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Muscle force production during bent-knee, bent-hip walking in humans.

Publication ,  Journal Article
Foster, AD; Raichlen, DA; Pontzer, H
Published in: Journal of human evolution
September 2013

Researchers have long debated the locomotor posture used by the earliest bipeds. While many agree that by 3-4 Ma (millions of years ago), hominins walked with an extended-limb human style of bipedalism, researchers are still divided over whether the earliest bipeds walked like modern humans, or walked with a more bent-knee, bent-hip (BKBH) ape-like form of locomotion. Since more flexed postures are associated with higher energy costs, reconstructing early bipedal mechanics has implications for the selection pressures that led to upright walking. The purpose of this study is to determine how modern human anatomy functions in BKBH walking to clarify the links between morphology and energy costs in different mechanical regimes. Using inverse dynamics, we calculated muscle force production at the major limb joints in humans walking in two modes, both with extended limbs and BKBH. We found that in BKBH walking, humans must produce large muscle forces at the knee to support body weight, leading to higher estimated energy costs. However, muscle forces at the hip remained similar in BKBH and extended limb walking, suggesting that anatomical adaptations for hip extension in humans do not necessarily diminish the effective mechanical advantage at the hip in more flexed postures. We conclude that the key adaptations for economical walking, regardless of joint posture, seem to center on maintaining low muscle forces at the hip, primarily by keeping low external moments at the hip. We explore the implications of these results for interpreting locomotor energetics in early hominins, including australopithecines and Ardipithecus ramidus.

Duke Scholars

Published In

Journal of human evolution

DOI

EISSN

1095-8606

ISSN

0047-2484

Publication Date

September 2013

Volume

65

Issue

3

Start / End Page

294 / 302

Related Subject Headings

  • Walking
  • Upper Extremity
  • Posture
  • Pan troglodytes
  • Muscle, Skeletal
  • Models, Biological
  • Male
  • Lower Extremity
  • Knee Joint
  • Humans
 

Citation

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Foster, A. D., Raichlen, D. A., & Pontzer, H. (2013). Muscle force production during bent-knee, bent-hip walking in humans. Journal of Human Evolution, 65(3), 294–302. https://doi.org/10.1016/j.jhevol.2013.06.012
Journal cover image

Published In

Journal of human evolution

DOI

EISSN

1095-8606

ISSN

0047-2484

Publication Date

September 2013

Volume

65

Issue

3

Start / End Page

294 / 302

Related Subject Headings

  • Walking
  • Upper Extremity
  • Posture
  • Pan troglodytes
  • Muscle, Skeletal
  • Models, Biological
  • Male
  • Lower Extremity
  • Knee Joint
  • Humans