Submaximal leaping in the grey mouse lemur.

In arboreal animals such as the grey mouse lemur (Microcebus murinus Miller, 1777), leaping is the most frequent strategy for predator avoidance. The aim of this study was to characterise the locomotor adaptation in response to the structural constraint of the habitat (i.e., position of the landing substrate). Thus, we characterised the push-off phase by inducing the lemurs to leap up to a range of heights from horizontal to their own individual highest performance. Using uniplanar high-frequency cineradiographs collected in a sagittal plane, the relative contributions of the centre of mass (CoM) velocity vector magnitude and orientation to leaping performance were evaluated. The kinematics of the push-off phase showed that for low landing heights, leaping performance was essentially due to hip and knee extensions. Higher leaps seemed to be related to an increase in ankle contribution. At all leaping heights, the proximal-to-distal sequence of the hind limb joints controlled the orientation and magnitude of the M. murinus CoM velocity vector while pushing off. Finally, the analysis of the velocity vector at the onset of take-off suggested that the optimal solution for predator avoidance was to leap for horizontal distance and not for vertical distance.