Transcript General considerations for the physically active individual

General Considerations For The
Physically Active Individual:
Chapter 7
Presented by: Professor Steven Dion
Salem State College
Sport, Fitness & Leisure Studies Department
The Food Guide Pyramid: A
Model for Good Nutrition
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Research in nutrition, cancer, and heart disease has shown
that the Four Food Group plan developed by the USDA
had an overemphasis on meat and poultry. This led to the
development of the food guide pyramid.
The food guide pyramid is a guideline for people age two
years and older. It categorizes foods according to their
nutrient contributions and recommends serving sizes for
each category.
Diverse grains, vegetables, and fruits should make up a
major source of calories in the diet.
Animal proteins, lipids, and dairy products should make
up the least calories in the diet.
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Personal Assessment
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Determining energy and nutrient intake by
recording daily food intake provides a very
close estimate of the adequacy of ones diet
related to recommended guidelines for
active men and women.
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The Quality of the Diet
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The Diet Quality index shows a person how healthy their
diet is. It gives a score based on a composite of the eight
food and nutrition based recommendations of the
National Academy of Sciences.
People who meet a given dietary goal receive a score of
0; they receive a 1 if their intake falls within 30% of the
dietary goal; the score becomes 2 when intake fails to
fall within 30% of the goal.
The eight categories are totaled with a score ranging
from 0-16; a score of 4 or less reflects a healthy diet; 10
or higher reflects a less healthy diet that needs
improvement.
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Macronutrient Needs for the
Physically Active
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Research indicates that physically active
men and women do not require additional
nutrients beyond those obtained through
eating a nutritionally well balanced diet.
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What the Physically Active Eat
They eat the same things as inactive people.
Athletes eat more of the same foods
consuming a larger total quantity of food to
support the extra energy used for training.
 Physically active people must maintain
adequate energy and protein intake, and an
appropriate level of carbohydrates to match
the use for energy during training.
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Proteins
The RDA for protein intake is .8 grams per
kilogram of body mass.
 The protein intake in the average American
diet exceeds the RDA and the competitive
athletes diet usually contains 2-4 times
more protein than the RDA.
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Is the RDA Really Enough?
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For men and woman who train for long periods of time
with resistance equipment dietary protein represents the
most important of the macronutrients.
Resistance training damages a muscle structure; this drain
on the body’s protein requires addition dietary protein
above the RDA to promote tissue re-synthesis.
Athletes also believe that training increases protein
catabolism to sustain the energy requirements of exercise
and that added protein offsets this energy drain.
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Is the RDA Really Enough?
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Some modification required for recommended protein
intake
Eating a high carbohydrate diet with adequate energy
intake conserves muscle protein in athletes who
engage in hard training.
Protein breakdown above the resting level does occur
to a degree greater than previously thought during
endurance and resistance training. It occurs more
when exercising with a low carbohydrate intake.
Athletes in heavy training especially aerobic training
should consume 1.2 and 1.8 grams of protein per
kilogram of body mass daily.
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Preparations of Simple Amino Acids
Some people believe that the body absorbs
simple amino acids more rapidly than protein,
but this is not true, it absorbs complex amino
acids just as rapidly.
 Research has not shown that amino acid
supplementation above the RDA significantly
increases muscle mass or improves strength,
power, or endurance.
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Lipids
Lipid intake should not exceed 30% of the
diets energy intake content, of this 70%
should come from unsaturated fatty acids.
 Low fat diets make it hard to furnish
sufficient energy to maintain body weight
and muscle mass and could lead to
malnutrition during strenuous exercise.
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Carbohydrates
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A low carbohydrate diet compromises energy reserves
and causes an individual to train in a state of relative
glycogen depletion, which may eventually slow down
performance.
Evidence suggests that eating a variety of fiber rich
complex carbohydrates (provided the intake is adequate
for the essential amino acids, fatty acids, minerals, and
vitamins) doesn’t negatively affect your health.
Physically active people should consume at least 50-60%
of calories as carbohydrates.
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A More Specific Recommendation
A diet low in total fat may not allow an athlete in
heavy training to match energy output with
energy intake. A diet with 20% total fat resulted
in poorer performance than a diet containing
42% total fat.
 Athletes undergoing heavy endurance training
should consume on a daily basis 10 grams of
carbohydrates per kilogram of body mass.
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Carbohydrate’s Possible Role in the
“Overtraining” Syndrome
A gradual depletion of the body’s
carbohydrate reserves with repeated
strenuous training can contribute to the
overtraining syndrome.
