Transcript 2005 Guidelines

Chapter 9 - Nutrition and Performance
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Principles of
Sports Nutrition
• Prudent diet is the cornerstone
• Increase total energy intake
• Keep dietary carbohydrate intake
high (55-70%)
• Drink large amounts of fluid
• Keep a close watch on iron
deficiency
• Vitamin & mineral supplements
are not needed
• Protein supplements do not benefit
• Rest and emphasize carbohydrates
prior to endurance events
• Use of ergogenic aids is unethical
• Fat loading is not recommended
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>1 hour/day exercise changes
• Increase energy intake
• Increase grams per kilogram of body weight
coming from carbohydrate
• Increase fluid intake
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Nutrition Basics
• Six groups of essential nutrients (see text and
Table 9.1)
–
–
–
–
Carbohydrates – 55%
Fats – 30%
Proteins – 15%
Vitamins – Fat soluble, Water
soluble
– Minerals
– Water – 60% of the body’s weight. 8 cups of water
or other liquids per day
– Alcohol – 7 kcals/gm
• RDA/DRI --- see Table 9.1
FOOD AS ENERGY
• Kilocalorie – unit of heat
– 14.5 to 15.5 degrees celsius
• 1600-2500 calories per day
• We poor Americans
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Year 2005---Dietary Guidelines for Americans
•
•
•
•
•
•
•
1.
2.
3.
4.
5.
6.
7.
WEIGHT MANAGEMENT
PHYSICAL ACTIVITY
FOOD GROUPS TO ENCOURAGE
CARBOHYDRATES
FOOD SAFETY
FATS
ADEQUATE NUTRIENTS WITHIN
CALORIE NEEDS
• 8. SODIUM AND POTASSIUM
• 9. ALCOHOLIC BEVERAGES
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2005---USDA Dietary Guidelines
• WEIGHT MANAGEMENT;
PHYSICAL ACTIVITY
Key Recommendations
• To maintain body weight in a healthy
range, balance calories from foods
and beverages with calories
expended.
• To prevent gradual weight gain over
time, make small decreases in food
and beverage calories and increase
physical activity.
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2005 Guidelines:
WEIGHT MANAGEMENT; PHYSICAL ACTIVITY (cont)
• Engage in regular physical activity and reduce sedentary activities to
promote health, psychological well-being, and a healthy body weight.
– To reduce the risk of chronic disease in adulthood: Engage in at
least 30
minutes of moderate-intensity physical activity, above usual activity, at work
or home on most days of the week.
– For most people, greater health benefits can be obtained by engaging in
physical activity of more vigorous intensity or longer duration.
– To help manage body weight and prevent gradual, unhealthy body weight
gain in adulthood: Engage in approximately 60 minutes of
moderate- to vigorous-intensity activity on most days of the week while not
exceeding caloric intake requirements.
– To sustain weight loss in adulthood: Participate in at
least 60 to 90
minutes of daily moderate-intensity physical activity while not exceeding
caloric intake requirements. Some people may need to consult with a healthcare
provider before participating in this level of activity.
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*2005 Guidelines:
FOOD GROUPS TO ENCOURAGE
• Consume a variety of fruits and vegetables (2 cups fruit, 2 ½ cups
vegetables per day for a 2,000-calorie intake (higher or lower
depending on the calorie level).
• In particular, select from all 5 vegetable subgroups (dark green,
orange, legumes, starchy vegetables, and other vegetables) several
times a week.
• Consume 3 or more ounce-equivalents of whole-grain products per
day, with the rest of the recommended grains coming from enriched or
whole-grain products (at least half the grains should come from whole
grains).
• Consume 3 cups per day of fat-free or low-fat milk or equivalent milk
products.
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*2005 Guidelines:
FOOD GROUPS TO ENCOURAGE
(cont.)
• The MyPyramid Food Guidance System provides food-based
guidance to help implement the recommendations of the Guidelines.
