Lecture 15 Flashcards
Lecture 15:
What are the 6 key nutrient groups?
1.) Carbohydrates (CHO)
2.) Fats (lipids)
3.) Proteins
4.) Vitamins
5.) Minerals
6.) Water
Lecture 15:
What are the 2 key determinants of glycogen replacement?
1.) Carbohydrate (CHO intake
2.) Exercise type (eccentric = decreased glycogen synthesis)
Lecture 15:
How many carbs are required per day to maintain glycogen levels?
- what happens if intake is not enough?
3-12g CHO/kg body weight per day required for glycogen maintenance
- hunger often isn’t sufficient enough for CHO consumption
- insufficient CHO intake leads to heavy & tired feeling
Lecture 15:
What is Glycemin Index (GI)?
Classification of food categorized by glycemic (blood sugar) responses
Lecture 15:
When discussing food Glycemic Index’s, What are some foods with High GI?
High GI = greater than 70
- sports drinks, jelly beans, baked/fried potatoes, cornflakes, pretzels, etc
Lecture 15:
When discussing food Glycemic Index’s, What are some foods with moderate GI?
Moderate GI = 56-70
- pastry, pita bread, white rice, bananas, soda, ice cream, etc
Lecture 15:
When discussing food Glycemic Index’s, What are some foods with low GI?
GI = less than or equal to 55
- spaghetti, legumes, milk, apples, pear, peanuts, m&ms, yogurt, etc
Lecture 15:
Why is the Glycemic Index (GI) not perfect?
Everyone responds to GI differently
- Fat & high GI = lower GI
- GI calculations differ depending on reference food (glucose vs white bread)
Lecture 15:
What is Glycemic Load (GL) & it’s calculation?
An improved carbohydrate index calculated by:
GL = (GI x CHO in g)/100
Lecture 15:
What are some carbohydrate (CHO) factors that increase exercise time?
- Low-GI pre-exercise snacks - normoglycemia
- CHO loading (1-3 days prior) lots of carbs before event
- CHO consumption during exercise
Lecture 15:
What are some carbohydrate (CHO) factors that decrease exercise time?
- high-GI pre-exercise snacks - cause hypoglycemia
- no CHO loading before event (lower glycogen stores)
- no CHO feeding during exercise
Lecture 15:
Impact of Carbohydrates during exercise?
Unlike pre-exercise CHO, CHO during exercise does not trigger hypoglycemia thus CHOICE during exercise is good
Lecture 15:
Why is Carbohydrate intake essential following exercise?
Glycogen resynthesis is high 2hours after exercise so want to consume CHO within 2hrs of workout
- protein & CHO intake enhance glycogen stores
- CHO intake also helps stimulate muscle tissue repair
Lecture 15:
Why are Fats (FFAs) important for fuel during exercise?
They delay exhaustion after glycogen depletion
- body cannot metabolize triglycerides (dietary fats) so must break down triglycerides into FFAs
Lecture 15:
Are high fat diets good or bad?
High fat intake will increase circulating FFAs (good) but decrease glycogen storage (bad).
*no conclusive evidence on high-fat diets and exercise
Lecture 15:
What are the protein requirements for athletes?
1.2-1.7g/kg body weight per day
- when endurance training, protein is a possible fuel substrate but when strength training, protein is needed for building muscle
*excessive protein intake can lead to health risks
Lecture 15:
What is the importance of CHO & Protein after exercise?
CHO & protein after exercise lead to improves glycogen & muscle protein synthesis
Lecture 15:
Water gain at rest - % composition from what?
33ml/kg/day water gain
- 60% from beverages
- 30% from food
- 10% from cellular respiration
Lecture 15:
How is water lost at rest? %’s from what?
1.) evaporated from skin & respiration (30%)
2.) excreted from kidneys {urine} (60%)
3.) excretion from large intestine {poop} (5%)
4.) sweat (5%)
Lecture 15:
How do you get dehydrated during exercise?
Sweating increases as body temperate increases making water loss greater than water gain
Lecture 15:
What are a couple factors that add to body temperature and sweating during exercise?
- environmental temperate/radiant heat load
- humidity
- air velocity
- body size
- metabolic rate
Lecture 15:
What 3 percentages make up water gain at rest?
1.) 60% = fluid intake
2.) 30% = food intake
3.) 10% = metabolic water production
Lecture 15:
What 4 percentages make up water loss at rest?
1.) 30% = insensible water loss from skin & respiration
2.) 5% = sweat loss
3.) 60% = urine
4.) 5% = fecal loss
Lecture 15:
What 2 percentages make up water loss during exercise?
1.) 90% = sweating
2.) 10% = insensible water loss
Lecture 15:
How does increased temperature and decreased plasma volumes impair aerobic performance?
1.) increased temperature causes more sweat loss which leads to decreased performance
2.) decreased plasma volume decreases cardiovascular and thermoregulatory functions
Lecture 15:
How are electrolytes lost in sweat?
Sweat is like & derived from plasma & includes mostly Na+ & Cl- so remaining ions on the body must be redistributed
Lecture 15:
What electrolytes are lost in urine?
Kidneys regulate electrolyte excretion & when urine production decreases so does electrolyte excretion
- aldosterone causes Na+retention which leads to increases in thirst & drinking (increased electrolyte loss)
Lecture 15:
What are the benefits of fluids during exercise?
Fluids minimize dehydration & water loss which helps maintain performance and cardiovascular functions
Lecture 15:
What is Hyponatremia?