 When the body runs out of carbohydrates
for energy it converts fat to energy
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Glycogen Takes Time to Replenish
It takes at least 24 hours to replenish muscle
glycogen levels after exhaustive exercise.
 At least 1-2 days of rest or lighter exercise
combined with a high carbohydrate intake
must be provided to reestablish the preexercise glycogen levels after exhaustive
training.
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The Coach’s And Athlete’s Dilemma about
Vitamin Supplementation
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Vitamin-mineral pills are the most commonly marketed
and used nutritional supplement by the public
(accounting for 70-90%)
Marketing targets are exercise fanatics, the athlete, and
those who coach the athlete
More than 50% of athletes consume supplements
regularly to enhance performance
Vitamin deficiencies tend to occur among vegetarian
athletes and athletes with low energy intake
Vitamin supplements can reverse symptoms of vitamin
deficiency and improve performance
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Vitamin Supplements:
The Competitive Edge?
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40 plus years of research does not confirm that
using vitamin supplements will enhance exercise
performance
Coaches, athletes, and fitness enthusiasts feel
“more is better” and believe in using vitamin
supplements above recommended levels
Supplementing with vitamin C had negligible
effects on endurance performance and did not alter
the rate, severity, or duration of injuries
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Vitamin Supplements:
The Competitive Edge?
No scientific data proves that vitamin E
benefits circulatory functions, stamina, or
energy metabolism
 Vitamin mineral supplementation for
healthy individuals does not benefit fitness,
athletic performance, or muscular strength
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Perhaps a Benefit from
Vitamin C
C intake above recommended levels doesn’t
protect the general population against upper
respiratory tract infections (URTI)
 Supplementing with C may benefit those who
engage in heavy exercise and have problems
with URTI
 Carbohydrate ingestion and additional vitamin
C and E before and after strenuous exercise will
boost immune mechanisms and fight infection
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Megavitamins
Active individuals eating well-balanced
meals do not need to take additional
vitamins
 Nutritionists feel that harm occurs in taking
multivitamin capsules.
 Those who try to “supercharge” by taking
vitamins for performance are potentially
causing harm to the body
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Vitamins Behave as Chemicals
Excess vitamins taken in megadose function as
chemicals (drugs) in the body
 Megadose of vitamin C can cause kidney stone
formation
 Some blacks, Asians, Sephardic Jews have a
genetic deficiency that becomes activated to
anemia with an excessive amount of C intake
 In healthy people Vitamin C may irritate bowels
and cause diarrhea
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Vitamins Behave as Chemicals
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Excessive B6 may induce nerve damage and liver disease
Excessive B2 can impair vision
Excessive amounts of Vitamin A are toxic to the nervous
system
Taking vitamin D in excess may damage the kidneys
30% of Americans use vitamin supplements in toxic
dosages
“Sale of vitamins is probably the biggest rip-off in our
society”
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Exercise, Free Radicals, and Antioxidants:
The Potentially Protective
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Micronutrients For Physically Active People
The possibility for negative effects from physical
activity has recently been addressed
Negative effects may occur because in exercise when
aerobic metabolism is elevated the production of free
radicals increases
Increased free radicals will overwhelm the body’s
natural defenses and potentially pose a health risk for
increased levels of oxidative stress
Free radicals have also been found to cause injury from
exercise
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Increased Metabolism and Free Radical
Production
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Exercise produces free radicals in two ways: through an
electron leak in the mitochondria and during alterations
in blood flow and oxygen supply·
Intense exercise followed by recovery can trigger free
radical generation
Free radical damage can also increase during trauma,
muscle damage, stress, and by environmental pollution
During exercise the risk of free radicals depends on the
intensity of the exercise and the state of training
Research says that for well nourished people the body’s
naturals defenses respond to increased physical activity
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A Prudent Recommendation
Consume a well-balanced diet containing fruits,
vegetables, and grains
 Nutrient antioxidants should be obtained from
different foods not from supplements
 Studies show that people who consume more
fruits and vegetables are less likely to contact
cancer
 Dietary Guidelines recommend 3-5 servings of
vegetables and 2-4 servings of fruits daily
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A Prudent Recommendation
Three potential mechanisms for antioxidant
health benefits include:
 (1) influence on molecular mechanisms and
gene expression
 (2) block uncontrolled growth cells, or
 (3) provide enzyme-inducing substances
that detoxify carcinogens
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MINERALS AND EXERCISE
PERFORMANCE
Mineral Loss in Sweat
 Mineral loss of mineral salt and water poses
a challenge in long exercise sessions in hot
weather
 Loss of water and electrolytes can lead to
cramps, heat exhaustion, and even stroke
 It is crucial to replace water lost through
sweating
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Defense Against Mineral Loss
Vigorous exercise triggers a rapid release of
the hormones renin, vasopressin, and
aldosterone to minimize the loss of sodium
and water through the kidneys
 Drinking an 8 oz glass of tomato or orange
juice replaces the potassium, calcium, and
magnesium lost through sweat
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Trace Minerals and Exercise
Strenuous exercise can increase excretion of
trace elements chromium which is
necessary for fat
 Women and men who engage in heavy
training should monitor mineral intake to
prevent deficiency
 For the most part trace mineral deficiency
doesn’t pose a problem
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Extremes of Physical Inactivity
Present a Different Picture
Bed rest depletes trace minerals such as
copper and zinc
 One half of the body’s zinc and copper are
constituents of the muscle and bone mass;
bed rest could drain these minerals from the
body
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Exercise Activity Makes a Difference
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Physical Activity Makes a Difference
Individuals who regularly engage in moderate to intense
physical activity eventually increase daily energy intake to
match the higher level of daily energy expenditure.
