Planar covariation of segment elevation angles in different gaits.

<p>A: covariation of limb segment elevation angles during walking, trotting, galloping (trailing limb) and swimming computed for ensemble-averaged elevation angles. The best-fitting plane is shown by grids. B: 95% confidence cones characterizing spatial distribution of the normal to the covariation plane between dogs in each gait and for each limb (left panel–HL, right panel–FL) in the 3D space defined by the elevation angles (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133936#sec002" target="_blank">Methods</a>). The foot (and hand for FL) semiaxis is positive, and the shank and thigh (lower and upper arm for FL) semiaxes are negative. Note overlapping of confidence cones in different gaits. C: direction cosines (<i>u</i>_3<i>t</i>, <i>u</i>_3<i>s</i>, <i>u</i>_3<i>s</i> for HL and <i>u</i>_3<i>ua</i>, <i>u</i>_3<i>la</i>, <i>u</i>_3<i>h</i> for FL) of the normal to the covariation plane (u₃ vector) for all individual strides and all dogs versus locomotion speed. D: percent of variance (+SD) accounted for by u₃ (PV₃). Asterisks denote significant differences.