chapter
10
Nutrition Strategies
for Maximizing
Performance
Chapter Objectives
• List pre-, during- and postcompetition nutrition
recommendations for different sports
• Provide guidelines for weight gain and weight loss
• Recognize signs and symptoms of eating disorders
• Understand the importance of having an
intervention and referral system in place for
athletes suspected of having an eating disorder
• Recognize the prevalence and etiologies of obesity
• Assist in the assessment process for obese
individuals
Precompetition, During-Event, and
Postcompetition Nutrition
• Precompetition meal
– Helps maintain hydration
– Provides carbohydrate to maximize blood glucose
and stored glycogen levels
– Keeps hunger pangs at bay
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• Minimizing gastrointestinal issues
– Try food in practice first.
– When the meal is closer in time to the start of the game or
event, consume smaller amounts of food and liquids.
– Avoid high-fat and high-fiber foods. Both slow down
digestion, which may result in stomach cramps.
– Avoid sugar alcohols (eg, Xylitol, Sorbitol, Hydrogenated
starch hydrolysates), which are often used as sugar
substitutes (2-3 kcal/g instead of 4 kcal/g for a typical
carbohydrate) with ~50-75% the sweetness of sugar.
Consumption can cause gas, bloating, cramping, and a
laxative effect.
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• Precompetition nutrition
– Aerobic endurance sports
• The most important competition meal for aerobic
endurance athletes who compete in long-duration
activity (>2 hours), especially in the morning after
an overnight fast
Key Point
• The primary purpose of the precompetition
meal is to provide sufficient fluid to
maintain hydration and carbohydrate to
maximize blood glucose and stored
glycogen while also satisfying hunger.
Precompetition, During-Event, and
Postcompetition Nutrition
• Precompetition nutrition
– Carbohydrate loading
• A technique used to enhance muscle glycogen
before aerobic endurance events, as depletion of
muscle and liver glycogen leads to fatigue.
• A commonly used carbohydrate loading regimen
includes three days of a high-carbohydrate diet in
concert with tapering exercise the week before
competition and complete rest the day before the
event.
Key Point
• Carbohydrate loading is an effective
strategy to maximize glycogen storage.
However, athletes must consume 8 to 10 g
carbohydrate per kilogram body weight per
day during the loading period to notice any
benefit from carbohydrate loading.
Precompetition, During-Event, and
Postcompetition Nutrition
• During-event nutrition
– Proper hydration during competition is essential for
performance. Athletes should hydrate themselves
several hours before exercise to allow for fluid
absorption and urine output before competing.
– The optimal sports drink contains 20 to 30 mEq of
sodium (460-690 mg with chloride as the anion) per
liter, 2 to 5 mEq of potassium (78-195 mg) per liter,
and 5% to 10% of carbohydrate (6-8% ideal).
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• During-event nutrition
– According to the American Academy of Pediatrics,
children weighing 40 kg (88 pounds) should drink 5
ounces of cold water or a flavored salted beverage
every 20 minutes during practice; adolescents
weighing 60 kg (132 pounds) should drink 9 ounces
every 20 minutes even if they do not feel thirsty.
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• During-event nutrition
– Aerobic endurance sports
• Consuming carbohydrates during prolonged aerobic
endurance exercise can improve performance while
also reducing exercise-induced stress and suppression
of immune system functioning.
• Simply rinsing carbohydrates through the mouth
(without actually ingesting) seems to improve
performance lasting approximately 1 hour by 2% to 3%,
presumably by affecting the central nervous system.
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• During-event nutrition
– Intermittent high-intensity sports
• Many team sports, such as soccer, tennis,
basketball, and American football, include
repeated bouts of short-duration, high-intensity
activity in addition to a wide range of skills.
• The provision of both fluids and carbohydrate is
essential for performance during prolonged
intermittent sports.
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• During-event nutrition
– Strength and power sports
• Carbohydrates are also an essential source of energy
used during resistance training and therefore in
strength and power sports.
