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Chapter 6
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Dietary Protein
• Protein is one of our most important essential
nutrients
– Structure of body tissues
– Formation of enzymes
– May provide energy
• Implications for sports
– Protein needs of strength and endurance athletes
• Implications for health
– The good proteins in the OmniHeart diet
What is protein?
• Protein is a complex structure containing carbon,
hydrogen, oxygen, and nitrogen, and in some cases
sulfur. These elements combine to form amino acids.
Formation of peptides and protein
Is there a difference between
animal and plant protein?
• First, let us consider the two main classes of amino
acids
– Indispensable (essential) amino acids
• Must be obtained from foods in the diet
– Dispensable (nonessential) amino acids
• May be formed in the body
Dietary Protein
• Dietary protein
– Animal protein
•
•
•
•
Complete protein
Contains proper blend of all essential amino acids
Contains higher concentration of protein
Higher quality protein
– Plant protein
• Incomplete protein
• May be low in one or more essential amino acids
• Contains lower concentration of protein
• Essential amino acids
Histidine
Isoleucine*
Leucine*
Lysine*
Methionine plus cysteine
Phenylalanine plus tyrosine
Threonine
Tryptophan
Valine
*BCAA
Animal and plant protein
• In natural, unprocessed foods, both animal and plant
protein have all 20 amino acids
• The quality of a protein source is in its ability to
provide nitrogen and amino acid requirements for
growth, maintenance and repair of tissues
• Various analytical techniques are used, most focus
on the concept of nitrogen balance
– Protein Digestibility-Corrected Amino Acid Score (PDCAAS)
– PDCAAS scores range from 1.0 to 0.0
Animal and plant protein
• Complete proteins
– Contain adequate amounts of all 9 essential AA
– Animal foods are complete proteins
• PDCAAS for egg white is 1.0
• PDCAAS for meat is 0.92
• Incomplete proteins
– Limiting AA: A deficiency of one or more essential AA
• Legumes (methionine)
Grains (Lysine)
– Plant foods are incomplete proteins
• PDCAAS for legumes is 0.68
• PDCAAS for wheat bread is 0.40
Animal and plant protein
• Two ounces of fish
– 14 grams of protein
• Two ounces of beans
– 5 grams of protein
• Two ounces of cooked macaroni
– 2 grams of protein
• Protein complementation
– Grains and legumes
What are some common foods that are
good sources of protein?
• The Food Exchange System
– High
• Meat and meat substitutes (legumes)
• Milk
– Lower
•
•
•
•
Starch
Vegetable
Fruit
Fat
Food Exchange Groups
Food Exchange
Carbohydrate
Fat
Protein
Calories
Skim/very low fat
12
0- 3
8
90
Low fat
12
5
8
120
Whole
12
8
8
150
Very lean
0
0- 1
7
35
Lean
0
3
7
55
Medium fat
0
5
7
75
High fat
0
8
7
100
Starch (1 oz; ½ cup)
15
0- 1
3
80
Fruit (1 medium; ½ cup)
15
0
0
60
Vegetable (1/2 cup)
5
0
2
25
Fat (1 teaspoon)
0
5
0
45
Milk (1 cup)
Meat/substitutes (1 oz)
Carbohydrate, fat and protein in grams per serving
1 g carbohydrate = 4 Calories; 1 gram fat = 9 Calories; 1 gram protein = 4 Calories
Figure 6.4
How much protein do I need?
• Humans need enough protein to provide adequate
amounts of nitrogen and essential amino acids
• Recommended Dietary Allowance (RDA)
– Based on age and body weight
• Acceptable Macronutrient Distribution Range (AMDR)
– Based on percentage of daily energy intake
Protein RDA
Protein AMDR
• Protein AMDR is 10-35% of daily energy intake
• Adult Female
– 132 lbs (60 kg)
– 2,000 Calorie diet
• RDA is 48 grams of protein (60 x 0.8)
• AMDR of 10% provides 50 grams of protein
– 2,000 x 0.10 = 200 protein Calories
– 200/4 Calories per gram of protein = 50 grams of protein
How much of the
essential amino acids do I need?
• RDA have been established for the 9 essential AA
What are some dietary guidelines to
ensure adequate protein intake?
• For omnivorous individuals
– Eat a wide variety of animal and plant foods
– Select animal foods low in fat
– Eat animal foods with plant foods
• 70% from plant foods; 30% from animal foods
• For vegans
– Need to ensure consumption of adequate
amounts of complementary protein foods
Metabolism and Function
What happens to protein in the human body?
