Carbohydrates And Fat

Question 1

What is the relationship between Liver (hepatic) glucose output and blood glucose?

Answer 1

• Exercise increases liver glucose output in an intensity dependent manner
• Close matching between muscle glucose uptake and liver glucose output

Question 2

What happens when exercise increases carbohydrate oxidation in an intensity dependent manner?

Answer 2

Increased liver glucose output
Increased muscle glycogen breakdown

Question 3

Fatigue during prolonged strenuous exercise? (Depletion, diet, carb loading, blood glucose)

Answer 3

• Fatigue strongly correlated with carbohydrate depletion
• Evidence that diet (carbohydrate feeding) can affect these processes
• Carbohydrate loading to increase muscle glycogen
• Carbohydrate during exercise to maintain blood glucose

Question 4

What are daily carbohydrate recommendations for sport based on?

Answer 4

Body weight (not % of energy intake)

Question 5

What are the daily carbohydrate intake goals for athletes (Light, moderate, high, very high) ?

Answer 5

Light = 3-5g/kg/d
Moderate = 5-7g/kg/d
High = 6-10g/kg/d
Very High = 8-12g/kg/d

Question 6

Why can carbohydrate be flexible?

Answer 6

Depends on training and competition needs

Question 7

Examples of carbohydrate usage day/days before a race?

Answer 7

• General fuelling up if event lasts < 90mins, 7-12g/kg/d as per daily needs
• Carb-loading if event lasts > 90 mins, 10-12g/kg/d for 36-48h pre event

Question 8

Carbohydrate usage day of event?

Answer 8

Exercise lasting > 60 mins, 1-4g/kg consumed 1-4h before exercise

Question 9

What is the priority after exercise?

Answer 9

Replenish muscle glycogen

Question 10

When is fat used as energy?

Answer 10

Low-to-moderate intensity aerobic exercise

Question 11

Fat daily intake recommendations for sport?

Answer 11

• Daily fat intake: 20-35% of total energy intake
• Proportion of saturated fat limited to less than 10% of energy intake

Question 12

Fat adaptation? (Adapting to a fat based diet)

Answer 12

• Increased fat oxidation
• Decreased carbohydrate oxidation
• Spared muscle glycogen
• Fat adaptation impairs high-intensity exercise performance

Question 13

Key things about Ketogenic diets?

Answer 13

• <50g carbohydrate/day, fat intakes >70-80% energy, 1.5g/kg/d protein
• At least 2-3 weeks adaptation
• Elevated blood levels of ketones and tissue adaptations to enhance their use of fuel
• Increase use of fat as muscle fuel

Question 14

What are the results of using a ketogenic, low carbohydrate, high fat diet in terms of fat oxidation?

Answer 14

Ketogenic diets increased rates of fat oxidation during exercise in race walkers over a range of exercise intensities.

Question 15

What are the results of using a ketogenic, low carbohydrate, high fat diet in terms of exercise economy?

Answer 15

Increased rates of fat result in reduced economy (increased oxygen demand for a given speed) at velocities that translate to real-life race performance in elite race walkers

Question 16

What are the results of using a ketogenic, low carbohydrate, high fat diet in terms of exercise performance? (Elite endurance athletes)

Answer 16

Adaptation to an LCHF diet impaired performance in elite endurance athletes

Question 17

What does the term ‘fast’ and ‘slow’ carbohydrates refer to?

Answer 17

The rate at which it can be oxidised as a fuel during exercise

Question 18

Metabolic adaptations and changes in substrate use when on a ketogenic diet (2 points)?

Answer 18

• Elevated blood ketones
• Increased fat oxidation

Question 19

What would be expected to happen to an endurance athlete’s ability to perform high-intensity exercise and why?

Answer 19

• Impaired high-intensity performance
• Reduced glycogen availability
• Reduced glycogen breakdown