• Strength and power athletes can maintain their
glycogen stores, which may decrease muscular fatigue
in slow-twitch fibers and possibly lead to better
performance, by supplementing with carbohydrate
before and during competition.
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• Postcompetition nutrition
– Data suggest that high-GI foods consumed after
exercise replenish glycogen faster than low-GI
foods.
– Although emphasis is usually placed on carbohydrate, in practical terms, consuming a balanced
meal ensures the availability of all substrates for
adequate recovery, including amino acids.
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• Postcompetition nutrition
– Aerobic endurance events
• After prolonged aerobic endurance events, it is important
to replenish carbohydrate stores before the next training
session or competition (whichever comes first) and
consume enough protein to build and repair muscle.
• Glycogen synthesis occurs at a rapid rate when large
amounts of carbohydrate, 1-2 g per kilogram body weight
per hour, are consumed immediately after exercise or
competition and at regular intervals every 15 to 60 minutes
thereafter for up to 5 hours.
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• Postcompetition nutrition
– High-intensity intermittent sports
• Fully replacing muscle glycogen before a subsequent
bout of exercise or competition may prolong time until
fatigue and improve performance.
• High-intensity intermittent sports can lead to some
degree of muscle damage. Consuming protein
postexercise helps decrease some markers of muscle
damage.
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• Postcompetition nutrition
– Strength and power sports
• During the recovery period after strength and power
competitions, athletes should focus on consuming
higher- glycemic carbohydrates immediately
postexercise if they must compete or train again over
the course of the 24-hour period after their initial
competition.
• Supplementing with protein after a muscle-damaging
bout of resistance training increases acute muscle
protein synthesis.
(continued)
Precompetition, During-Event, and
Postcompetition Nutrition (continued)
• Postcompetition nutrition
– Concurrent training
• Exercise interference is a concept suggesting that
endurance exercise, when combined with strength training
(back-to-back sessions), blunts gains in strength compared
to strength training alone, but results in improvements in
endurance performance.
• The consumption of carbohydrate after endurance exercise
and prelift can help suppress skeletal muscle breakdown.
• For optimal muscle remodeling, at least 20 to 30 g of protein
should be consumed per meal and meals should be eaten
every 3 to 4 hours.
Weight and Body Composition
• Energy Requirements
– Energy is commonly measured in kilocalories
(kcal or calories).
• A kilocalorie is the work or energy required to raise
the temperature of 1 kg of water 1° C (or 2.2 pounds
of water 1.8° F).
– Factors Influencing Energy Requirements
• Resting metabolic rate
• Thermic effect of food
• Physical activity
Table 10.7
Nutrition Strategies for Altering
Body Composition
• Weight gain
– Off-season is the time to focus on gaining weight.
– General guideline: Consume approximately 500
additional calories per day.
– Eat enough protein to maximize gains in lean body
mass: 1.5 to 2.0 g per kilogram body weight per day.
– Seek regular nutrition counseling (or coaching) by a
sports dietitian or sports nutritionist with an
advanced degree.
Key Points
• Gains in body mass and strength occur when
the athlete consumes adequate calories and
dietary protein and engages in a progressive
resistance training program.
• If all the extra calories consumed are used for
muscle growth during resistance training, then
about 2,500 extra kilocalories are required for
each 1-pound (0.45 kg) increase in lean tissue.
Nutrition Strategies for Altering
Body Composition (continued)
• Weight (fat) loss
– No difference between the amount of weight loss on a
low-carbohydrate as compared to a low-fat diet.
– Weight loss during dieting may come from muscle, and
caloric restriction may decrease muscle protein synthesis.
– If all the expended or dietary-restricted kcal apply to body
fat loss, then a deficit of 3,500 kcal will result in a 1-pound
(0.45 kg) fat loss.