The body requires several days to attain new energy
equilibrium when balancing food intake to meet a new
level of energy output.
The lack of precision in regulating food intake at low end
of the physical activity spectrum probably accounts for the
“creeping obesity”.
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High – Risk Sports for Marginal Nutrition
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Gymnasts, dancers, ice dancers and weight-class athletes
engage in arduous training.
Due to the nature of their sport, these men and women
strive to maintain a lean, light body mass.
Energy intake often intentionally falls short of energy
expenditure and a relative state of malnutrition
develops.
Nutritional supplementation could be beneficial.
Training and competition often take place in the
carbohydrates-depleted state
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Eat More, Weigh Less
Men and women who ate considerably more on a
daily basis weighed less than those who
exercised at a lower total caloric expenditure.
 There is a strong argument that regular exercise
provides an effective means for a person to eat
more and weigh less, maintaining a lower
percentage of body fat.
 Active people maintain a lighter and leaner body
and a healthier heart disease risk profile.
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The Pre-competition Meal
Athletes often compete in the morning
following an overnight fast.
 Depletion occurs in the body’s carbohydrate
reserves over an 8 to 12 hour period without
eating.
 Pre-competition meal provides the athlete
with adequate carbohydrate energy and
ensures optimal hydration.
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The Pre-competition Meal
Fasting before competition or training
rapidly depletes liver and muscle glycogen,
and impairs exercise performance.
 Food high in lipid and protein content
should be eliminated from diet on the day of
competition.
 Three hours is sufficient time to digest and
absorb a Carbohydrate-rich pre-competition
meal.
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Protein or Carbohydrate?
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Dietary carbohydrates replenish the significant
depletion of liver and muscle glycogen from
overnight fasting.
Carbohydrates become digested and absorbed more
rapidly than either proteins or lipids. Carbohydrates
provide energy faster and reduce the feeling of
fullness.
A high protein meal elevates resting metabolism more
than a high carbohydrate meal due to greater energy
requirements for digestion, absorption, and
assimilation.
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Protein or Carbohydrate?
Protein breakdown for energy facilitates
dehydration during exercise because the
products of amino acids breakdown require
water for urinary excretion.
 Carbohydrates serves as the main energy
nutrient for short-term anaerobic activity as
well as prolonged high-intensity endurance
exercise.
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Make It Carbohydrate Rich
The ideal pre-competition meal maximizes
muscle and liver glycogen storage and
provides glucose for intestinal absorption
during exercise.
 The meal should contain 150 to 300g of
carbohydrate (3 to 5g per kg of the body
mass in either solid or liquid).
 Meals should be consumed within 3 to 4
hours before exercising.
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Liquid and Prepackaged Meals
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Liquid meals provide high carbohydrate content but
contain enough lipid and protein to contribute to satiety.
Liquid meal digests rapidly, leaving essentially no
residue in the intestinal tract.
Liquid meals digest rapidly leaving essentially no
residue in the intestinal tract.
Liquid meals provide an approach to supplement caloric
intake during high-energy output phase of training.
Athletes can use liquid nutrition if they have a difficult
time maintaining a relatively large body mass, and as a
ready source of calories to gain weight.
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