• Digestion into specific amino acids
• Metabolic fate of amino acids
– Role of the liver
– Protein synthesis in body cells
– Protein catabolism
• Nitrogen: excreted as urea
• Alpha-ketoacid:
–Used as energy
–Converted to carbohydrate or fat
Figure 6.5
Formation of carbohydrate and fat from
excess protein
• Glucogenic amino acids
– Form pyruvate
– Gluconeogenesis
• Ketogenic amino acids
– Form acetyl CoA
Formation of carbohydrate and fat from
excess protein
• Glucogenic amino acids
– 14 glucogenic amino acids
• Ketogenic amino acids
– Only leucine and lysine
• Glucogenic and ketogenic amino acids
– 5 amino acids can be both glucogenic and ketogenic
– Isoleucine, phenylalanine
Can protein be formed from
carbohydrates and fats?
• Nitrogen from excess amino acids can combine with
an alpha-ketoacid to form some non-essential amino
acids in the liver. The ketoacids are derived from
carbohydrate or fat metabolites or intermediates in
the Krebs cycle
What are the major functions of protein in
human nutrition?
• Dietary protein serves all three major functions of
nutrients
– Forms the structural basis for the vast majority of body
tissues
– Forms numerous enzymes and hormones to help regulate
body metabolism
– Used as an energy source if needed
• Importance of carbohydrate for protein-sparing effect
Summary of protein functions in the
human body
•
•
•
•
•
•
•
•
•
Structural
Transport
Enzyme
Hormone and neurotransmitter
Immune
Acid-base balance
Fluid balance
Energy
Movement
Proteins and Endurance Performance
• Protein Use as Energy Source
– During rest
• <5% of total daily expenditure
• Endurance training may reduce protein oxidation at rest,
increasing the amount of energy derived from fat
Proteins and Exercise
•
•
•
•
•
•
Protein use for energy during exercise
Exercise and protein losses
Protein metabolism during recovery from exercise
Effect of training on protein metabolism
Protein needs of athletes
Prudent protein recommendations for athletes
Are proteins used for energy
during exercise?
• Measures of protein use during exercise
–
–
–
–
Urea concentration
Measures of 3-methylhistidine in urine
Nitrogen balance
Labeled isotopes
Protein use during exercise
• Resistance exercise training
– Does not appear to increase protein oxidation
– May provoke muscle tissue catabolism
– Both catabolism and anabolism may occur during
recovery, with anabolism prevailing over time
Protein use during exercise
• Aerobic endurance exercise training
– Protein use is minimal compared to carbohydrate and fat
– Dynamic exercise activates BCAA dehydrogenase, an
enzyme that oxidizes BCAA
– Some amino acids are used to promote gluconeogenesis
– Protein use may increase when body carbohydrates stores
decrease
Protein use during exercise
• Aerobic endurance exercise training
– Exact mechanism not determined, but proposed
mechanisms include activation of proteolytic enzymes that
degrade myofibrillar protein
– Six amino acids may be metabolized in the muscle,
including the three BCAA
– Exercise by-products include ammonia, alanine, and
glutamine which can transport nitrogen and ketoacids to
the liver
– Glutamine is an important fuel for the immune system
Protein use during exercise
• Leucine and the Glucose-Alanine Cycle
– Leucine is the major BCAA to be oxidized during exercise
– The alpha-ketoacid may enter the Krebs cycle
– The amino group combines with pyruvate to form alanine,
which may be transported to the liver to form glucose
– Estimated glucose generation from alanine is very limited
Figure 6.6
Protein use and
importance of carbohydrate
• An important factor affecting the use of protein as
an energy source during aerobic endurance exercise
is carbohydrate availability
• Research indicates that elevate endogenous stores
of carbohydrate or provision or exogenous
carbohydrate during exercise may exert a proteinsparing effect
Does exercise increase protein losses in
other ways?
• Urinary losses
– Proteinuria
– Greater losses following intense or prolonged exercise
– Losses are small, about 3 grams per day
• Sweat losses
– Losses are minor, about 1 gram of AA/liter of sweat
• Gastrointestinal losses
– Minor losses
What effect does exercise training have
upon protein metabolism?
• Training induces specific adaptations in body cells
depending on the type of training
– Resistance or strength training
– Aerobic endurance training
• In general, exercise training produces a positive
protein balance that may contribute to performance
enhancement
What effect does exercise training have
upon protein metabolism?
