Myoglobin and O2 Consumption in Exercising Human Gastrocnemius Muscle

The regulation of oxygen transport to the mitochondria in exercising muscle is a key issue in biology, since oxygen demand can increase dramatically from the resting state. As the oxygen consumption (VO2) increases, a coordinate set of controls must enhance the oxygen delivery from the lung to the cell. As VO2 approaches its maximum rate (VO2max), convection, diffusion or enzymatic activity must also become limiting. Identifying the rate- determining step is then a central issue (Sutton, 1992).