Rabbit hindlimb kinematics model: Angular velocity and elastic energy analysis

Kinematics is a modern tool used in furthering musculoskeletal and osteoarthritis research. When rabbits are used as an animal model, this furthers our understanding of human biomechanics, specifically when focused on hindlimb movements. Through hindlimb biomechanics, kinematic patterns in rabbit hopping can be used to determine multiple variables such as landing methods, joint contact force, velocities, and different joint angles. Previous work on other hopping vertebrates points to the use of elastic energy when hopping, leading to our prediction that rabbits store elastic energy in their muscles to support hopping motions. In order to test this assumption, a pet rabbit trained for specifically jumping over various heights had knee and ankle joint angles recorded over six trials. The trials of the two different heights at 15 and 45 centimeters were observed and manipulated through the Kinovea, a biomechanical video annotation tool designed for sport analysis. With hip, knee, ankle, and metatarsal/phalanges movements monitored, the ankle and metatarsals are observed to be moving at the last stages of leg extension, loaded by the large muscles extending before them. Therefore, we can assume elastic energy is being stored. The angular velocity data calculated from the knee and ankle angles support that a longer pre-loading stage for higher jumps is required. This results in higher compression of limbs, making the angular velocity vary in data when compared between jumping heights 15 and 45 centimeters. With limited available data for rabbits as an animal model for kinematics, there is a need for further research that can ultimately contribute to our understanding of human biomechanics.