Energy and Carbohydrates Flashcards
Explain why sport nutrition goals are not static.
Training plans are periodized for peak performances and daily needs are always changing.
What is the primary goal of training?
To ADAPT the body to the physical and metabolic stresses of exercise - the nutrition plan needs to support these adaptations.
What is energy availability?
AE = energy intake - energy cost of exercise
Explain why you would want to have an athlete practice their meal plans.
Need to practice nutrition plan as well, so that competition is predictable performance.
How should nutrition guidelines be presented?
g/kg/day
Is a keto diet recommended? Why?
No, never.
Explain energy balance.
Energy intake (calories from food) must equal energy expenditure for an energy balance to be acheived.
When would you want a positive energy balance?
When would you want a negative energy balance?
Positive energy balance:
- bulking
- trying to increase body mass/weight or lean body mass
- during growth and development
- heavier training and/or leading into a training camp or aerobic endurance event
- beginning a new training program
Negative energy balance:
- to make a weight category
- to drop weight in the off-season
- drop body weight for a peak comp. or time trial
What are daily energy needs based on?
- Duration of
exercise/training session - Intensity
- Type of physical training
- Gender of the athlete
- Environmental factors
- Nutritional status prior to
exercise - Age
- Genetics
- Body size, body weight
- Fat free mass (FFM)
What are the most popular methods for measuring caloric intake?
- 24hr recall
- Diet history
- 3 day food record
(weighed or measured) - 7 day food record
(weighed or measured) - Food frequency
questionnaire (FFQ)
Prospective vs. retrospective
What factors decrease energy needs?
- Decreased training demands
- Aging (macronutrients change)
- Decreases in FFM
- Follicular phase of the menstrual cycle (beginning of cycle, day 0-14)
What factors increase energy needs?
- exposure to hot/cold
- fear
- stress
- high altitude exposure
- physical injuries
- increases in FFM
- increased training demands
- luteal phase of the menstrual cycle (end of cycle, day 14-28)
What is BMR?
Basal metabolic rate: energy needed for cellular tissue function / lowest calculated energy needs
What is RMR?
Resting metabolic rate: slightly higher than BMR, accounts for energy needs associated with eating and small amount of physical movement (approx. 10% higher than BMR)
What is REE?
Resting energy expenditure: energy needs for rested state; typically used to calculate daily energy needs
What is TEF?
It represents what % of daily energy needs?
Thermic effect of food:
energy costs of food absorption, digestion, transport.
Usually it is the highest 1 hour post-meal.
Represents 5-10% of daily energy needs.
What is EER?
Estimated energy requirement: calculated based on age, gender, height, weight, level of PA
How do you convert between lbs to kg?
_lbs/2.2 = _kg
How do you convert between ft and inch to m?
1 foot = 0.3048m
1 inch = 0.0254 m
What are the 2 types of dietary fibre?
Soluble fibre
Insoluble fibre
What are the simple carbohydrates?
sugars: monosaccharides (glucose, fructose, galactose); & disaccharides (maltose, lactose, sucrose)
What are the complex carbohydrates?
Starches (polysaccharides)
Glucose polymers (maltodextrins)
What macronutrients begin digestion in the stomach?
fat, fibre, and protein
What is an example of a high fat / slow digestion food?
Pastries, cakes, chips, and chocolate
What is the difference between nutrient-dense and nutrient-poor foods?
Nutrient poor: foods and fluids that contain CHO but minimal or no other nutrients.
Nutrient rich foods: ex. breads and cereals, grains, fruit, starchy veggies (potato, cron), legumes, low-fat dairy
What are the 2 types of starches?
Amylose & amylopectin
Discuss why or why not there is good vs. bad carbohydrates.
Should talk about why there is really no good or bad.
What carbs have a faster oxidation?
- glucose
- maltose
- sucrose
- maltodextrins
- amylopectin
What carbs have a slower oxidation?
