Chapter 4 PowerPoint

Question 1

Energy requirements at rest

Answer 1

100% of ATP produced by aerobic metabolism.
Blood lactate levels are low (<1.0 mmol/L).
Resting O2 consumption: 0.25 L/min (absolute) and 3.5 ml/kg/min (relative).

Question 2

Why is there a lower oxygen deficit when the individual is trained?

Answer 2

Better developed aerobic bioenergetic capacity.

Cardiovascular and muscular adaptations.

Question 3

Recovery from exercise

Answer 3

O2 uptake increases then rest during recovery from exercise.

Excess post-exercise oxygen consumption (EPOC).

Question 4

Factors contributing to EPOC

Answer 4

Resynthesis of phosphocreatine in muscle.
Lactate conversion to glucose.
Restoration of muscle and blood oxygen stores.
Elevated body temperature.
Post-exercise elevation of HR and breathing.
Elevated hormones.

Question 5

Rapid portion of EPOC

Answer 5

Resynthesis of stored phosphocreatine.

Replenishing muscle and blood O2 stores.

Question 6

Slow potion of EOPC

Answer 6

Elevated heart rate and breaking = increase energy needed.
Elevated body temperature = increased metabolic rate.
Elevated epinephrine and norepinephrine = increased metabolic rate.
Conversation of lactic acid to glucose (glucogenesis).

Question 7

Metabolic responses to short-term, high intensity exercise

Answer 7

First 1-5 seconds = ATP via ATP-PC system.
>5 seconds = shift to ATP via glycolysis.
Events >45 seconds = ATP via ATP-PC, glycolysis, and aerobic (60 seconds = 70% anaerobic/30% aerobic; 2 minutes = 50% anaerobic/50% aerobic).

Question 8

Metabolic responses to prolonged exercise:

Answer 8

Prolonged exercise is more than 10 minutes.

Steady state oxygen uptake can generally be maintained during submaximal exercise (below lactate threshold.

Question 9

Changes in oxygen uptake during incremental exercise:

Answer 9

The VO2 steadily increases and the work rate (increases), but the VO2 plateaus once the work rate reaches 250 watts.

Question 10

Changes in blood lactate concentration during incremental exercise:

Answer 10

The amount of lactate increases very slowly until VO2 max reaches 60%, where the lactate threshold is reached. The lactate then increases dramatically.

Question 11

Mechanisms to explain the lactate threshold

Answer 11

Low muscle oxygen
Accelerated glycolysis
Recruitment of fast-twitch fibers
Reduced rate of lactate removal

Question 12

Practical uses of the lactate threshold:

Answer 12

Prediction of performance, combined with exercise economy.

Planning training programs: marker of training intensity, choosing a training heart rate based on lactate threshold.

Question 13

Lactic acid removal following exercise:

Answer 13

70% of it is oxidized by cells and used as a substrate by the heart and skeletal muscle.
20% of it is converted to glucose.
10% of it is converted to amino acids.

Question 14

Does lactate cause muscle soreness?

Answer 14

Physiological evidence does not support this claim. Lactate removal is rapid (60 minutes) following exercise. If lactate caused muscle soreness, power athletes (sprinters) would experience delayed onset muscle soreness (DOMS) after every workout.

Question 15

What causes DOMS?

Answer 15

Microscopic injury to muscle fibers leads to inflammation.

Occurs 24-48 hours following an exercise session.

Question 16

As VO2 max increases, the energy from fats _________, and the energy from carbohydrates ____________.

Answer 16

Decreases

Increases

Question 17

Is low-intensity exercise best for burning fat?

Answer 17

At low exercise intensities (about 20% VO2 max), a high percent of energy expenditure is derived from fat, while the total energy expenditure is low. This means that the total fat oxidation is also low.
At higher exercise intensities (about 60% VO2 max), a lower percent of energy expenditure is derived from fat, while the total energy expended is higher. This means that the total fat oxidation is also higher.

Question 18

Glycogen depleted in prolonged high-intensity exercise…

Answer 18

Decrease rate of glycolysis and production of pyruvate.
Decrease Kreb’s cycle intermediates.
Decrease fat oxidation.

Question 19

Sources of protein during exercise:

Answer 19

Proteins broken down into amino acids. Muscle can directly metabolize BCAAs and alanine. The liver can convert alanine to glucose.
Only 2% to total energy production during exercise. May increase to 50-10% late in prolonged-duration exercise.