Taken together, they would result in the following changes from a
typical diet (Figure 9.1, Box 9.3):
– Increased intake of vitamins, minerals, dietary fiber, and other essential
nutrients, especially of those that are often low in typical diets.
– Lowered intake of saturated fats, trans fats, and cholesterol and increased intake
of fruits, vegetables, and whole grains to decrease risk for some chronic
diseases.
– Calorie intake balanced with energy needs to prevent weight gain and/or
promote a healthy weight.
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Physical activity
oils
fruits
milk
vegetables
meat
and
beans
Grains
Visit www.mypyramid.gov for details (and to
choose your food intake plan).
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*2005 Guidelines:
CARBOHYDRATES
• Choose fiber-rich fruits, vegetables, and
whole grains often (Table 9.3).
• Choose and prepare foods and beverages
with little added sugars or caloric
sweeteners, such as amounts suggested by
the USDA MyPyramid and the DASH
Eating Plan (see Chapter 10).
• Reduce the incidence of dental caries by
practicing good oral hygiene and
consuming sugar- and starch-containing
foods and beverages less frequently.
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2005 Guidelines:
CARBOHYDRATES (cont.)
• Carbohydrates are part of a
healthful diet. Choose fiberrich fruits, vegetables, and
whole grains often (Table
9.3).
• The recommended intake of
carbohydrates is 45 to 65%
of total Calories.
• For an individual eating
2,000 calories a day, this
would be 900-1,300
Calories or 225-325 grams
of carbohydrate (divide by
4, the number of Calories
per gram of carbohydrate).
Protein
35
10
20
Carbohydrate
35
Fat
0
10
20
65
45
30
40
50
60
Percent of Total Energy Intake
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70
2005 Guidelines:
CARBOHYDRATES (cont.)
• As mapped out by MyPyramid, more servings of grain
products should be consumed at each meal than any other
type of food, followed by fruits and vegetables.
• Although dietary fiber provides no energy, it has many
beneficial actions in the body and promotes a low risk of
colon cancer, heart disease, and diabetes.
• There are two kinds of dietary fiber: soluble fiber which is
soluble in water and forms a gel, and insoluble fiber which
is insoluble in water.
• Soluble fiber is found in many fruits and vegetables, and in
some grains like oats. Insoluble fiber is found in many
vegetables and whole grains (e.g., wheat bran).
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*The Food Label
(Figure 9.3)
• In 1990, the FDA approved a procedure for
nutrition labeling of processed foods and
authorized appropriate health claims.
• The food label focuses on the shortcomings
of Americans, total fat, saturated fat,
cholesterol, sodium, dietary fiber, and
sugars.
• The Nutrition Facts food label uses the
Daily Values to help consumers plan
healthy diets.
• The Daily Values are based on a 2,000
calorie diet. A Daily Value of 20% for total
fat means that a serving of this particular
food provides 20% of the total fat allowed
for the average adult.
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*2005 Guidelines:
FOOD SAFETY
• To avoid microbial foodborne illness:
– Clean hands, food contact surfaces, and fruits and vegetables.
Meat and poultry should not be washed or rinsed.
– Separate raw, cooked, and ready-to-eat foods while shopping,
preparing, or storing foods.
– Cook foods to a safe temperature to kill microorganisms.
– Chill (refrigerate) perishable food promptly and defrost foods
properly.
– Avoid raw (unpasteurized) milk or any products made from
unpasteurized milk, raw or partially cooked eggs or foods
containing raw eggs, raw or undercooked meat and poultry,
unpasteurized juices, and raw sprouts.
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2005 Guidelines: FATS
• Consume less than 10% calories from saturated fatty acids
and less than 300 mg/day of cholesterol, and keep trans
fatty acid consumption as low as possible.
• Keep total fat intake between 20 to 35% of calories, with
most fats coming from sources of polyunsaturated and
monounsaturated fatty acids, such as fish, nuts, and
vegetable oils.
