Meeting Abstract
Legged locomotion across non-level terrain poses several challenges to animals, requiring them to adjust their limb joint kinematics and kinetics to either dissipate or produce more mechanical energy. These strategies used can shed valuable insight into which muscles are crucial during a limb’s given function (e.g. braking or propulsion). Previous work has investigated the effects of slope (i.e. incline or decline) on the limb mechanics of various taxa, but such movements in non-erect quadrupeds remains poorly understood. Here we compare the limb joint mechanics of the American alligator, a semi-erect quadruped, during locomotion across a sloped (15°) and level trackway. We use high-speed videography (dorsal and lateral views) and force plate ergometry on juvenile alligators walking down a 15° decline, up a 15° incline, and across a level trackway. We show that mechanical function remains segregated between limb pairs as forelimbs (FLs) tend to provide more a braking function, whereas hindlimbs (HLs) more a propulsive one. Within each limb we also assess which limb joints are involved most significantly during braking in the FLs and propulsion in the HLs. Our preliminary results show that average FL braking impulse significantly increases during decline walking (relative to level) and HLs shift to a braking function. During incline walking, FLs produce little to no propulsive impulse while average HL propulsive impulse significantly increases (relative to level). These results illustrate how semi-erect quadrupeds like crocodilians accomplish locomotion across sloped terrain and indicate which limb muscles are likely to contribute to braking and propulsion in alligators. This work expands the range of sloped locomotion to include semi-erect vertebrates and will serve as a foundation for future studies investigating muscle specializations in quadrupedal walkers.
