Carbohydrates Flashcards
True or False
Aerobic glycolysis provides ATP at a faster rate than oxidation fats
True
True or False
During prolonged exercise sessions (>90min) CHO becomes a limiting factor
True
How much glycogen is in muscle?
200-500g
How much glycogen is in liver?
60-120g
What are the 2 types of Glycogen particles?
- Proglycogen (15%) - First particles to add glucose units after depletion
- Macroglycogen (85%) - slower to add glucose units
What are the 3 roles of glycogen relevant to exercise performance?
- Fuel sensor
- Regulates signalling pathways involved in training adaptation
- Glucose homeostasis: 80g stored liver glycogen constantly replenish 4g blood glucose. At rest 60% of glucose in blood goes to the brain.
How much CHO for light training?
3-5 g/kg/day
How much CHO for moderate (1 hr/day) training?
5-7 g/kg/day
How much CHO for high (endurance 1-3 hr/day) training?
6-10 g/kg/day
How much CHO for very high (endurance 4-5 hr/day) training?
8-12 g/kg/day
How many gr of water are stored for every gr of CHO?
3g
Who should carb load?
- marathon and triathlons
- events lasting >90 min
Which menstrual phase affects CHO loading in women?
Follicular and luteal phase. Women need ~ 10 g.kg-d to
super-compensate
What are the determinants of effectiveness of CHO loading in women?
- Total energy intake
- Total carbohydrate intake
- Phase of menstrual cycle
CHO Recommendation for women:
Eat CHO rich diet the day before competition and consume high CHO meal/snack 3-4 hrs before competition
CHO Practical Guidelines
*Start exercise with sufficient muscle glycogen
* Trained individuals should eat carbohydrate
rich for 2 days prior to a race, whilst reducing glycogen use (reducing training)
* Don’t overeat - higher carbohydrate intake
should not be the result of just eating more
* Choose either solid and liquid carbohydrate
sources, high GI seems to be more effective than lower GI
* 5-7 g/kg per day seems to be sufficient in
the majority of cases (with low energy
expenditure)
* If experience gastro-intestinal issues select
carbohydrate sources carefully - try lower
fibre intake
What are 3 important effects of the pre-competition meal (3-5 hrs before)?
- to continue to fill muscle glycogen stores after previous ex session
- to restore liver glycogen concentrations, especially morning events
- to improve endurance capacity during prolonged exercise
How much does high GI pre-competition meals increases muscle glycogen?
10-15% in 3 hrs
Low GI meal effect on muscle glycogen:
No effect. However, may promote greater rate of fat oxidation - insulin suppresses lipolysis
What are the characteristics of the pre-competition meal (3-5 hrs before)?
- Should contain relatively little fat or fibre
- Low to moderate protein
- Liquid meal supplements quickly digested option
How much CHO liquid (pre-competition) is recommended?
- ACSM: 200-300g, 3-4 hrs prior
- ISSN: 1-2 g/kg BW, 3-4 hrs prior
- IOC 1-4 g/kg BW, 1-4 hrs prior
How does CHO ingestion delay fatigue?
- prevents hypoglycaemia
- provides CHO for oxidation
- spares liver glycogen
- modifies motor output
How can CHO oxidation rates be increased from 60 g/h to 90 g/h?
Multi transport mechanisms
60g glucose / 30 g fructose
True or false
Fructose does not stimulate insulin response or elicit major changes in blood glucose
True
Why is recommended to ingest high GI sugars rather than fructose alone?
to maintain blood glucose concentration
How can CHO oxidation rates be increased from 60 g/h to 90 g/h?
by combining CHO: 60g glucose / 30 g fructose
What is the recommendation of fluid intake?
between 120-180 ml each 15-20 min
What is the recommendation of CHO content in a sport drink?
6-8% (60-80 g/l)
What is the benefit of the “Training the gut” method?
- Reduced gastrointestinal symptoms
- Improved performance
What is the amount of CHO (drinks) needed during exercise?
- 30-75 min: small amounts or mouth rinse
- 1-2 hrs: 30g/hr
- 2-3 hrs: 60g/hr
>2.5 hrs: 90g/hr
What are the 2 phases of CHO for recovery?
- Rapid phase: 30-40min. Low muscle glycogen stimulates glycogen synthase. Insulin independent.
- Slow phase: several days with sustained CHO intake. Insulin dependent.
What are the recommendations of CHO for recovery?
Consume high GI CHO-rich foods as quickly as possible
1. Consume 50 – 75 g high to moderate GI within 15 mins ceasing exercise
2. Continue eating 50 – 75 g CHO every 2 hours until 500 – 700 g has been consumed or until eating a large CHO meal
3. If not practical eat 2.5 g high GI CHO per Kg bw at 2, 4, 6, 8 and 22 hours after event or 0.6 g/kg every 30 min during 4 hour recovery period
What are the disadvantages of “train low - compete high”?
- Not suitable for high-intensity workouts
- Could have negative effects on blood glucose
- Consistently training low can increase susceptibility to illness/infection
Which sugar is oxidised at a slower rate?
Fructose
Which foods would be a good choice to include in a pre-competition meal?
Oatmeal, banana, bagels
What are the benefits of sports drinks?
- they provide fluids for rehydration
- they provide carbohydrates for energy
For optimal recovery, what nutrients should be included in a post workout meal?
carbohydrates
protein
fluid
A pre-event meal should:
- Be light and carbohydrate rich
- Consistent of familiar foods
Carbohydrate mouth rinsing may be effective at improving cycling performance because:
Glucose sensors in the mouth activate reward centres in the brain
True or false
Carbohydrate oxidation provides energy at a slower rate than fat oxidation
False
True or false
A high carb meal will reduce the rate of fat oxidation following the meal
True
True or false
Exercise performance of less than 1hr can be improved by mouth rinsing with a carbohydrate solution
True (presence of glucose)