• When selecting and preparing meat, poultry, dry beans, and
milk or milk products, make choices that are lean, low-fat,
or fat-free.
• Limit intake of fats and oils high in saturated and/or trans
fatty acids, and choose products low in such fats and oils
(see Figure 9.4).
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*2005 Guidelines:
ADEQUATE NUTRIENTS WITHIN
CALORIE NEEDS
• Consume a variety of nutrient-dense foods and beverages
within and among the basic food groups while choosing
foods that limit the intake of saturated and trans fats,
cholesterol, added sugars, salt, and alcohol.
• Meet recommended intakes within energy needs by
adopting a balanced eating pattern, such as the USDA Food
Guide or the DASH Eating Plan.
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SALT
2005 Guidelines:
SODIUM AND POTASSIUM
• Consume less than 2,300 mg (approximately 1 tsp of salt) of
sodium per day.
• Choose and prepare foods with little salt. At the same time,
consume potassium-rich foods, such as fruits and vegetables
(see Table 9.4).
• Individuals with hypertension, blacks, and middle-aged and
older adults. Aim to consume no more than 1,500 mg of
sodium per day, and meet the potassium recommendation
(4,700 mg/day) with food.
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2005 Guidelines: ALCOHOLIC
BEVERAGES
• Those who choose to drink alcoholic beverages should do so
sensibly and in moderation—defined as the consumption of up
to one drink per day for women and up to two drinks per day for
men.
• Alcoholic beverages should not be consumed by some
individuals, including those who cannot restrict their alcohol
intake, women of childbearing age who may become pregnant,
pregnant and lactating women, children and adolescents,
individuals taking medications that can interact with alcohol, and
those with specific medical conditions.
• Alcoholic beverages should be avoided by individuals engaging
in activities that require attention, skill, or coordination, such as
driving or operating machinery. (See Table 9.5, page 302).
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Principle 1: Prudent Diet Is the Cornerstone
(Table 9.7): Dietary Practices of Athletes
• Athletes tend to have high energy intakes
(dependent on size and sport energy demands).
(See Table 9.6).
• Diet quality is similar to that of general population
(too high in fat, low in carb), falling short of
standards established for athletes.
• Vitamin and mineral intake generally exceeds RDA
standards, primarily because of high energy intake.
• Athletes at risk of nutrient deficiency: sports that
emphasize leanness (gymnasts, wrestlers, ballet
dancers, body builders, female runners). See Box
9.4 for recommendations for wrestlers.
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Notes on Athletes
• Studies support the idea that sports training
does not have a negative effect on
nutritional status of athletes. Performance
is not decreased and nutrients are adequate
for what is necessary. In short, supplements
are not needed.
• Athletes will consume more calories per kg
of body weight.
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Principle 2: Increase Total Energy Intake
• Athletes are capable of amazingly high levels of energy
output (see Figure 9.5).
– In UK 24-h cycling time trial in a lab, one cyclist expended
20,166 kcal
• Athletes are high energy expenders for two reasons:
– High working capacities
– Ability to work at a high % of maximal capacity (70-90%)
• Expended in short period of time
– High glycogen depletion
– High sweat rates
– Muscle and GI trauma
• Energy and ATP Production (Figures 9.6, 9.7, 9.8) later
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• Table 9.4
Nutritional needs for athletes
• Higher carbohydrate needs (utilization of
glycogen)
• High water needs (high sweat rates)
• Protein and iron needs may increase
(musculoskeletal trauma)
• Iron balance (GI disturbance)
Tips for Refueling - Protein Needs
• Sedentary
0.8g/kg
• Fitness Enthusiast
1 g/kg
• Elite Endurance Athlete 1.2 - 1.4 g/kg
– Fuel
– Muscle Repair
• Elite Strength Athlete
– Muscle Repair
– Accretion of Lean Mass
1.4 – 2.0 g/kg
Energy and ATP Production
• ATP (small amount stored in muscles)
– Constantly replinished.
• ATP-PC or _________.
– Time ____.
