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