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• Starch• Fibre

What happened to your breakfast??

Carbs and energy

GlycolisisGlucogenesisGluconeogenesisGlucogenolysis

Energy!

(ATP)

-Glucose

Glycogen- ST storage

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 fiber 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

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

CHO & protein requirementsPre competition mealsFluid replacement

Daily intake

Normal people 1500—2500 calories

50-60% carbs 20-30% fat 15-20% protein

Athletes 1400 (gymnasts) –

6000 (TDF cyclists)

70-80% carbs 20% fats 10% protein

RDI’s- Protein

Sedentary people and recreational athletes have similar protein requirements Sedentary: 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 Endurance athletes

(training > 60 min p/day: 8-10 g /kg

59 kg x 8 g = 472 g p/day

20

465

404075

17 10

2085

204580

Preparation for Competition

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 150 – 300g carbohydrate (3-5g CHO p/kg BW)

OR

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

CHO ingestion every 20 min

CHO ingestion late in exercise

No CHO ingestion

65-75% VO2max

Liquid Carbohydrate Ingestion

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

Need at least 45 g/CHO/Hr

Drink of 60 g CHO/L would require at least 750 mL/Hr

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

Most people can not ingest more than 1.2 L/Hr

CHO should be mostly glucose

“Hitting the Wall”

Muscle glycogen lowLiver glycogen lowBlood glucose lowExtreme fatigueDizzinessHunger - hypoglycaemia

Post Competition

Depends on time and intensity50 - 75 g every 2 hours 500gLarge carbohydrate rich mealRestRehydrate

Muscle Glycogen SynthesisMuscle glycogen is synthesized very slowly. The rate of synthesis differs depending on the prior exercise conditions,

after low intensity exercise - 7-9 mmol/kg/Hr

after high intensity exercise - ~ 15 mmol/kg/Hr

Muscle glycogen synthesis is optimized when,

there has been no exercise-induced muscle damage

recovery is passive

at least 0.7 g CHO/kg/Hr is ingested

ingestion occurs as soon after exercise as possible

glucose should be the predominant CHO and the source food should have a high glycemic index

Tour de France riders

Require CHO intake of 13 g/kg BWPre competition meal

Breakfast 3 hours before start

High Carb (100g) snack Energy bars/ energy drinks 1 hour before start

During the race Glucose gels- 15g CHO

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% = dangerConsume 500-1000 ml per hour

Fluids- Gisolfi & Duchman, 1992

Before: <1 hr @ 80-130% Vo2max= 300-500ml liquid w/ 30-50g CHO >1 hr @30-90% Vo2 max= 300-500ml H20

During <1 hr @ 80-130% = 500-1000ml H2o 1-3 hr @60-90% =800-1600ml liquid + 6-8% CHO + Na and Cl >3 hr = 500-1000ml H20 + 6-8% CHO + NA and Cl

After Continue H2o consumption Caffeine, energy drinks and alcohol further dehydrate

Gisolfi, C.V., & Duchman, S.M. (1992). Guidelines for optimal replacement of beverages for different athletic events. Medicine and Science in Sports and Exercise. 24, 679-687.

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

Fad Diets

Low CHO Atkins, Zone, South Beach Depletes glycogen, “eats” muscle and reduces

performance Relies on ketosis Bad breath

Starvation Body conserves fat stores Lose h20 only

Diet pills Fat metabolisers do not exist Placebo effect Legal action against diet companies

Summary

Sports nutrition has a huge impact on performance

Nutrition and rehydration account for huge gains Expensive pills, potions and fads account for

minute gains if any at all Avoid fads as many are counterproductive and

may be illegal, banned substances