Abstract
Quantifying the preferred transition speed (PTS) from walking to running has provided insight into the underlying mechanics of locomotion. The dynamic similarity hypothesis suggests that the PTS should occur at the same Froude number across gravitational environments. In normal Earth gravity, the PTS occurs at a Froude number of 0.5 in adult humans, but previous reports found the PTS occurred at Froude numbers greater than 0.5 in simulated lunar gravity. Our purpose was to (1) determine the Froude number at the PTS in actual lunar gravity during parabolic flight and (2) compare it with the Froude number at the PTS in simulated lunar gravity during overhead suspension. We observed that Froude numbers at the PTS in actual lunar gravity (1.39±0.45) and simulated lunar gravity (1.11±0.26) were much greater than 0.5. Froude numbers at the PTS above 1.0 suggest that the use of the inverted pendulum model may not necessarily be valid in actual lunar gravity and that earlier findings in simulated reduced gravity are more accurate than previously thought.
FOOTNOTES
-
Author contributions
All authors contributed to the writing of this paper, the initial draft being prepared by J.K.D. and W.B.E.
-
Competing interests
The authors declare no competing financial interests.
-
Funding
This work was a directed study funded by the Human Health and Countermeasures Element of the National Aeronautics and Space Administration's Human Research Program.
- © 2014. Published by The Company of Biologists Ltd
Article navigation
Related articles
Cited by...
More in this TOC section
Similar articles
Other journals from The Company of Biologists
The Company of Biologists commits to the Transformative Journal approach
The Company of Biologists is the first not-for-profit publisher to commit to this approach. The Company's three hybrid journals - Development, Journal of Cell Science and Journal of Experimental Biology - have chosen the 'transformative' route towards Open Access. Find out more in this interview with Claire Moulton, Publisher at The Company of Biologists and on our dedicated Transformative Journals page.
Handing over the reins
The start of August signals a change for Journal of Experimental Biology as we say a fond farewell to Editor-in-Chief of 25 years Hans Hoppeler and extend a warm welcome to his successor, Craig Franklin.
Minute mecysmaucheniid spider triggers fastest trap-jaws
Research by Hannah Wood shows that Zearchaea spiders use a spring loaded catapult mechanism to slam closed the fastest spider jaws on the planet, at an astonishing speed of 18.2 m s−1.
In the field: an interview with Sandra Binning and Dominique Roche
Together, Sandra Binning and Dominique Roche investigate how animals respond to environmental stress. In an interview, they talk about taking their children into the field and keeping safe while working in marine locations.
Surviving anoxia: the maintenance of energy production and tissue integrity during anoxia and reoxygenation
In their Review, Georgina Cox and Todd Gillis use knowledge gained from studies of anoxia-tolerant species to identify common strategies and novel solutions for the challenges of anoxia exposure.