Meeting Abstract
Our previous studies into the effects of short term exposure to centrifuge induced hypergravity on the kinematics and kinetics of running mice have shown that mice transiently adapt their postures and gaits in response to higher effective gravity; this is consistent with the minimization of muscle activation costs due to peak power demands. It is well known that long term exposure to both increased and reduced gravity has significant effects on animals’ musculoskeletal systems; could longer exposure to hypergravity therefore cause adaptations in mouse muscle that would optimize its capacity to produce power, and hence further reduce muscle activation costs? To investigate this we exposed 12 mice to hypergravity equivalent to 1.5 times Earth gravity (1.5g) for 22 hours a day for up to 12 weeks. An equal number of age, sex and strain matched control mice were housed in identical conditions, and with the same array of instruments, at Earth gravity. During this exposure period, kinematic and kinetic measurements were made using an instrumented exercise wheel which measured speed and vertical peak ground reaction force, and an automatically triggered infra-red high speed camera which recorded at 200Hz. At three week intervals three hypergravity mice and three control mice were culled, and their hind limbs dissected. This allowed hind limb muscle properties to be analyzed in conjunction with the kinematic and kinetic data. Not only is this data of interest in the context of fundamental biomechanics, it could also inform our understanding of how long term changes in body weight, such as obesity, affect bone and muscle.