- fructose
- galactose
- trehalose
- isomaltulose
- amylose
Glucose, fructose, galactose, and sucrose are all ______ carbohydrates?
simple carbohydrates
Amylose and amylopectin are _______ carbohydrates.
complex carbohydrates
What is the metabolic fate of glucose?
Meal (containing CHO), causes blood glucose to rise, stimulating the pancreas to release insulin into the blood. Insulin facilitates the uptake of glucose by various tissues within the body (muscle and fat cells). GLUT-4 receptors on the cell membrane are activated by insulin (and exercise for glucose to go to the muscles).
What 4 things occur to glucose after entering the body?
1 - can be used by the brain, CNS, and red blood cells; which are primarily dependent on glucose for their fuel needs / metabolism.
2 - glucose stored as muscle or liver glycogen when fuel is not needed by the body.
3 - if large amounts of simple sugars are consumed, some blood glucose may be excreted in the urine.
4 - glucose will be converted and stored as body fat (in adipose tissue).
What 2 things cause glucose uptake?
insulin and exercise
CHO supplies __% of energy at rest; What % is being used by muscle?
40%; 15-20% of that is being used by muscle
What happens to CHO oxidation during exercise?
CHO oxidation increases in proportion to exercise intensity
What are 3 reasons why we care so much about carbohydrates with sport?
- It actually has performance benefits (increases performance)
- Primary source of energy - for anaerobic and aerobic
- Can manipulate it (used in so many different areas of the body, stored in different ways)
When does CHO become the dominant fuel source in relation to % VO2max?
> 65-70% VO2max (depending on training status of the individual)
What is an essential nutrient for moderate to high intensity, intermittent sports (e.g., hockey, football, soccer, basketball)?
CHO - carbohydrates
As exercise intensity increases, what happens to reliance on carbohydrates and fat?
As exercise intensity increases, reliance on carbohydrate use increases; fat decreases.
How can CHO be acutely manipulated on a daily basis?
By usage (aerobic training) and storage (CHO intake/endogenous sources)
What is the key fuel source for the brain and CNS?
carbohydrates
Is CHO used in both anaerobic and aerobic/oxidative energy production pathways?
yes, both
Does the body contain limited or a lot of endogenous stores of CHO?
limited endogenous stores; diet dependent
CHO is more oxygen efficient than fat by about _%
7%
Is the carbohydrate or fat metabolic pathway more efficient?
carbohydrates produce ATP up to 3x faster than fat in aerobic glycolysis
Why is carbohydrate so vital for anaerobic exercise?
it is the only source for anaerobic energy production in lactic acid system
What are the internal carbohydrate sources of energy during exercise?
Blood glucose - 5g; 20 cal
Liver glycogen - 75-100g; 300-400 cal
Muscle glycogen - 300-400g; 1200-1600 cal
What happens as muscle glycogen is being used and blood glucose enters the muscle cell to maintain homeostasis and prevent hypoglycemia?
The liver will release glucose to maintain blood glucose levels.
What happens with a decrease in CHO stores and no replacement with exogenous CHO?
increased fatigue
decreased work rate
impaired skill
impaired concentration
increased rating of perceived exertion (RPE)
Is the theory of eating low, training high true?
In theory, “eat low, train high” with carbs could cause performance enhancing effects. In the lab there is an increased glucose response, but when it comes to actual athlete performance, the same results are not there.
Is the ketogenic diet recommended for athletes?
No, provides calories but it does not provide the acute fueling strategies necessary for that athlete.
How does aerobic training impact carbohydrate metabolism? (6)
- increase VO2max by increasing oxygen utilization and oxygen delivery efficiency
- work at a higher %VO2max without fatigue
- enhance use of glucose (less used at low intensity, increased capacity during more intense/maximal exercise)
- decrease fatigue by increasing lactate clearance which decreases lactate and H+ accumulation
- increase glucose uptake in cells by an increase in GLUT-4 transporters
- increase muscle glycogen resynthesis and storage
What is the RDA?
