10.4 Supplying Energy for Skeletal Muscle Metabolism, Oxygen Debt

Muscle ATP

• very little ATP in storage

• stored is spent 5 seconds

• additional ATP produce vis myokinase

  • phosphate transferred from ADP to make ATP

3 ways generate ATP

• CP

• Glycolysis

• Aerobic cellular respiration

Creatine Phosphate

• high-energy bond between creatine and phosphate

• Pi transferred to ADP to make ATP, catalyzed by creatine kinase

• 10-15 seconds additional energy

Glycolysis

• no O2

• glucose (MG or BG) converted to two pyruvate molecules

• 2 ATP per glucose molecule

• occurs in cytosol

Aerobic Cellular Respiration

• requires O2, within mitochondria

• pyruvate oxidized to CO2

• transfer chemical bond energy to NADH and FADH2, energy used to generate ATP by oxidative phosphorylation

• 30 ATP

• TGs used fuel for ATP

  • longer chain = more ATP

Energy supply and varying intensity of exercise

• sprint (<10 seconds): phosphate transfer system

• 400-meter sprint (<60 seconds): glycolysis

• 1500-meter run (>60 seconds): aerobic

Oxygen Debt

• amount additional O2 needed after exercise to restore pre-exercise conditions

  • replace O2 on hemo/myoglobic

  • replenish glycogen

  • replenish ATP/CP

  • convert lactic acid back to glucose