDF]

				S. Nauwelaerts, C. D. Wilga, G. V. Lauder, and C. P. Sanford Fluid dynamics of feeding behaviour in white-spotted bamboo sharks J. Exp. Biol., October 1, 2008; 211(19): 3095 - 3102. [Abstract] [Full Text] [PDF]

				T. E. Higham and A. A. Biewener Integration within and between muscles during terrestrial locomotion: effects of incline and speed J. Exp. Biol., July 15, 2008; 211(14): 2303 - 2316. [Abstract] [Full Text] [PDF]

				K. Phillips SWINGERS DON'T SHARE FORCES J. Exp. Biol., April 15, 2008; 211(8): ii - ii. [Full Text] [PDF]