• Chronic exercise training appears to decrease
protein catabolism during standardized exercise
tasks
• Aerobic endurance training appears to increase the
ability of the muscle to use protein as an energy
source, if needed.
– May help preserve glucose for the brain when
carbohydrate levels are low
Exercise training and protein
• Training may decrease the formation of ammonia
during standardized exercise
– Ammonia is thought to contribute to fatigue, possibly by
impairing muscle cell metabolism
• Eccentric muscle training may help prevent muscle
protein damage and delayed onset of muscle
soreness (DOMS)
Do individuals in strenuous physical training,
including the developing adolescent athletes,
need more protein in the diet?
• Varying viewpoints
– Need more protein
• ACSM, ADA, DC Position Statement on Nutrition for the
athlete
– Do not need more protein
• National Academy of Sciences in DRI report
– May need less protein
• Opinion of a protein/exercise scientist
Dietary protein needs:
Strength-type activities
• Additional protein is often recommended to
help support or promote increases in muscle
tissue
• Photo of body builder
Dietary protein needs:
Strength-type activities
• Some exercise scientists recommend an
optimal intake of about 1.5 to 1.8 grams/kg
body weight
• The NAS indicates that the RDA is sufficient
• Michael Rennie suggests training makes
athletes more efficient protein users so they
may actually need less dietary protein
Dietary protein needs:
Endurance-type activities
• Need to recognize that carbohydrate is the
main fuel for endurance-type athletes
• More dietary protein is recommended to
– Restore protein used for energy
– Promote synthesis of oxidative enzymes and
mitochondria
– Help prevent sports anemia
Dietary protein needs:
Endurance-type activities
• Some exercise scientists recommend an optimal
intake of about 1.1 to 1.4 grams/kg body weight for
aerobic endurance athletes, and 1.4 to 1.7 grams/kg
body weight for intermittent high-intensity sports
• The NAS indicates that the RDA is sufficient
What are some general recommendations
relative to protein intake for athletes?
1. Obtain the RDA for protein
– All athletes should obtain at least their RDA for
protein
– About 0.95 to 0.85 g/kg for young athletes
– About 0.80 g/kg for adult athletes
Recommendations for protein intake in athletes
2. Increase the protein RDA by 50 to 100 %
– Will increase an adult’s protein intake to 1.2 to 1.6
grams/kg body weight, and a young athlete to
about 1.7 to 1.9 grams/kg body weight
– These values are within the AMDR of 10-35% of
daily energy intake
One pound of muscle mass
• Goal: To gain one pound of muscle mass per week in
a young teenage athlete (70 kg) whose protein RDA
is about 60 g/day
–
–
–
–
–
–
1 pound of muscle = 454 grams
Muscle is 22% protein
454 x 0.22 = 100 grams of protein in 1 pound
100 grams/7 days = about 14 grams of protein/day
May use 20 grams of protein during exercise
Protein needs
• 60 + 14 + 20 = 94 grams of protein/day
• 94 g/70 kg = 1.34 grams of protein/day
Recommendations for protein intake in athletes
3. Obtain about 15 percent or more of daily energy
intake from protein
– Some athletes may need more protein than
others
• Athletes in weight-control sports
• Female endurance athletes with low energy intake
– Protein intake is within the AMDR
Protein intake in a wrestler
•
•
•
•
College wrestler of 132 pounds (60 kg)
RDA is 48 grams of protein/day
Diet of 1,600 Calories to maintain body weight
A diet with 12% protein will provide the RDA
– 0.12 x 1,600 = 192 Calories; 192/4 = 48 g of protein
• A diet with 20% protein will provide about 1.7 grams
of protein/kg body weight, which is near the
recommendation for strength athletes
– 0.20 x 1,600 = 320 Calories; 320/4 = 80 g of protein
– 80/48 = 1.66 grams of protein/kg
Recommendations for protein intake in athletes
4. Consume protein, preferably with carbohydrate,
before and after workouts: The concept of Nutrient
Timing.
