Meeting Abstract
Gravity manipulation is a powerful tool for investigating the fundamental mechanics of legged locomotion; observations of how animals adapt their gait and posture to increased load allow work and power optimization to be studied, while changes in gravitational acceleration enable the predictions of pendulum or ballistic based models of locomotion to be tested. Centrifuge induced hypergravity has a number of advantages over other techniques such as mass loading or attaching springs to the body; it has the same effect on both the body and limbs, animals are able to move around freely, and exposure can be maintained for long periods, allowing long term physiological adaptations to be studied as well as shorter term changes in gait or posture. Previous studies of the effects of centrifuge induced hypergravity on animal locomotion have been limited to estimates of overall activity or measurements of gait and posture after the animal has been removed from the centrifuge. The system presented here allows us to make high resolution observations of kinematic and kinetic parameters while the animals are inside the centrifuge; an instrumented exercise wheel measures speed and vertical ground reaction force, and an automatically triggered camera records high speed video at 200Hz. The centrifuge itself comprises two sets of arms of different lengths, allowing two levels of hypergravity to be achieved simultaneously; the maximum effective gravity at the end of the outer arms is 10 times Earth gravity (10g). We have used this system to investigate acute effects of different effective gravity levels on the kinematics and kinetics of mouse locomotion, and we are in the process of investigating the effect of chronic exposure to hypergravity over a period of months on both locomotion and bone and muscle growth in mice.
