Fig. 1. Schematic of mathematical model showing one-dimensional spatial domain where the position in the cell, x, ranges from x=0 (sarcolemma) to x=L (fiber center). O₂ is supplied at a constant concentration on the outside of a membrane that constitutes the vascular endothelium, extracellular space and sarcolemma (hatched area), and the myosin ATPase and mitochondrial reactions are distributed uniformly through the spatial domain.