title: The preferred walk to run transition speed in actual lunar gravity.
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.
authors.affiliation: Wyle Science, Technology & Engineering Group, Houston, TX 77058, USA john.k.dewitt@nasa.gov.
authors.forename: John K
authors.initials: JK
authors.lastname: De Witt
authors.affiliation: University of Calgary, Calgary, AB, Canada T2N 1N4.
authors.forename: W Brent
authors.initials: WB
authors.lastname: Edwards
authors.affiliation: Wyle Science, Technology & Engineering Group, Houston, TX 77058, USA.
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Scott-Pandorf
authors.affiliation: Wyle Science, Technology & Engineering Group, Houston, TX 77058, USA.
authors.forename: Jason R
authors.initials: JR
authors.lastname: Norcross
authors.affiliation: NASA Johnson Space Center, Houston, TX 77058, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Gernhardt
mesh_terms: D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D018472:Hypogravity; D008297:Male; D016081:Moon; D012420:Running / Q000502:physiology*; D016138:Walking / Q000502:physiology*; D018474:Weightlessness Simulation
keywords: Biomechanics; Froude number; Locomotion; Microgravity; Preferred transition speed