Dr. Hermanson will study the relationship between muscle architecture and its functional role in mammalian running. When muscles shorten more than one/third of their length, the chemical cross-bridges that control muscle length cease to overlap and thus cease to generate force. He will test a primary hypothesis that short-fibered muscles are active during high-speed gaits and that they function as elastic energy storage structures during locomotion. The study is unique in that it focuses on pairs of well-studied muscles in horses that have been well characterized for their role in passive stay apparatus. This research will provide new perspective into the design of normal mammalian muscle in a system (equine) that is of importance and also provides fundamental insight into issues of muscle design.