“Aside from the limits imposed by heredity and the physical improvements associated with training, no factor plays a bigger role in exercise performance than does nutrition.” Dr. David Costill, 1988

Energy Balance

Hypothetical daily energy needs of an Ironman triathlete in training. ActivityMETSDuration (h) Energy Expenditure (kcal) Sleep Office work Running (7.5 mph)* *810 Swimming (2 mph)*8.00.5*318 Bicycling (18.6 mph)* *1,530 Home activities (e.g. cooking, washing dishes, etc.) Miscellaneous activities (reading newspaper, talking on phone, etc.) ,856 *Based on data from O’Toole, Energy expenditure calculated as: (METS  75 kg body weight  hours of activity = kcal)

Daily Energy Intakes of Elite Athletes

Map of the Trek Torry LarsenRune Gjeldnes WR 2,928 km Unsupported Ski Trek March - June, 1996

WR 2,928 km Ski Trek Details 2,928 km (1,815 miles) in 83 days 9 hrs/d of trekking (~22 miles/d) Each pulling 150 kg (330 lb sled) Average energy intake was 6,000 kcal/d Average weight loss was only 5.3 kg (~12 lbs) and 4% reduction in body fat (DEXA) Average weight loss of Army Rangers during 64 days of training is 10 – 20 kg (22 – 44 lbs)!

Macronutrients

60 -70% of kcal g/d 5-10g/kg/d CHO PRO FAT 15-25% of kcal 15% of kcal g/kg/d Macronutrient Composition and Performance: Overview

Dietary Protein

Protein Intake (g/kg/d) Nitrogen Balance (mg/kg/d) RDA Meredith et al., 1989 Mean =.94g/kg/d

Whole Body Protein Synthesis (mg/kg/hr) Protein Intake (g/kg/d) Sedentary Strength Athletes Tarnopolsky et al., 1992 * *

Current Protein Intake Recommendations

Protein and Amino Acid Contents of Common Foods and Popular Supplements

Dietary Carbohydrate

Why Are Carbohydrates So Important? í Carbohydrates are the primary muscular fuel source for intense exercise

FAT CHO Adapted from: Brooks and Mercier, 1994 The “Crossover Concept”

Adapted from: Romijn et al., 1993

Why Are Carbohydrates So Important? í Carbohydrates are the primary muscular fuel source for intense exercise í Carbohydrate body stores are limited; when depleted, athletes cannot exercise intensely and experience fatigue

Adapted from: Bergstrom and Hultman, 1967

Adapted from: Gollnick, 1974

Adapted from: Bergstrom et al., 1967  Low CHO Diet  Normal Diet  High CHO Diet

Why Are Carbohydrates So Important? í Carbohydrates are the primary muscular fuel source for intense exercise í Carbohydrate body stores are limited; when depleted, athletes cannot exercise intensely and experience fatigue í Athletes who train regularly and intensely require more dietary carbohydrates to replenish what is used

Adapted from: Costill, 1985

Are athletes eating enough carbohydrates?

Recommendations for Training í Absolute CHO intakes should approach g/d or 5-10g/kg/d í The % of calories coming from CHO is not as important as long as absolute needs are met

Adapted from: Nieman et al., 1989

Data from: Lamb et al., 1990

Why Are Carbohydrates So Important? í Carbohydrates are the primary muscular fuel source for intense exercise í Carbohydrate body stores are limited; when depleted, athletes cannot exercise intensely and experience fatigue í Athletes who train regularly and intensely require more dietary carbohydrates to replenish what is used í Carbohydrates consumed before, during, and after exercise maximize performance

Sports Drinks

Adapted from: McConell et al., 1999

Adapted from: Tsintzas et al., 1993

Adapted from: Wright et al., 1991

Dorando Pietri, 1908 Olympic Marathon Carbohydrates and Performance

Carbohydrates in the post-exercise period: Glycogen Resynthesis

* Adapted from: Fallowfield et al., 1993

Nutrition and Athletic Performance: Summary Number one nutritional priority is maintaining energy balance Athlete protein needs are higher than the RDA, but athletes* already consume even more than the upper scientific recommendations Carbohydrate needs are best expressed on a g/kg/d basis (or in absolute terms: g/d) Carbohydrates improve athletic performance for endurance exercise (> 90 continuous minutes)