– Activities?
• Lactate Pathway or AKA ________.
– Time ____.
– Activities?
• ATP produces at a high rate from glycogen via
glycolysis. LA byproduct that causes fatigue.
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Energy and ATP Production
• Oxygen system or ________.
– Time ________.
– Activities?
•
•
•
•
•
Stores of fatty acids and CHO
ATP produced at a slower rate than LA path
Mitochondrial respiration
O2 is the limiting factor
Longer distances this pathway is the main provider
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Figure 9.7, page 308
Aerobic and anaerobic systems work together. Fat and CHO are the primary fuel sources of
endurance exercise.
Fat stores = 140,000 calories
CHO = 1,450
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Factors That Influence Fuel Utilization
Intensity and duration of exercise
% carb usage greater during high intensity exercise,
with fat usage increasing as duration increases (Tables
9.8, 9.9; Figures 9.9, 9.10).
 Fitness status
At any given workload, fit people use a greater %fat for
fuel, sparing glycogen (Figure 9.11).
 Previous diet
If pre-event meal is high in carb, relatively more is
stored and available, increasing exercise time (Figure
9.12).
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Figure 9.11 – Relationship between intensity of exercise and fitness status
and use of glycogen
Increased glycogen used with an increase in intensity. Increased fitness levels spare glycogen and use fat as a
fuel source.
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Fig 9.9: Fuel Utilization during 1 mile run at 70% VO2max
Gradual utilization of fat as a fuel source to produce ATP
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Principle 3: Increase intake of carbohydrate (55-70%)
• Glycogen found to play important role in
intense exercise (70-85%) (e.g., running,
cycling, soccer) (Figures 9.11 and Table
9.9).
• Endurance training leads to a higher level
of stored carbohydrate and a greater
utilization of fat (Table 9.8, Figure 9.11).
• Exhaustion is tied to low muscle glycogen
levels and is limiting in bouts lasting
longer than 60-90 minutes (Figure 9.14).
• When muscle and liver glycogen is low, a
high work output cannot be maintained.
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Principle 3: Carbohydrate (cont.)
• During the first hour, most of the carb and fat
come from within the muscle (Figures 9.10,
9.15). As exercise continues, more and more
demands are placed on fat stores and blood
glucose.
• During strenuous training, muscle glycogen
stores undergo rapid day-to-day fluctuation
(Figures 9.16, 9.17). 70% CHO diet required.
• Ingest 8-10 g/kg carbohydrate soon after longterm exercise to restore glycogen quickly (and
consider high-glycemic-index foods (Figure
9.18, Box 9.5).
• High Glycemic Index foods (such as simple
carbohydrates) will increase the body’s sugar
levels rapidly. See Box 9.5, page 313 for GI.
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Figure 9.16, page 312
Low-carbohydrate diet leads to muscle glycogen depletion. Each successive 2 hour workout the next days leads to
decreased performance and the exercise feels harder than normal.
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- Refueling - Post Exercise
Replacement of Glycogen Stores
• High glycemic index – bread, potatoes, fruit
– Low in fiber
– No fructose
• Beginning 15 min postexercise
• Repeat every 2 hr if you did not eat a meal
• Protein 40% of CHO dose (?)
Principle 4: Increase Fluid Intake
• As the muscle burns fuel, 70-80% is transformed into heat
(body heat can rise 1°C/5 min, causing death in 20-30 min).
• During exercise, sweat evaporation accounts for >80% of
heat loss (1 liter of sweat evaporation on the skin removes
600 kcal heat) (Figures 9.19, 9.20).
• Sweat losses can range from 0.5-3.7 Liter/hr of exercise,
depending on the workrate and environmental conditions
(Figure 9.21).
• Loss of >2% body water impairs performance due to
decreased endurance capacity, increased core temperature
and decreased cardiac output. (see Table 9.12, Figure 9.22).
