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EPHE 441 > exercise metabolism > Flashcards

exercise metabolism Flashcards

1
Q

What is the lactate paradox?

A

Lactate rises in parallel with VO2 increases, but lactate is not an indicator of VO2 max.

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2
Q

What is the glycolytic rate dependent on? (2 things)

A

Intensity and duration

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3
Q

What is the live-high, train-low hypothesis?

A

Live in high altitude to produce less lactate through beta-oxidation, and train at low altitude.

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4
Q

Why is lactate not as high during high-altitude exercise?

A

Less oxygen is available, and stimulus intensity is downgraded

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5
Q

What stimulates lactate production?

A

exercise

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6
Q

What happens in lactate production?

A

Use epinephrine to stimulate glycloysis

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6
Q

How does the lactate threshold relate to the ventilatory threshold?

A

Ventilation is measured concurrently and similar patterns are followed.

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7
Q

Define OBLA

A

onsite blood lactate accumulation

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7
Q

What does OBLA do?

A

Occurs when more efflux of lactate comes into the system, sits at 4 mmols. Is related to the maximum lactate steady state.

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8
Q

Blood lactate concentration =

A

blood lactate entry into the blood - blood lactate removal (ratio of efflux and influx to determine if OBLA is occurring)

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9
Q

What helps to reduce lactate and why?

A

Movement; bc of blood flow stimulation and metabolic engine movement.

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10
Q

What is the lactate (anaerobic) threshold?

A

the point where OBLA begins

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11
Q

OBLA is associated with

A

hyperpnea (hyperventilation); breathing at a rate somewhat contrary to metabolic rate.

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12
Q

True or false - the brain greatly increases lactate extraction?

A

False… increases metabolism, has a high resting point and wants to maintain that level.

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13
Q

T or F, the lactate threshold separate from the anaerobic threshold?

A

False

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14
Q

Four factors contributing to lactate threshold

A
  1. reduced rate of lactate removal (impacts intensity)
  2. low muscle oxygen
  3. accelerated glycolysis due to epinephrine
  4. recruitment of fast twitch fibers (higher glycolytic enzyme)
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15
Q

What happens to arterial PO2 in high altitude?

A

decreases; o2 stimulates breathing and can get acclimatization response over time (no hypoxia)

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16
Q

What are 3 practical uses of the lactate threshold?

A
  1. describes a shift in what energy source we are using
  2. could be used to shape training intensities
  3. training energy system for purpose of a task
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17
Q

Define anaerobic threshold

A

classical term to describe the intensity/workload where anaerobic metabolism becomes prevalent

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18
Q

Define lactate threshold

A

The point at which blood lactate levels begin to rise exponentially during exercise (between 50-60% VO2 max)

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19
Q

Define maximal lactate at a steady state

A

the maximal lactate achieved at a steady state workload (often 80% of VO2 max)

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20
Q

Define critical power

A

the point at which workload can be maintained at a steady state

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21
Q

Define the cross-over concept

A

Where the substrate utilisation crosses over from primarily fat oxidation to mostly CHO. (usually a mix during moderate exercise and switches to CHO at vigorous).

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22
Q

Why is there a crossover from fat to carb utilization

A
  1. Carbs are easier to break down
  2. Shift in demand (more fast twitch muscle recruitment, increase in intensity)
  3. Increase in catecholamine circulation (epinephrine), increases phosphorylation of glucose
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23
Q

Where does epinephrine come from?

A

sympathetic response, glycolysis stimulation

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24
Q

What is RER going to look like based on the fuels we use?

A

Mostly fat: 0.7
Some fat, some carbs: between 0.7 and 1
CHO: 1

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25
Q

T or F, glycogen depletion increases the rate of glycolysis

A

F, reduces the rate and lowers pyruvate

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26
Q

T or F, lower levels of pyruvate reduce Krebs intermediates and slow Krebs activity?

A

True, impacts ATP production from fat oxidation.

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27
Q

3 physiological differences between men and women in exercise

A

VO2 max = 45 ml/kg/min in women
VO2 max in men = 50”()”

Women have 18% body fat at 50kg, men have 10% at 75kg

54.9m/kg lean mass/min in women, 55.6 in men.

Women also have higher risk of stroke and worse stroke outcomes post-menopause.

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28
Q

T/F.. women use more fat oxidation?

A

True, higher % fat stores help maintain energy during reproduction.

29
Q

4 factors that increase fat oxidation in women?

A
  1. increased type 1 fiber %
  2. increased IMCL availability
  3. increased Adipose FFA production
  4. Increased FFA oxidative protein
30
Q

What can we learn from the impact of exercise intensity on substrate utilization?

A

Might not have same metabolic stimulation/requirements for RER equation for men and women… if females don’t hit the mark set for the men, then they aren’t getting the adaptation.

31
Q

What does MLSS (CP) stand for?

A

maximum lactate capacity of critical power

32
Q

What are the 3 storage sites of CHO

A
  1. liver glycogen
  2. glucose in blood and extracellular fluid
  3. muscle glycogen
33
Q

What are the two storage sites for fat?

