Frogs must generate a high level of mechanical power when they jump. T
he muscular system of frogs that jump is presumably designed to delive
r these high powers. The length changes and activation pattern that mu
scles undergo during jumping were measured, and isolated muscle bundle
s were driven through this in vivo pattern. During jumping muscles gen
erated maximum power. Specifically the muscle fibers (i) operated at o
ptimal sarcomere lengths, (ii) operated at optimal shortening velociti
es, and (iii) were maximally activated during power generation. Thus,
many different parameters must have evolved in concert to produce a sy
stem capable of this explosive jumping movement.