SPORTS NUTRITION

1. SPORTS NUTRITION Diana Dickenson, B.ExSci & Rehab

2. 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

3. Energy Sources • FAT 37 kJ/g • ALCOHOL 19 kJ/g • PROTEIN 17kJ/g • CARBOHYDRATE 16kJ/g

4. Carbohydrates • 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

5. ‘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

6. 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 Index

7. Glycemic Index • If you combine a high and a low GI food source within a meal, the overall effect will be moderate GI

8. 3 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

9. How much Carbohydrate? • 7 – 11 g/kg body mass per day • For a 60kg athlete, 420 – 660g per day

10. 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

11. Not 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!

12. PROTEIN • Used as a minor energy source • Body prefers to use for building and repairing muscle and body cells Animal SourcesPlant Sources Meat Nuts Chicken Legumes/Lentils Seafood Wholemeal bread Dairy Products Breakfast cereal Eggs Soy milk/Tofu

13. PROTEIN • 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

14. 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

15. FAT • 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

16. TIPS 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

17. ALCOHOL • 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)

18. Components of a well balanced diet for cycling • Increase intake of carbohydrates, water, dietary fibre • Decrease intake of fats, salt & alcohol • Ensure adequate levels of protein, vitamins and minerals

19. HYDRATION • Sweat losses vary between athletes but increase withtemperature, 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%

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 iscomfortable 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)

21. Physiological Response to Heat • Increased 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)

22. IRON • 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

23. PREPARATION • 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

24. RECOVERY • 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

25. Further Information

26. Further Information • www.ais.org.au/nutrition • www.daa.asn.au