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Exercise Physiology > Week 2: Applied Physiology of Human Performance > Flashcards

Week 2: Applied Physiology of Human Performance Flashcards

1
Q

Endurance performance is….
- Greater than …. minutes
- 60-….% V02max
- ATP demand?

A
  • 30 minutes
  • 60-85% of V02 max
  • <2.5mmol/kg/dm/s (relativey low to alllow us to maintain this duration of exercise)
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2
Q

Major limiting factors to endurance performance? What affects these factors?

A

Hydration status (fluid intake -if you start from a dehydrated state your performance is going to be limited)

Both affected by behaviour (intake during, before & after) and environment (eg heat = negative on hydration and warmer weather = increase in glycogen use

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3
Q

Goals of endurance overload training

A
  • Increase rate of oxidative ATP supply
  • Oxidative phosphorylation of CHO and lipid fuels
  • Increased work while avoiding fatigue with oxidative metabolism
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4
Q

Mechanisms of endurance training

A
  • Increase 02 supply by blood
  • Increase fuel supply (carbohydrate, glycogen or lipid stores)
  • Improve extraction from blood
  • Muscle (morphological changes – fibre types)
  • Improved metabolism
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5
Q

Central adaptations from endurance training

A

central: develop functional capacity of the central circulation. Includes the following:

Increased plasma volume & increased red blood cell mass

This increases total blood volume.

Which increase ventricular compliance, internal ventricular dimensions, venous return, myocardial contractility.

Increased end diastolic volume and increased ejection fraction.

Overall increased stroke volume.

This increases cardiac output ie increased blood flow to active muslce

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6
Q

Peripheral adaptations from training

A

peripheral: enhance aerobic capacity of the specific muscles

Includes the following:
- change in fibre type
- increased myoglobin
- increased capillary density
- increased 02 diffusion
- increased krebs cycle enzymes
- increased lactate clearance
- increased muscle buffering capacity
- increased mitochondrial density
- increased mitochondrial protein synthesis
- increased intramuscular storage

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7
Q

What equation can be used to model some of the effects of central and peripheral adaptations on oxygen consumption? Explain its components.

A

Fick equation
V02 = HR x SV x (a-v)02diff

HR & SV= central
(a-v)02diff = peripheral

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8
Q

How important is V02max for performance?

A

High absolute V02max is needed! In a study it was found that those with a higher v02 max had a higher average racing speed

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9
Q

What are the key determinants of endurance performance

A
  1. V02max
  2. Anaerobic threshold
  3. Movement economy

1& 2 affect performance V02 and rate of ATP synthesis.

1,2 & 3 affect mean race/pace and power output

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10
Q

What happens in relation to blood volume after endurance training?

Physiological adaptations from endurance training.

A

It increases as a result of increased hematocrit & increased plasma volume

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11
Q

What happens in relation to stroke volume after endurance training?

Physiological adaptations from endurance training.

A

SV increases due to increased contractility & increased ventricular volume

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12
Q

What happens in relation to heart rate after endurance training?

Physiological adaptations from endurance training.

A

Decreased submaximal HR (HRmax unchanged)

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13
Q

What happens in relation to cardiac output after endurance training?

Physiological adaptations from endurance training.

A

Cardiac output increases due to stroke volume

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14
Q

What happens in relation to 02 extraction after endurance training?

Physiological adaptations from endurance training.

A

Increased (a-v)02 difference
- Red cell 2,3-diphosphoglycerate (2,3, DPG)
- Angiogenesis = capillarisation
- Myoglobin

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15
Q

What happens in relation to blood pressure after endurance training?

Physiological adaptations from endurance training.

A

Decrease systolic and diastolic at rest and during exercise

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16
Q

What happens in relation to ventilation after endurance training?

Physiological adaptations from endurance training.

A

Increased max ventilation, increased tidal volume and increased frequency

17
Q

What are the metabolic adaptations that occur as a result of endurance training?

A
  • Changes in fibre content
  • Capillarisation
  • Myoglobin
  • Mitochondrial density
  • Krebs Cycle Enzymes
  • ETC enzymes
  • Fuel stores
  • Metabolic response & integration
18
Q

How does endurance training affect muscle fibre type?

A

Endurance training may cause increased slow type 1 (slow twitch) fibres

Conversion of type IIb to type IIa characteristics

19
Q

Type 1 fibres are larger in number (up to …% vs …%) and diameter (….) in elite endurance athletes (Costill et al., 1976)

A

98% vs 58%
30%

Note: Limit to extent of fibre hypertrophy as increased diameter increases diffusion distance

20
Q

Between …. - ….% of fibre types are genetically determined

A

70-90%

21
Q

Effects of 8 weeks of training, 30 mins/day 4x per week. Results indicated a shift to more type 1 fibres – ….. to …. after 8 weeks.

