Transcript Nutrition for Exercise & Sport

Nutrition for
Exercise & Sport
Exercise Physiology
McArdle, Katch, Katch: Chapter 3 (Part 2)
Overview
• Nutrient Consumption: Fit & Non-fit
• Dietary Reference Intakes
• Calorie and Macronutrient Needs
– Pre workout (competition) Meal
– Water
– Carbohydrate
– Fat
– Protein
• Nutrient Timing for Resistance Training
Nutrient Consumption: Fit & Unfit
• Active people do not require additional
nutrients beyond those obtained in a
nutritionally well balanced diet.
• What physically fit eat compared to unfit.
– Small differences in energy intake (low vs high)
– Higher dietary fiber & lower cholesterol intakes
– Diets more closely approach recommendations
• Sound human nutrition represents sound
nutrition for athletes.
Nutrient Consumption: Fit & Unfit
• Most obvious distinction in nutrient needs
between active and inactive is more total
calories.
– Volume of physical activity determines energy
intake requirements
– Relatively high caloric intakes of physically
active usually increases protein, vitamin, and
mineral nutrients intake above recommended,
– Percentage of calories from energy nutrients
should remain in normal ranges.
Dietary Reference Intakes
• Dietary Reference Intakes (DRIs) is an
umbrella term encompassing an array of
standards: the RDAs, Estimated Average
Requirements (EARs), Adequate Intakes
(AIs), and tolerable Upper intake Levels(UL).
• DRIs differ from predecessor RDAs by
focusing on promoting health maintenance
and risk-reduction for nutrient-related
disease rather than preventing deficiencyrelated diseases.
Dietary Reference Intakes
• EAR is average level
of daily nutrient intake
sufficient to meet
requirements of ½
healthy people in
given age/gender
group.
• RDA is average daily
nutrient to meet
requirements of nearly
all people in given
age/gender group.
Dietary Reference Intakes
• Adequate intake (AI) provides a nutritional
goal when no RDA exists.
• Tolerable upper intake level (UL) is highest
average daily nutrient intake likely to pose
no risk or adverse health effects to most
age/gender group.
My Pyramid Replaces Food
Guide
• My Pyramid replaces Food
Guide Pyramid to provide food
intake guidance based on age,
sex, and level of daily exercise.
• Recommend consuming
between 45% and 65% of total
calories from CHO.
• Recommend consuming
between 20% to 35% of total
calories from Fat.
• Recommend consuming
between 10% to 35% of total
calories from Protein.
• Recommended meal
composition includes 60%
CHO, 25% protein, 15% Fat
(Institute of Medicine).
Exercise and Food Intake
• Mean energy intakes
peak between ages 16
and 29 years then
declines thereafter.
• For individuals who
exercise regularly food
intake balances daily
energy expenditure.
• Lack of precision in
regulating food intake
at low end of energy
expenditure leads to
creeping obesity.
Rough Estimate Minimum Calories Needed:
Current wt (lb) X 23 = total calories for males
Current wt (lb) x 20 = total calories for females
Exercise and Food Intake
• Except for high energy
intake at extremes,
daily intake does not
exceed 4000 kCal for
men and 3000 kCal
for women.
• Some sport activities
require extreme
energy output (sometimes > 1000 cal/hr).
Exercise and Food Intake
• Phelps told ESPN he
eats roughly 8,00010,000 cal/d, including
lots of pizza & pasta.
• Breakfast of champions
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3 fried egg sandwiches
2 cups coffee
5-egg omelet
1 bowl grits
3 slices French toast
3 chocolate chip
pancakes
Beijing 4 x 100 freestyle relay, 8-11-08
Exercise and Food Intake
• To support 6’4”, approximately 190#,
training regimen requires ~1,000 cal/hr
while training or racing.
• Probably eats closer to 6,000 cal/day.
Precompetition Meal
Preworkout Meal Goal: Maximize muscle & liver
glycogen stores and provide glucose for
intestinal absorption during exercise.
– Be consumed within 3-4 hours before
exercising sufficient time to digest & absorb.
– Reasons precompetition meal high in CHO:
• Foods high in lipid & protein digest slowly
• Protein catabolism facilitates dehydration
– Contain 150 – 300 g CHO in solid or liquid
– Benefits of precomp liquid meal: contribute to
fluid needs, absorb rapidly leaving no residue
Pre-Workout Meals
3 hours before
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Pasta
Stir fry
Sandwiches
Fajitas
Eggs & toast
Chicken, potato,
veggies
– Veggie burger
2-3 hours before
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Bagels
Crackers
Pretzels
Smoothies
Cereal and milk
Waffles/pancakes
Pasta salad
Carbohydrate Needs
• Optimal fuel for EXERCISE
• Intense training depletes carbohydrate
stores (glycogen) resulting in poor
performance and fatigue.
• Consume carbohydrate with every meal.
• In general, carbohydrates (CHO) should
always provide at least 55% of total daily
calorie (TDC) intake. Ideally 60-70% of
TDC.
• Needs increase with increased training.