Relatively rare but occurs with Excessive loss of sodium (Na+) & excessive rehydration (serum Na+ <135mmol/L)
Lecture 15:
What are the mild symptoms of Hyponatremia? Severe symptoms?
1.) Mild = bloating/puffiness, nausea/vomitting, headache
2.) Severe = cerebral or pulmonary edema, cognitive or central nervous system dysfunction, coma, death
Lecture 15:
What are the fluid replacement guidelines for 2hr before exercise?
400-600ml of fluids 2h before
Lecture 15:
What are the fluid replacement guidelines for during exercise?
Intake fluids to stay within 2% of per-exercise body weight (not over-drinking)
Lecture 15:
What are the fluid replacement guidelines for after exercise?
Replace all fluid losses & have salty snack for sodium replensihment
Lecture 15:
what is Carbohydrate Loading?
Training is tapered week before event as max glycogen stores lead to better performance
- days 6-4 before event have normal CHO diet
- days 3-1 before event have high CHO diet
*this allows muscle glycogen stores to double
Lecture 15:
How do you prepare the liver for endurance exercise & why?
Prepare liver with CHO loading to greatly increase liver glycogen levels & reduce hypoglycemia
- 1g glycogen is stored with 2.6g water
(CHO loading = glycogen = water weight gain)
Lecture 15:
What is the difference in speed of liver vs muscle glycogen synthesis?
Liver glycogen is resynthesized quickly but muscle glycogen is resynthesized slowly
- so is important to increase CHO & protein intake less than 2h after competition
Lecture 15:
How do Na+ concentrations in sports drinks help with rehydration?
High glucose and Na+ levels in the drink stimulate water absorption as Na+ increases thirst, palatability, & water retention
- 20-60mmol?L
Lecture 15:
What increases the palatability of sports drinks?
Light flavour with no strong aftertaste and increases ad libitum consumption
Lecture 15:
What are the 3 General models of body composition?
1.) Chemical
2.) Anatomical
3.) Two Compartment
Lecture 15:
Why is it important to assess body composition?
It is a source of key information as height and weight are not enough to know one’s fitness status
- increased percent body fat = decreased performance
Lecture 15:
What are a few (5) ways to measure body composition?
1.) Densitometry & hydrostatic weighing
2.) DEXA
3.) Air plethysmography
4.) skin folds
5.) bioelectric impedance
Lecture 15:
When discussing measurement methods for body composition, What is Densitomitry & how is it done?
Densitometry measures body density using hydrostatic (underwater) weighing as muscle is heavier than water but fat is lighter than water
- most used method
Lecture 15:
What are the limitations of Densitometry & Hydrostatic Weighing?
1.) Lung Air volume is confounding
2.) conversion of body density to percent fat
3.) fat-free density is variable among people
Lecture 15:
When discussing measurement methods for body composition, What is the DEXA measurement?
DEXA = Dual-Energy X-ray Absorptiometry
Very precise, reliable method that quantifies bone and soft-tissue composition but is very expensive & technical
Lecture 15:
When discussing measurement methods for body composition, What is the Air plethysmography (body pod) method?
A type of Densitometry technique but uses air displacement instead of water
- easy for the subject but difficult for the operator and expensive
Lecture 15:
When discussing measurement methods for body composition, What is the Skinfold Technique?
The most widely used field technique where thickness is measured at a minimum of 3 sites
- it is reasonable accurate and uses quadratic equations
Lecture 15:
When discussing measurement methods for body composition, What is the Bioelectric Impedance Technique?
Places electrodes on ankle, foot, wrist, & hand and sends a currant through proximal to distal sites
- looks at conduction as fat-free mass is a good electrical conductor & fat is a poor conductor
* reasonably accurate but room for improvement
Lecture 15:
How are weight standards used inappropriately?
Weight standards are seriously abused by coaches & players
- misconception that small weight loss is good but large weight loss better
- weight standards could possibly decrease performance and cause eating disorders
Lecture 15:
How is dehydration a risk during severe weight loss?
Fasting & extreme caloric restriction leads to water loss 2-4% weight loss as water can impair performance
- risk of kidney & cardiovascular dysfunction & possibly death
Lecture 15:
How is chronic fatigue a risk for severe weight loss?
Underweight leads to fatigue, substrate depletion, & decreased performance & injuries
- fatigue mimics overtraining
Lecture 15:
What is the female athlete triad? How is it a risk of severe weight loss?
Eating, menstruation, & bone disorders are the triad that lead to increased risks & seen in women with lean physique, low body weight or endurance
Eg; skating, h gymnastics, dance, running, swimming
Lecture 15:
What is Menstrual Dysfunction when discussing risks of severe weight loss?
Delayed menarche, oligomenorreha or amenorrhea
- prevalent in low-body-weight sports
- occurs due to caloric intake less than caloric expenditure
Lecture 15:
How is bone mineral loss a risk of severe weight loss?
Serious consequence of athletic amenorrhea & anorexia leads to 7x higher fracture rates due to lowered bone mineral levels
Lecture 15:
Why are weight standards not always appropriate?
- inappropriate standards are risky for athlete health
- technical measurement errors occur and “ideal” composition is not always best for performance
Lecture 15:
When trying to achieve optimal weight, why should you avoid fasting & crash diets?
They cause more water & muscle loss and less fat loss
- ketosis accelerates water loss
Lecture 15:
When achieving optimal weight, what s the optimal weight loss technique?
Decrease fat mass and increase FFM
- moderate caloric restriction & exercise
- caloric deficit ~200-500kcal/day
- loss = <0.5-1kg/week
- slowing of weight loss when near goal weight
