Nutritional Factors in Health

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Nutritional Factors in Health PerformanceCh. 12
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• Proper nutrition is important consideration for
  athletes who seek to maximize their performance
• No diet directly increases strength, power, or
  endurance, but an adequate diet allows athletes
  to train compete to best of their ability
• Ideal diet for athlete depends on
• Age, body size, sex, genetics, environmental
  training conditions, duration, frequency,
  intensity of training
• Best diet for athlete is one that is
  individualized

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How to evaluate the adequacy of the diet

• Athletes have 2 basic dietary goals
• Eating to maximize performance
• Eating for optimal body composition
• 2 fundamental components of diet must be present
• Appropriate calorie level
• Appropriate nutrient levels to prevent nutrient
  deficiency or toxicity

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• Food guide pyramid displays recommended types
  amounts of food to eat daily
• If diet provides minimum of servings, then
  should be adequate for vitamins minerals
• If diet excludes one group, then specific
  nutrients may be lacking
• Guidelines may need to be adjusted to meet
  dietary requirements specific to the demands of
  training program

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• Classifies food into 5 groups
• Bread, cereal, rice, pasta (6-11 servings)
• Fruit (2-4 servings)
• Vegetables (3-5 servings)
• Milk, yogurt, cheese (2-3 servings
• Meat, poultry, fish, dry beans, eggs, nuts (2-3)
• Fats, oils, sweets (use sparingly)

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• In general
• Breads, cereals, rice, pasta provide carbs, as
  do fruits vegetables
• Also primary sources of dietary fiber,
  riboflavin, thiamin, niacin, folate, vitamin C,
  beta carotene
• Meat, poultry, fish, dry beans, eggs, nuts are
  major sources of protein, iron, zinc, vitamin B
• Dairy products are excellent sources of protein,
  calcium, riboflavin

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Macronutrients

• Macronutrient- nutrient that is required in
  significant amounts in diet
• 3 important classes
• Protein
• Carbohydrates
• Lipids (fats related compounds)

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Protein

• Structure function of proteins
• Composed of carbon, hydrogen, oxygen, nitrogen
• 4 kcal per gram
• Amino acids- molecules that when joined together
  form thousands of proteins occurring in nature
• Nonessential amino acids- manufactured in the
  body
• Essential amino acids- must be obtained through
  diet
• Majority exists as skeletal muscle, organs, bone
  tissue

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• Dietary protein
• Amino acid content of dietary protein affects its
  value in supporting growth tissue maintenance
• Protein quality- amino acid amounts proportionate
  to bodys needs
• Complete proteins amino acid pattern similar to
  bodys needs
• Eggs, meat, fish, poultry, dairy
• Incomplete proteins deficient in 1 or more of
  essential amino acids
• Grains, beans, vegetables, gelatin

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• Complementary proteins- consume variety of foods
  that provide different amino acids
• If you do not eat meat (vegan) or a lot of it
• Beans rice, corn beans, peanut butter bread

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• Protein requirements are actually amino acid
  requirements
• General requirements
• 2 key factors
• Caloric intake biological value of protein
• Protein can be metabolized for energy in state of
  negative calorie balance (fewer calories consumed
  than expended)
• Recommended dietary allowance (RDA) for adults is
  0.8g per kilogram of body weight

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• Increased requirements for athletes
• Aerobic endurance athlete needs might be for
  tissue repair use of branched-chain amino acids
  for auxiliary fuel
• Strength power athletes needs might be for
  tissue repair maintenance of positive nitrogen
  balance so that hypertrophic stimulus is
  maximized
• 1.5-2.0g/kg body weight
• Excess protein is excreted as urea in urine, if
  too much consumed

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Carbohydrates

• Primary role is energy provision
• Structure function of carbohydrates
• Composed of carbon, oxygen, hydrogen atoms
• 4 kcal per gram
• Classified into 3 groups according to of sugars
  (saccharide) they contain
• Monosaccharides, disaccharides, polysaccharides
• Glycogen found in small amounts in human animal
  tissue as temporary source of stored energy
• Glucose enters body, if not used, stored as
  glycogen

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• Dietary carbohydrate
• Breads, cereals, pasta, fruits, starchy
  vegetables are ideal sources
• All types are capable of supplying body with
  glucose glycogen
• Consumption of mix of sugars starches is
  desirable

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• Glycemic Index (GI)
• Classifies food by how high how long it raises
  blood glucose
• Sugars do not always rank higher than starches
• Cooking, processing, eating the food as part of
  a meal, eating a different amount, eating at a
  different time of day all affect GI of food in
  individual

