Carbohydrate and fat Flashcards
What are 4 functions of carbs?
- Energy (no.1)
- Physical Activity
- Fibre: Health Benefits
- CNS
Energy expenditure at rest is provided by what?
Plasma FFA and glucose
As exercise intensity increases, what happens to liver glucose output?
Liver glucose output essentially doubles as exercise intensity increases.
How does exercise increase carb oxidation?
In an intensity dependent manner. This involves:
- Increase liver glucose output (to = muscle glucose uptake)
- Increased muscle glycogen breakdown
At high relative workloads, what is a decisive factors for maximal work time?
Glycogen stores in exercising muscle
Why is fatigue strongly correlated with carbohydrate depletion?
- Muscle glycogen depletion
- Hypoglycaemia reflecting liver glycogen depletion
What is the evidence that carb feeding can effect fatigue due to carb depletion?
–Carbohydrate loading to increase muscle glycogen
–Carbohydrate during exercise to maintain blood glucose
What is the relationship between repeated sprint ability and glycogen % drop?
The greater the glycogen % drop, the greater the drop in repeated sprint ability.
What are daily carb recommendations based on?
Body weight (not % energy intake)
What are the daily targets (g of carbs) for light energetic demands of training?
Light = 3-5 g/kg/d
What are the daily targets (g of carbs) for moderate energetic demands of training?
Moderate = 5-7 g/kg/day
What are the daily targets (g of carbs) for high energetic demands of training?
High = 6-10 g/kg/day
What are the daily targets (g of carbs) for very high energetic demands of training?
V high = 8-12 g/kg/day
When would ‘general fuelling up’ be used?
Prep for events lasting <90 min exercise.
7-12 g/kg/d fuel needs
When would ‘carb-loading’ be used?
Prep for event >90 min in sustained, intermittent exercise.
10-12 g/kg/d for 36-48h pre-event
What is the main goal on the day of the event?
Ensuring liver glycogen stores are high ready for performance
What are carb targets for ‘pre-event fuelling’ (>60 mins)?
1-4 g/kg body mass, consumed 1-4 h before exercise
What happens as you get closer to the competition (on day of event)?
Decrease amount of carbs, less fat, less fibre
What is main goal after exercise (before next session/comp)?
Replenish muscle glycogen after training/competition.
What should daily fat intake be?
20-35% of total energy intake
What should proportion of saturdated fat be?
Less than 10% of energy intake.
What does fat adaptation, carb restoration study cause?
Fat adaptation:
Increased fat oxidation
Decreased carbohydrate oxidation
Spared muscle glycogen
Does fat adaptation, carbohydrate
restoration study cause any effect on a cycle time trial?
No - despite fat adaptations
What adaptation does fat adaptation, carbohydrate restoration studies have on high-intensity exercise performance?
Fat adaptation impairs HIIE performance
What is a ketogenic diet?
<50g carb/day, fat intake >70-80% energy
~15% or 1.5 g/kg/d protein (not >25%)
- Ensure adequate sodium/potassium
How long is a keto diet adaptation?
at least 2-3 weeks
- elevated blood levels of ketones and tissue adaptation to enhance their use as fuel.
- increases use of fat as muscle fuel
What does increased rates of fat oxidation result in?
Reduced economy (increased oxygen demand for a given speed).
What were the effects of lowcarb/highfat diet compared to high carbs diet?
In contrast to training with diets providing chronic or periodised high carbohydrate availability, adaptation to an LCHF diet impaired performance in elite endurance athletes.
