CARBOHYDRATES Flashcards
Anaerobic Glycolysis
carbohydrate is broken down to release energy to ADP and form ATP, and making lactate as the final product
Glycolysis - glucose to pyruvate to lactate - 2 ATP produced
Glycogenolysis - Glycogen - 3 ATP produced
how much does glucose vs glycogen makes
2 vs 3
Aerobic Metabolism
glucose/glycogen to pyruvate (form lactate) to acetyl CoA to the krebs cycle, then to the transport electron chain to undergo a number of reactions releasing energy from ADP to ATP
oxidises carbs, protein and fat, to continuously supply ATP using O2, which occurs in the mitochondria
What is the main fuel of energy metabolism
carbs
muscle and plasma glucose/glycogen
Carbohydrate Digestion
1 - Mouth
salivary amylase hydrolyses dietary starch
2 - Stomach
the acidity of the stomach temporary inhibits amylase and stops the carb digestion
3 - Small intestine
bicarb secretion from the pancreas neutralises the stomach contents and pancreatic amylase continues to digest the starch
4 - the carbs are broken down to dissarchides in the brush boarder of the small intestines forming monsaccradies (fructose, glucose, one more?
Intestinal Carbohydrate Absorption
small intestine -
- glucose is absorbed here via a sodium glucose transporter
- fructose is absorbed via a different transported
- both these are transported across the basolateral membrane via the transported GLUT-2
- they are then transported to the liver where fructose is removed from circulation
Glycogen Synthesis
- carb ingestion simulates the released of insulin from the pancreas
- insulin stimulates the GLUT 4 translocation to the muscle membrane
- glucose-6-P stimulates the production of glycogen
one in the muscle it can’t be released back out into the blood stream, but if it goes to the liver is can be which helps regulate the blood glucose levels
Limited Carb Stores and where
the stores can be affected by fasting, exercise and diet. most carb stored in the muscles
Daily Needs from Carbs
- fuel for muscle and brain during exercise
- low levels of carbs stores are a factor in fatigue and reduced performance
- ensuring stores are increased result in performance enhancements
Carbs and Training Guidelines
depends on what exercise you do each day
very light training - 3-5 kg/day
mod/light intensity training - 5-7kg/day
mod to heavy endurance - 6-10kg/day
extreme exercise - 8-12kg/day
Carbs on Rest day
on rest days you don’t require as many carbs in the diet
Actual Carb Intake for Athletes
athletes don’t often eat as many carbs as they should be due to lack of knowledge, and applied guidelines. It is hard to eat so much, availability, GI discomfort and having protein instead.
What happens when insufficient Carb is ingested
- their is a progressive decrease in muscle glycogen.
- the glycogen is not replaces after the training session.
- effects the amount of glycogen in muscles changing their capacity
Carb before Exercise
high glycogen muscle and liver concentrations are believed to be essential for good performance.
- fatigue can often be associated with carb depletion
- when we sleep we use carb so need to replenish them, but for early exercise this can be hard to do
Gastrointestinal Distress
- these occur frequently, especially in long distance races
- problem are high individual, some can tolerate more than others
- may be related to intake of high carb, low fibre diet and hyper osmotic drinks
Carbohydrate Loading
super compensated glycogen levels improve performance by 2-3%, no need for a depletion stage before for the loading. But glycogen storage is associated with weight gain as a result of water retention which puts alot of athletes off
only realistic for little key events per year
Carbs During Exercise
prevents muscle and liver glycogen depletion, hypoglycaemia, and gastro distress
thinks like lollies and gels are good as easy to have on the go rather than a meal.
only beneficial if training for over an hour
can fake the brain by something?
take more carbs then lose to do oxidation limitations
____ carbs intakes cause greater _____ capacity
Training the Gut
increase carb exposure over time to adapt, gradually increase the intakes
Carb Post Exercise
we need to restore, the muscle and liver glycogne liver to prepare for the next session
1.5g/kg for the first 30 mints and again for every 2 hr for the next 4-6 hr
Female Athletes and Carb Intake
little research done and often poor quality
oestrogen may increast FFA availability during exercise and promote lipid oxidation and progesterone may limit fat oxidation
with the menstrual cycle around half of elite athletes don’t get their period
- late luteal phase to early follicular phase = low carb oxd but high fat oxd during high intensity, but simillar during mod exercise
sufficient evidence about diet over peroids
Hormonal Contraception
elevated plasma oestrogen conc. increase the reliance on fat as energy source during endurance exercise