Recommended dietary allowance: the avg. daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all (97-98%) healthy individuals in a particular life-stage and gender group. RDA = the goal for usual intake by an individual.
What is the AI?
Adequate intake: when enough evidence is not available to establish an estimated average requirement (EAR). AI is the recommended avg. daily nutrient intake level based on observed or experimentally determined approximations or estimates of nutrient intake by a group of apparently healthy people who are assumed to be maintaining an adequate nutritional state.
- expected to meet or exceed the needs of most individuals
- can be used as a goal for usual intake when RDA is not avail.
- AI is not equiv. to RDA
What is the UL?
Tolerable Upper Intake Level (UL): higher avg. daily nutrient intake level likely to pose no risk of adverse health effects to almost all individuals in a given life-stage and gender group. UL is not a recommended level of intake. Increases potential risks as intake goes above UL.
What is the AMDR?
Acceptable macronutrient distribution range: range of intake for a particular energy source that is associated with a reduced risk of chronic disease while providing adequate intakes of essential nutrients.
What is total fibre?
sum of dietary fibre and functional fibre
What is the difference between dietary fibre and functional fibre?
Dietary fibre: non-digestible carbohydrates and lignin that are intrinsic and intact in plants. (includes plant non-starch polysaccharides, plant carbohydrates that are not recovered by alcohol precipitation, lignin, and some resistant starch)
Functional fibre: isolated non-digestible carbohydrates that have been shown to have beneficial physiological effects in humans. Includes isolated non-digestible plant, animal, or commercially produced carbohydrate.
What is the AMDR? For CHO intake recommendations?
Acceptable Macronutrient Distribution Range
45-65% of total calories consumed should be CHO
How does total fibre differ for males and females?
males: 38g/day
females: 25g/day
What is the CHO recommended dietary allowances for males and females?
130g/day
this is the min amount set for adults and children for brain function
What are the carbohydrate recommendation for light, moderate, high, and very high physical activity intensity?
light: 3-5g/kg BW/day
moderate: 5-7g/kg BW/day
high: 6-10g/kg BW/day
very high: 8-12g/kg BW/day
What are acute fueling strategies?
adding or consuming carbohydrates to boost performance; by adding in carbohydrate targets prior to, sometimes during exercise, and post-exercise to refuel.
If CHO stores are adequate, CHO feeding may be unnecessary for continuous exercise <__ minutes.
<90 minutes
When is there a benefit vs. no benefit to CHO feeding strategies?
likely no benefit:
high intensity <30 min
high intensity resistance training
possible benefit:
high intesity exercise 30-90min
(possible benefit due to increase in glucose provision for fast-twitch muscle fibres)
benefit:
intermittent high intensity exercise 60-90 min
Why is there a benefit to CHO feeding strategies for intermittent high intensity exercise of 60-90min?
the increased CHO ingestion may spare muscle glycogen
Why is performance enhanced with CHO feeding strategies for high-moderate intensity for exercise >90 minutes?
maintains/raises plasma glucose concentrations to help sustain high rates of CHO oxidation
What if exercise intensity is sort of low for >90 minutes (ex. ~2hrs)?
the body becomes less reliant on carbs and more reliant on fatty acids
When would you want to promote high CHO availability vs promote low CHO availability?
high CHO availability for performance/comp.
low CHO availability for selected non-performance training sessions (ex. concept of training low)
- on low training day, don’t have to eat as much and don’t have to worry as much about acute fueling strategies -
How many g of CHO should be consumed prior to exercise >90min?
@ 4hrs out?
@ 1hr out?
@ 15-60min out?
