Transcript SPORTS NUTRITION

SPORTS NUTRITION
Diana Dickenson, B.ExSci & Rehab
Today’s Topic Menu

Energy sources; carbs (GI), protein, fat,
alcohol
 Fluid intake / Exercise in the heat
 Iron
 Preparation and Recovery
 Further information
Q&A
Energy Sources
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FAT
37 kJ/g
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ALCOHOL
19 kJ/g
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PROTEIN
17kJ/g
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CARBOHYDRATE
16kJ/g
Carbohydrates
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Carbohydrate foods digested to release glucose
into bloodstream
Glucose is the body’s preferred fuel source
Glucose stored in muscle and liver as ‘glycogen’
Stored glycogen is enough for 90min of moderate
exercise
Depletion of muscle ‘glycogen’ linked to fatigue
Equally important for sprint and endurance
cyclists to have adequate carb intake
‘Simple’ Carbohydrate

Certain carbohydrate foods cause a sudden
rise in blood sugar, if this energy is not used
immediately, the body releases insulin
which causes blood sugar to fall, meaning
less energy available to the muscles.
 It is high Glycemic Index (GI) foods rather
than ‘simple’ carbohydrates that cause this
Glycemic Index
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HIGH
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–
–
–
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Glucose, honey
Sports drinks
Bananas, watermelon
Cornflakes, Coco Pops
Weet-Bix, Rice
Bubbles
– White rice
– Potato
– Wholemeal & white
bread
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LOW
– White & wholemeal
–
–
–
–
–
–
pasta
Beans & lentils
Porridge, All Bran
Apples, oranges,
grapes, peaches
Flavoured yoghurt
Vitari
Chocolate
Glycemic Index
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If you combine a high and a low GI food
source within a meal, the overall effect will
be moderate GI
3 CATEGORIES OF CARBS
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Carbs can also be divided in to 3 categories:
– Nutritious carbohydrates
 Breads, b’fast cereal, rice, pasta, fruit, starchy
vegetables (potato, sweet potato, corn), beans, milk.
– Refined carbohydrates
 Sugar, sweet spreads, soft drink, lollies, icecream
– High-fat carbohydrates
 Toasted muesli, full fat milk, pastries, chocolate,
chips, cakes
How much Carbohydrate?
7 – 11 g/kg body mass per day
 For a 60kg athlete, 420 – 660g per day
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Bkfst
MT
1 cup muesli + 250mL milk + 1 glass juice
Banana + handful dried fruit
Lunch
AT
Large salad roll + tub yoghurt
Muesli bar + apple + 500mL sports drink
Dinner
2 cups spaghetti bolognaise
1 cup stewed fruit + 2 scoops IC
1 glass milk milo
Supper
How much Carbohydrate?
During Training and Racing:
 30 – 60g per hour
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In each 600mL powerade drink = 46g
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2.5 muesli bars = 50g
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1 energy gel = 25g (need ~200mL water with gels)
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2 bananas = 50g
Not Just a Question of Energy
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Consuming adequate carbohydrate in the
days leading up to as well as during
strenuous exercise will reduce the amount
of circulating stress hormones
This may prevent suppression of the immune system
Stress hormones cause breakdown of muscle tissue, so
they are good to limit where possible!
PROTEIN

