Sports Nutrition Flashcards
1
Q
What is sports nutrition
A
- the science of food constituents that best supply energy to meet the demands of the body
2
Q
what are the basic elements of a diet
A
- nutrients, vitamins and minerals
3
Q
Macronutrients
A
CHO, Protein and fat
4
Q
Carbohydrates
A
sugar and starches found in food that are converted into glucose
5
Q
What are the 2 classifications of CHO
A
Simple CHO: - monosaccharides (glucose, fructose, galactose) - Disaccharides (sucrose, lactose) Complex CHO: - Polysaccharides (starch and fibre)
6
Q
What happens when someone eats CHO
A
- processed and absorbed as glucose from the duodenum
- Blood glucose increases and it is transported around the body for use as energy
- in the absence of activity insulin levels increase and promote the storage of glucose in the muscle and liver as glycogen
7
Q
What happens to food when you exercise
A
- increase epinephrine/norepinephrine and decrease insulin
- increase glucagon and glycogen phosphorlayse
- promotes glycogenlysis
- glycogen conversion to glucose
- increase blood glucose and intracellular muscle glucose levels
8
Q
Whys is CHO so important at the beginning of exercise
A
- on the onset of exercise there is a latency of oxygen delivery therefore there is an increase use in CHO stores
9
Q
How much CHO do we store
A
Muscle glycogen = 300-400g Liver Glycogen = 50-100g Blood Glucose = 5g Total = 350-500g enough to fuel 2hours of exercise
10
Q
What happens when we run out of CHO during exercise
A
- fat becomes the predominate fuel source
- exercise intensity will fall by 50%
11
Q
CHO loading in history
A
- load muscle glycogen stores in the days leading up to the event
- 7 day model, 3-4 days of CHO depletion via high intensity training and low CHO food, 3-4 days of CHO loading and training taper
12
Q
CHO loading present
A
3-day model
- CHO loading
- Training taper (give muscle time to recover)
13
Q
CHO loading benefits
A
- time to fatigue increase by 20%
- TT performance is increased by 2-3%
- the decline in power output over time is reduced
14
Q
Pre-event meal prior to competition
A
- 2-4hours prior to the event
- LowGI
- CHO intake of 200-300g in the 2-4h pre-exercise has been shown to prolong fatigue
- increase liver glycogen/attenutation of the rise of insulin
Considerations: - gastrointentsional upset
- in the hour before rebound hypoglycemia could occue therefore decreased performance
15
Q
CHO during exericse
A
- for exercise longer than 60mins
- liquid form
- increase plasma glucose
- increased CHO oxidation
- when consumed excessivley oxidation rates remain th same however atheltes get cramps and dicomfort.
16
Q
What is the process of CHO oxidation and how to increase it
A
- glucose is absorbed in the gut via sodium-dependant glucose transporters
- consumption of 1g/min glucose saturates these transporters
- mix CHO types for example glucose and fructose
- as fructose is absorbed by GLUT5 transportation
- oxidation rates up by 55%
17
Q
Post exercise CHO
A
- glycogen resynthesis begins immediatley post-exercise
- consume 1 to 1.5g of CHO/kg immediatley post-exericise repeat at 2hr intervals until next meal
- Consumption of 1.2g CHO/kg/h in 30min blocks repeat for every 5h
- mutiple feeds which promotes glucose uptake into the muscles for glycogen synthesis
18
Q
What are proteins
A
- the major structural component of all body tissues
- proteins are a sequence of amino acids in a polypeptide chain
- 20 different amino acids
- excess AA are converted to glucose or fat for fuel utilisation
19
Q
What are the types of protein
A
- body cannot synthesis 8 of the 20 AA
- food eaten must contain these 8 AA (essential AA)
- the body synthesis the remaining AA (non essential AA)
20
Q
Complete proteins
A
- food containing all essential AA in the right quantity and ratio to allow for tissue growth
21
Q
Incomplete Proteins
A
food lacking one or more of the essential AA
22
Q
Role of protein
A
- muscular growth and cellular repair
- enzyme regulation
- red blood cell production
- hormones
- antibodies resisting infection
- source of energy when CHO and fats are not available
23
Q
Athlete protein requirements
A
- 1.5g per kg (70kg person) = 105g of protein
- increased muscle damage
- increased protein turn over
24
Q
protein and athleteic performance
A
- no research suggests that protein intake >1.5g/kg will enhance athletic performance or increase muscle mass
Considerations: - gastrointentinal upset
- to burn protein as fuel (metabolic waste)
- dehydration
25
Post exercise protein intake
- essential in helping the repair process from the breakdown that just occured
- within 30min of finishing an exercise
- 20g or 0.3g/kg should occur within 30mins of finishing the workout
26
What are the cateogories of fat
- saturated fat
- unsaturated fat (monounsaturated, polyunsaturated)
fats exist in the body in 2 forms:
- free fatty acids
- triglycerides
27
fat use during exericse
- low intensity
- training enhances the delivery and oxidation of FFA during exercise
- peak blood concentrations of FFA are lower in athletes
- glycogen sparing in athletes
28
How much fat should an athete eat
80g per day
29
fat and athletic performance
- aerobic training increases the oxidation of fat relative to CHO and improves endurance performance
- this attenuates CHO depleteion
30
Fat loading diet
```
two options:
1- High fat diet: 70% fat + 7% CHO
2- High CHO diet: 12% Fat and 74% CHO
- increase sub maximal TTF
- increase rate of fat oxidation
```
31
Vitamin D functions
- Immune system
- inflammatory modulation
- Bone health
- Muscle function
32
iron functions
- O2 transport
- energy metabolism
- brain function
- immune function
- recommended daily intake is 8mg/d (M) and 18mg/day (F)
33
what are the three stages of iron depletion in athletes
1- iron stores in bone marrow, liver and spleen are depleted
2-iron deficient erythropoisis: dimishes the iron supply to the erythoid marrow is reduced
3- iron deficent anmeia: hemoglobin production falls resulting in anemia
34
who is at risk for iron deficency
- female athletes
- distance runners
- vegetarians
35
avenues of iron loss during exercise
- poor nutrition
- gastrointestional bleeding
- urine
- sweating
- red blood cell destruction
- hormone activity = hepcidin
36
What are the three ways to increase iron intake
1- increase dietary intake
2- oral iron supplmentation
3- intramusuclar injections/IV infusion