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Components of Body Water
•
•
•
•
•
60% of Body Weight
Intracellular fluid (67%)
Interstitial fluid (27%)
Plasma Volume (6%)
Loss of >2% body water impairs
performance due to decreased
endurance capacity, increased
core temperature, increased heart
rate and decreased cardiac output.
Early Warning Signs: clumsiness,
stumbling, excessive sweat,
cessation of sweating, headache,
nausea, or dizziness
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Core Temperature Responses
to Exercise of Different Intensities
Primary method the body cools itself is sweating. Other methods are convection, radiation,
conduction, and respiration.
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Importance of Evaporation As Heat-Loss Mechanism
in High Environmental Temperatures
Importance of Evaporation As Heat-Loss
Mechanism in Heavy Exercise
•
"Convection
When wind blows against the skin, it helps speed up the processes of evaporation, making the person feel much colder
(often known as the wind chill factor).
Conduction
Heat may be lost through contact with surfaces at a lower temperature than that of the body.
Radiation
Heat is lost through radiation from all over the body.
Evaporation
Heat is lost through the body's natural cooling system (perspiration) which evaporates from the skin.
•
Respiration
The only other way in which heat is lost is through respiration (breathing).
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Hydration
• 2 cups of water immediately prior to exercise
• 1 cup every 15 mins
• Postexercise – water replacement
– Drink 2 cup/lb lost
– Drink 3 cup/lb if exercise again same day
• Heat – electrolytes + water
• Endurance exercise >1.0 hr
– CHO supplements to maintain
glucose levels and delay fatigue
(GU, Gatorade, bars, etc.)
– 30-60 gms/hr of CHO
– 0.5-0.7 gms/L of water of sodium
Figure 9.21, Page 317
Sweat rates are affected by running pace
and weather conditions.
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Box 9.6 ACSM Position Stand on
Exercise & Fluid Replacement
• Emphasize fluid intake before exercise by drinking adequate
fluids during the day before the event, and drink about 500
ml 2 hours before exercise.
– Urine should be light-colored, good volume, no strong smell.
• Athletes should start drinking early and at regular intervals
during exercise to replace nearly all the water lost from
sweating.
–
–
–
–
2% drop in body wt from fluid impairs exercise
0.5-2 cups fluid / 10-15 min of exercise
2 cups / pound of weight loss
Gastric emptying is promoted by >600 ml gastric volume
(maintain largest fluid volume in stomach that is tolerable)
– Fluids should be sweetened (6-8% carb), flavored, and cooled to
stimulate intake.
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ACSM Position Stand on Exercise & Fluid Replacement (cont.)
• If the event is longer than 1 hour, carbohydrates and
electrolytes should be included in fluids ingested (F 9.24).
– Peformance enhanced (fatigue delayed) (Figures 9.25, 9.26)
– Water delivery to body not impaired
– Enhance palatability
• Carbohydrates should be ingested at a rate of 30-60 g/hr
(0.6-1.2 lof most sports drinks with 4-8% carb) (T 9.13).
– The carbohydrates can be glucose, sucrose, or maltodextrin
(fructose can cause GI distress)
• Inclusion of sodium (0.5-0.7 g/l water) enhances
palatability, promotes fluid retention (less urination), and
helps prevent hyponatremia in certain athletes who drink
excessive plain water during ultra events
– 1 liter sweat has 0.4-1 g sodium
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Figure
9.25
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Acclimatization
• Takes 5-10 days
• Increased plasma volume (400-700 ml)
• Increased sweat earlier in exercise with less
loss of sodium
• Heart rate and body temperature are lower
for a given workload.
• Slow progression is ideal
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Principle 5: Watch for Iron Deficiency
• In the human body, iron is present in all cells and has
several vital functions. Too little iron can interfere with
these vital functions and lead to morbidity and mortality.
Iron has these functions:
– carrier of oxygen to the tissues from the lungs in the form of
hemoglobin
– facilitator of oxygen use and storage in the muscles as myoglobin
– transport medium for electrons within the cells in the form of
cytochromes
– integral part of enzyme reactions in various tissues.