Used as a minor energy source
 Body prefers to use for building and repairing
muscle and body cells
Animal Sources
Plant Sources
Meat
Nuts
Chicken
Legumes/Lentils
Seafood
Wholemeal bread
Dairy Products
Breakfast cereal
Eggs
Soy milk/Tofu
PROTEIN
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Both strength and endurance athletes have greater
protein needs than general popn (1.0g/kg/d)
- Strength 1.6-1.7g/kg/d
- Endurance 1.2-1.4g/kg/d
 Due to greater need for muscle building and an
increased use of protein as muscle fuel
 High food intake of most athletes ensures
generous protein intake
 Requirements generally met by food rather than
supplements
High Protein Diet?
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Extreme high protein diets:
- displace other nutrients from diet
- expensive (often higher in saturated fat)
- increase dehydration
- promote calcium loss from bones
Excess protein is not stored – it is used as
an energy source or is converted to fat
FAT
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Dietary fat provides energy, essential fatty
acids, carries fat-soluble vitamins and adds
taste/texture to food
Most concentrated source of energy in diet
Aim is for low fat food choices to maintain
body weight
TIPS TO REDUCE FAT
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Reduce butter, margarine, oil or spreads
Select lean cuts meat
Choose low fat/ skim dairy foods
Limit take-away/snack foods
Choose low fat cooking methods – grilling,
steaming, microwaving, non-stick frypans
ALCOHOL
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Alcohol can cause water and heat loss,
increased swelling, poor nutrition choices,
risky behaviour
 National guidelines recommend no more
than 4 standard drinks on any one occasion
 Health guidelines do not recommend that
you begin drinking if you don’t already
(antioxidants etc)
Components of a well
balanced diet for cycling
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Increase intake of carbohydrates, water,
dietary fibre
 Decrease intake of fats, salt & alcohol
 Ensure adequate levels of protein, vitamins
and minerals
HYDRATION
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Sweat losses vary between athletes but increase
with temperature, intensity & duration (3.7 L/hr)
 Physiological responses to dehydration:
 1%: thirst, increased RPE
 2%: decreased sweat rate, cardiac output, VO2, work
capacity, muscle strength and liver glycogen, therefore,
decreased performance
 5%: discomfort, alternating states of lethargy and
nervousness, irritability, fatigue, loss of appetite
 7%: Extreme danger; salivating & swallowing becomes
difficult
 Upper tolerance is 20%
Guidelines for Fluid Intake
Before Exercise: 500mL 2 – 3hrs prior to exercise
(water, juice, milk, cordial, sports drink) and
5ml/kg immediately before exercise
 During: 250mL every 15-20min OR as much is
comfortable during exercise (water, sports drink)
 After: 150% of fluid deficit; Aim for 500mL to
1000mL (sports drinks, as the electrolytes help
stimulate the thirst drive)
 Trial and error, useful to weigh pre and post
(1kg lost = 1L of water)
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Physiological Response to Heat
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Increased core temperature causes
– Sweating
– Increased blood flow to the periphery (skin,
arms, legs, head)
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Light lowers temp at which sweating starts
(avoid a pre-comp nap in a dark room)
 Pre-cooling improves endurance
performance (cool shower/bath/vests)
IRON
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Iron helps to transport oxygen in blood & muscle
Restricted diets can cause low iron (blood tests
will show low haemoglobin & ferritin levels)
Symptoms: reduced performance due to
breathlessness, less resistance to infection,
impaired recovery
Enhance iron absorption by adding VitC &
avoiding strong tea/coffee with meals
Red & white meat, seafood, eggs, cereals, dried
fruit
PREPARATION
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Pre-event food: high carb, low fat
– Larger meal 3 – 4 hrs before:
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Cereal, skim milk & fruit / Toast with baked beans
– Smaller snack 1 – 2 hrs before:
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Banana / Bread with honey / sustagen drink
Having a combined carb/protein snack before
training can slow the break down of muscle and
help protein synthesis during the session
 Early-morning training; have some carbs to help
fat utilisation
RECOVERY
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If <8hrs before the next training session/event,
recovery strategies are needed
 Carb (1g/kg) & Protein (10 - 20g) snack posttraining (within 30min)
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50g carb serves that contain 10g protein: 250ml fruit
smoothie, 500ml flavoured low-fat milk, 1.5 cups b’fast
cereal with ½ cup milk, 1 sandwhich with cheese/meat
filling and 1 piece fruit
Eating during a ride > 90min will aid immune
function
 For athletes trying to reduce body fat, recovery
snacks should not add to total energy intake
Further Information
Further Information

www.ais.org.au/nutrition
 www.daa.asn.au