Carbohydrate (CHO) And Sport Part 2 Flashcards
How much CHO per day on ketogenic diet
<20g/day
6 aerobic training response and CHO metabolism
- Increase VO2 max
- Work at higher % VO2 max without fatigue
- Enhance use of glucose (less used at low intensity, increased capacity during intense/max exercise)
- Decrease fatigue
- Increase glucose uptake in cells
- Increase muscle glycogen resynthesis and storage
How is there an increase vo2 max as aerobic training response
By increasing oxygen utilization and oxygen delivery efficiency
How is fatigue decrease as aerobic training response
By increasing lactate clearance which decreases lactate and H+ accumulation
How is glucose uptake increase in cells as an aerobic training response
By an increase in transporters
What should a dietician do to figure out CHO intake for an athlete
Start with the equation then break it down based on athletes characteristics
General population male and female recommended dietary allowances (RDA) of CHO
130g/day
Minimum amount set for adults and children for brain function
(1g CHO=4cal, 130g =520cal)
Acceptable macronutrient distribution range (ADMR) for CHO
45-65% of total calories consumed
The more extreme the exercise (intensity and length)
The more CHO needed for fuel and recovery
General fueling up
Prep for events <90 min
7-12g/kg per 24h as for daily fuel needs
carbohydrate loading
Prep for events >90min of sustained/intermittent exercise
36-48 hrs of 10-12 g/kg BM per 24 hr
Pre-event fuelling
Before exercise >60min
1-4 g/kg BM (consumed 1-4 hr pre-comp)
During brief exercise
<45min
Not required
During sustained high-intensity exercise
45-75min
Small amounts including mouth rinse
during endurance exercise including “stop and start” sports
1-2.5 hrs
30-60 g/hr
When new start at 30 and build up to 60
During ultra endurance exercise
> 2.5-3 hrs
Up to 90 g/hr using multiple transportable carbs (glucose, fructose mix)
Speedy refuelling
<8 hr recovery between 2 fuel demanding sessions
1-1.2 g/kg BM every hr for first 4hr then resume daily fuelling needs
When should recovery meal happen
As close to exercise as possible
If CHO stores are adequate during continuous exercise <90 mins
CHO feeding may be uneccessary
AM training session after overnight fast?
As increase of duration, should eat
If short not eating may not effect
CHO ingestion shortly before short duration exercise (<30mins)
May have a negligible effect on performance
When should what works best for you with CHO intake be tested
In training not in competition
Is there benefit in CHO before high intensity exercise (<30min) and high intensity resistance training
No benefit?
See what works for athlete
Is there benefit for CHO feeding during high intensity exercise (30-90min)
Possible benefit
Due to increase in glucose provision for fast twitch muscle fibers
Is there benefit to CHO feeding during intermittent high intensity exercise (60-90min)
Benefit
Increased CHO ingestion may spare muscle glycogen
Is there benefit to CHO feeding during high to moderate intensity exercise >90mins
Yes
If exercise intensity is high enough
Why is performance enhanced by CHO during >90min high to moderate intensity exercise
Maintaining/raising plasma glucose concentrations to help sustain high rates of CHO oxidation
4 CHO feeding strategy concepts
- Manipulate daily CHO intake to match likely fuel requirements
- Promote high CHO availability for performance and comp
- Promote low CHO availability for selected non-performance training sessions
- Provide adequate CHO for refuelling when speedy recovery is priority (training or compete within 8 or less hrs)
Why promote low CHO availability for selected non-performance training sessions
Concept of training low
Low glycogen availability
See how athlete reacts
Forming glucose
Gluconeogenesis
Where is glucose stored
Muscles and liver
What is main site for gluconeogenesis
Liver
What is path of fat cells to liver for gluconeogenesis
Triglycerides -> glycerol -> glucose in liver
Where does glucose go once made in liver
Muscle to be made to muscle glycogen
Muscles cells from muscle glycogen to glucose in liver
Muscle glycogen -> pyruvate -> lactate -> glucose
Muscle cells from muscle protein to glucose in liver
Muscle protein -> glucogenic amino acids -> alanine -> glucose
4-5 g/kg BWof CHO <4 hrs prior to exercise (>90 min)
Benefit
Increases glycogen stores
1-2 g/kg BW <1hr prior to exercise (>90 min)
Benefit during intense exercise
No benefit during light-moderate exercise
What must the meal be if <1 hr before >90 min exercise
Low in fat and fiber, high CHO, moderate protein
50-60g 15-60 min before exercise (>90 min)
Detriment or may benefit extended exercise - based on athlete tolerance
What is reactive hypoglycemia
Rapid increase in blood glucose
Increased secretion of insulin (causes low blood sugar)
Increased transport of glucose into tissues
- may speed up muscle glycogen utilization
What does insulin do
Keeps blood glucose in tight range
When does reactive hypoglycemia happen
Extreme situation
Too many CHO, no protein to slow digestion
If athlete responds with reactive hypoglycemia
Avoid CHO (particularly high GI foods) 15-60 mins prior to performance/training
6 characteristics of the meal/snack to have before exercise
- low fibre to facilitate gastric emptying
- minimize GI distress
- High CHO
- familiar
- well tolerated by athlete (practice, practice)
- not hungry or full
Why have high CHO meal/snack
Maintain blood glucose
Maximize glycogen storage
What type of CHO should be ingested prior
Glucose
Fructose
Glucose polymer (maltodextrins)
Why ingest fructose prior
Absorbed more slowly from GI tract
- will reduce insulin response and possible reduce reactive hypoglycemia
Why not ingest fructose before
May cause GI irritation/distress and negatively affect performance
Why ingest a glucose polymer (maltodextrins)
Does not seem to cause GI disturbance
Improved digestion and absorption when compared to simple sugars
CHO loading?