– There appears to be little difference in anabolic
responses if protein is consumed either before or
after exercise
– The protein source should contain all essential
amino acids
• About 0.1 gram per kg body weight is recommended
• 7 grams for a 70-kg individual
Recommendations for protein intake in athletes
– Consuming carbohydrate with the protein may
also enhance the anabolic effects after exercise,
possibly attributed to increase insulin secretion
– Whole foods, such as a turkey breast sandwich,
appear to be as effective as amino acid solutions
– The carbohydrate: protein ratio should be about
3:1 or 4:1
• Commercial products such as Endurox
• Chocolate milk
Recommendations for protein intake in athletes
5. Be prudent regarding protein intake.
– There is insufficient evidence that increased protein intake
will enhance exercise performance
– Experts contend that given sufficient energy intake, lean
muscle mass may be maintained within a wide range of
protein intakes
– There is a metabolic rationale for increasing protein intake
if muscle hypertrophy is the goal, but the intake need not
be excessive and may be within the AMDR of 10-35% of
daily energy intake
Protein: Ergogenic Aspects
• Three of the top 5 most popular sport supplements
– Protein
– Amino acids
– Creatine
What types of protein supplements are
marketed to physically active individuals?
• Variety of products, but the protein source is usually
natural protein from milk, eggs, or soy
– Special high protein foods or diets
– Commercial liquid meals such as Nutrament
– Sports drinks and shakes; sports bars
• Whey and colostrum
– Whey protein isolates from cheese-making process
– Colostrum is first milk form cows (Theory: IGF-1)
• Other protein sources
• Protein/carbohydrate solutions
Do high-protein diets or protein supplements
increase muscle mass and strength in
resistance-trained individuals?
• High-protein diets
– Research data are
equivocal, but suggest
additional protein may
increase lean body mass
but has no effect on
measures of strength
– Consuming protein after
strenuous resistance
exercise may enhance
muscle repair
Do high-protein diets or protein supplements
increase muscle mass and strength in
resistance-trained individuals?
• Whey
– Research findings are mixed, but in general show positive
effects of whey protein supplementation, about 1.2-1.5
grams per kg body weight daily, on lean body mass and
muscular strength. In one study, soy protein was also
effective.
• Colostrum
– Several studies suggest colostrum supplementation may
increase lean body mass, but effects on strength are mixed
• Additional research is recommended to evaluate the
ergogenic potential of whey and colostrum
Do high-protein diets or protein supplements
improve aerobic endurance performance in
endurance-trained individuals?
• High-protein diets or meals
– The Zone Diet (40:30:30), a high-protein diet, has been
advocated for endurance athletes
– Studies do not support an ergogenic effect of high-protein
diets on aerobic endurance
– Several studies suggest that a Zone Diet eating plan over
the course of a week may actually impair aerobic
endurance performance, particularly if protein replaces
carbohydrate in the diet
High-protein diets and aerobic endurance:
Protein/Carbohydrate Preparations
• Effects on aerobic endurance performance
– Early studies have shown increased endurance with
protein/carbohydrate versus carbohydrate alone;
however, the protein/carbohydrate solutions contained
more energy
– More recent studies balanced the energy content of both
solutions and report no difference between the two
High-protein diets and aerobic endurance:
Protein/Carbohydrate Preparations
• Effects on recovery from exercise
– Recent studies find that when energy content is balanced,
protein/carbohydrate solutions provide no advantage over
carbohydrate alone on subsequent exercise performance
– Some data suggest protein/carbohydrate solutions may
prevent muscle soreness, while other research does not
High-protein diets and aerobic endurance:
Colostrum
• Preliminary research suggests that colostrum
supplementation during training (10-20 grams of
colostrum daily for 9-10 weeks) could improve
performance in some tasks
– Cycle time trial after 2-hours of cycling
– Performance in a 40-kilometer time trial
• However, the data should be considered preliminary
and additional research is recommended
Are amino acid, amine, and related nitrogencontaining supplements effective ergogenic
aids?
