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Exercise Science > Lesson 2 > Flashcards

Lesson 2 Flashcards

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1
Q

Explain Oxygen consumption (Vo2)

A
  • measure of how much oxygen is being consumed
  • reflects the level of energy expenditure
  • more oxygen consumed= increased EE
  • measured in L/min or mL/min or ml/kg/min
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2
Q

Explain maximal oxygen consumption (Vo2max)

A

-the maximal capacity of the cardiovascular system to deliver oxygenated blood to dynamically working muscle

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3
Q

explain muscle glycogen

A
  • approx 79.5% of bodys carbs stored as muscle glycogen

- provides fuel for muscular contraction

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4
Q

explain liver glycogen

A
  • approx 20% of the bodys carbs are stored in liver glycogen

- provides temp storage for glucose and produces new glucose

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5
Q

explain plasma glucose

A

-only a small portion of body’s carbs (0.5%) stored as plasma glucose

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6
Q

where is fat stored in the body?

A
  1. adipose tissue= >95% fat storage
  2. plasma= triglycerides contained in lipproteins (HDL,LDL, VLDL)
  3. muscle= intrtamuscular trigly. (IMTG)
  4. liver= small percentage in healthy individual
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7
Q

where is protein stored in the body?

A
  1. skeletal muscle= 50-75% of total body protein and in the form of contractile, structural, storage proteins
  2. constituents of plasma membranes; transport proteins
  3. globular proteins
  4. free amino acids in blood- immune proteins, transport proteins (albumin), clotting proteins
  5. there are NO AA reserves in the body- excess amino acids are converted to glucose, converted to triglyceride or excreted in urine
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8
Q

What is RMR

A 
resting metabolic rate
-required for:
all cellular functions
maintenance of systems of the body
regulation of body temp
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9
Q

What % of RMR is required for regular protein turnover?

A

15-20%

  • body protein stores are continually turned over (replaced) to preserve protein function
  • muscle protein turnover accounts for approx 30% of whole-body protein turnover
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10
Q

What is RMR proportional to?

A

body size: surface area and FFM

  • bigger people have larger and more tissue, therefore need to consume more Oxygen
  • decreases w age, primarily due to decreases in FFM

-typically ranges from 1100-2500 kcal/day

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11
Q

Explain exercise and RMR

A
  • Exercise training has little to no effect on RMR
  • metabolic rate of muscle is only a small fraction of whole body RMR
  • at true rest, REE is almost completely aerobic
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12
Q

What are the typical available fuel sources during exercise?

A 
carbs= muscle glycogen & plasma glucose
fat= FFA from adipose, IMTG, TGs in lipoproteins

protein not considered due to low contribution

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13
Q

How do catecholamines (epinephrine & norepinephrine) change during exercise?

A
  • increases FFA supply by stimulating lipolysis in adipose tissue
  • stimulates gluconeogensis and glycogenolysis in liver
  • stimulates glycogenolysis in skeletal muscle
  • inhibit insulin release and stimluate glucagon release
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14
Q

How do growth hormone change during exercise?

A
  • increases FFA supply by stimulating lipolysis in adipose tissue
  • stimulates gluconeogensis and glycogenolysis in liver
  • attenuates glucose uptake in skeletal muscle
  • indirectly promotes growth and repair of skeletal muscle
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15
Q

How do cortisol change during exercise?

A
  • increases FFA supply by stimulating lipolysis in adipose tissue
  • stimulates gluconeogensis and glycogenolysis in liver
  • attenuates glucose uptake in skeletal muscle
  • aids in recovery and repair after strenuous exercise
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16
Q

How does glucagon change during exercise?

A
  • increases FFA supply by stimulating lipolysis in adipose tissue
  • stimulates gluconeogensis and glycogenolysis in liver
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17
Q

How does insulin change during exercise?

A
  • stimulates uptake of glucose by muscle, fat, liver
  • inhibits lipolysis in adipose tissue
  • inhibits glucose release from liver
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18
Q

Which hormones increase with increasing exericse intensity and duration?

A
  • catecholamines
  • GH
  • cortisol
  • glucagon
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19
Q

Which hormones decrease with increasing exercise intensity and duration?

A

insulin

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20
Q

How do fuel sources change during exericse duration?

A
  • as duration increases, more fat and less carb burned
  • as duration increases, more fuel (carb and fat) derived from plasma sources and less from endogenous (intramuscular) sources
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21
Q

How do fuel sources change during exercise intensity?

