|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Journal of Experimental Biology, Vol 201, Issue 19 2753-2762, Copyright © 1998 by Company of Biologists
JOURNAL ARTICLES |
TJ Roberts, MS Chen and CR Taylor
Harvard University, Museum of Comparative Zoology, Concord Field Station, Old Causeway Road, Bedford, MA 01730, USA. robertst@bcc. orst.edu.
Compared with quadrupeds, bipedal runners of the same weight have longer legs, take longer steps and can presumably use slower, more economical muscle fibers. One might predict that bipedal running is less expensive, but it is not. We hypothesized that bipeds recruit a larger volume of muscle to support their weight, eliminating the potential economy of longer legs and slower steps. To test our hypothesis, we calculated the relative volume of muscle needed to support body weight over a stride in small dogs (Canis familiaris) and wild turkeys (Meleagris gallopavo) of the same weight. First, we confirmed that turkeys and dogs use approximately the same amount of energy to run at the same speed, and found that turkeys take 1. 8-fold longer steps. Higher muscle forces and/or longer muscle fibers would require a greater volume of active muscle, since muscle volume is proportional to the product of force and fascicle length. We measured both mean fascicle length and mean mechanical advantage for limb extensor muscles. Turkeys generated approximately the same total muscle force to support their weight during running and used muscle fascicles that are on average 2.1 times as long as in dogs, thus requiring a 2.5-fold greater active muscle volume. The greater volume appears to offset the economy of slower rates of force generation, supporting our hypothesis and providing a simple explanation for why it costs the same to run on two and four legs.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  P. G. Weyand, M. W. Bundle, C. P. McGowan, A. Grabowski, M. B. Brown, R. Kram, and H. Herr The fastest runner on artificial legs: different limbs, similar function? J Appl Physiol, September 1, 2009; 107(3): 903 - 911. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Rubenson and R. L. Marsh Mechanical efficiency of limb swing during walking and running in guinea fowl (Numida meleagris) J Appl Physiol, May 1, 2009; 106(5): 1618 - 1630. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. E. Nelson and T. J. Roberts Task-dependent force sharing between muscle synergists during locomotion in turkeys J. Exp. Biol., April 15, 2008; 211(8): 1211 - 1220. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. M. Gabaldon, F. E. Nelson, and T. J. Roberts Relative shortening velocity in locomotor muscles: turkey ankle extensors operate at low V/Vmax Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2008; 294(1): R200 - R210. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. D. Sockol, D. A. Raichlen, and H. Pontzer Chimpanzee locomotor energetics and the origin of human bipedalism PNAS, July 24, 2007; 104(30): 12265 - 12269. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Rubenson, D. G. Lloyd, T. F. Besier, D. B. Heliams, and P. A. Fournier Running in ostriches (Struthio camelus): three-dimensional joint axes alignment and joint kinematics J. Exp. Biol., July 15, 2007; 210(14): 2548 - 2562. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Pontzer Effective limb length and the scaling of locomotor cost in terrestrial animals J. Exp. Biol., May 15, 2007; 210(10): 1752 - 1761. [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]
|
|
|
|
|
|
A. Arampatzis, G. De Monte, K. Karamanidis, G. Morey-Klapsing, S. Stafilidis, and G.-P. Bruggemann Influence of the muscle-tendon unit's mechanical and morphological properties on running economy J. Exp. Biol., September 1, 2006; 209(17): 3345 - 3357. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. J. Roberts and R. A. Belliveau Sources of mechanical power for uphill running in humans J. Exp. Biol., May 15, 2005; 208(10): 1963 - 1970. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Pontzer A new model predicting locomotor cost from limb length via force production J. Exp. Biol., April 15, 2005; 208(8): 1513 - 1524. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. P. McGowan, R. V. Baudinette, and A. A. Biewener Joint work and power associated with acceleration and deceleration in tammar wallabies (Macropus eugenii) J. Exp. Biol., January 1, 2005; 208(1): 41 - 53. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. M. Griffin, R. Kram, S. J. Wickler, and D. F. Hoyt Biomechanical and energetic determinants of the walk-trot transition in horses J. Exp. Biol., November 15, 2004; 207(24): 4215 - 4223. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. J. Roberts and J. A. Scales Adjusting muscle function to demand: joint work during acceleration in wild turkeys J. Exp. Biol., November 1, 2004; 207(23): 4165 - 4174. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. M. Griffin, T. J. Roberts, and R. Kram Metabolic cost of generating muscular force in human walking: insights from load-carrying and speed experiments J Appl Physiol, July 1, 2003; 95(1): 172 - 183. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. J. Roberts and J. A. Scales Mechanical power output during running accelerations in wild turkeys J. Exp. Biol., May 15, 2002; 205(10): 1485 - 1494. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M Verstappen, P Aerts, and R Van Damme Terrestrial locomotion in the black-billed magpie: kinematic analysis of walking, running and out-of-phase hopping J. Exp. Biol., January 7, 2000; 203(14): 2159 - 2170. [Abstract] [PDF]
|
|
