energy systems in muscle cells

• Impact of Exercise on Muscle Cells

  • Muscle cells during vigorous exercise do not get sufficient oxygen to support the electron transport chain. Under these conditions, pyruvate is converted to lactate.
• Production of Lactate

  • When pyruvate is converted into lactate, this involves the transfer of hydrogen ions from the NADH produced in glycolysis to pyruvate in order to produce lactate.
  • This regenerates the NAD needed to maintain ATP production though glycolysis.
• Muscle Fatigue and Oxygen Debt

  • As lactate accumulates muscle fatigue occurs.
  • The oxygen debt is repaid when exercise is complete. This allows respiration to provide the energy to convert lactate back to pyruvate and glucose in the liver.
• Slow-twitch muscles

  • Slow-twitch muscles fibres contract relatively slowly but can sustain contractions for longer.
• • Slow-twitch muscle fibres rely on aerobic respiration to generate ATP and have many mitochondria, a large blood supply and a high concentration of the oxygen-storing protein myoglobin.
  • The major storage fuel of slow-twitch muscle fibres is fat.
• Fast-twitch muscles

  • Fast-twitch muscle fibres contract relatively quickly, over short periods.
• • Fast-twitch muscle fibres can generate ATP through glycolysis only and have fewer mitochondria and a lower blood supply compared to slow twitch muscle fibres.
  • The major storage fuel of fast-twitch muscle fibres is glycogen.
• Patterns of Muscle Tissue in Athletes

  • Most human tissue contains a mixture of both slow- and fast-twitch muscle fibres.
  • Athletes show distinct patterns of muscle fibres that reflect their sporting activities.