Nutritional Factors in Health and Performance

1
Nutritional Factors in Health and Performance
chapter 10
Nutritional Factorsin Health and Performance
Kristin Reimers, PhD, RD
2
How to Evaluate the Adequacy of the Diet

• Standard Nutrition Guidelines
• Food Guide Pyramid
• Used to evaluate appropriate calorie level
• Used to evaluate appropriate nutrient levels to
  prevent nutrient deficiency or toxicity
• Developed by the U.S. Department of Agriculture
  in 1992
• Updated to MyPyramid in 2005
• Standard Nutrition Guidelines
• Most athletes have two basic dietary goals
• Eating to maximize performance
• Eating for optimal body composition

3
Figure 10.1
www.mypyramid.gov
4
Key Point

• MyPyramid is an excellent starting point from
  which to evaluate the adequacy of an athletes
  diet. If a diet provides a variety of foods from
  each group, it is likely adequate for vitamins
  and minerals. However, if the diet excludes an
  entire food group, specific nutrients may be
  lacking.

5
Table 10.1
6
Macronutrients

• Protein
• Dietary Protein
• high-quality (complete) protein A protein with
  an amino acid pattern similar to that needed by
  the body. Usually of animal origin.
• low-quality (incomplete) protein A protein that
  is deficient in one or more of the essential
  amino acids. Usually of plant origin.

7
Macronutrients

• Protein
• Protein Requirements
• General Requirements
• Assuming that caloric intake is adequate and that
  two-thirds or more of the protein is from animal
  sources, the recom-mended intake for protein for
  adults is 0.8 g/kg (0.36 g/pound) of body weight
  for both men and women.
• Expressed as a percent of daily caloric intake, a
  common protein intake recommendation is 10 to
  15.

8
Key Point

• Recommendations to increase or decrease protein
  intake should be made on an indi-vidual basis
  after the normal diet has been analyzed and
  caloric intake considered. A mixed diet is the
  best source of high-quality protein. Strict
  vegetarians must plan their diet carefully to
  ensure an adequate intake of all essential amino
  acids.

9
Macronutrients

• Protein
• Protein Requirements
• Increased Requirements for Athletes
• Based on current research, it appears that the
  protein requirements for athletes are between 1.5
  and 2.0 g/kg of body weight, assuming that
  caloric intake and proteinquality are adequate.

10
Macronutrients

• Carbohydrates
• Structure and Sources of Carbohydrates
• Monosaccharides (glucose, fructose, and
  galactose) are single-sugar molecules.
• Disaccharides (sucrose, lactose, and maltose) are
  composed of two simple sugar units joined
  together.
• Polysaccharides, also known as complex
  carbohydrates, contain up to thousands of glucose
  units.

11
Macronutrients

• Carbohydrates
• Dietary Carbohydrate
• All types of dietary carbohydratesugars as well
  as starchesare effective in supplying the
  athlete with glucose and glycogen.
• Consumption of a mix of sugars and starches is
  desirable.
• The primary role of carbohydrate in human
  physiology is to serve as an energy source.
• Carbohydrates provide 4 kcal/g.

12
Macronutrients

• Carbohydrates
• Glycemic Index
• The GI classifies a food by how high and for how
  long it raises blood glucose.
• The reference food is glucose or white bread (GI
  100).
• Foods that are digested quickly and raise blood
  glucose (and insulin) rapidly have a high GI.
• Foods that take longer to digest and thus slowly
  increase blood glucose (and therefore stimulate
  less insulin) have a low GI.

13
Table 10.3
Adapted, by permission, from Foster-Powell, Holt,
and Brand-Miller, 2002.
14
Macronutrients

• Carbohydrates
• Fiber
• The DRI for fiber is 38 and 25 g/day for young
  men and women, respectively.
• This level of fiber may be excessive for some
  aerobic endurance athletes.
• Carbohydrate Requirements
• The general recommendation is to consume 50 to
  55 of total daily calories as carbohydrate.
• Aerobic endurance athletes who train for long
  durations (90 minutes or more daily) should
  replenish glycogen levels by consuming maximal
  levels of carbohydrate, approxi-mately 8 to 10
  g/kg of body weight.

