Transcript Chapter 14: Sports Nutrition

Chapter 10
Nutrition:
Fitness &
Sports
Outline
Assignments Due
 Chemistry 80A - Class interests?
 Chapter 10: Nutrition: Fitness and Sports
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New Diet Analysis 2~
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See website for assignment/details
http://people.ucsc.edu/~taj/
Chem 80A Class Interests
Physical Fitness
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“The ability to perform moderate to
vigorous activity without undue
fatigue”
 Fat
usage by the body
– Increased physical fitness means
improved usage of fat for energy
Benefits of Physical Activity
Nutrition and Physical Activity
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Only 15% of adults are regularly physically
active (U.S.)
NUTRITION (intake)
Physical Performance
Nutrient Use
Beginning an Exercise Program
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Start out slowly
Vary your workout—Make it fun
Include others—Keep accountable (notebook/log)
Set attainable goals
Set aside specific time (daily or weekly)
Reward yourself
Focus on long-term and not on occasional
setbacks
2005 Dietary Guidelines for
Americans
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30 minutes/day physical activity
– Reduce risk of chronic disease
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60 minutes/day physical activity
– Manage body weight and prevent weight gain
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90 minutes/day physical activity
– Sustain considerable weight loss
Challenge Question
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What is your target heart rate zone?
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How do you calculate it?
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Why does it matter?
Fuel for Muscle Work
ATP
 Chemical energy
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– Used by cells for muscle contractions
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Only small amount is stored in resting cells
– 2-4 seconds worth of work
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Other sources of energy are needed
Phosphocreatine (PCr)
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High-energy compound
– Formed and stored in muscle cells
PCr + ADP
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Cr + ATP
Activated instantly
– Replenishes ATP
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Sustains ATP (work) for a few minutes
Anaerobic Glycolysis
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Limited oxygen—Intense physical activity
(running)
Pyruvate is converted to lactate
Produces 2 ATP per glucose
– ~5% of energy potential
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Replenishes ATP quickly
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Cannot sustain ATP production
– 30 seconds to 2 minutes of work
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Lactate build-up (soreness)
– Changes acidity that inhibits glycolysis enzymes
Aerobic Glycolysis
Plenty of oxygen available (talk test)
 Low to moderate intensity (jogging)
 Produces 36-38 ATP per glucose
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– 95% of energy potential
ATP replenished slowly
 Sustained ATP production
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– 2 minutes to 3 hours of work
– Best for burning fat
Glucose Utilization
Glycogen
Temporary storage of glucose in liver and
muscle
 Muscle glycogen
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– Used only by that muscle
Liver glycogen released into bloodstream
 During low to moderate intensity
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– Can sustain work for up to 2 hours
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“Bonking”
– Depleted glycogen
– Work at ~50% of maximal capacity
ATP Formation
Maintaining Normal Blood
Glucose Level
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Important
– For activity lasting longer than 20-30 minutes
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Intake of 30-60 gm carbohydrates per hour
– During strenuous endurance activity
– Delays fatigue by 30-60 minutes
34 grams
Fat Fuel (Fatty Acid)
Majority of stored energy in the body
 Fatty acids
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– Converted to ATP by muscle cells
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12 ATP produced
– Per each turn of the Citric Acid Cycle
– 108 ATP for each 16 C fatty acid chain!!!!!!!!!
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Trained muscles
– Have more mitochondria
– Have greater ability to use fat as fuel
– The more trained muscles respiring, the more fat burned
– Advocate full body workout(s): dancing, swimming, biking,
jogging, yoga, weightlifting, brisk walking, sports
Fat Fuel
 Rate
of fat use
– Dependent on concentration of fatty acids
in the bloodstream
 Prolonged
exercise >>20 min
– Fat becomes main fuel source
 Intense
activity (e.g. sprinting)
– Fat is not a major source of fuel
– Requires more oxygen for aerobic
breakdown (than glucose)
Protein—Minor Source of Fuel
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During rest and low/moderate exercise
– Provides 2%-5% of energy needs
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During endurance exercise
– Provides 10%-15% of energy needs
Branched-chain amino acids provide most
of the energy (Leu, Isoleu, Val)
 Resistance exercise uses protein less
 Average diet
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– Provides ample amount of these amino acids
– Supplements not needed (usually)
Fuel Use During Physical Activity
Calorie Needs
Individual needs vary
 Monitoring weight and body fat
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– If weight falls, increase intake
– If body fat increases, cut back in fat
(& kcal) and maintain activity
Desirable body fat for male athletes:
5%- 18%
 Desirable body fat for female athletes:
17%-28%
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Carbohydrate Needs
Main fuel for many types of activity
 Consume ~60% of total kcal from
carbohydrate
> 5 gm of carbohydrate/kg body weight
 Aerobic and endurance athletes
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– 7-10 gm carbohydrates/kg body weight
– ~ 500-600 gm of carbohydrates/day
Carbohydrate Loading
 Events
lasting longer than 60-90
minutes
 Maximize glycogen stores
 Tapering of exercise while
increasing carbohydrate intake
 Additional water weight
Carbohydrate (CHO) Loading
Days
Before
Competition
6
5
4
3
2
1
Exercise
Time
60
40
40
20
20
rest
CHO
(grams)
450
450
450
600
600
600
Fat Needs
 ~35%
of total kcal (runner, otherwise
much less . .
