Chapter 4

Question 1

What is the oxygen deficit?

Answer 1

It is the lag of Oxygen uptake at the start of exercising. (the lack of o2)

Question 2

How long does it take to reach steady state?

Answer 2

Depends on intensity. Trained people reach it faster than untrained people.

Question 3

What is the oxygen debt?

Answer 3

The excess oxygen uptake above rest after exercise.

Question 4

What does EPOC stand for?

Answer 4

Excess Post-exercise Oxygen Consumption

Question 5

Why is the oxygen consumption elevated following exercise?

Answer 5

REEL PR: Resynthesis of PC in muscle
Lactate removal
Restoration of muscle and blood oxygen stores
Elevated body temp
Post-exercise elevation of HR and breathing
Elevated hormones

Question 6

How does exercise intensity influence the oxygen debt? Why does it have this effect?

Answer 6

High intensity - slower and more oxygen debt that needs to be replaced
Low-intensity - faster and less oxygen debt that needs to be replaced. (think of running 400m vs. walking 400m)

Question 7

What energy systems are being used during short duration, high intensity exercise?

Answer 7

Anaerobic sources (ATP-PC 1-5 sec, gylcolysis 5-6 sec) - gradual shift

Question 8

What energy systems are being used during prolonged exercise?

Answer 8

Aerobic sources

Question 9

Under what conditions might the oxygen cost rise during prolonged exercise?

Answer 9

Hot/Humid environments & Continuous exercise

Question 10

What causes this drift in oxygen consumption?

Answer 10

Increased body temp & rising hormones

Question 11

Define VO2 max.

Answer 11

Q (HR x SV) x a-v o2 diff. The maximal ability of the body to transport and utilize oxygen. (Maximum oxygen uptake)

Question 12

What energy systems are used during a graded exercise test (incremental exercise)?

Answer 12

Both anaerobic and aerobic energy systems

Question 13

What rises in the blood during incremental exercise? What type of rise does lactate follow?

Answer 13

Blood levels of lactate rise during incremental exercise in an exponential fashion.

Question 14

What is the OBLA / lactate threshold?

Answer 14

The point at which there is a sudden rise in lactate. Onset of Blood Lactate Accumulation.

Question 15

Lactate Accumulation is influenced by what two factors?

Answer 15

Rate of glycolysis to the ability to transport NADH to the mitochondria.
Rate of lactate removal from the blood.

Question 16

BLOOD CONCENTRATION = Lactate entry - Lactate removal

Answer 16

Lactate entry - Lactate removal

Question 17

At what exercise intensity does lactate rise for?

Answer 17

Trained Athletes: 65-85% VO2 max

Untrained Athletes: 50-60% VO2 max

Question 18

What is the respiratory exchange ratio and how is it calculated?

Answer 18

VCO2/VO2

Estimates the % contribution of carbohydrates and fats. ( the ratio of CHO produced to the O2 consumed. ) REMEMBER LAB!

Question 19

Under what respiratory condition must the RER be calculated?

Answer 19

When steady state has been reached.

Question 20

The following fuels are being used at R values of:

Answer 20

1. 0 - CHO 100%
2. 85 - CHO 50% Fat 50%
3. 70 - Fat 100%

Question 21

What are the two main energy sources for the body?

Answer 21

1. Fats

2. Carbohydrates

Question 22

How much does protein contribute to the total energy pool during exercise?

Answer 22

Less than 2% , it plays a very minor role.

Question 23

What two factors are the main determinants of substrate use?

Answer 23

1. Intensity (CHO)

2. Duration (Fats)

Question 24

At low intensities of exercise this fuel is primarily being used…

Answer 24

30% VO2 max, Fats

Question 25

At high intensities of exercise this fuel is primarily being used…

Answer 25

70% VO2 max, CHO

Question 26

Why does the body shift from fats to carbohydrates as the main energy source with increasing intensities?

Answer 26

• the recruitment of fast twitch fibers
• increases in epinephrine
• process rate capability of oxidative metabolism

Question 27

As duration increases, the body relies more heavily on what energy source?

Answer 27

Fats

Question 28

Why aren’t fats used as an immediate source of energy?

Answer 28

Lypolysis is a slow process.

An increase in fat metabolism occurs only after several minutes of exercise.

Question 29

When do muscle glycogen stores begin to deplete?

Answer 29

After more than 2 hours

Question 30

Why does muscle gylcogen depletion result in fatigue? And what does the saying “Fat burns in a CHO flame” mean?

Answer 30

• Depletion of available carbohydrate reduces the rate of glycolysis - concentration of pyruvate reduced in the muscle.
• Lowers the rate of aerobic production of ATP by reducing the number of krebs-cycle compounds
• When carbohydrate stores are depleted in the body, the rate at which fat is metabolised is also reduced.

Question 31

Lactate is a metabolic waste product. Does lactate have any useful roles?

Answer 31

Acts as a buffer to H+ (acidity)

Question 32

In what ways can we use lactate as a fuel source?

Answer 32

Cori cycle - Converts lactic acid back into gluecose in the liver.
Lactate Shuttle - Slows skeletal and cardiac muscle. Convert to pyruvate and then into Acetyl-CoA.
(Intracellular - processed through the cell)
(Cell-to-cell - come in from blood and processed through different cell)