Figure 5.

(A) Platform (blue) and vertical head displacements (black) during the first second of a backward fall (forward translation) for several subjects. (B) Illustration of representative head kinematics: superposition of four trials after a forward fast translation of the support surface and instantaneous dispersion curve (red thick line). The “variability threshold“ (separating passive and active phase), was determined using the inflection point on the curves separating the trajectories with low and high dispersion (purple line). (C) Onset of deviation of the various body parts with respect to height. Note that there is a linear relation between segment height and its inertial latency of displacement. (D) Simulated (black) vs. Experimental (colored dotted lines) data for the head displacement (z axis) of a subject after a forward fast translation. Note that both curves superimpose in the passive part (light blue background).