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 Glycolisis Glucogenesis Gluconeogenesis Glucogenolysis 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.

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 requirements Pre competition meals Fluid 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: g protein p/kg BM 87 kg x 1.8 g or 87 kg x 1.2g = g p/day x 26 x 232 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

Preparation for Competition In general  Taper exercise, 50% CHO diet 1 st 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 ( g)

Bergstrom, Hermansen, Hultman, & Saltin (1967) Mixed dietLow Carb dietHigh 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 low Liver glycogen low Blood glucose low Extreme fatigue Dizziness Hunger - hypoglycaemia

Post Competition Depends on time and intensity g every 2 hours  500g Large carbohydrate rich meal Rest Rehydrate

Muscle Glycogen Synthesis Muscle glycogen is synthesized very slowly. The rate of synthesis differs depending on the prior exercise conditions, after low intensity exercise 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 BW Pre 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 L/hr  Sodium (Na), Potassium (K), Magnesium (Mg), Chlorine (Cl) Loss of body weight > 3% = danger Consume ml per hour

Fluids- Gisolfi & Duchman, 1992 Before:  < % Vo2max= ml liquid w/ 30-50g CHO  >1 Vo2 max= ml H20 During  < % = ml H2o  1-3 = ml liquid + 6-8% CHO + Na and Cl  >3 hr = ml H % 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,

Gastric emptying Maximal rates of L /hr with gastric volumes of mL.

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