De Witt John K, Edwards W Brent, Scott-Pandorf Melissa M, Norcross Jason R, Gernhardt Michael L
Wyle Science, Technology & Engineering Group, Houston, TX 77058, USA
University of Calgary, Calgary, AB, Canada T2N 1N4.
J Exp Biol. 2014 Sep 15;217(Pt 18):3200-3. doi: 10.1242/jeb.105684.
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.
量化从步行到跑步的偏好转换速度（PTS）有助于深入了解运动的潜在力学原理。动态相似性假说表明，在不同重力环境下，PTS应在相同的弗劳德数时出现。在正常地球重力下，成年人的PTS在弗劳德数为0.5时出现，但先前的报告发现，在模拟月球重力下，PTS在大于0.5的弗劳德数时出现。我们的目的是：（1）确定抛物线飞行期间实际月球重力下PTS时的弗劳德数；（2）将其与头顶悬挂期间模拟月球重力下PTS时的弗劳德数进行比较。我们观察到，实际月球重力下（1.39±0.45）和模拟月球重力下（1.11±0.26）PTS时的弗劳德数远大于0.5。PTS时弗劳德数大于1.0表明，在实际月球重力下使用倒立摆模型不一定有效，而且先前在模拟微重力环境下的研究结果比之前认为的更为准确。