A

-as intensity increases, greater proportion of ATP derived from glycolysis

-the greater the intensity, the greater the reliance on non-aerobic pathways
ATP regeneration must be rapid
increased recruitment of fast twitch muscle fibers
influence of increased catecholamines

-at lower intensities, greater reliance on aerobic pathways
fuel source tends to be an equal mix of carb and fat

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22
Q

How is FFA mobilized during exercise?

A

By lipolysis; hydrolysis of triglycerides into FFAs

  • primarily facilitated by the enzyme hormone sensitive lipase in adipocytes
  • stimulated by GH, cortisol, testosterone
  • inhibited by insulin (HSL very senssitive)
23
Q

What are the effects of catecholamines on HSL ?

A
  • they depend on exercise intensity
  • low/mod intensity=small increase in epinephrine mobilizes FFA to fuel aerobic metabolism
  • high intensity= large increase in epinephrine inhibits FFA mobilization, as the primary fuel source for this intensity is glucose
  • the other stimulating hormones (GH, cortisol, testosterone) have slower effects and may act to modulate the action of catecholamines
24
Q

When does fat oxidation tend to be the greatest?

A

during mod intensity exercise (50-60% vo2max)

  • blood flow to adipocytes greatest
  • blood flow decreases at higher intensities
  • demand for carb in muscle is low
  • creates a system with high fat delivery and high fat utilization
  • total fat oxidation = FFA +IMTG

FFA oxidation highest at low intensity and decreases wtih intesnity
IMTG ox greatest at mod intensity

25
Q

When does fat oxidation decrease?

A

with high intensity exercise

  • increased catecholamine concentration causes shift from fat to carbs
  • increased signal to stimulate glycolysis and glucose use in the muscle
26
Q

Explain blood glucose uptake by skeletal muscle

A
  • faciliated by GLUT proteins in the cell membrane
  • GLUT1 = many cells, does not require insulin to be active
  • GLUT2= liver, does not require insulin to be active
  • GLUT4= muscle and adipose cells, activated by insulin (after a meal) and muscular contraction

once in the muscle, glucose (and muscle glycogen) cannot be transported out of the muscle for use by other tissues

27
Q

Define insulin resistance

A

impaired ability of insulin to active GLUT4 receptors

-decreases glucose uptake, resulitng in hyperglycemia

28
Q

How is plasma glucose maintained during exercise?

A
  1. increasing reliance on fatty acids. lipolysis stimulated by catecholamines, glucagon, GH, cortisol and inhibited by insulin
2. attentuating glucose uptake into muscle (conserving plasma glucose)
decreased insulin removes stimulus to take up glucose into the muscle
hormonal changes (increased cortisol) further inhibit glucose uptake
  1. obtaining glucose from liver
    -increased glycogenolysis and gluconeogenesis release glucose into circulation
    -hepatic glucose output (HGO) is controlled by:
    stimulated by glucagon, catecholamines, increased sympathetic input, slower acting hormones (GH, cortisol) and inhibited by insulin
29
Q

What is steady state?

A

Vo2, HR and or RR do not change over time

-an unchanging level of a physiologic variable during an activity

30
Q

What is rest to exercise transition?

A

At exercise initiation, ATP production changes almost immediately, while cardiopulmonary changes do not (o2 does not immediately increase), which creates an o2 deficit.

  • ATP demand > O2 supply
  • ATP not produced fast enough aerobically
  • high proportion of ATP generated at start of exercise is derived from non-aerobic metabolic pathways
31
Q

How is the O2 deficit determined?

A

intesnity of exercise
training status
health status

32
Q

What are the factors that contribute to a decreased oxygen deficit in trained individuals?

A
  • increased mitochondrial content
  • greater oxygen storage in muscle (myoglobin)
  • greater oxygen delivery to muscle

these factors increase the supply of O2 at the start of exercise, permitting the aerobic pathway to contribute more to ATP production at the start of exercise, reducing reliance on non-aerobic pathways

33
Q

Describe the fast portion of EPOC

A

2-3 min

  • O2 used to restore ATP and PC to resting levels
  • muscle and blood O2 stores replenished
34
Q

Describe the slow portion of EPOC

A
  • energy to support increased HR and RR
  • reduction of body temp to normal
  • oxidation of excess lactate back to glucose
  • elevated norepinephrine and epinephrine levels contribute to increased metabolic rate
35
Q

What is EPOC?

A

excess post-exercise oxygen consumption

  • proportional to exercise intensity
  • other factors that can increase EPOC; exercise in heat/cold, increased duration of exercise
36
Q

What is the acute response to sprint training on the immediate energy system?

