Week 2: Applied Physiology of Human Performance

Question 1

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

Answer 1

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

Question 2

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

Answer 2

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

Question 3

Goals of endurance overload training

Answer 3

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

Question 4

Mechanisms of endurance training

Answer 4

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

Question 5

Central adaptations from endurance training

Answer 5

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

Question 6

Peripheral adaptations from training

Answer 6

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

Question 7

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

Answer 7

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

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

Question 8

How important is V02max for performance?

Answer 8

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

Question 9

What are the key determinants of endurance performance

Answer 9

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

Question 10

What happens in relation to blood volume after endurance training?

Physiological adaptations from endurance training.

Answer 10

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

Question 11

What happens in relation to stroke volume after endurance training?

Physiological adaptations from endurance training.

Answer 11

SV increases due to increased contractility & increased ventricular volume

Question 12

What happens in relation to heart rate after endurance training?

Physiological adaptations from endurance training.

Answer 12

Decreased submaximal HR (HRmax unchanged)

Question 13

What happens in relation to cardiac output after endurance training?

Physiological adaptations from endurance training.

Answer 13

Cardiac output increases due to stroke volume

Question 14

What happens in relation to 02 extraction after endurance training?

Physiological adaptations from endurance training.

Answer 14

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

Question 15

What happens in relation to blood pressure after endurance training?

Physiological adaptations from endurance training.

Answer 15

Decrease systolic and diastolic at rest and during exercise

Question 16

What happens in relation to ventilation after endurance training?

Physiological adaptations from endurance training.

Answer 16

Increased max ventilation, increased tidal volume and increased frequency

Question 17

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

Answer 17

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

Question 18

How does endurance training affect muscle fibre type?

Answer 18

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

Conversion of type IIb to type IIa characteristics

Question 19

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

Answer 19

98% vs 58%
30%

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

Question 20

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

Answer 20

70-90%

Question 21

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

Answer 21

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

Question 22

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

Answer 22

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)

Question 23

1. What is capillary density referring to?
2. Increased capillary density allows higher extraction by….
3. When and where do these changes occur?

Answer 23

1. Number of capillaries per unit area
2. • 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

Question 24

What is myoglobin?

Answer 24

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

Shuttles 02 from cell membrane to mitochondria

Question 25

Role of myoglobin during exercise? More myglobin found in .... fibres Can increase up to ....% after training

Answer 25

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%

Question 26

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

Answer 26

True

Question 27

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

Answer 27

* 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%

Question 28

Size of mitochondria in untrained vs trained individuals?

Answer 28

120nm (untrained) vs 160nm (athlete)

Question 29

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

Answer 29

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.

Question 30

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

Answer 30

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

Question 31

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

Answer 31

Watch video

Question 32

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)

Answer 32

* 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)

Question 33

Metabolic responses to endurance training

Answer 33

* 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

Question 34

Training effects on blood lactate response? What contributes to this from a metabolic perspective?

Answer 34

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

Question 35

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

Answer 35

True