• Arginine and Citrulline
• Arginine, Lysine, and
Ornithine
• Tryptophan
• BCAA
• Glutamine
• Aspartates
• Glycine
• Glucosamine and
Chondroitin
• Creatine
• HMB
• Beta-alanine and
Carnosine
• Tyrosine
• Inosine
Arginine and Citrulline
• Theory
– Arginine
• A precursor for nitric oxide (NO), a vasodilator
• Theory: Enhanced blood flow and oxygen to muscles
– Citrulline
• Metabolism increases blood levels of arginine
• Main research findings:
– May improve exercise ability in cardiac patients
– Research does not support an ergogenic effect with
healthy individuals, and arginine may be ergolytic
• Increased RPE values
• Decreased time to exhaustion
Arginine, Lysine, and Ornithine
• Theory
– Infusion of these amino acids may increase human growth
hormone (HGH); may increase IGF-1
• Main research findings:
– Arginine may decrease HGH response to exercise
– Early, poorly controlled research found ergogenic effects
– More recent well controlled studies report
• No significant increases in HGH
• No favorable changes in body composition
• No increases in strength
Tryptophan
• Theory
– Needed to form serotonin, a neurotransmitter in the
brain, which has been theorized to decrease pain
perception and delay fatigue during exercise
• Main research findings:
– Findings from studies are somewhat equivocal, but in
general suggest that tryptophan supplementation is not an
effective ergogenic aid for either strength or aerobic
endurance exercise
Branched Chain Amino Acids (BCAA)
• Leucine, isoleucine, and valine are three major
amino acids in muscle tissue
• Theoretical ergogenic mechanisms:
– Use as a fuel during exercise and spare muscle glycogen
– Decrease the rate of muscle tissue degradation
– Prevent adverse changes in brain neurotransmitter
function
BCAA supplementation and
the Central Fatigue Hypothesis
1. Prolonged aerobic endurance exercise decreases
muscle glycogen and increase serum FFA
2. BCAA uptake by exercising muscles is
enhanced in prolonged exercise
3. Serum free tryptophan:BCAA ratio (fTRP:BCAA) increases
4. High levels of serum free tryptophan may induce
formation of serotonin
5. Elevated brain serotonin may induce fatigue through
depressant activity
6. High levels of BCAA compete with free tryptophan
for entry into brain cells, thereby decreasing
serotonin formation and preventing fatigue
BCAA and the Central Fatigue Hypothesis
• Main research findings:
– Some human research suggests increases in serotonin may
be associated with fatigue, but other neurotransmitters,
like dopamine, are also involved
– BCAA supplementation may be used for energy and may
help maintain serum BCAA levels
BCAA and the Central Fatigue Hypothesis
• Main research findings:
– Mental performance: Results of field studies are equivocal,
but several have found enhanced mental alertness in
prolonged sport events, such as tennis and soccer
– Perceived exertion: Results of laboratory studies involving
intense endurance exercise are equivocal.
BCAA and the Central Fatigue Hypothesis
• Main research findings:
– Physical performance with acute supplementation
• Study with 193 marathon runners suggested improved
performance in slower runners (3:05-3:30) but not faster runners
(<3:05) when consuming 7-12 grams during running
• Suggested slower runners may have depleted muscle glycogen
earlier and thus benefited more from supplementation
• Criticism of the study
– Unorthodox statistical procedure
BCAA and the Central Fatigue Hypothesis
• Main research findings:
– Physical performance with acute supplementation:
Most well-controlled laboratory and field studies
have reported no significant effects on exercise
performance. Studies usually involved 3 separate
treatments:
• Carbohydrate alone
• BCAA alone
• Carbohydrate with BCAA
BCAA supplementation
• Additional research findings:
– Acute B CAA supplementation does not enhance
exercise performance in the heat
– Results of chronic BCAA supplementation (2
weeks) are equivocal, but generally indicate no
ergogenic effect
• A recent study with leucine (45 g/kg for 6 weeks) found
improved endurance in a rowing test
BCAA supplementation
• Additional research findings:
– BCAA supplementation not necessary if
carbohydrate is available
• Carbohydrate is the best fuel for endurance athletes
• Carbohydrate helps attenuate decreases in fTRP:BCAA
– BCAA supplementation may be an effective
protocol for athletes in weight-control sports who
are on a diet
– Research is needed to help clarify the role of BCAA
supplements, or protein in general, on muscle
tissue recovery following strenuous exercise
Glutamine Supplementation and Endurance
Performance
• Theory
– May promote muscle growth
• Stimulate HGH
• Increase cell volume
– May stimulate glycogen synthesis
• Glutamine is gluconeogenic
– Major fuel for key cells in the immune system
• Prevent infections associated with overtraining
Glutamine Supplementation and Endurance
Performance
• Main research findings
– Recent studies and reviews indicate that
glutamine supplementation will increase plasma
glutamine levels but will not
• Increase muscle mass or strength
• Provide any advantage over adequate carbohydrate on
muscle glycogen levels
• Prevent the effects of overtraining
• Decrease the frequency of respiratory infections
Aspartates
• Theory
– Potassium and magnesium aspartates hypothesized to
• Spare muscle glycogen
• Reduce accumulation of ammonia
• Improve psychological motivation
• Main research findings
– Studies are equivocal, finding
• Either increased or decreased ammonia levels
• Laboratory cycling tests to exhaustion
– Additional research recommended: Dosage may be a
factor
Glycine
• Theory
– Glycine is used in the formation of creatine
• Main research findings
– Contemporary research reveals no ergogenic effect of
glycine supplementation
– Glycine is part of a multicomponent supplement
containing arginine and alpha-ketoisocaproic acid that has
been found to enhance sprint power in one study.