Increase muscle and liver glycogen for prolonged, intermittent high intensity exercise
Classic/old views surrounding CHO loading
Depletion, CHO deprivation, CHO load
Current views for CHO loading
Taper aerobic exercise, moderate CHO, high CHO/rest
What is CHO dosage during CHO loading
8-12 g/kg/day
At what rate does a single source CHO oxidize
1g/min
How much CHO benefitted during prolonged exercise
15-25g every 15-20 mins
Why have 15-25g every 15-20 mins during prolonged exercise
May spare muscle glycogen and regulate blood glucose levels
What are CHO recommendations during endurance events dependent on
- exercise duration
- type of sport
- rules and regulations of the sport
- exercise intensity
With lower absolute intensity
Lower CHO oxidation rates= adjust the CHO dosage downwards
What do athletes need to do for all fueling strategies
Need to train/practice all fuelling strategies - liquids, CHO type, etc
What food options should we avoid during high intensity training or competitions
High fat, fibre, protein foods
These slow down digestion
When has CHO mouth rinse improved performance
During moderate to high intensity exercise (~60-75% VO2 max) of at least 1 hr
Why does mouth rinse seem to improve performance
Improvement may not be metabolic but neural
Via oral CHO receptors (glucose and Maltodextrin) that activate brain regions related to sensation of reward and pleasure
What does mouth rinse not have affect on
Fuel storage or glycogen stores
What do we have to look at on sports products
Dosage and formulation of CHO
Also other ingredients
Does Gatorade zero give energy
No sugar no energy
Sugar alcohols can also cause stomach upset
Can give electrolytes and fluid
Benefit of fructose during exercise
Absorbed more slowly from GI tract
Will reduce insulin response and possible reactive hypoglycemia
Possible negative impact of fructose during exercise
May cause GI irritation/distress and negatively affect performance
Benefits of glucose polymer during exercise
Does not seem to cause GI disturbance
Improved digestion and absorption when compared to simple sugars
5 CHO related causes of fatigue in exercise
- Hypoglycemia
- Increased acidity (accumulation of H+)
- Low muscle glycogen stores during aerobic exercise
- Training (mod-high int) in a fasted state
- Low muscle glycogen stores during anaerobic exercise
Fatigue delaying mechanisms: exogenous CHO feeding
- maintenance of blood glucose levels
- reduction of psychological effect (impact on RPE)
- sparing of muscle glycogen
What should athletes of long duration exercise aim to achieve
CHO intakes that meet needs of training programs
Replace CHO stores during recovery between sessions and competitions
What are other pieces of recovery
Protein, fluids, electrolytes
What happens in absence of CHO intake
Muscle glycogen storage rate post workout is low
Immediate intake of ~1 to 1.2g/kg BW CHO causes
Slightly enhanced rate of muscle glycogen synthesis
What is the optimized recovery window
~15-30 mins post workout
What may be better tolerated after workout then large bonus amount of CHO post workout
Grazing on CHO food sources
How much CHO after exercise depleted msucle glycogen stores
Consume 1-1.2g/kg within 30min and again every 2h for 4-6h
3-4g of CHO:1g protein
What is the most important factor for long term recovery
Total amount of CHO consumed in a 24hr period
What is the type of CHO consumed based on
Athlete tolerance
Amount consumed of CHO should be related to
Intensity, type, duration of the training session
Possible challenged with optimal CHO consumption
- too tired, body releases hormone that makes you not want to eat
- not having something available
