What are some reasons why nutritional advice varied and contradictory? (6)
- ancestry and genetic adaptations will affect an
individual’s response to food - some long-held beliefs are wrong
- some research has been conducted incorrectly
- too many rules for the general public to digest
- nutritional guidelines are not objective – government
guidelines versus scientific ones… “Canada Food Guide”
in an example - manufacturers make unreliable claims – “Based on science”
What are some things in general to avoid eating? (5)
- processed meats
- high fructose corn syrup
- large amounts of sugar
- refined flour
- industrially processed fats
(ex: soybean oil,
canola or corn oil)
What are the 3 major macronutrients? How many kcals/g to each of them produce?
- proteins: 4 kcal/g
- fats: 9 kcal/g
- carbs: 4 kcal/g
Fill in the blank: 1g of alcohol can be metabolised to liberate ___
- 7 kcal
Protein can be used for energy but under normal circumstances our muscles use 4 major sources of energy?
carbs - plasma (blood) glucose - muscle glycogen fats - intramuscular triglycerides - plasma fatty acids
It is the goal of our body to maintain blood glucose levels. What maintains it (2) and what is it produced by?
- hormones: insulin and glucagon
- produced in the pancreas
Explain what happens to the blood glucose after a meal and between meals/ during exercise.
- after a meal: blood glucose is higher and the liver
removes the excess glucose from the blood to store it
as glycogen - between meals/ during exercise: blood glucose decreases and the liver releases the stored
glycogen to be broken down to glucose; lactate produced during exercise can be converted to glucose for fuel during exercise
The use of glycogen during exercise by a specific
muscle, and by muscle fibres (cells) within that
muscle, depends on (3)
- exercise intensity (higher % of VO2 max= higher use of glycogen)
- muscles involved in the exercise (glycogen will be
depleted in the muscles used) - type of muscle fibre or motor unit recruited
When is protein used as an energy source?
- in exercise only if available calories from fat and carbs are insufficient
- if there is sufficient calories from fats and carbs, the break down of protein to amino acids contributes to total energy by 2-5% at most; BUT during the final moments of an exercise session lasting 3-5 hours, protein use may reach 5-15% of fuel supply
Fill in the blank: intramuscular stores may account for about ____ the total fat used in endurance events
- half`
What factors govern the selection of fuel for muscular work? (2)
- exercise intensity (At rest about ⅔ of the ATP production comes from fatty acids, the other ⅓ from glycogen and glucose. At 95% of VO2 max. and above carbohydrate is used almost
exclusively ) - duration (At exercise intensities between 65–85% of VO2 max, it commonly takes 80–120 min to deplete muscle glycogen stores. As exercise duration increases, the proportion of energy
produced from fat begins to increase.)
An athlete with a ____________ will get a greater amount of energy from fatty acids compared to a _______
- higher aerobic capacity
- less fit person
Endurance training brings about increased number of ________ and increased __________ in trained muscle fibers. What does this allow aerobically fitter individuals to do?
- mitochondria
- aerobic enzymes
- get a greater proportion of
energy from fat at any given percentage of VO2 max, compared with
the same percentage of VO2 max for the less fit person
A person on a high-carbohydrate
diet will have _________________ than a person on a
low-carbohydrate diet.
higher muscle glycogen levels
What is the benefit of training on a low carb diet?
- improve the body’s ability to metabolize fats
There is considerable evidence that diets with a lot of ______ foods are associated with many chronic diseases.
- high- GI (glycemic index)
Explain if High-GI foods are beneficial/ detrimental:
- before exercise
- during exercise
- after exercise
- before: detrimental
- during: essential in long endurance activity
- after: important; helps refuel carb stores after exhaustive exercise
If athletes want to replenish muscle glycogen, they should
ingest at least ______ within ____ after a hard workout or competition.
- 1.5g of carbs/ kg of weight
- 1 hour
What is the problem with counting calories?
- errors when counting both calories in and calories out can each be up to 25%. Total error can be as high as 50%
- it is more important to focus on food quality and check
performance measures.
Quiz yourself: During high-intensity exercise at ≥ 95% VO2 max, muscles primarily get their energy from:
a) proteins
b) fat
c) carbohydrates
d) vitamins
e) minerals
b) fat (double check to be sure)
Quiz yourself: Which of the following nutrients does not provide muscles with a significant amount of energy during exercise (assuming normal diet): a) plasma FFA b) muscle glyocgen c) stored protein d) muscle triglyceride e) plasma glycogen
c) stored protein
Quiz yourself: Which of the following nutrients does not provide you with energy (calories).:
a) fats
b) vitamins
c) proteins
d) carbohydrates
e) they all provide calories to the diet
b) vitamins
Quiz yourself: A large influx of glucose into the bloodstream 20-30 minutes before an exercise session can trigger a
hormonal response that can often result in something
called _________? (This would occur 20-30 minutes
later during the exercise).
a) osteoporosis
b) hyperglycemia
c) increased fat catabolism
d) rebound hypoglycemia
e) liver damage
b) hyperglycemia?
d) rebound hypoglycemia?