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Principle 5: Watch for Iron Deficiency
• 10-80% female athletes (depending on sport and study
design) have mild iron deficiency (serum ferritin <12 g/l).
Reasons:
– Inadequate dietary iron
– Increased hemolysis (trauma, temperature, increased blood flow,
acidosis, catecholamines)
– Increased iron loss in sweat and feces (GI bleeding most important
cause)
• Extremely rare to find that athletes have anemia
(hemoglobin <12 mg/dl for females) (Figure 9.28). (See
Table 9.14 & Figure 9.27 for review of iron deficiency).
• Mild iron deficiency does not impair health or performance
in most female athletes (unlike anemia).
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Principle 6: Vitamin and Mineral
Supplements Are Not Needed
In a joint statement, the American College of
Sports Medicine, American Dietetic Association,
and Dietitians of Canada have stated,
“In general, no vitamin and mineral supplements should be required
if an athlete is consuming adequate energy from a variety of foods to
maintain body weight. If an athlete is dieting, eliminating foods or
food groups, is sick or recovering from injury, or has a specific
micronutrient deficiency, a multivitamin/mineral supplement may be
appropriate. No single nutrient supplements should be used without
a specific medical or nutritional reason (e.g., iron supplements to
reverse iron deficiency anemia).”
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Figure
9.29
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Principle 6: Vitamin & mineral supplements are
not needed
• Most studies show that intake of major vitamins and
minerals by athletes exceeds 67% RDA (but 50- 80%
still use supplements on a regular basis). (Fig 9.30).
• Exercise does increase the requirement for some
nutrients (e.g., iron, zinc, copper, magnesium,
chromium, B6, riboflavin), but can by met by
consuming a balanced diet that matches energy
expenditure.
• Nutrient deficiencies can impair physical
performance, but these are rare among athletes.
• Studies do not back the claim that performance is
enhanced when nutrient intake exceeds recommended
levels (in well-nourished athletes).
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Principle 7: Protein supplements do not benefit the
athletes Protein and Exercise Historical Background
• 19th century
– Belief that protein was the major exercise
fuel
• Most of 20th century
– Thought that exercise had little effect on
protein needs
• 1970 to present
– Research has shown that protein needs of
those who exercise heavily exceeds that of
sedentary individuals (see Figure 9.31 for a
review of protein/amino acid metabolism).
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Acute Exercise-Induced Changes in
Protein Metabolism
• Decrease in protein synthesis (but then an increase
during recovery). (Figure 9.32).
• Increase in branched-chain amino acid (BCAA)
oxidation, especially during prolonged endurance
exercise (enhanced by an increase in skeletal
muscle branched chain 2-oxoacid dehydrogenase
enzyme activity).
• Increase in protein degradation.
• Increase in gluconeogenesis (liver converts amino
acids into glucose).
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Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Factors That Influence Dietary
Protein Need for Athletes
• Exercise Intensity
– Amino acid oxidation increases with exercise intensity.
• Carbohydrate Availability
– The exercising muscle uses more BCAAs for fuel as glycogen
stores become depleted.
• Exercise Type: Aerobic vs. Resistance Exercise
– In contrast to prolonged aerobic exercise, resistance exercise
does not stimulate BCAA oxidation (carbohydrate is the primary
fuel).
– Diet protein needs are still greater in resistance- compared to
aerobic-trained individuals due to larger muscle mass
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Practical Implications
Estimated dietary protein needs of sedentary individuals and athletes
See Tables 9.16, 9.17
• RDA = 0.8 g/kg/day or 56 g for sedentary
individual (actual intake in U.S. is ~90 g/day).
• Strength athletes need about 1.4 g/kg/day to stay
in nitrogen balance (1.6-1.7 g/kg/day, safety
margin added).
• Endurance athletes need 1.2-1.4 g/kg/day.
