EDU2EXP Exercise & Performance Nutrition for Exercise

EDU2EXP Exercise & Performance

Nutrition for Exercise


What is Nutrition ?

• Science involving study of food and liquid requirements of the body for optimal functioning


Nutrients

• Macronutrients– Carbohydrates

• Monosaccardides- Glucose, Fructose, galactose

• Disaccharides- Sucrose, Lactose, Maltose

• Polysaccharides– Plant– Animal

– Protein• Complete• Incomplete

– Lipids• Saturated• Unsaturated

• Micronutrients– Vitamins

• Fat Soluble• Water Soluble

– Minerals• Essential• Trace

Water


Carbs

• Monosacchardides- – Glucose – Fructose– Galactose

• Disaccharides– Sucrose– Lactose– Maltose

• Polysaccharides– Glycogen-– Starch-– Fibre


Carbs- The basics

• Glucose is a type of monosaccharide that is in the food that we consume

• Blood glucose is used to fuel the working muscles

• Called glycogen when stored in muscles or the liver


What happened to your breakfast??

• Carbohydrate meal is eaten and digested, • Blood glucose levels rise, and the pancreas secretes insulin• GLYCOGENESIS- glucose converted to glycogen [for ST

storage] as long as both insulin and glucose remain plentiful• Blood glucose used for immediate energy requirements• When glucose levels begin to fall, insulin secretion is reduced,

and glycogen synthesis stops.• About four hours after a meal glycogen begins to be broken

down to be converted again to glucose [GLYCOGENOLYSIS]• For the next 8–12 hours, glucose derived from liver glycogen

will be the primary source of blood glucose to be used by the rest of the body for fuel.


Carbs terminology

• Glycogenesis = glucose glycogen

• Glycogenolysis = glycogen glucose

• Gluconeogenesis=non CHO sources glucose

• Glycolysis = Glucose Pyruvic acid Krebs cycle

4 calories of Energy

(+ Co2 and H20)1 gram glucose

(+ oxygen)


Storage• LIVER- Only the glycogen stored in the liver can

be made accessible to other organs. 100–120 g stored in an adult

• MUSCLES- lower concentration (1% of the muscle mass), but the total amount exceeds that in liver.

• Small amounts of glycogen are found in the kidneys, and even smaller amounts in certain glial cells in the brain and white blood cells

Once muscle glycogen stores are depleted performance decreases




Glycaemic Index

Index for comparing the blood glucose response from the ingestion of different foods.

- The more complex the carbohydrate, and the more fat, protein and fibre in the food lower glycaemic index.

FOOD ITEM GLYCEMIC INDEX

Cornflakes 121Instant mashed potatoes 120Whole wheat bread 100

Baked beans 70

Skim milk 46

White pasta (boiled) 45

Lentils (boiled) 36

High = GI>70

Mod = GI 56-70

Low = GI<55

Lower = slower


Whole wheat pasta

Glucose

White breadIngestion

Note the differences in the area under the curve

Note that the blood glucose response to white bread is the standard reference


Proteins

• ‘Building blocks’

• Complete- Animal –

• Incomplete- plant


Lipids

• Saturated

• Unsaturated– Monounsaturated

– Polyunsaturated



Micronutrients

• Vitamins– Vital to release energy from food

• Minerals– Important in catabolism and anabolism of

macronutrients

• Athletes– Iron, especially for women athletes– Calcium.


Energy for Sport


Major Considerations

• RDI’s - CHO & protein requirements

• Pre competition meals

• Fluid replacement


Daily intake Normal people• 1500—2500 calories

Athletes• 1400 (gymnasts) –

6000 (TDF cyclists)

• Carbohydrate= 55-60%• Fats <35%• Protein= 10-15%


RDI’s- Protein• Sedentary people and recreational athletes

have similar protein requirements– Sedentary Adults: 0.8 to 1 gram of protein p/kg BM. – Athletes: 1.2-1.8 g protein p/kg BM

