Does Height Matter? The Effects of Take-off Elevation on Forelimb Movements during Jumping and Landing in Cane Toads
MetadataShow full item record
Past research has shown the significance of the musculoskeletal system in enabling deceleration during certain actions, including landing from a step, hop or jump. For instance, in toads, landing forces increase with hop distance, and pre-landing forelimb muscle activity is greater in longer hops. Toads prepare for landing differently depending on hop distance by altering forelimb muscle recruitment patterns prior to impact. In this study I tested whether differences in underlying muscle activity translate into differences in toad forelimb movements depending upon the length of the hop. Using high-speed video I characterized elbow joint angular excursions and humeral movements from toads hopping on flat surfaces and from elevated platforms. I found that the animals extended their arms in mid-air while protracting and depressing their humerus until they landed. Upon landing, the forelimbs flexed as the humerus retracted and elevated. On flat surfaces, extension and flexion increased with greater hop distance, indicating a compensatory relationship between the two that helps maintain a consistent “final” elbow angle after landing. Elbow movements were greater in elevated hops, but hop distance no longer influenced these variables. Thus, arm movements do appear to depend on hop distance, but this dependence is eliminated during elevated hops.