Exercise Phys 3: Metabolism and bioenergetics

Question 1

Amount of calories in 1g of
fat
carbs
protein
alcohol

Answer 1

protein 4Kcal/g
carbs 4Kcal/g
fat 9Kcal/g
alcohol 7Kcal/g

Question 2

3 ATP synthesis pathways

Answer 2

ATP-PCr pathway - anaerobic
Glycolytic system - anaerobic
Oxidative system - aerobic

Question 3

Describe ATP-phosphocreatine system

• equation
• when is it useD?

Answer 3

PCr + creatine kinase -> CR + Pi + energy (energy generated converts ADP to ATP)

• > PCr cannot be used to cellular work
• > can be used for ATP re-assembly

Replenishes ATP stores during rest

used in explosive exercise 3-15s

Question 4

How is ATP-PCr mainly regulated?

Answer 4

feedback loops

• positive feedback from increase in ADP
• negative feedback from increase in ATP

Question 5

Enzymes used in glycolysis?

Answer 5

Hexokinase Glucose to G6P

GAPDH glyceraldehyde 3-phosphate dehydrogenase

Pyruvate kinase

Question 6

Summary of fatty acid metabolism - net yield?

Answer 6

1) Fat store
(mobilised by hormone sensitive lipases) ->
2) triglyceride ->
3) 3x FFA palmitate
4) Mitochondria degradation spiral pathway -> loses 2 carbons via A-CoA per cycle
5) feeds into krebs cycle
6) oxidative phosphorylation

128ATP per FFA

Question 7

Summary of protein as a fuel source

Answer 7

protein -> amino acids ->

Lipogenesis, Acetyl-CoA, Gluconeogenesis

->more Acetyle-CoA, energy storage, glycogen storage

very minimal contribution to ATP synthesis

Question 8

Primary substrate in myocardial metabolism?

Answer 8

FFA’s -> ~80% of energy supplied in untrained athlete, more in trained athlete

After a heavy meal, glucose plays a larger role in ATP supply

Question 9

Equation for respiratory quotient? Example for each primary metabolite?

Answer 9

RQ = VCO2(eliminated) / VO2 (consumed)

carbs -> RQ = 6CO2/6O2 -> RQ = 1
fat -> RQ = 16CO2/23O2 -> RQ = 0.696

protein ~ 0.8

Question 10

Factors that determine oxidative capacity in muscles?

Answer 10

Enzyme activity (succinate dehydrogenase, citrate synthase)

Fibre type composition, endurance training

O2 availability vs O2 need

Question 11

Types of muscle fibres and their characteristics?

Answer 11

Type I (slow twitch)

• have great oxidative capacity
• more mitochondria so higher conc. of oxidative enzymes
• high anaerobic endurance, maintain exercise for long periods

Type II (fast twitch)

• produce ATP anaerobically
• higher contraction speed +motor unit strength
• Faster ATPase activity,
• useful in explosive exercise, but fatigue quickly