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

First published online January 25, 2005
Journal of Experimental Biology 208, 439-445 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01408

This Article Figures Only Full Text Full Text (PDF) An erratum has been published 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 Doke, J. Articles by Kuo, A. D. Search for Related Content PubMed PubMed Citation Articles by Doke, J. Articles by Kuo, A. D.

Mechanics and energetics of swinging the human leg

Jiro Doke^1,*, J. Maxwell Donelan² and Arthur D. Kuo¹

¹ Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125 USA
² Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7 Canada

^* Author for correspondence (e-mail: jdokeh{at}umich.edu)

Accepted 25 November 2004

We measured how much metabolic energy is expended to swing a human leg. A previous dynamical model of walking predicted that increasing metabolic costs for walking with step length and step frequency trade-off against each other to determine the optimum step combination at a given speed. Simple pendulum dynamics indicate that the cost of walking at high step frequencies could be associated with driving the legs back and forth relative to the body, at a rate increasing approximately with the fourth power of frequency, possibly due to the low economy of producing muscle force for short durations. A similar cost would be expected for isolated swinging of a leg at faster than its natural frequency. We constructed an apparatus to measure work performed on the leg, and measured metabolic cost as human subjects (N=12) swung one leg at frequencies 0.5-1.1 Hz and fixed amplitude. Rate of mechanical work ranged from 0.02-0.27 W kg^-1 over these frequencies. Net metabolic rate for leg swinging (subtracting that for quiet standing) increased from 0.41-2.10 W kg^-1, approximately with the fourth power of frequency (R²=0.92) and in proportion to a hypothesized cost of force production for short durations. The costs of producing force and work could account for the increase. In a crude comparison, moving the legs back and forth at a typical stride frequency of 0.9 Hz, might consume about one-third of the net energy (2.8±0.8 W kg^-1) needed for walking at 1.3 m s^-1.

Key words: metabolic energy, locomotion, biomechanics, muscle, force production

This article has been cited by other articles:

				J. M. Donelan, Q. Li, V. Naing, J. A. Hoffer, D. J. Weber, and A. D. Kuo Biomechanical Energy Harvesting: Generating Electricity During Walking with Minimal User Effort Science, February 8, 2008; 319(5864): 807 - 810. [Abstract] [Full Text] [PDF]

				J. Doke and A. D. Kuo Energetic cost of producing cyclic muscle force, rather than work, to swing the human leg J. Exp. Biol., July 1, 2007; 210(13): 2390 - 2398. [Abstract] [Full Text] [PDF]

				H. Pontzer Predicting the energy cost of terrestrial locomotion: a test of the LiMb model in humans and quadrupeds J. Exp. Biol., February 1, 2007; 210(3): 484 - 494. [Abstract] [Full Text] [PDF]

				P. G. Adamczyk, S. H. Collins, and A. D. Kuo The advantages of a rolling foot in human walking J. Exp. Biol., October 15, 2006; 209(20): 3953 - 3963. [Abstract] [Full Text] [PDF]

				C. P. McGowan, H. A. Duarte, J. B. Main, and A. A. Biewener Effects of load carrying on metabolic cost and hindlimb muscle dynamics in guinea fowl (Numida meleagris) J Appl Physiol, October 1, 2006; 101(4): 1060 - 1069. [Abstract] [Full Text] [PDF]

				R. L. Marsh, D. J. Ellerby, H. T. Henry, and J. Rubenson The energetic costs of trunk and distal-limb loading during walking and running in guinea fowl Numida meleagris: I. Organismal metabolism and biomechanics J. Exp. Biol., June 1, 2006; 209(11): 2050 - 2063. [Abstract] [Full Text] [PDF]