• Most athletes can obtain the added protein by
ensuring that protein intake is ~15% total energy
intake, using foods from the traditional food
supply (supplements not needed).
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
ADA Summary on Protein Intake
• “Recommended protein intakes can generally be met
through diet alone, without the use of protein or amino
acid supplements, if energy intake is adequate to maintain
body weight...Athletes should be aware that increasing
protein intake beyond the recommended level is unlikely
to result in additional increase in lean tissue because there
is a limit to the rate at which protein tissue can be
accrued...Although the protein quality of a vegetarian diet
is adequate for adults, plant proteins are not as well
digested as animal proteins. Thus, to adjust for
incomplete digestion, an increase of about 10% in the
amount consumed may be made.”
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Principle 8: Rest and Emphasize
Carbohydrates Before Long
Endurance Events
• For events lasting longer than 60-90 minutes:
– Taper exercise gradually during the week before the
event (Figure 9.33).
– Consume 8-10 g/kg carbohydrate during the 3 days
before the event.
• The pre-event meal should be ingested 3-5 hours
before the event, and contain 500-800 Calories of
light, low-fiber starch.
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Figure 9.33
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Principle 10: Fat Loading Is Not Recommended
for Enhanced Performance or Health
• Premise: Greater availability of fat during
exercise, through supplementation or
dietary alternatives (fat loading), can
improve performance by further sparing
muscle glycogen. Dietary manipulations
include high-fat diets for:
– 1-5 days before events
– 2-4 weeks before events
– Immediately before and/or during events
• In general, data do not support “fat loading”
for performance enhancement or health.
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Principle 9. Use of ergogenic aids is
unethical (and usually of no value)
• Ergogenic = substances or methods that
tend to increase performance capacity
– Nutritional aids (carbohydrates, vitamins,
proteins)
– Pharmacological aids (steroids, amphetamines)
– Physiological aids (oxygen, blood doping)
– Psychological aids (hypnosis, mental imagery)
– Mechanical aids (biomechanical aids)
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Nutritional Ergogenic Aids (see Table 9.18)
• Prohormones: compounds such as androstenedione,
androstenediol, and dehydroepiandrosterone that are
purported to increase testosterone, improve recovery, and
build muscle mass.
• Creatine preparations: supplements that contain creatine
monohydrate, and are advertized to improve power
performance and build muscle mass.
• Proteins and amino acids: claimed effects include
increases in muscle mass, strength, and endurance.
• Natural and herbal products: ginseng, Echinacea, saw
palmetto, tribulus, and kava kava which are claimed to
improve energy, strength, endurance, and immune
function.
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Nutritional Ergogenic Aids (cont.)
• Diuretics: herbal diuretics and stinging nettle which
purportedly prevent water retention, swelling, gout, and
high blood pressure.
• Energy enhancers, vitamins, and antioxidants: vanadyl
sulfate, taurine, and vitamins which are postulated to
improve recovery, aid in rehydration and glycogen
replenishment, and provide added energy.
• Mental enhancers: plant extracts, amino acids, alkaloids
(ephedrines and caffeine), minerals, and vitamins that are
alleged to modulate mood, boost metabolism, increase
adrenaline output, and provide energy and power.
• Fat burners: L-carnitine, inositol, and choline that are
asserted to increase lean muscle mass and burn fat.
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
ADA/ACSM Guidelines
• The 1994 Dietary Supplement Health and Education Act
allows supplement manufacturers to make claims regarding the
effect of products on the structure/function of the body, as long as
they do not claim to diagnose, mitigate, treat, cure, or prevent a
specific disease. Performance can be categorized as follows:
– Those that perform as claimed.
– Those that may perform as claimed but for which there is
insufficient evidence of efficacy at this time.
– Those that do not perform as claimed.
– Those which are dangerous, banned, or illegal, and
consequently should not be used.
• Athletes should be counseled regarding the use of ergogenic aids,
which should be used with caution and only after careful
evaluation of the product for safety, efficacy, potency, and
legality.