15
Key Point

• Some aerobic endurance athletes have maximal
  carbohydrate requirements, up to 10 g/kg per day.
  Most athletes do not deplete muscle glycogen on a
  daily basis, however, and therefore have lower
  carbo-hydrate requirements.

16
Macronutrients

• Lipids
• Structure and Function of Lipids
• Fatty acids containing no double bonds are
  saturated.
• Fatty acids containing one double bond are
  mono-unsaturated.
• Fatty acids containing two or more double bonds
  are polyunsaturated.
• Fats provide approximately 9 kcal/g.

17
Macronutrients

• Lipids
• Fat Requirements and Recommendations
• The recommendation for the general public from
  health organizations such as the American Heart
  Association is that fat should constitute 30 or
  less of the total calories consumed.
• It is recommended that 20 of the total calories
  (or two-thirds of the total fat intake) come from
  monounsaturated or polyunsaturated sources and
  10 from saturated fats (one-third of total fat
  intake).

18
Key Point

• Fat phobia, or fear of eating fat, can leadto
  nutrient deficiencies, which harm performance.
  Athletes who eat very littleor no fat should
  receive nutritional coun-seling and information.

19
Fluid and Electrolytes

• Water
• Water is the largest component of the body,
  representing from 45 to 70 of a persons body
  weight.
• Total body water is determined largely by body
  composition muscle tissue is approximately 75
  water, whereas fat tissue is about 20 water.

20
Fluid and Electrolytes

• Water
• Fluid Balance
• The average fluid requirement for adults is
  estimated to be 2 to 2.7 quarts (1.9-2.6 L) per
  day.
• Athletes sweating profusely for several hours per
  day may need to consume an extra 3 to 4 gallons
  (11-15 L) of fluidto replace losses.

21
Fluid and Electrolytes

• Water
• Risks of Dehydration
• Fluid loss equal to as little as 1 of total body
  weight can be associated with an elevation in
  core temperature during exercise.
• Fluid loss of 3 to 5 of body weight results in
  cardio-vascular strain and impaired ability to
  dissipate heat.
• At 7 loss, collapse is likely.

22
Fluid and Electrolytes

• Water
• Monitoring Hydration Status
• Each pound (0.45 kg) lost during practice
  represents1 pint (0.5 L) of fluid loss.
• Signs of dehydration include the following
• Dark yellow, strong-smelling urine
• Decreased frequency of urination
• Rapid resting heart rate
• Prolonged muscle soreness

23
Precompetition and Postexercise Nutrition

• Precompetition Food Consumption
• Purpose
• The primary purpose is to provide fluid and
  energy for the athlete during the performance.
• Timing
• The most common recommendation is to eat 3 to 4
  hours prior to the event to avoid becoming
  nauseated or uncom-fortable during competition.

24
Precompetition andPostexercise Nutrition

• Precompetition Food Consumption
• Practical Considerations
• It is important for athletes to consume food and
  beverages that they like, that they tolerate
  well, that they are used to consuming, and that
  they believe result in a winning performance.

25
Precompetition andPostexercise Nutrition

• Postexercise Food Consumption
• Data suggest that high-GI foods consumed after
  exercise replenish glycogen faster than low-GI
  foods.
• Although emphasis is usually placed on
  carbo-hydrate, in practical terms, consuming a
  balanced meal ensures the availability of all
  substrates for adequate recovery, including amino
  acids.

26
Table 10.7
27
Weight and Body Composition

• Weight Gain
• If all the extra calories consumed are used for
  muscle growth during resistance training,
  thenabout 2,500 extra kilocalories are required
  foreach 1-pound (0.45 kg) increase in lean
  tissue.

28
Weight and Body Composition

• Weight Loss
• If all the expended or dietary-restricted
  kilocalories apply to body fat loss, then a
  deficit of 3,500 kcal will result in a 1-pound
  (0.45 kg) fat loss.
• The maximal rate of fat loss appears to be
  approx-imately 1 of body mass per week.
• This is an average of 1.1 to 2.2 pounds (0.5-1.0
  kg) per week and represents a daily caloric
  deficit of approximately 500 to 1,000 kcal.

29
Key Point

• The most important goal for weight loss is to
  achieve a negative calorie balance. Therefore,
  the types of foods the individual consumes are
  less important than the portions of those foods.
  The focus is on calories.