What happened to IIa and IIb

A

41 to 43
IIa increased (37-42)
IIb decreased (19-14)

22
Q

Sports with the highest slow-twitch muscle fibre composition and max 02 uptake?

A

Cross country skiing
- 78% ST Fibres
- 90 V02max

Long distance running
65% ST Fibres
85 V02 max

(In comparison to sprinters 45-50% ST and 55 V02)

23
Q
  1. What is capillary density referring to?
  2. Increased capillary density allows higher extraction by….
  3. When and where do these changes occur?
A
  1. Number of capillaries per unit area
    • Increases diffusion area
    • Decreases diffusion distance
    • Increases gas exchange potential duration
  3. Increase shown in first few weeks of training & greater in type 1 and type 2a
24
Q

What is myoglobin?

A

Oxygen carrying protein in the muscle (equivalent to haemoglobin in the blood)

Shuttles 02 from cell membrane to mitochondria

25
Q

Role of myoglobin during exercise?

More myglobin found in …. fibres

Can increase up to ….% after training

A

Myoglobin stores 02 and releases it when 02 is limited during exercise. Provides mitochondria with 02 during lag in delivery of 02 at start of exercise

Type 2

80%

26
Q

True or False - Endurance athletes have low content of glycolytic enzymes (large % type 1 fibres)

A

True

27
Q

How does increased mitochondrial intensity affect endurance performance and physiology?

Composition of mitochondria also affected….

Effects of training on number of mitochondria (%): 15 weeks & 30 weeks

A
  • Increases ability to produce ATP aerobically (oxidative ATP supply)
  • Increase in size and number of mitochondria per unit area

Composition of mitochondria also affected:
- Oxidative enzymes
- Electron transport chain (ETC) enzymes

15 weeks = 50% & 30 weeks = 120%

28
Q

Size of mitochondria in untrained vs trained individuals?

A

120nm (untrained) vs 160nm (athlete)

29
Q

How does succinate dehydrogenase change in response to activity (kreb cycle enzyme)? Also citrate synthase?

A

Gradually increased up to 19mmol/kg/min in highly traine vs 9mmol/kg/min in untrained.

Citrate synthase increased up to 60mmol/kg/min in highly trained vs 20mmol/kg/min in untrained.

30
Q

Citrate synthase, isocitrate dehydrogenase & succinate dehydrogenase increase …..% with endurance training

A

90% - these are the rate limiting enzymes in krebs cycle

*double check

31
Q

Time course of adptations for kreb cycle enzymes, enhanced oxidative potential of type II fibres, capillary density, V02max & cross-sectiona area of type fibre

A

Watch video

32
Q

Fuel stores in response to endurance training

  • Higher muscle glycogen content (up to ….. times)
  • Increased sensitivity to …..
  • Increased…… protein (….%)
  • Increases in:
  • ….. activity (channels glucose into cell’s glycolytic pathway)
  • Glycogen ….. activity – glycogen synthesis)
A
  • Higher muscle glycogen content (up to 2.5 times)
  • Increased sensitivity to insulin
  • Increased GLUT 4 protein (25%)
  • Increases in:
  • Hexokinase activity (channels glucose into cell’s glycolytic pathway)
  • Glycogen synthase activity – glycogen synthesis)
33
Q

Metabolic responses to endurance training

A
  • Greater capability for CHO oxidation
  • Increased acetyl-CoA moves through Krebs cycle
  • Increased fat oxidation
  • Increase activity in lipoprotein lipases (LPL) – helps fat breakdown
  • Endurance athlete uses more fat and less CHO at same intensity (lower RER)
  • Need for liver glycogenolysis is decreased – better use of blood glucose
34
Q

Training effects on blood lactate response?

What contributes to this from a metabolic perspective?

A

Delayed LT2 - ie the rapid accumulation of lactate

  • Greater use of intramuscular lipids
  • Better maintenance of blood glucose homeostasis during exercise
  • Trained have lower rate of glycogenolysis and glycolysis
  • Decreased lactate production at same intensity
  • Increased lactate clearance – better buffering capacity. Increased clearance of H+ ions - prevents acidic state -drop in pH levels
35
Q

True or false - Trained individual relies less on glycogen and more on lipids/fats?

A

True

Exercise Physiology (12 decks)

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