The main objective of this study is to examine how the musculoskeletal system of the vertebrate hindlimb acts to accommodate gross changes in locomotor functions, as during a shift from steady to unsteady locomotion, or during movement in different physical environments. One possible mechanism underlying such accommodation is that limb muscle might individually alter their mechanical function depending upon the circumstances. Alternatively, many limb muscles might be architecturally constrained in their mechanical operations, and thus, to accommodate broad changes in function, largely different sets of muscles must become activated. Studies of limb muscle function during locomotion have largely focused on steady-state locomotion within a single environment, thus, the functional breadth of individual limb muscles is poorly understood.
The specific aims os this project are to elucidate patterns of limb muscle length change, force generation, and activation, in vivo during locomotion, using sonomicrometry, force buckle measurements, and electromyography. These techniques will be used on a range of vertebrate taxa (amphibian, avian, and mammalian), performing a variety of locomotor behaviors across a range of environments. This work will elucidate modes of locomotion and physical environments which maximize and minimize limb muscle stress and strain. This work will elucidate modes of locomotion and physical environments which maximize and minimize limb muscle stress and strain. Furthermore, understanding how muscle-tendo systems are integrate to permit gross changes in function is critical to understanding the evolutionary design of the vertebrate musculoskeletal system.
