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How muscles use fuel.

ALL living cells consume energy to perform work, but skeletal muscle does its work in a most conspicuous way, in bodily activities such as walking, running, jumping, and lifting. How muscle actually transforms chemical energy into mechanical energy was the first great question addressed by modern biochemistry, and by the middle of this century the main outlines of the story were complete. The immediate source of chemical energy for muscle contraction is the hydrolysis of ATP to ADP. In the short term, ATP can be regenerated from muscle stores of phosphocreatine, but the rephosphorylation of ADP during long-term exercise requires . . .