Exercise Metabolism - Chap 4

Question 1

What is the VO2 of a 70 kg individual at rest?

Answer 1

0.25 L/min = 3 ml/kg/min

Question 2

Why does O2 deficit and EPOC occur?

Answer 2

1. O2 - That aerobic metabolism is not fully activated at the onset of exercise
2. EPOC occurs because oxygen use (VO2) remains elevated above rest. Then it goes into recovery oxygen used to support Rapid EPOC (right after) and Slow EPOC (several minutes after)

Question 3

Why do trained individuals have lower O2 deficit?

Answer 3

Trained subjects have a better developed aerobic bioenergetic capacity, resulting from either cardiovascular or muscular adaptations induced by endurance training

Question 4

Why do trained individuals have a higher VO2 max?

Answer 4

Trained subjects have a better developed aerobic bioenergetic capacity, resulting from either cardiovascular or muscular adaptations induced by endurance training

Question 5

What are the factors responsible for EPOC?

Answer 5

• Replenishing oxygen in muscle and blood
• Resynthesis of phosphocreatine

Elevated heart rate and breathing (heart and
diaphragm contraction = energy)

• Elevated body temperature (sweat)
• Elevated epinephrine & norepinephrine (increase
  metabolic rate)
• Conversion of lactic acid to glucose
  (gluconeogenesis)

Question 6

What is the simplest and most rapid method to produce ATP during exercise?

Answer 6

Muscle Glycogen

Question 7

What is the predominant fuel source used during exercise?

Answer 7

Carbohydrates

Question 8

What is the crossover concept? What does “shift” refer to?

Answer 8

Crossover - As the exercise intensity increases, there is an exercise intensity at which the energy derived from carbohydrate exceeds that of fat

Shift -

1. Type I muscle fiber recruitment
2. Epinephrine and “other hormone” secretion
3. Lactate is not produced

Question 9

What is the primary hormone that stimulates glycogen breakdown during high intensity exercise?

Answer 9

Epi

Question 10

What hormones stimulate hormone sensitive lipase/lipolysis during long duration exercise?

Answer 10

Epi
Glucagon
Growth Hormone
Cortisol

Question 11

Why do endurance athletes consume liquid glucose supplements during an event?

Answer 11

1. Increased muscle glycogen stores, as well as delayed onset of fatigue.
2. Main energy substrates for muscle contraction during exercise.

Question 12

Why is glucose required in the muscle to burn fat during long duration exercise?

Answer 12

No glucose = no pyruvate = no OA = no Krebs = no fat utilization

Question 13

What are the potential fates of lactate?

Answer 13

1. Lactate in muscle can be
   reconverted to pyruvate
   and oxidized (50-70%)
2. Lactate can leave muscle
   and enter liver where it is
   converted to glucose via
   gluconeogenesis.
   Glucose is then used by
   muscle.

Question 14

Is protein significant source of energy for the body?

Answer 14

No

Question 15

What is RER/RQ? How do you interpret a given value?

Answer 15

RER/RQ is the ratio between fat and carbs being used. We can determine it based on the intensity of our exercise.

Question 16

What system is used during sustained moderate intensity exercise?

Answer 16

Aerobic Metabolism

1. First 1-5 seconds = ATP through stored ATP and PCR
2. Longer than 5 sec, but < 45 seconds = Shift to ATP production via Glycolysis (Glucose)
3. Exercise lasting longer than 45 seconds = Shift to ATP production via aerobic metabolism

Question 17

What system is used during high intensity exercise?

Answer 17

Anaerobic Metabolism