Additional research is needed for confirmation.
Glucosamine and Chondroitin
• Dietary supplements
– Glucosamine derived from shellfish; chondroitin from cattle cartilage
• Theory
– Glucosamine helps form the structural basis of cartilage
(proteoglycans), and chondroitin helps provide resiliency
– May help prevent joint pain associated with exercise training
Glucosamine and Chondroitin
• Research findings
– Limited research with highly trained individuals; most are
with older, arthritic individuals
– A substantial number of studies and reviews indicate
supplementation reduced joint pain and improved
mobility
– Large NIH study (GAIT) found no overall reduction in knee
pain in osteoarthritic individuals, but the supplement did
provide relief to a subset of individuals with moderate to
severe knee pain
Glucosamine and Chondroitin
• Research findings
– Beneficial effects were minimal in two studies with
younger, physically active males
– Glucosamine sulfate appears to be the most effective
form; chondroitin is not effective
Glucosamine and Chondroitin
• Precautions and recommendations for use
– Considered safe, but may cause bloating and diarrhea
– Consult with your physician as there may be
complications, such as with blood glucose control in
diabetics
– Reasonable dose would be 1,500 mg of glucosamine and
1,200 mg of chondroitin for 2-4 months. If pain symptoms
have not improved, they probably are not going to.
Creatine
• Creatine is found naturally in animal foods,
especially meat
• Creatine may also be synthesized by the liver
and kidney
Food
Milk
Tuna
Salmon
Beef
Pork
g/Kg
0.1
4.0
4.5
4.5
5.0
Creatine
• Discovered 1927
• Synthesized in 1990s as
a dietary supplement
• Research as an
ergogenic aid
progressed rapidly
Creatine Supplements: Forms
• Powder
• Pills
• Candy
• Chews
• Gels
• Serum
• Micronized
Runners AdvantageTM Male
Runners AdvantageTM Female
Teen Advantage Serum Creatine
Creatine Supplementation
• Theory
– May increase muscle levels of PCr
– May increase performance in very high intensity
exercise
– May enhance performance in prolonged
endurance events which incorporate short sprints
– May enhance interval training
Recommended Protocol
Loading phase
Fast protocol: 20-30 grams/day for 5-7 days
Slow protocol: 3 grams/day for 30 days
Maintenance phase
2-5 grams/day
Creatine Supplementation
(20g/day for 5 days) with and
without Carbohydrate (360g)
Adapted from Green, A., et al. ACTA Physiol Scand, 1996.
Creatine supplementation:
Effect on the ATP-PCr energy system
• An ergogenic effect has been reported for numerous
exercise tasks dependent on PCr
–
–
–
–
–
Maximal force in isometric contraction
Strength and endurance in isotonic tests
Muscular force and endurance in isokinetic tests
Maximal cycle ergometer performance from 6-30 seconds
Sprint run, swim, and cycle performance from 5-100
meters or up to 30 seconds duration
• These findings may be applicable to sports such as
weightlifting, cycle, swim and run sprints, and soccer
Creatine Supplementation
• In general, research findings also indicate that creatine
supplementation may enhance performance in very highintensity exercise tasks, such as the 100-meter sprint in track
and sprint cycling
Creatine Supplementation
• Of seven recent well-controlled studies using a standard
creatine-loading protocol and evaluating the effect on single
or repetitive sprint-run or sprint-cycle performance ranging
from 5 to 100 meters, creatine supplementation improved
performance in five of the trials, but had no effect in the
other two.
• For example, one study reported significant improvements in
male sprinters in 100-meter sprint velocity and time to
complete six intermittent 60-meter sprints.