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• Fiber
• Diets low in fiber have been associated with
  diverticulosis, constipation, heart disease,
  cancer of colon, diabetes
• National Cancer Institute suggests 20-30g per day
• May be too high for some, especially runners,
  runners trots
• Can help with irritable bowel syndrome to help
  normalize bowel habits
• Found in fruits, vegetables, nuts, seeds,
  legumes, whole-grain products, high-fiber
  cereals, supplements

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• Carbohydrate requirements
• Roughly 50-100g per day is needed to prevent
  ketosis (high levels of ketones in bloodstream)
• Recommended 55 of total calories from carbs
• Because of relationship of carb intake to muscle
  liver glycogen stores to protein-sparing
  effect of high concentrations of muscle glycogen,
  high-carb diet is often recommended for athletes
• Notion that all athletes need to consume high
  amounts should be dispelled

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• Individualizing carb intake based on training
  program, sport, diet history is imperative
• Aerobic endurance athletes who train for 90 min
  should consume 8-10g/kg of body weight
• Because of amount of glycogen depleted
• Carb intake muscle glycogen levels seem to have
  little if any effect on strength performance
• Intake of 5-6g/kg of body wt. per day is
  reasonable to support training performance of
  strength, sprint, skill athletes

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Lipids

• Fat lipid are interchangeable terms
• Lipid is broader
• Lipids include triglycerides, fatty acids,
  phospholipids, cholesterol
• Majority found in foods body is triglycerides
• 2 perspectives of fat
• Fat its role in disease
• Fat its impact on performance

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• Structure function of lipids
• Contain carbon, oxygen, hydrogen atoms
• Because fatty acid chain has more carbon
  hydrogen relative to oxygen, it provides more
  energy per gram
• 9 kcal per gram
• Saturated fatty acid is related to amount of
  hydrogen it contains
• Unsaturated fatty acid, some hydrogen atoms are
  missing carbon is joined by double bonds (more
  reactive)
• Monounsaturated- one double bond
• Polyunsaturated- 2 or more double bonds

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• Saturation of fats affects their physiological
  effect
• Saturated increase blood low-density-lipoprotein
  (LDL) high-density-lipoprotein (HDL)
  cholesterol
• Monounsaturated usually do not exert effect on
  cholesterol
• Polyunsaturated tend to lower HDL LDL

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• Energy is stored primarily as adipose tissue in
  humans
• Body fat is necessary for insulation protection
  of organs hormonal regulation
• Carrier for fat-soluble vitamins A, D, E, K
  supplies essential fatty acids linoleic acid
  (omega-6) linolenic acid (omega-3)
• Essential fatty acids necessary for formation of
  cell membranes, proper development function of
  brain nervous system, production of hormones

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• Fat is responsible for flavor, aroma, texture
  of many foods
• Promotes feeling of fullness after meal
• Cholesterol (thought of as negative) is important
  structural functional component of cell
  membrane
• Necessary for production of bile salts, vitamin
  D, several hormones
• Synthesized in liver intestine

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• Fat disease
• High levels of cholesterol or unfavorable ratios
  of lipoproteins are associated with increased
  risk of heart disease
• High levels of HDL protect against heart disease
• Can be increased by exercise wt. loss
• Low-fat diet can decrease total cholesterol
  decrease ratio of total cholesterol to HDL
• 200-239 mg/dl borderline-high
• 240 mg/dl high

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• Feat requirements recommendations
• Should consume at least 3 of energy from omega-6
  0.5-1 from omega-3 fatty acids
• Negative view of fat evolved from research
  linking dietary fat to CV disease, cancer,
  diabetes, obesity
• Very few performance enhancements from
  significantly reducing fat in athletes diet
• Emphasis on low-fat or no-fat diets may be
  negative

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• When should athletes decrease dietary fat?
• Need to increase carb intake to support training
• Need to reduce total caloric intake to achieve
  wt. loss
• Achieving negative calorie balance is only way to
  reduce body fat
• Need to decrease elevated blood cholesterol

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• How much fat should athletes consume?
• 30 or less of daily calories should come from
  fat for general public
• 20 mono- or polyunsaturated
• 10 saturated
• Upper limit of fat intake of 35 for active
  people
• Diets to low in fat (15 or less of total
  calories) may decrease testosterone production,
  thus decreasing metabolism muscle development

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• Fat performance
• With low body storage of carbs, fats are vast
  source of fuel for exercise
• Both intramuscular (activity) circulating
  (recovery) fatty acids are potential energy
  sources during exercise
• During low-intensity exercise, high of energy
  from fatty acid oxidation
• Higher intensities (70-80 VO2max), gradual shift
  from fats to carbs as fuel source
• Some studies have shown an enhancement in
  performance in trained runners, but not suggested
  for every one

