A.2.3.4 Oxygen Deficit and EPOC (HL)

Oxygen Deficit - the difference between the oxygen that your muscles demand and the oxygen you can actually provide your muscles

Oxygen Debt / EPOC (Excess Post-exercise Oxygen Consumption) - after prolonged exercise aerobic or anaerobic exercise, the body accumulates an oxygen debt. During recovery, the body needs to repay this debt and requires extra oxygen to remove lactic acid

Factors that occur in muscle cells during exercise

ATP = Decrease

Phosphocreatine = Decrease

Glycogen = Decrease

Triglycerides = Decrease

CO2 = Increase

Oxygen/myoglobin stores = Decrease

Lactic acid = Increase

Water = Increase

What does this graph show us?

Oxygen deficit: at the start, oxygen demand exceeds supply, so relies on anaerobic systems are used

Steady-state exercise: oxygen supply meets demand

EPOC Phase: After exercise, oxygen consumption remains elevated to restore homeostasis. This curve gradually decreases as the recovery progresses

The steep initial decline represents the alactacid acid phases (fast recovery)

The slower, prolonged decline represents the lactacid phase (slow recovery)

EPOC has two components:

• Fast component:

  • ATP and PCr are resynthesized

  • Myoglobin is replenished with oxygen

  • The first few minutes of recovery

• Slow component:

  • Removal of lactic acid

  • Maintenance of ventilation and body temp

  • Takes mins to hours