A

Adipocytes and muscle

34
Q

How much (%) do proteins contribute to fuel used in exercise less than 1hr? More than 1 hr?

A

<2%, increases to 5-10% in longer duration

35
Q

What are the different ways of carb-restricted training?

A
  1. fast training
  2. low glycogen
  3. post-Ex- CHO restriction
  4. sleep-low, train-low
36
Q

Fasted training

A

liver glycogen altered
- enhances genes linked to substrate utilization and mitochondrial function

37
Q

low glycogen (2x/day training)

A

increases citrate synthase and exercise capacity

38
Q

Sleep low, train low

A

Improves gene expression (PGC-1a)
Greater fat oxidation (but similar gene expression)
Improved cycling efficiency and TT perfusion.

39
Q

What is the Cori cycle?

A

conversion of lactic acid to glucose (gluconeogenesis - glucose synthesis)…
- glucose to pyruvate in muscle, to lactate in blood, to pyruvate in liver, to glucose-6-phosphate in liver, to glucose in the blood.

40
Q

McCardle’s syndrom

A

muscle glycogen phosphorylase deficiency; cannot convert glycogen to glucose… partly hinders glycolysis.

41
Q

Is low-intensity exercise best for burning fat?

A

Yes.At 25% intensity, about 75% plasma FFA used as fuel source. Decreases at high intensity levels.

42
Q

Where does the lactate to pyruvate conversion occur?

A

Anywhere

43
Q

T/F - almost 100% of ATP is produced by aerobic metabolism?

A

True

44
Q

What is resting O2 consumption?

A

0.25L/min - 250 ml.min^-1
3.5mL/kg/min (1 MET)

45
Q

When is the aerobic steady state reached?

A

After 1-4 minutes

46
Q

What pathways is initial ATP production through?

A

Anaerobic - ATP-PC system, glycolysis.

47
Q

Oxygen deficit

A

lag in oxygen uptake at the beginning of exercise

48
Q

T or F, the [CP] in skeletal muscle is 5-7x greater than [AYP] (26 mmol.kg wet wt)

A

F, 4-6x

49
Q

Name the 3 types of phosphagen systems

A
  1. CP +ADP +H uses creatine kinase to create C + P +Energy
  2. ADP +ADP uses adenylate kinase to get ATP +AMP
  3. AMP +H uses AMP deaminase to creat IMP +NH4
50
Q

The high-energy Pi reservoir that is crucial during transitions to low-high energy systems is:

A

creatine phosphate

51
Q

Anaerobic lactic system

A

Glycolysis only
- in cytoplasm, near contractile muscle units

52
Q

Safety valve for aerobic energy system

A

Anaerobic lactic system
- when O2 isn’t available or ATP is being demanded at greater rate than aerobic system can supply

53
Q

The fuel source/signaling molecule for other organs (liver, heart, brain)

A

Lactate

54
Q

Accumulation of lactate depends on 4 things

A
  1. Rate of glycolysis
  2. oxidative enzyme activity
  3. cellular O2 level (lactate paradox)
  4. Net rate of La- influx vs efflux
55
Q

Lactate shuttle

A

Pyruvate to lactate
NAD to NADH
FAD to FADH2
- reduction

56
Q

How does the Wingate sprint exercise demonstrate how PCr, glycolysis, and oxidative phosphorylation contribute over time?

A

PCR and glycolysis most prominent over first 6 seconds, mostly, glycolysis between 6 and 15, and mostly oxidative phosphorylation between 15-30 seconds.

57
Q

What do you want to see in the wingate test?

A

elevated plasma glucose stores

58
Q

What is required in rest to exercise transitions?

A

inertia

59
Q

What senses CO2 produced by buffering?

A

Peripheral and central chemoreceptors

60
Q

Oxygen debt

A

elevated O2 uptake (above rest) following exercise

61
Q

T or F, people who are fitter have smaller O2 deficit for all intensities than untrained people.

A

True

62
Q

What percentage of O2 debt does EPOC make up?

A

20%

63
Q

gluconeogenesis

A

convert lactate to glucose (primarily in the liver)

64
Q

EPOC

A

excess post-exercise oxygen consumption

65
Q

Rapid O2 debt

A
  1. resynthesis of stored PC and ATP
  2. Replenishing muscle and blood O2 stores (20%)
66
Q

Slow o2 debt

A
  1. elevated heart rate and breathing = energy need
  2. elevated body temperature = metabolic rate
  3. elevated epinephrine and norepinephrine = metabolic rate
  4. Conversion of lactic acid to glucose
67
Q

Why is O2 so high or why is it not so high in EPOC

A

Depends on the intensity/duration of exercise
- body temperature, breathing, epinephrine level, lactic acid conversion
Depends on O2 debt

68
Q

Which system has the greatest capacity for energy?

A

Phosphagen system

69
Q

How do we modify ADP production?

A

Exercise and become acidotic

70
Q

What stimulates phosphofructokinase?

A

Adenylate kinase

71
Q
A

EPHE 441 (1 decks)

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