– Athletes should consume 1.5-2.5 g protein/kg body weight
per day in addition to maintaining a moderate energy
deficit of approximately 500 calories per day (would result
in 1 pound of fat loss per week)
Weight and Body Composition
• Weight (fat) Loss
– The maximal rate of fat loss appears to be
approximately 1% of body mass per week.
– The initial goal for weight loss in overweight and obese
individuals should be 10% of initial weight within 6
months (eg, from 200 lb to 180 lb; from 225 lb to 202 lb))
– For most people, this is an average of 1.1 to 2.2 pounds
(0.5-1.0 kg for 50-100 kg mass individuals) per week,
and represents a daily caloric deficit of approximately
500 to 1,000 kcal.
– For athletes who desire to minimize lean tissue loss,
small decreases in caloric intake to achieve gradual
weight loss are indicated.
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.
• Athletes need to choose a dietary approach
based on whether it is safe and effective for
them, contains enough protein to meet their
needs, and fits their lifestyle so they can
easily adhere to it.
Nutrition Strategies for Altering
Body Composition (continued)
• Body mass index (BMI)
– Often used to assess if a person is underweight, normal
weight, overweight, or obese
– Often used to assess risk for diseases that are associated
with excess body fat (overweight & obese)
– Is a measure of excess weight — cannot distinguish
between excess fat, muscle, or bone mass
– To calculate, use one of the following equations:
• Weight (kg) / Height (m²)
• [Weight (pounds) / Height (inches)²] × 703
Table 10.8
Nutrition Strategies for Altering
Body Composition (continued)
• Overweight and obesity
– Increase risk of morbidity
• Hypertension
• Dyslipidemia
• Coronary heart disease
• Gallbladder disease
• Stroke
• Type 2 diabetes
• Respiratory problems
• Endometrial, breast, prostate, and colon cancers
Key Point
• Body mass index should not be used as a
diagnostic tool but instead as an initial
screening tool to identify potential weight
issues in individuals and to track
population-based rates of overweight and
obesity.
• Obesity is not the same condition in each
individual. Thorough assessment helps
determine which treatment is appropriate
and, more important, whether the individual
is ready for treatment.
Nutrition Strategies for Altering
Body Composition
• Rapid weight loss
– Athletes may use a variety of techniques to cut
weight quickly in order to compete in a desired
weight class, meet a weight goal set by their coach,
or improve performance.
(continued)
Nutrition Strategies for Altering
Body Composition (continued)
• Rapid weight loss
– Potentially dangerous weight loss techniques
• Fasting
• Fad diets
• Voluntary dehydration (diuretics, sauna, water and
salt manipulation, wearing multiple layers of clothing)
• Self-induced vomiting
• Laxative abuse
• Inappropriate or excessive use of thermogenic aids
(continued)
Nutrition Strategies for Altering
Body Composition (continued)
• Rapid weight loss
– Attempting to lose too much weight too quickly may
result in the following:
• Loss of lean body mass
• Fatigue
• Headaches
• Mood swings
• Dehydration
• Heat illness
• Muscle cramping
(continued)
• Dizziness
Nutrition Strategies for Altering
Body Composition (continued)
• Rapid weight loss (continued)
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Suppressed immune system functioning
Hormone imbalances
Hyperthermia
Reduced muscle strength
Decreased plasma and blood volume
Low blood pressure
Electrolyte imbalances
Kidney failure (diuretic abuse)
Fainting
Death (extreme cases)
Feeding and Eating Disorders
• Anorexia nervosa
– Self-imposed starvation in an effort to lose weight
and achieve thinness
– Symptoms include
• Thinning of the bones (osteopenia or
osteoporosis)
• Brittle hair and nails
• Dry and yellowish skin
• Growth of fine hair all over the body (lanugo)
• Mild anemia and muscle wasting and weakness
(continued)
Feeding and Eating Disorders (continued)
• Anorexia nervosa
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Severe constipation
Low blood pressure, slowed breathing and pulse
Damage to the structure and function of the heart
Brain damage
Multiorgan failure
