Skeletal muscle (anaerobic glycolysis)

Anaerobic glycolysis in skeletal muscle is important in three different situations:

• type IIb muscle fibres:
  • optimized for rapid bursts of contraction by evolutionary loss of most mitochondria
  • therefore, cannot undertake oxidative phosphorylation and instead have very active anaerobic enzymes
• initial few minutes of exercise:
  • supply of energy substrates from blood cannot match sudden increase in energy demands
  • anaerobic metabolism sustains demand for first few minutes
• on-going exercise with increased energy demands:
  • if oxidative glycolysis and tricarboxylic acid cycle cannot process substrate any faster, lactate dehydrogenase can convert pyruvate to lactate for subsequent reformation of glucose within the liver - the Cori cycle