1. Metabolic Responses to Endurance Exercise

Question 1

Define Endurance Exercise

Answer 1

Exercise that utilises mainly aerobic metabolism to provide energy for muscle contraction.
Muscle require adequate 02 + fuel (carbs + fats)
Low - moderate intensity (exc. endurance athletes)
Prolonged duration (>30 mins)

Question 2

Energy type used for muscle contraction

Answer 2

ATP
ATP - ADP + Pi + Energy

Question 3

What is Pi

Answer 3

Free Inorganic phosphate

Question 4

Enzyme that catalyses hydrolysis of ATP

Answer 4

ATPase

Question 5

Intramuscular ATP

Answer 5

Immediately available BUT limited supply
7.3 kcal available
Few secs of max exercise

Question 6

3 basic energy systems

Answer 6

1. ATP-PCr system
2. Glycolytic system (glycolysis)
3. Oxidative system (oxidative phosphorylation)

Question 7

Phosphocreatine (PCr) Breakdown Equation

Answer 7

PCr - Cr + Pi + ENERGY

Question 8

Phosphocreatine (PCr) Breakdown (5 points)

Answer 8

1. Intramuscular store of PCr
2. Immediately available
3. Enzyme – creatine kinase
4. V rapid ATP resynthesis
5. Very limited store - 6 - 10 s max exercise

Question 9

Creatine Kinase

Answer 9

Enzyme that catalyses hydrolysis of phosphocreatine molecule

Question 10

How is energy for ATP resynthesis produced

Answer 10

Breakdown of glucose or glycogen

Question 11

Storage form of glucose

Answer 11

Glycogen

Question 12

Anaerobic Glycolysis Equation

Answer 12

Glucose/ glycogen - 2 pyruvate + ENERGY

Question 13

Where does Anaerobic Glycolysis occur

Answer 13

Cytoplasm (where relevant enzymes are available)

Question 14

Primary enzyme of glycogen breakdown

Answer 14

Glycogen phosphorylase

Question 15

ATP yield of Anaerobic Glycolysis

Answer 15

2-3 ATP

Question 16

End point of glycolysis

Answer 16

Two molecules of produced go through aerobic and anaerobic reaction, producing lactate and oxidation (…)

Question 17

Anaerobic Glycolysis in exercise (4 points)

Answer 17

1. Does not produce large amounts ATP
2. Combines with ATP-PCr system for force generation (even when 02 limited)
3. Predominate during early mins of high intensity exercise.
4. Other system needed for longer during (can’t supply every >2mins)

Question 18

Limitations of Anaerobic Glycolysis (3 points)

Answer 18

1. Build up of lactic acid in muscles and body fluids
2. Decreases muscle fibres’ calcium-binding capacity, impedes
   muscle contraction
3. Acidification inhibits further glycogen breakdown, impairs
   glycolytic enzyme function

Question 19

Most complex of energy systems

Answer 19

Oxidative system

Question 19

Process of cellular respiration (oxidative system)

Answer 19

Body breaking down substrates with aid of O2 to generate energy

Question 20

Site of Oxidative production of ATP

Answer 20

Mitochondria

Question 21

Why do muscles need steady supply of energy during long activity

Answer 21

To continuously produce force needed to sustain exercise

Question 22

Oxidative system capacity

Answer 22

Large energy-producing capacity

Question 23

Primary method of energy production for what activity

Answer 23

Endurance

Question 24

Speed of oxidative system to turn on

Answer 24

Slow

Question 25

Oxidation of Carb equation

Answer 25

Pyruvate (anaerobic glycolysis) - C02 + H20 + ENERGY

Question 26

What is pyruvate converted into (Oxidation of Carb)

Answer 26

acetyl coenzyme-A in mitochondria - Krebs cycle - electron transport train

Question 27

Net yield of Oxidation of carbs

Answer 27

38-39 ATP

Question 28

Oxidation of fat equation

Answer 28

Plasma free fatty acids/ intramuscular triglyceride - C02 + H20 + ENERGY

Question 29

What is substrates converted into (Oxidation of Fat)

Answer 29

acetyl coenzyme-A (in mitochondria) → Krebs Cycle → electron transport chain

Question 30

Speed and net yield of ATP (resynthesis)

Answer 30

Slow, 130 ATP

Question 31

Carb stores capacity

Answer 31

Limited

Question 32

Fat stores capacity

Answer 32

Large

Question 33

What is fat stored as

Answer 33

triacylglycerol (fatty acids + glycerol)

Question 34

Where is fat stored

Answer 34

adipose tissue, some skeletal muscle

Question 35

Fat vs carb fuel storage

Answer 35

9 : 4

Question 36

Process of breaking down triacylglycerol

Answer 36

lipolysis: release free fatty acids into plasma - transported to exercising muscle

Question 37

Enzyme that catalyses process of lipolysis

Answer 37

Hormone-sensitive lipase

Question 38

Muscle glycogen v liver glycogen v plasma glucose v fat energy comparison

Answer 38

1. fat (93,000) (4,900 mins) 2. muscle glycogen (1600) (80 mins) 3. liver glycogen (400) (20 mins) 4. plasma glucose (40) (2 mins)

Question 39

Use of blood glucose (Glucose/ Glycogen Interaction) regulated by

Answer 39

regulated by availability of GLUT4 + hexokinase

Question 40

What is hexokinase

Answer 40

enzyme inhibited by rapid glycogen breakdown

Question 41

Fuel used in early exercise

Answer 41

Mainly glycogen

Question 42

Fuel used in later exercise

Answer 42

Less glycogen (stores reduced) More glucose (hexokinase inhibition lifted)

Question 43

What is lipolysis regulated by

Answer 43

Adipose tissue blood flow

Question 44

Effect of prolonged exercise on blood flow

Answer 44

Increase 50% V02 max

Question 45

reduced blood flow in intense exercise causes:

Answer 45

release of FFA

Question 46

increased lactate in intense exercise promotes:

Answer 46

formations of triglyceride

Question 47

Onset of exercise (3 points) causes:

Answer 47

1. Immediate energy from PCr + anaerobic glycolysis (+oxidation) 2. Fast and immediately available 3. PCr stores limited + anaerobic glycolysis inefficient (low yield)

Question 48

Continued exercise (2 points) causes: (energy store used)

Answer 48

1. less utilisation of blood glycogen (store reduced) 2. more utilisation of blood glucose (+ reduction of liver glycogen store)

Question 49

Further exercise (4 points) causes :

Answer 49

1. >2hrs fat oxidation max rate 2. increased fat utilisation (more efficient) high yield 3. limited glycogen store 4. slow, limited intensity