87 kg x 1.8 g or 87 kg x 1.2g

= 104.4 - 156.6 g p/day

8 28.5 x 2 6 x 2 32 x 2


RDI’s- Carbs

• Depends on sport– Normal people: 5 g/kg– Athletes: 5-13 g /kg depending on training

intensity59 kg x 8 g = 472 g p/day

20

465

404075

17 10

2085

204580


Preparation for Competition- Carb loading

• In general– Taper exercise, 50% CHO diet 1st 3 days– V. low exercise, 80% CHO diet 3 days prior

• Strict protocol– Depletion

• Day 1- Exhaustive exercise• Day 2,3,4 mod intensity training & low carb

intake (100g p/day)• Day 5,6,7 High CHO intake (400-700g)


Bergstrom, Hermansen, Hultman, & Saltin (1967)

Mixed diet Low Carb diet High carb diet


Day of Competition Nutrition

• 1-4 hours before= Large CHO meal – 200-500 calories– 150 – 300g carbohydrate (3-5g CHO p/kg

BW)

OR

• 4 hours before – meal (200 g CHO)• 1 hour before- snack (100g CHO)


Rebound hypoglycaemia

• High GI carbohydrate consumed 15-45 min before exercise

it can stimulates insulin secretion

converts glucose to glycogen and stores it

low blood glucose levels

• Less fuel available for exercise

Pg 333 of text


Liquid Carbohydrate Ingestion

Suited for long duration (> 60 min) exercise where a glucose source is needed to support blood glucose

As long as it is consumed late in exercise when muscle glycogen stores are low it will not cause rebound hypoglycaemia

Need at least 45 g/CHO/Hr

During hot and humid conditions, a lower [CHO] drink would allow greater volumes to be ingested.

CHO should be mostly glucose


CHO ingestion every 20 min

CHO ingestion late in exercise

No CHO ingestion

65-75% VO2max


Post Competition

• Depends on time and intensity– after low intensity exercise - 7-9 mmol/kg/Hr – after high intensity exercise - ~ 15 mmol/kg/Hr

• Important to consume 2 hours post exercise while rate of glycogen synthesis is high

• Large carbohydrate rich meal• With some addition protein• Rest• Rehydrate


Liquids - Rehydration

• Sweat rates increase with intensity of exercise

• Fit people sweat more and sooner; and it is more dilute

• Can be up to 1- 2.8 L/hr– Sodium (Na), Potassium (K), Magnesium

(Mg), Chlorine (Cl)

• Loss of body weight > 3% = danger• Consume 500-1000 ml per hour


Fluids-

• 2 hours before: – 400-600 ml fluid

• During– 150-350 ml every 15-20 minutes– If > 1 hour- 4-8% CHO plus Na and Cl

• After– Continue H2o consumption- thirst not an accurate indicator– 900-1200 ml for every kg lost– Caffeine, energy drinks and alcohol further dehydrate

• Recommendations from text box in page 347


Gastric emptying

Maximal ratesof 1-1.2 L /hr with gastric volumes of 100 - 200 mL.


DRINK CHO(g/100 mL)

Na+(mEq/L)

K+(mEq/L)

Caffeine(mg/L)

Osmolality(mOsmol/kg)

10K 6.3 52 26 350

Coca-Cola 10.7 2 0 136.8 554

Cranberry juice 10-15 2 7 890

Dioralyte 1.6 60 20 ?

Exceed 6.0 21 3 250

Gatorade 6.0 21 3 280

Isostar 7.6 24 4 305

Orange juice 11.8 0.5 58 690

Sprite 10.2 5 0 695

Water 0 trace trace 0-20

Nutrient and electrolyte content of commercial drinks.


Important nutrients & fads

• Female Athlete Triad

• Steroid use/abuse• Over-consumption proteins• Muscle building powders• Creatine


Summary

• Sports nutrition has a huge impact on performance

• Nutrition and rehydration account for huge gains• Need to be careful of rebound hypoglycaemia

and gastric emptying• Expensive pills, potions and fads account for

minute gains if any at all

Documents

EDU2EXP Exercise & Performance Nutrition for Exercise