Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Chapter 3 Optimal Nutrition for Exercise

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Nutrient Requirements Recommended nutrient intake –Protein 0.83 g/kg body weight –Lipid < 30% total kCals –Carbohydrate 55 – 60% kCals –Increased need for endurance athletes

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition High-Fat Versus Low-Fat Diets High-fat diets may stimulate adaptive responses that enhance fat use –Controversial due to increased risks for CHD Research has not demonstrated benefits of a high-fat diet for improving endurance performance A high-carbohydrate diet is still recommended over a high-fat diet

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition The Food Guide Pyramid The essentials of good nutrition are displayed in this model –The model has been modified to guide modified diets –Mediterranean Diet Pyramid Protection against CHD –Vegetarian Diet Pyramid Complete nutrition without meat/fish

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Exercise and Food Intake Energy requirements vary depending upon the volume of training Examples of events requiring increased energy intake –Tour de France –Ultraendurance running competition –Extreme ultraendurance sports

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Eat More, Weigh Less Compared to sedentary people, active individuals –Maintain a lower body weight –Are leaner –Have a better CHD risk profile This is true despite having an increased intake of food.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Precompetition Meal The ideal meal –Provides adequate carbohydrate –Ensures optimal hydration –Is well tolerated by the athlete –Is easily digestible The meal should be consumed around 3 hours prior to competition.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Protein or Carbohydrate? The evidence supports carbohydrate –Carbohydrate is the main energy nutrient –Carbohydrates replenish liver and muscle glycogen –Carbohydrate digestion and absorption are faster –High-protein meals elevate resting metabolism –Protein breakdown facilitates dehydration

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition How Much Should Be Consumed? Carbohydrates –3 to 5 grams/kg body weight 150 – 300 grams total –Consume 3 hours prior to exercising –Contain relatively little fat and fiber

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Liquid Meals Liquid meals are convenient. Other benefits of liquid meals –Provide some lipid and protein –Provide fluid and high carbohydrate content –Digest rapidly

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Prepackaged Meals Contain relatively high protein content May provide dietary supplements –Weight loss –Meal replacement

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Nutrition Powders and Drinks High protein content Dietary supplement ingredients Replace glycogen reserves before and after exercise and competition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Carbohydrate Feedings Prior to exercise –Should be consumed between 1 and 3 hours prior to event to prevent rebound hypoglycemia The glycemic index and preexercise feedings –Fructose is absorbed more slowly than glucose –If glucose is used, allow 1 hour for reestablishment of hormone levels

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Carbohydrate Feedings During prolonged high-intensity exercise –Spares muscle glycogen –Maintains more optimal blood glucose –Postpones fatigue –Improves endurance performance –Augments sprint capacity near the end of performance

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Carbohydrate Feedings In recovery –Use moderate- to high-glycemic index foods –Keep lipid content low Consuming food after exercise increases cellular uptake of glucose due to –Increased activity of GLUT 1 and GLUT 4 –Lowered catecholamine levels and increased insulin levels –Increased activity of glycogen synthase

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Postexercise Meals Consume high-glycemic carbohydrate-rich foods as soon as possible after exercise. –50 – 75 grams every 2 hours up to 500 grams Remain inactive to enhance glycogen resynthesis

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Glucose, Electrolytes, and Water Uptake Glucose, water, and electrolytes are all important. Glucose and water influence one another’s uptake. –Large fluid volume impairs carbohydrate uptake. –Concentrated sugar solutions impairs fluid replacement.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Gastric Emptying & Intestinal Absorption High fluid volumes speed gastric emptying –Consume 400 – 600 mL immediately preexercise –Ingest 150 – 200 mL every 15 minutes during exercise –Carbonated beverages slow emptying –Caffeine and alcohol promote diuresis –Osmolarity Particles in solution Polymers may improve emptying rate Sodium reduces urine output

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Consume ~ 250 mL every 15 minutes Use a drink containing 5 – 8% carbohydrates Fluid Replacement During Exercise