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Vitamins Minerals

• Vitamins- organic substances that cannot be
  synthesized by the body
• Needed in very small amounts perform specific
  metabolic functions Table 12.5
• Minerals- various types perform wide variety of
  metabolic functions Table 12.6
• Iron- necessary for oxygen transport
• Calcium- needed for bone tooth formation
  function, nerve transmission, muscle contraction

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• Dietary Reference Intakes (DRIs)
• Recommendations of Food Nutrition Board of
  National Academy of Sciences for intake of
  vitamins minerals
• Replaced Recommended Dietary Allowances

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• Dietary supplements
• If inadequate intake of vitamins minerals, then
  the use of multivitamins dietary mineral
  supplements is helpful
• Supplement use by athletes is indicated when diet
  is deficient in one or more nutrients dietary
  change is unlikely
• Placebo effect- phenomenon of a belief causing
  real physical change
• Athlete might feel certain supplement provides
  benefit stop in usage might decrease
  performance even if nothing is really gained

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• Effects on performance
• 2 ways that vitamins minerals can affect
  performance
• Athletes individual requirements are not being
  met
• Not enough in diet
• Heavy training may alter tissue concentrations of
  vitamins minerals, even if intake is adequate
• Athlete needs more because metabolically using
  more

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Fluid Electrolytes

• Water
• Largest component of body
• 45-70 of body wt.
• Affects athletic performance more than any other
  nutrient
• Proper amounts essential for normal cellular
  function thermal regulation
• Most athletes only replace 2/3 of water they
  sweat off
• Called voluntary dehydration

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• Fluid balance
• Under normal environmental conditions, achieved
  by regulation of fluid intake through changes in
  thirst regulation of loss by kidneys
• Average requirements 2-2.7 qt per day
• Replace losses from urine, insensible loss from
  skin lungs, loss in feces
• Athletes sweating profusely may need 3-4 gal extra

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• Risks of dehydration
• Unless sweat losses are replaced, body temp.
  rises, leading to heat exhaustion, heat stroke,
  even death
• Fluid loss equal to 1 of body wt. can be
  associated with elevation of core temp.
• Fluid loss of 3-5 of body wt. can result in CV
  strain impaired ability to dissipate heat
• At 7, collapse is likely
• Common to lose 2-6 during practice in heat

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• Monitoring hydration status
• Record athletes body wt.s immediately before
  after practice
• Each lb. lost represents 1 pt of fluid lost
• Must be replaced before next practice
• 5-10 lbs lost over a week could be chronic
  dehydration, not loss of fat (does not occur that
  fast)

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• Signs of dehydration
• Dark yellow, strong-smelling urine
• Normal is color of lemon juice, unless on
  supplements (bright yellow)
• Decreased frequency of urination
• Rapid resting heart rate
• Prolonged muscle soreness

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• Electrolytes
• Major ones lost in sweat are sodium, chloride,
  potassium
• Physiological adaptive mechanisms decrease
  electrolyte loss in urine sweat
• Sweat of athlete is more diluted than normal
  individual
• Sweat loss over days or low sodium intake can
  experience heat cramps from sodium depletion
• May need to eat foods high in salt or add salt to
  foods
• Potassium losses in sweat can usually be replaced
  with diet providing 2-6g per day
• Citrus fruits juices, melons, bananas,
  potatoes, meat, milk

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Fluid Replacement Guidelines

• Encourage athletes to hydrate properly before
  prolonged exercise in hot environment
• 16 fl. oz. 2 hours before workout
• During activity should drink fluid frequently
• 6-8 fl. oz. Every 15 min.
• Provide cool beverages (50-70oF)
• Have fluids readily available, since thirst does
  not function adequately when large amounts of
  water are lost
• May times need to be reminded or made to drink

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• After workout, should replenish fluids at rate at
  or exceeding 1pt for every lb. of wt. lost
• Wt. should be regained before next workout
• Water is ideal fluid replacement, flavored drinks
  may be more effective at promoting drinking
• Addition of salt to beverage or food can promote
  hydration if significant wt. has been lost
  through sweating
• Ideal fluid replacement beverage depends on
  duration intensity of exercise, environmental
  temp., athlete
• Sport drinks good if more than one game or
  workout

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Precompetition Food Consumption

• Primary purpose is to provide fluid energy
  during performance
• Most common timing recommendation is 3-4 hrs
  prior to event to avoid becoming nauseated or
  uncomfortable during competition
• Optimal timing varies greatly from athlete to
  athlete
• Eating foods that the athlete does not like at a
  time when nervous tension is high can cause
  nausea vomiting
• Athlete should eat food beverages that they
  like, are well tolerated, usually eaten, are
  believed to result in winning performance (record
  keeping)