Carbohydrate Needs
• 3 grams/lb body weight for 1 hour training
• 4.5 grams/lb body weight for 2 hours training.
• 5 grams/lb body weight for 3 hours training.
• 6 grams/lb body weight for 4+ hours training.
How many calories per gram of CHO?
Sources: Bread, Tortillas, Rice, Vegetables, Bagels, Pasta,
Potatoes, Fruit, Sports Drinks, English Muffins, Cereals, Fruit
Juices, Soda Pop, Muffins, Crackers, Pita, Pretzels, Popcorn
Carbohydrate Needs
• Before exercise
– consuming rapidly absorbed, high glycemic CHO w/i 1
hr before exercising accelerates glycogen depletion by
insulin overshoot rebound hypoglycemia
– consuming low glycemic CHO immediately (< 30 min)
allows for relatively slow absorption rate into blood
• During exercise: 30-60 grams per hour, 5-10 oz of 58% CHO electrolyte drink every 15-20 min or 2 gels
per hour
• After exercise
– To speed up glycogen replenishment consume 50-75 g
moderate to high glycemic index w/i 15 minutes
– Under optimal CHO intake, takes 20 hrs to replenish
glycogen stores at rate of 5% per hour.
Fluid Intake (Chapter 2)
• Fluid needs = body weight X .67 = ounces you
require daily NOT including exercise
• What should you drink:
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Night before: 16 oz. of water before bed
Morning of practice: 16 oz. of water ASA get up
If practice later in day: 16 oz. of water 2 hrs. b4 practice
Pre-exercise: 6-8 oz. water or sports drink 15 min before
practice, try avoid carbonated beverages or caffeine, NO fruit
juices before exercise – can cause loose bowels & gas
– During exercise: 4-8 oz. every 15 minutes water & sports drink
alternate between two
– Post exercise: 15 oz. for every pound lost w/i 2 hrs. exercise
Fluid Intake
Recommendations
• Monitor dehydration rate from BW changes. Each
pound (.45 kg) ~ 450 mL
• Rate of stomach emptying affects intestinal
absorption. Fluid volume within stomach exerts
greatest effect on rate of gastric emptying.
• To maintain a relatively large fluid volume in
stomach & speed gastric emptying, consume
400-600 ml (13.5-20.3 oz) 10 – 20 minutes
before,
• With subsequent regular ingestion of [250 ml 8.45
oz] every ? throughout exercise.
Fluid Intake
• To optimize water & CHO absorption use
a 6% carbohydrate-electrolyte solution.
• Adding sodium to rehydration beverage
maintains plasma osmolarity, reduces
urine output, motivates.
• Theoretically, water absorption across
intestinal mucosa may be enhanced by
concurrent absorption of glucose & Na.
• Glucose stimulates sodium absorption, sodium is
necessary for glucose absorption, and co-transport
stimulates water’s passive uptake by osmotic action.
Best ways to replace K & Na post-exercise:
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Orange juice & salted pretzels, Baked potato with ketchup or salt,
Nectarine and some Chex mix, Mix of dried apricots and salted nuts
Carbohydrate Needs in Intense
Exercise
• Successive days of
intense training
gradually deplete
glycogen reserves
even with typical CHO
intakes.
• When dietary CHO
increased to 70% of
caloric intake, no
further glycogen
depletion.
Carbohydrate Needs
Glycogen Loading: procedure increases muscle
glycogen levels more than normal (1.7 g/100 g)
• Amount of glycogen that can be packed in:
– 5 g glycogen/ 100 g muscle
• What is major benefit of carbohydrate loading?
– Endurance capacity
– Unless athlete begins competing completely
depleted, exercise < 60 min requires normal
carbohydrate intake
– Each gram glycogen stores 2.7 grams H2O,
makes “heavy” fuel.
Carbohydrate Needs
• Classic Carbohydrate Loading
– Stage 1: depletion
• Day 1: perform exhaustive exercise to deplete
• Days 2, 3, 4: Maintain low CHO food intake
– Stage 2: loading
• Days 5, 6, 7: maintain high CHO food intake
– Stage 3: competition
• Modified Loading
• Days 1-3: exercise @ 75% VO2 max, 1.5 hrs, 50%
CHO
• Days 4-6: taper exercise duration, 70% CHO
Fat Needs
• Too much can cause cramps
• Not enough can cause fatigue more quickly
• Try to limit high fat foods before and during
exercise.
• Foods to avoid before & during exercise:
chips, ice cream, nuts, nut butters, french
fries, doughnuts, fried meats, pizza, chocolate,
bologna, salami, pepperoni, burgers
• In general, limit TDC intake < 30% fat.
Protein Needs
• Body can’t use more than 1 gram of protein
per pound of body weight!
• Not immediately available as an energy
source for exercise.
• Important for recovery and to boost
immune system.
• Sources: chicken, turkey, soy burgers, fish,
eggs, dried beans, beef, cheese, nuts and nut
butters, pork, milk, veal, shellfish
• In general, 15-20% TDC intake.