At the onset of a very intense sprint, oxygen delivery to muscle is limited. What immediate metabolic fate will pyruvate most likely undergo in the working muscle?

• A. Be transported directly into mitochondria and fully oxidized to CO2 and water via the citric acid cycle despite the oxygen limitation.
• B. Be converted to lactate to regenerate NAD+ allowing glycolysis to continue and provide ATP anaerobically.
• C. Spontaneously form creatine phosphate which is then exported to the bloodstream to fuel other tissues.
• D. Be polymerized into glycogen in the cytosol to store energy for the next sprint interval.

Answer: (B)