# FIGURE 1. Walking speed as a function of gravity.

## From the following article:

Biomechanics: Walking on other planets

Alberto E. Minetti

Nature 409, 467-469(25 January 2001)

doi:10.1038/35054166

The curves represent the predictions of the theory of dynamic similarity. These predictions were made using the Froude-number equation, Fr = *v*^{2}/(*g* *l*), where *v* is the velocity in m s^{-1}, *g* is the acceleration due to gravity in m s^{-2}, *l* is 0.92 m (the average leg length for adult male humans), and Fr is 0.25 (which sets the optimal walking speed on Earth^{9, }^{10, }^{11, }^{12}) or 0.5 (at which humans move spontaneously from a walk to a run on Earth^{3}). Squares and orange circles refer to measurements of optimal walking speeds^{4} and walk-to-run-transition speeds^{5}, respectively, in simulated low-gravity conditions. The triangle represents a previous estimate of reduced walking speed on the Moon^{13}. Green circles represent recent measurements of optimal speed obtained using parabolic flight to simulate low- and high-gravity conditions^{6, }^{7}.