Drop in internal body temperature, causing a person
to feel cold all the time
• Lethargy, sluggishness, or feeling tired all the time
• Infertility
(continued)
Feeding and Eating Disorders (continued)
• Warning Signs for Anorexia Nervosa
– Commenting repeatedly about being or feeling fat
– Asking questions such as “Do you think I’m fat?” when
weight is below average
– Dramatic weight loss for no medical reason
– Reaching a weight that is below the ideal competitive
weight
– Continuing to lose weight even during the off-season
– Preoccupation with food, calories, and weight
Feeding and Eating Disorders (continued)
• Binge-eating disorder
– Characterized by repeated episodes, occurring at
least once a week for a period of three weeks, of
uncontrolled binge eating (eating significantly more
food in a short period of time than most people
would eat under the same circumstances)
(continued)
Feeding and Eating Disorders (continued)
• Binge-eating disorder
– Associated with three or more of the following:
• Eating much more rapidly than normal
• Eating until feeling uncomfortably full
• Eating large amounts of food when not feeling
physically hungry
• Eating alone because of feeling embarrassed by how
much one is eating
• Feeling disgusted with oneself, depressed, or very
guilty afterward
(continued)
Feeding and Eating Disorders (continued)
• Bulimia nervosa
– Recurrent consumption of food in amounts
significantly greater than would customarily be
consumed in a discrete period of time, followed by
episodes of purging
– The binging and purging occur at least once a week
for a period of three months.
(continued)
Feeding and Eating Disorders (continued)
• Bulimia nervosa
– People with bulimia nervosa feel a lack of control
over their eating during binge episodes.
– They are more likely to be normal weight as
opposed to underweight, are unhappy with their
weight and body, and fear weight gain (fat phobia).
(continued)
Feeding and Eating Disorders (continued)
• Bulimia nervosa
– Characterized by the following symptoms:
• Chronically inflamed and sore throat
• Swollen salivary glands in the neck and jaw area
• Worn tooth enamel, increasingly sensitive and decaying
teeth as a result of exposure to stomach acid
• Acid reflux disorder and other gastrointestinal problems
• Intestinal distress and irritation from laxative abuse
• Severe dehydration from purging of fluids
• Electrolyte imbalance (too low or too high levels of sodium,
calcium, potassium, and other minerals), which can lead to
heart attack.
(continued)
Feeding and Eating Disorders (continued)
• Warning Signs for Bulimia
– Eating secretively
– Disappearing repeatedly immediately after eating
– Appearing nervous if something prevents the person from
being alone after eating
– Losing or gaining extreme amounts of weight
– Smell or remnants of vomit in the rest room or elsewhere
– Disappearance of large amounts of food
Feeding and Eating Disorders (continued)
• Warning Signs for Both Anorexia and Bulimia
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Complaining frequently of constipation or stomachaches
Mood swings
Social withdrawal
Relentless, excessive exercise
Excessive concern about weight
Strict dieting followed by binges
Increasing criticism of one’s body
Strong denial that a problem exists even when there is
hard evidence
Feeding and Eating Disorders (continued)
• Avoidant/restrictive food intake disorder (ARFID)
– An eating or feeding disturbance that includes one or
more of the following:
• Apparent lack of interest in eating or food
• Avoidance based on the sensory characteristics of food
(smell, taste, visual appearance)
• Concern about aversive consequences of eating
(continued)
Feeding and Eating Disorders (continued)
• Pica
– Eating nonnutritive substances for a period of at
least one month
– Substances may include clay, laundry starch, ice,
cigarette butts, hair, or chalk
• Rumination disorder
– Involves chewing, reswallowing, or spitting of
regurgitated food
Key Point
• The strength and conditioning professional
is not responsible for treating eating
disorders but instead should be aware of
the symptoms associated with an eating
disorder and refer athletes to the
appropriate professional.