Meeting Abstract
Moving in the real world requires that animals – including humans – effectively maneuver obstacles and navigate terrain with complex properties. Variation in the mechanical properties of the environment, like surface compliance, can alter impact forces and energies that an animal must absorb and dissipate. Rhinella marina, the cane toad, is already a model species for understanding controlled decelerations which makes it an ideal organism for exploring the effects of surface compliance and damping on its locomotion. Using inverse dynamics during landing in toads (n = 8) we generated joint-level work across four compliance treatments (0, 2.5, 5 and 10 mm BW-1) and two platform masses (123 and 725 g). We furthered our initial analyses by collecting muscle activity of the palmaris longus, anconeus, pectoralis, and deltoideus throughout 186 jumps from five toads landing on 0, 2.5 and 5 mm BW-1 compliance treatments. Our results suggest muscles at the shoulder are more involved as compliance increases and as surface damping increases while the elbow exhibits the inverse trend. We also found preparatory activation of forelimb muscles in a proximal-to-distal pattern which corresponds to observed shoulder protraction followed by elbow and wrist extension. Additionally, all four muscles investigated exhibit activity after impact providing support for our inverse dynamics findings across each joint. This work can help us understand how animals coordinate robust behaviors in the face of environmental variation.
