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Chapter 8
Nutritional Considerations
for Intense Training and
Sports Competition
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Precompetition Meal
 Readily digestible foods
 Should contribute to energy and fluid requirements
 Meals high in carbohydrates and relatively low in lipids
and proteins
 Three to four hours to digest and absorb the
precompetition meal
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Ideal Precompetition Meal
 The ideal precompetition meal:
•
Contains 150 to 300 grams of carbohydrates
•
Is consumed 3 to 4 hours before the event
•
Contains little fat
•
Contains little fiber
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Liquid Meals
 High carbohydrate content
 Supply fluids
 Digest rapidly
 Can be used for day-long events
 Supplement calorie intake in those with difficulty
maintaining body weight
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nutrition Bars
 High protein content
 Approximately 25 g of carbohydrate
 Often include vitamins and minerals
 May contain dietary supplements
 Should not substitute for normal food intake
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nutrition Powders and Drinks
 High protein content
 Contain vitamins, minerals, and other dietary
supplements
 Come in powdered form or premixed
 Contain fewer calories per serving than nutrition bars
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Carbohydrates before Exercise
 If simple sugars are consumed, they should be consumed
at least 60 minutes before exercising.
•
This time gives hormones the chance to rebalance.
 Fructose absorbs more slowly compared to glucose or
sucrose.
•
High-fructose beverages can produce significant
gastrointestinal distress.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Carbohydrates during Exercise
 Allows for a greater intensity during prolonged activities
 Consuming about 60 g of liquid or solid carbohydrates
each hour benefits:
•
High-intensity, long-duration aerobic exercise
•
Repetitive short bouts of near-maximal effort
 Spares muscle glycogen
 Helps maintain a more optimal blood glucose level
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Carbohydrates after Exercise
 High-glycemic carbohydrate-rich foods
 Either a single large meal or small frequent meals will
replenish glycogen stores.
 Should be consumed as soon as possible after the
activity
 Avoid legumes, fructose, and milk products.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Glycemic Index
 Indicates how a carbohydrate-containing food affects
blood glucose levels
 High-glycemic index
 Moderate-glycemic index
 Low-glycemic index
 Affected by food preparation, ripeness, and how foods
are combined
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Glycogen Depletion
 High-intensity aerobic exercise for 1 hour decreases liver
glycogen by about 55%.
 A 2-hour strenuous workout nearly depletes the glycogen
content of the liver and specifically exercised muscles.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Hydration Solutions
 Carbohydrate-containing solutions consumed
during exercise enhance endurance performance by
maintaining blood sugar concentration.
 Glucose supplied in the blood can:
•
Spare existing glycogen in active muscles
•
Serve as “reserve” blood glucose for later use
should muscle glycogen become depleted
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Oral Rehydration Solutions
 Provide additional glucose
 Minimize the effects of dehydration on:
•
Cardiovascular dynamics
•
Temperature regulation
•
Exercise performance
 Adding electrolytes aids in:
•
Maintaining thirst mechanism
•
Reducing the risk of hyponatremia
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Carbohydrate-Electrolyte Beverages
 The ideal hydration solution contains between 5% and
8% carbohydrates.
 This permits carbohydrate replenishment without
adversely affecting fluid balance and
thermoregulation.
 Maintains glucose metabolism and preserves glycogen
during prolonged exercise
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Hydration during Exercise
 Adding moderate amounts of sodium to the ingested
fluid helps to maintain plasma sodium concentration.
 This benefits the ultra-endurance athlete at risk for
hyponatremia.
 Maintaining plasma osmolality with added sodium in
the hydration beverage reduces urine output and
sustains the sodium-dependent osmotic drive to
drink.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
High-Fat Diets
 Conflicting research findings
 Detrimental health risks are possible.
 Heath risks may not apply to athletes.
 Significant restrictions in fat impair exercise endurance.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins