Crossover Concept and EPOC

Question 1

What does the Crossover Concept relate to?

Answer 1

the progressive increase in CHO use for energy (high intensity, >60% VO2max) and decrease of fats (low intensity, <30% VO2max) as exercise intensity increases

Question 2

Reasoning for Crossover Concept

Answer 2

1. epinephrine blood levels increase
2. epinephrine increases glycogen breakdown
3. recruitment of fast fibers
4. fast fibers means more glycolytic enzymes (speed up)

Question 3

Shift from CHO to fat metabolism

Answer 3

• as exercise duration increase (low intensity), energy usage shifts from CHO to fat metabolism
• steady state O2 uptake is maintained
• fat metabolism is slow, but produces a lot of ATP

Question 4

EPOC

Answer 4

Excess Post-Exercise Oxygen Consumption
it’s the excess of the oxygen consumed following exercise to re-fuel energy systems (i.e. O2 consumption is higher post-exercise than it is at rest)

Question 5

EPOC factors (5)

Answer 5

higher body temp.
PCr depletion
higher blood lactate concentrations
higher blood epinephrine and norepinephrine concentrations
exercise duration and intensity