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Ergogenic Aids That Work??
• Caffeine
– Claim: Increases long-term endurance; improves
performance during intense exercise lasting 5 min
– Fact: drinking more than 5 cups of coffee one hour
before exercise will enhance performance 10-30%.
(IOC bans if urine levels are greater than 12 g/ml,
which is >6 cups coffee).
• Soda-loading
– Claim: Sodium bicarbonate (Alka Seltzer) counters
lactic acid during intense effort lasting 1-4 minutes
– Fact: 300 mg/kg decreases 800 m run time by 2.9
seconds.
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Ergogenic Aids That Work??
• Blood doping and EPO (erythropoetin)
– Claim: Increases long-term endurance
– Fact: 900 ml blood removed from athlete, stored at 80C for 6-8
wks, and then reinfused 1-7 days before competition increases
hemoglobin by 10% (4-11% increase in aerobic power; run 10
sec/mile faster); EPO has similar effect
– A typical regimen is to administer 5000 U of r-EPO three times
weekly for four weeks. Hematocrit values will typically
increase from 40-43% to 50-53%, increasing VO2max by 810%. Once r-EPO administration is discontinued, red cell
mass gradually returns to its original state, but this may take
weeks. As a result, an “open window” exists where there is no
evidence of r-EPO misuse but where performance is enhanced.
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Figure 9.36
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Ergogenic Aids That Work??
• Steroids and Steroid-Like Compounds
– Fact: Claims are true for most people who also engage in intensive
resistance exercise. Side effects are legion (Box 9.9).
– Prohormones are a class of androgenic steroids that either convert to
testosterone directly or mimic testosterone by forming androgen-like
derivatives (e.g., nandrolone). See Figure 9.37. These compounds
include dehydroepiandrosterone (DHEA), androstenedione, 5androstenediol, and 4-androstenediol, all now sold as prohormones in
the U.S. marketplace. Most studies indicate that some androgen
supplements convert to testosterone, but also estrogen subfractions.
The net effect is no increase in protein synthesis, muscle mass, or
strength.
– Claim: Increase muscle mass & strength, decrease fat mass, increase
aggressiveness
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
• Doping with growth hormone:
– Reputation of being effective in building skeletal mass,
reducing fat mass, and improving submaximal and
maximal aerobic endurance among athletes.
– Crucial in energy metabolism and body anabolism, and
has multiple benefits when administered to adults with
growth hormone deficiencies.
– Insulin-like growth factor I (IGF-I) mediates the
principal effects of growth hormone.
– Currently, the effects of rGH or IGF-I in improving
athletic performance, muscle strength, and recovery
from intensive exercise are unproven.
– The few controlled studies that have been performed
with supraphysiological growth hormone doses to
athletes have shown no significant performance effects.
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Ergogenic Aids That Work??
• Creatine---ACSM consensus statement
– Creatine supplementation can increase muscle phosphocreatine content,
but not in all individuals.
– Exercise performance involving short periods of extremely powerful
activity can be enhanced with creatine supplementation (e.g., 5-7 d of 20
g/d), especially during repeated bout of activity; does not increase
maximal isometric strength, the rate of maximal force production, nor
aerobic exercise performance.
– Creatine supplementation leads to weight gain within the first few days;
due to water retention.
– Does not(???) cause gastrointestinal, renal, and/or muscle cramping
complications.
– Exhibits small but significant physiological and performance changes, but
the increases in performance are realized during very specific exercise
conditions. This suggests that the apparent high expectations for
performance enhancement are inordinate.
Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e.
Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.
Exercise in the Heat
• 5-7 g/kg for athletes daily
• 1 hour before exercise –1.5-2.5 cups water
• Sports Drinks – 10-25 mmoles/liter
(concentration)
• 6 to 8% CHO – 8 oz every 15 to 20 minutes
• Electrolyte concentration – sodium and
potassium - 4-8% (g CHO/ml)
• Sodium 0.5 -0.7 g/L – salt foods
The End