4-5g/kg BW when <4hrs to increase glycogen stores
1-2g/kg BW when <1hr would benefit for intense exercise (no benefit for light-mod exercise)
50-60g 15-60min prior –> detriment or may benefit extended exercise (based on athlete tolerance)
What are 3 things that slow down gastric emptying?
fibre, fat, protein
What is reactive hypoglycemia? What should be changed if athlete respond with reactive hypoglycemia?
causes rapid increase in blood glucose
increased secretion of insulin
increased transport of glucose into tissues which may speed up muscle glycogen utilization
if athlete responds with reactive hypoglycemia, avoid CHO (particularly high GI foods) - 15-60 minutes prior to performance/training
Do you want low or high fibre CHO before exercise?
low fibre to facilitate gastric emptying
Should the athlete feel hungry or totally full prior to performance?
neither - just content and minimize GI distress
What type of CHO should be ingested prior to to exercise?
Which only is absorbed more slowly from GI tract, reducing insulin response, but may cause GI irritation?
glucose
fructose
glucose polymers (maltodextrins)
fructose may cause GI irritation and negatively affect performance
Why can it be beneficial to mix up the types of sugars/carbs?
often beneficial in order to decrease GI irritation by mixing up the carbs
Is carb loading always beneficial?
no, not always; depends on the sport, timing, etc.
What is carbohydrate loading?
What is the current view for how to carb load?
it increases muscle and liver glycogen for prolonged intermittent high intensity exercise
current view: taper aerobic exercise, moderate CHO, high CHO/rest over a couple of days
What is the classic old view for how to carb load?
depletion, CHO deprivation, CHO load
What is the CHO dosage for carb loading?
8-12g/kg BW/day
For every gram of stored glycogen, how much water is retained?
3g of water is retained for every gram of carbohydrates
Is carb loading proven to work for males and females?
More research is needed for female athletes, however there are proven benefits among males
What amount of carbs should be consumed during exercise?
consume 30-60g/h (0.7g/kg/h)
15-25g every 15-20 minutes during exercise benefits prolonged exercise
this may spare muscle glycogen and regulate blood glucose levels
CHO recommendations during endurance events are dependent on what?
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
Athletes need to practice their fueling strategies (all - including liquids, CHO type, etc.)
What food/fluid options would be a good choice for DURING high intensity training or competitions?
gogo squeez, squeeze gels, gummies, waffles, sports drinks
avoid “zero sugar”
caffeine? may or may not be good depending on type of activity and individual
What is the benefit of a CHO mouth rinse?
How does this work?
CHO mouth rinse seems to improve performance during moderate-high intensity exercise (~60-75% VO2max) of at least 1h duration.
probable that the mechanism involved in this improvement may not be metabolic but neural via oral CHO receptors (glucose and maltodextrin)
Sports drinks are usually about _% carbohydrate.
6% carbohydrate
Do glucose polymers or simple sugars seem to have improved digestion and absorption?
glucose polymers - improved digestion/absorption
What are CHO related causes of fatigue in exercise?
hypoglycemia
increased acidity
low muscle glycogen stores during aerobic exercise
training (mod-high intensity) in a fasted state
low muscle glycogen stores during anaerobic exercise
How does exogenous CHO feeding work to delay fatigue?
maintains blood glucose levels
reducing psychological effort (impact on RPE)
sparing of muscle glycogen
How should CHO be consumed for optimal recovery, especially when training session is scheduled within 8 hrs?
i.e., what is the optimal recovery window for CHO?
optimal recovery window ~15-30 minutes post-workout for speedy recovery
An immediate intake of about _ to __g/kg BW CHO causes a slightly enhanced rate of muscle glycogen synthesis.
1-1.2g/kg BW CHO
Recommendation for CHO recovery post-workout:
1-1.2g/kg within 30min and again every 2h for next 4-6h
What is the most important factor for longterm recovery of CHO?
total amount consumed in a 24hr period (g CHO/kg BW/day)
meeting your personal needs, replenishing what’s lost
What are some of the challenges with optimal CHO consumption in recovery?
Access
Preferences
Body sometimes doesn’t feel like eating after
Time to prepare (not being prepared)
Not understanding the benefit