• A meta-analysis of 57 studies revealed an effect size of 0.24
favoring creatine over the placebo treatment
Creatine supplementation:
Effect on the Lactic Acid energy system
• Fewer studies are available, but research findings
suggest an enhancement effect in some events
where athletes maximize power output from 30 to
150 seconds
• Some beneficial effects noted in a 300-meter run
• No beneficial effects in 100-meter swimming
• Additional research is merited
Creatine supplementation:
Effect on the Oxygen energy system
• There is very little theoretical support
• Possible adverse effects
– Weight gain
• Some theories include:
– Enhanced performance in events with short
sprints
– Enhanced interval training
Creatine Supplementation:
Effect on 6-kilometer cross-country run
• In a well designed Swedish study, 18 habitually active males
consumed either a placebo or creatine (20 g/day for 6 days). ‘
• They ran a 6K terrain run on a forest trail before and after
supplementation
• Major findings: Creatine supplementation significantly
– Increased body mass 0.9 kg
– Impaired run performance (pre = 23.36; post = 23.79)
Creatine Supplementation:
• Increase in body water weight
Creatine Supplementation
Effect On Training For Aerobic Endurance
• Creatine supplementation has been shown to improve
performance in interval run repeats of 300 and 1000 meters.
Theoretically, if creatine supplementation could help an
athlete train more effectively at shorter distances,
conceivably performance in longer distances might eventually
be improved.
Creatine Supplementation: Effects on
Training for Aerobic Endurance
• Trained competitive rowers undertook standard creatine
loading for 5 days with a maintenance dose for 5 weeks,
coupled with rowing and resistance training for 6 weeks.
• Although the training significantly improved body
composition, VO2max, repeated power interval performance,
and 2000-meter rowing times in both groups, creatine
provided no additional advantage.
Creatine Supplementation:
Effect on body mass
• In general, research indicates increases in body mass, mainly
as muscle tissue, in both males and females, including both
trained and untrained
• Studies report increases in myosin and myonuclei
concentration
Creatine supplementation:
Other points of consideration
• Caffeine and creatine
– Some research suggest caffeine may counteract the effect
of creatine in high-power events as the caffeine may
prolong muscle relaxation time
• Formulation
– Creatine powder has been used in most studies.
– Serum creatine may not contain significant amounts of
creatine
Creatine supplementation: Safety
• Kidney and liver function
– Consuming recommended dose does not appear to
increase health risks
– Those with liver or kidney disease may be at risk
• Gastrointestinal distress
– Large doses may cause nausea, vomiting and diarrhea
• Dehydration, muscle cramps and tears
– Appears to cause few problems with exercise in the heat
– Possibility of anterior compartment syndrome
• Overdoses and contaminants
– Creatine appears to be safe at 5 grams per day
– Some products may contain contaminants, like ephedrine
Creatine supplementation:
Medical applications
• Increased strength in some conditions
– Muscular dystrophy
– Patients with heart disease
– Injury to the spinal cord
• Facilitate rehabilitation from musculoskeletal injury
• Reduce the loss of muscle mass (sarcopenia) with
aging
Beta-Hydroxy-Beta-Methylbutyrate
(HMB)
• Theory
– Beta-hydroxy-beta-methylbutyrate (HMB), a by-product of
leucine metabolism, is theorized to inhibit the breakdown
of muscle tissue during strenuous exercise
Beta-Hydroxy-Beta-Methylbutyrate
(HMB)
• Main research findings with strength-trained
athletes
– Overall, research findings are equivocal regarding the
ergogenic effect of HMB supplementation on muscle mass
and strength in untrained individual
– The available data indicate that HMB supplementation
does not appear to affect muscle strength, body
composition, or anaerobic exercise performance in
resistance-trained individuals
– Research does not support any protective effects against
muscle tissue damage during resistance training
Beta-Hydroxy-Beta-Methylbutyrate
(HMB)
• Main research findings with endurance athletes
– One study with distance runners reported HMB
supplementation (3 g/day for 6 months) decreased
markers of muscle damage following a 20K run
– One recent study found HMB could increase VO2max
during 5 weeks of interval training in active college
students
– No studies have shown improvement in endurance
exercise performance following HMB supplementation
Beta-alanine and Carnosine
• Theory
– Beta-alanine may increase intramuscular stores of
carnosine, which can serve as an antioxidant or as a buffer
of hydrogen ions, reducing acidity, and increasing the
lactate threshold
– Beta-alanine may also form another peptide, anserine,
which may function as an antioxidant in muscles
Beta-alanine and Carnosine
• Main research findings
– Anserine supplementation increases muscle
carnosine
– Research findings are equivocal relative to
ergogenic effects on anaerobic-type exercise
performance
• Improved performance cycling @ 110% VO2max
• No effect on 400-meter run time