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• Carbohydrate loading
• Technique used to enhance muscle glycogen prior
  to long-term aerobic endurance
• Most effective regimen with least side effects is
  3 days of high-carb diet in concert with tapering
  exercise week before competition complete rest
  the day before event
• Diet needs to provide adequate calories 600g of
  carbs per day, or 8-10g/kg of body wt.
• Should increase muscle glycogen stores 20-40
  above normal

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• Data indicates that it increases carbohydrate
  oxidation during submaximal exercise improves
  high-intensity, short-duration performance
• Benefit varies among individuals (trial error)
• Potential side effects are increased water
  retention, wt. gain, flatulence, diarrhea

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Postexercise Food Consumption

• Some studies suggest that high-GI foods consumed
  after exercise replenish glycogen faster than
  low-GI foods
• Carbohydrate ingestion up to 2 hrs post-exercise
  does not inhibit glycogenesis 8-24 hrs later, as
  long as adequate carbs are consumed over the day
• Athletes that train 2-3 times a day may need to
  consume carbs in form of food or supplements
  immediately after

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• One study suggests as long as adequate calories
  are consumed after exercise that it will be just
  as effective in replacing muscle glycogen
• Proper mixture of carbs, proteins, fats
• Realistically, consuming a balanced meal ensures
  availability of all substrates for adequate
  recovery, including amino acids

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Weight Body Composition

• Energy requirements
• Energy is commonly measured in kilocalories
  (kcal)
• Kilocalorie is the work or energy required to
  raise temp of 1kg of water 1o C
• of calories athlete needs depends on
• body size,
• demands of sport,
• length of training,
• training conditions,
• age
• Energy (calorie) requirement is defined as energy
  intake equal to expenditure, resulting in
  constant body wt.

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• Factors influencing energy requirements
• Wide range of energy expenditures energy
  intakes among sports due to differences in body
  mass, intensity of training, work efficiency
• Size of muscle mass involved also affects rate of
  energy use total energy used
• Large-muscle-mass RT requires greater rate of
  energy use then small-muscle-mass exercises
• In absence of dehydration, constant body wt.
  indicates calorie balance

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• Energy requirement determined by 3 factors
• Resting metabolic rate
• Thermogenesis
• Physical activity
• Each of these can be affected directly or
  indirectly by
• Age
• Genetics
• Body size
• Body composition
• Environmental temperature
• Training conditions
• Non-training physical activity
• Caloric intake
• Adolescence growing increases energy requirements

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Weight Gain

• 2 reasons why athletes attempt to gain wt.
• Improve physical appearance
• Enhance athletic performance
• For gains in the form of muscle mass strength,
  combination of diet (adequate calories protein)
  progressive RT is essential
• 350-700 kcal above daily requirements would
  supply calories needed to support 1-2 lb weekly
  gain in lean tissue as well as energy
  requirements for training

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• To accomplish increased caloric intake, an
  athlete should
• Eat larger portions of foods at mealtime
• Eat more items at each meal
• Eat frequently
• Choose higher-calorie foods
• Has been shown that it is difficult for athletes
  to gain wt. if they eat fewer than 5 times per
  day
• Use of meal replacement drinks is sometimes done
  to replace extra eating Table 12.10

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Weight Loss

• When athlete starts trying to lose wt., keep in
  mind the following facts
• Ability to achieve maintain minimal body fat is
  largely genetic
• Whether athlete can gain muscle lose body fat
  simultaneously depends primarily on their level
  of training
• Substantial amounts of body mass cannot be lost
  without losing marked amounts of lean body mass,
  particularly with calorie restriction
• 1-2 lbs or 1 of body mass is excepted amounts

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• Gradual wt. loss ensures maximum fat loss
  preservation of lean tissue
• Caloric intake of no less than 1800-2000 kcal per
  day can be starting point
• Add or subtract based on progress
• Diet should be composed of foods high in nutrient
  density (nutrients present per calorie of food)

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• Diet should be composed of food low in energy
  density (calories per wt. or volume of food)
• These foods can be eaten in larger portions
  without consuming more calories help control
  hunger
• Diet should be nutritionally balanced provide
  variety of foods
• Wt. loss is usually best achieved in off-season
  or preseason
• In-season, too busy

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Rapid Weight Loss

• Rapid loss to compete is different from gradual
• Accomplished by restricting food fluids for
  3-10 days before competition
• Usually followed by refeeding rehydration after
  weigh-in
• Athletes who attempt to lose too much can suffer
• Heat illness - Weakness
• Muscle cramping - Decreased
  concentration
• Fatigue - Even death
• Dizziness
• Proper info should be given to the athlete before
  they attempt to do this on their own