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

First published online December 10, 2003
Journal of Experimental Biology 207, 249-261 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00745

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 Similar articles in this journal Similar articles in PubMed 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 Higham, T. E. Articles by Jayne, B. C. Search for Related Content PubMed PubMed Citation Articles by Higham, T. E. Articles by Jayne, B. C. Social Bookmarking                         What's this?

In vivo muscle activity in the hindlimb of the arboreal lizard, Chamaeleo calyptratus: general patterns and the effects of incline

Timothy E. Higham^* and Bruce C. Jayne

Department of Biological Sciences, University of Cincinnati, PO Box 210006, Cincinnati, OH 45221-0006, USA

^* Corresponding author at present address: Section of Evolution and Ecology, University of California, One Shields Avenue, Davis, CA 95616, USA (e-mail: tehigham{at}ucdavis.edu)

Accepted 6 October 2003

Arboreal animals often move on surfaces with variable and steep inclines, but the changes in hindlimb muscle activity in response to incline are poorly understood. Thus, we studied the hindlimb muscle activity in the arboreal specialist, Chamaeleo calyptratus, moving up and down 45° inclines and on a horizontal surface. We quantified electromyograms (EMGs) from nine hindlimb muscles, and correlated EMGs with three-dimensional hindlimb kinematics. Kinematics changed little with incline, but the EMGs changed substantially. Most of the changes in EMGs were for amplitude rather than timing, and the EMGs of the hip and thigh muscles had more conspicuous changes with incline than those of the lower limb muscles. Unlike most other vertebrates, chameleons flexed the knee substantially during the first half of stance while the foot was anchored to the perch, and the amplitude of two large knee flexors increased when moving uphill compared to level and downhill. Thus, knee flexion in early stance probably contributes significantly to propulsion in C. calyptratus. During stance, the caudofemoralis EMGs of C. calyptratus correlated well with femur retraction, knee flexion and posterior femur rotation, and their amplitudes were higher on uphill and level surfaces than on the downhill surface. During the second half of stance, iliotibialis EMGs correlated well with knee extension, and their amplitude was highest on the uphill surface and lowest on the downhill surface. Many of the muscles in the hindlimb of C. calyptratus changed activity with incline in a manner similar to the propulsive limb muscles in mammals. Although muscle strain often increases when animals need more power to move uphill, the minimal changes in the hindlimb kinematics of C. calyptratus with incline imply little change in muscle strain.

Key words: locomotion, lizard, C. calyptratus, arboreal, kinematics, incline, slope, hindlimb, electromyography, muscle

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

This article has been cited by other articles:

				T. E. Higham and A. P. Russell Flip, flop and fly: modulated motor control and highly variable movement patterns of autotomized gecko tails Biol Lett, September 9, 2009; (2009) rsbl.2009.0577v1. [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]

				A. M. Berg and A. A. Biewener Kinematics and power requirements of ascending and descending flight in the pigeon (Columba livia) J. Exp. Biol., April 1, 2008; 211(7): 1120 - 1130. [Abstract] [Full Text] [PDF]

				T. E Higham, A. A Biewener, and J. M Wakeling Functional diversification within and between muscle synergists during locomotion Biol Lett, February 23, 2008; 4(1): 41 - 44. [Abstract] [Full Text] [PDF]

				T. E. Higham The integration of locomotion and prey capture in vertebrates: Morphology, behavior, and performance Integr. Comp. Biol., July 1, 2007; 47(1): 82 - 95. [Abstract] [Full Text] [PDF]

				R. J. Gregor, D. W. Smith, and B. I. Prilutsky Mechanics of Slope Walking in the Cat: Quantification of Muscle Load, Length Change, and Ankle Extensor EMG Patterns J Neurophysiol, March 1, 2006; 95(3): 1397 - 1409. [Abstract] [Full Text] [PDF]

				K. Autumn, S. T. Hsieh, D. M. Dudek, J. Chen, C. Chitaphan, and R. J. Full Dynamics of geckos running vertically J. Exp. Biol., January 15, 2006; 209(2): 260 - 272. [Abstract] [Full Text] [PDF]