– No ergogenic effect on aerobic-endurance
• No effect on maximal aerobic power
Tyrosine
• Theory
– Tyrosine is a precursor for the catecholamine hormones
and neurotransmitters epinephrine, norepinephrine, and
dopamine; augmentation may have an ergogenic effect
• Main research findings
– Research is very limited
– No effect on aerobic endurance, anaerobic power, or
muscular strength
Taurine
• Theory
– Taurine is synthesized from amino acids, but is not
classified as an amino acid
– Theorized to help prevent muscle tissue damage during
exercise; may function as an antioxidant
• Main research findings
– One study has shown stroke volume during exercise
– One study reported VO2max and exercise time to
exhaustion associated with antioxidant effects
– These preliminary findings need further research
Inosine
• Theory
– Inosine is a nucleoside, not an amino acid
– Theorized to improve ATP production and also to improve
oxygen delivery to muscles during exercise
• Main research findings
– Well-controlled studies indicate inosine supplementation
• Does not increase VO2max or related physiological
variables
• Does not improve 3-mile treadmill run time
• Has no effect on cycling tests of the three energy
systems
• May impair anaerobic energy production
Dietary Protein: Health Implications
• Acceptable Macronutrient Distribution Range (AMDR)
– 10-35% of daily energy intake for adults
– 10-30% of daily energy intake for older children
– 5-20% of daily energy intake for younger children
Does a deficiency of dietary protein
pose any health risks?
• Protein-Calorie malnutrition is a worldwide problem
– Political and economic problems
– Impaired immune functions
• The elderly may be prone to protein undernutrition
– May impair immune functions; increase infections
– May hamper optimal bone development
• Young athletes in weight-control sports
– Loss of muscle mass and hemoglobin
Does excessive protein intake pose any
health risks?
• Excess amounts of specific proteins may cause
allergic reactions in some individuals
• AMDR range is 10-35% of energy intake
• No UL has been established for protein intake
– High protein intake poses no health risks to most persons
– NAS indicates the source of protein may be related to
various health risks
Excessive protein intake and health risks
• Cardiovascular disease and cancer
– Dietary protein itself does not appear to cause CHD or
cancer
• High meat diets may be rich in saturated fats
• AICR indicates there is convincing evidence that red and processed
meats contribute to colorectal cancer
– High protein diets may actually help promote weight loss,
a preventive measure against CHD
– The OmniHeart diet plan focuses on good proteins, such as
from plants and very lean meat, fish and poultry
– Soy protein in natural, whole foods may have beneficial
health effects
Soy protein
• Cardiovascular disease and cancer
– Soy products include tofu, tempeh, soy nuts, soy milk and
others; Soy products meeting recommendations may carry
a health claim
– Soy protein and intact phytochemicals (isoflavones; omega3 fatty acids) may elicit a favorable serum lipid profile;
however, the effect is small compared to other strategies
– Isoflavones may function as phytoestrogens and block
effects of natural estrogen, possibly preventing breast
cancer before menopause
– Some scientists think excess isoflavones may function as
estrogens and promote cancer after menopause
Excessive protein and health risks
• Liver and kidney function
– The liver processes ammonia and the kidneys excrete urea
and ketones, which are formed on high protein diets
– In general, high-protein diets do not have adverse effects
on individuals with normal liver and kidney functions
– Individuals prone to liver or kidney disease should use
caution with protein intake
• Chronic kidney or liver disease
• Diabetics
• Individuals prone to kidney stones
Excessive protein and health risks
• Bone and joint health
– Excessive protein intake may increase urine acidity, which
may increase calcium excretion
– Calcium loss is predicted to be 1 mg of calcium for an
average increase of 1 gram of dietary protein
– A diet low in calcium and high in protein may promote
bone loss
– The key is to obtain adequate calcium and protein because
both are needed in adequate amounts for bone formation
Excessive protein and health risks
• Heat illnesses
– The excretion of urea and ketone bodies in urine could lead
to excessive fluid losses and dehydration
– A high-protein diet could increase resting energy
expenditure
– Both of these effects could compromise temperature
regulation during exercise in the heat, which will be
discussed in chapter 9
Does the consumption of individual
amino acids pose any health risks?
• No UL has been established for specific AA, but the
NAS notes caution is warranted in using any single
AA in amounts greater than normally found in food
• Free AA are manufactured to serve as drugs or
dietary supplements
• Excessive amounts may cause health problems
– Interfere with absorption of other AA
– Cause gastrointestinal distress
• Sound advice is to obtain your AA through foods
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