SPORTS NUTRITIONSPORTS NUTRITION
Diana Dickenson, B.ExSci & Rehab
TodayToday’’s Topic Menus Topic Menu
Energy sources; carbs (GI), protein, fat, alcohol
Fluid intake / Exercise in the heatIron Preparation and RecoveryFurther informationQ & A
Energy SourcesEnergy Sources
FAT 37 kJ/g
ALCOHOL 19 kJ/g
PROTEIN 17kJ/g
CARBOHYDRATE 16kJ/g
CarbohydratesCarbohydrates
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
‘‘SimpleSimple’’ Carbohydrate 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 IndexGlycemic Index HIGH
– Glucose, honey– Sports drinks– Bananas, watermelon– Cornflakes, Coco Pops– Weet-Bix, Rice
Bubbles– White rice– Potato– Wholemeal & white
bread
LOW – White & wholemeal
pasta– Beans & lentils– Porridge, All Bran– Apples, oranges,
grapes, peaches– Flavoured yoghurt– Vitari– Chocolate
Glycemic IndexGlycemic Index
If you combine a high and a low GI food source within a meal, the overall effect will be moderate GI
3 CATEGORIES OF CARBS3 CATEGORIES OF CARBS
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?How much Carbohydrate?7 – 11 g/kg body mass per dayFor a 60kg athlete, 420 – 660g per day
Bkfst 1 cup muesli + 250mL milk + 1 glass juice
MT Banana + handful dried fruit
Lunch Large salad roll + tub yoghurt
AT Muesli bar + apple + 500mL sports drink
Dinner 2 cups spaghetti bolognaise
1 cup stewed fruit + 2 scoops IC
Supper 1 glass milk milo
How much Carbohydrate?How much Carbohydrate?
During Training and Racing: 30 – 60g per hour
In each 600mL powerade drink = 46g 2.5 muesli bars = 50g 1 energy gel = 25g (need ~200mL water with gels) 2 bananas = 50g
Not Just a Question of EnergyNot Just a Question of Energy
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!
PROTEINPROTEIN
Used as a minor energy source Body prefers to use for building and repairing
muscle and body cellsAnimal Sources Plant SourcesMeat NutsChicken Legumes/LentilsSeafood Wholemeal breadDairy Products Breakfast cerealEggs Soy milk/Tofu
PROTEINPROTEIN
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? High Protein Diet?
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
FATFAT
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 FATTIPS TO REDUCE FAT
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
ALCOHOLALCOHOL
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 Components of a well balanced diet for cyclingbalanced diet for cycling
Increase intake of carbohydrates, water, dietary fibre
Decrease intake of fats, salt & alcohol Ensure adequate levels of protein, vitamins
and minerals
HYDRATIONHYDRATION 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 IntakeGuidelines 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)
Physiological Response to Physiological Response to HeatHeatIncreased core temperature causes
– Sweating– Increased blood flow to the periphery (skin,
arms, legs, head)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)
IRONIRON
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
PREPARATIONPREPARATION Pre-event food: high carb, low fat
– Larger meal 3 – 4 hrs before: Cereal, skim milk & fruit / Toast with baked beans
– Smaller snack 1 – 2 hrs before: 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
RECOVERYRECOVERY If <8hrs before the next training session/event,
recovery strategies are needed Carb (1g/kg) & Protein (10 - 20g) snack post-
training (within 30min) 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 InformationFurther Information
Further InformationFurther Information
www.ais.org.au/nutritionwww.daa.asn.au