A
  • ATP and CP stores rapidly depleted 5-10 sec
  • within 20 s recovery, ATP and CP stores at least 50%
  • within 3 min, ATP and CP stores at least 85%
  • replenishment of stores is NOT dependent on diet
37
Q

What is the chronic response to sprint training on the immediate energy system?

A
  • small increase in resting ATP, CP and free creatine within muscle
  • increase in creatine kinase activity, increasing the rate at which ATP can be resynthesized= small change compared to effects of training on other pathways
38
Q

What is the acute response to high-intensity training on the glycolytic energy system?

A

-muscle glycogen depletion;
dependent on amount of work and carb intake, depletion to low levels usually occurs in about 2 hours
-complete replenishment requires up to 24 hours and is diet dependent

39
Q

What is the chronic response to high-intensity training on the glycolytic energy system?

A
  • increased muscle glycogen stores

- increased maximal enzyme activity (increased rate of glycolysis)

40
Q

What is the acute response to endurance training on the aerobic energy system?

A
  • glycogen store depletion

- increased fat mob and utilization

41
Q

What is the chronic response to endurance training on the aerobic energy system?

A
  • modest increases in IMTG
  • substantial increases in mitochondrial volume and muscle capillarization= contributed to an increase in fat oxidation during submax exercise
  • increased max activity of enzymes that regulate:
    1. lipolysis; maximal HSL activity increased, HSL becomes more sensitive to catecholmines
  1. b-oxidation; maximal rate of enzymes involved increases
  2. citric acid cycle; total amount of enzymes increases bc mitochondrial volume increases, max activity of citric acid cycle enzymes increases, rate at which acetylcoA and all other intermediates can be passed through the cycle is increased
42
Q

When does endurance training cause a shift to use more fat and less carbs?

A

submax exercise intensities
due to:
-increased sensiyivty of fat-mobilizng enzymes (HSL)
-increased activity of fat-mobilization enzymes
-a possible increase in number/activity of fatty acid transporters

43
Q

At absolute submax intensities, do trained and untrained individuals use the same amount of fat and carbs?

A

yes.
because:
-similar levels of catecholamines
-trained individuals possibly use more IMTG

44
Q

When do trained individuals utilize more fat?

A

during prolonged submax exercise

45
Q

When do trained individuals utilize more fat than untrained individuals?

A

at the same relative intensities

46
Q

Describe the effects of endurance training on hepatic glucose output

A
  • increases liver glycogen storage
  • increases gluconeogenic capacity
  • enhances insulin sensitibity
  • after endurance training, HGO decreases….muscle utilizes more fat, therefore the liver needs to supply less carb to muscle during exericse
47
Q

Changes in blood lactate in response to exercise reflect changes in …

A
  • glycolytic capacity

- capacity of citric acid cycle and ETC

48
Q

explain lactate threshold

A
  • workload at which blood lactate concentrations begin to increase incrementally
  • typically believed to represent a shift from predominantly aerobic metabolism to increased reliance on anaerobic metabolism
49
Q

explain onset of blood lactate accumulation (OBLA)

A
  • workload at which blood lactate concentration > 4 mM
  • believed to represent the max exercise intensity that can be sustained for long periods
  • strong predictor of endurance performance
  • endurance training increases the workload at which the lactate threshold and OBLA occur
  • less lactate produced at the same workload
50
Q

What are the factors influencing decreased blood lactate after endurance training?

A
  • less reliance on carb oxidation leading to less pyruvate being formed
  • increased mitochondria allow more pyruvate to be passed to the citric acid cycle
  • greater removal of lactate to tissues such as the liver

-mod intensity exercise facilitates lactate removal

51
Q

Define economy

A

absolute energy required for a specific power output or obtained velocity

  • endurance training may improve exercise economy during submax exercise
  • measured as either oxygen consumption or EE
52
Q

How does exercise training improve exercise economy?

A
  1. Phyiologic factors:
    metabolic adapation; increased capacity to resynthesize ATP via oxidative phosphorylation= more mitochondria, higher acttivity of TCA and ETS

muscle fiber type; slow twitch are more oxidative, individuals w greater distribution of slow twitch tend to be more economical

  1. biomechanical factots:
    improved coordination of muscle rescruitment (NM efficiency)
    increased elastic energy
53
Q

What can limit a patient’s ability to perform ADLs?

A

a 5-10 % decrease in economy/efficiency

-compounded by low aerobic capacity

Exercise Science (4 decks)

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