 Rich in monounsaturated fats
 Limit saturated fats
 Limit trans fat
Protein Needs
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Recommend 1.0 - 1.6 gm protein/kg body weight
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Up to 1.7 gm/km body weight for athletes beginning
strength training
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Needs are easily met by a normal diet ~ sort of
– Major Protein supplements are not necessary unless
attempting to build muscle mass (protein shakes)
– Excessive protein has not been shown to be beneficial
Current Protein Recommendations
Vitamins and Minerals
 Vitamin
E and C
– Slightly higher needs
– Antioxidant properties
Vitamin C
 Thiamin,
riboflavin, vitamin B-6, potassium,
magnesium, iron, zinc, copper, and
chromium needs
– May also be higher (role in metabolism or
sweat)
 Increase
intake of fruits and vegetables
Iron Needs
 Iron
deficiency affects performance
 Sports anemia
– Increase in plasma volume but not RBCs
 Women
at risk because of
menstruation
 Focus on iron-rich foods
 Use of iron supplement may cause
toxic effects
Calcium Needs
 Restriction
of dairy products by
women – not good (yogurt, cheeses)
 Irregular menstruation/Amenorrhea
– Severe bone loss and osteoporosis
– Extra calcium does not compensate for
effects of menstrual irregularities
– Compromises bone health
 Calcium
deficiency increases risk of
stress fractures
Challenge Question
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What can the female athlete do to her diet
and physical activity level to reestab. Monthly
mensus?
Fluid Needs
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Needs of average adults
– 9 cups per day for women
– 13 cups per day for men
Athletes need more (depending on sweeting
 Maintenance of body’s cooling system
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– Water helps dissipate heat from working muscles
Avoid losing more than 2% of body weight
during exercise
 For every 1lb. lost replace 2.5-3 cups of fluid
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Confirming your knowledge -Break
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What are the recommended levels of
protein in g/kg/body wt. for athletes?
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What are the recommended additional
vitamin antioxidants required for athletes?
Heat Exhaustion
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Heat stress causes depletion of blood volume due
to fluid loss
Body heat is dissipated through evaporation of
sweat (fluid)
Fluid loss (sweat): ~3-8 C per hour
Humidity interferes with sweat production
Dehydration decreases endurance, strength,
performance
Signs: Profuse sweating, headache, dizziness,
nausea, weakness, visual disturbances
Heat Cramps
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Frequent complication of heat
exhaustion
– Exercising in heat
– Significant sweating
– Consuming water without sodium
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Painful muscle contractions
– 1-3 minutes at a time
Ensure adequate salt and fluid intake
 Exercise moderately at first in the heat
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Heat Stroke
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High blood flow to working muscles
– Overloads body’s cooling system
– Sweating ceases
– Internal body temperature reaches 104° F
– Fatality rate high
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Symptoms:
– Nausea, confusion, irritability, poor
coordination, seizures, coma
Replace fluids
 Monitor weight change (fluid loss)
 Avoid exercising in hot humid conditions
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Sports Drinks For
Endurance Exercise
 Recommended
for activity > 60 minutes
– Help maintain blood glucose level and blood
volume
– Delay “bonking”
 Supply
 <60
electrolytes: Na, K, P, Cl
minutes: Water adequate:
– Nutrients are easily replaced by diet
Gels and Bars
 Provide
additional fuel
 Should be taken with fluids
 Expensive source of nutrients
 Ideal bars for endurance athletes
– Contain 40 gm carbohydrate, 10 gm of
protein, 4 gram fat, 5 gm of fiber
– Fortified with vitamins and minerals
– Toxicities possible with overuse
Content of Energy Bars and Gels
Confirming your knowledge
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After what duration of exercise are Sports
drinks considered necessary for replenishment
of glucose and electrolyte stores?
Pre-Endurance (running) Event Meal
Light meal 2-4 hours prior to event
 Consisting primarily of carbohydrate (top
off glycogen stores)
 Low fat (<25% of energy intake)
 Little fiber (prevent bloating, gas)
 Moderate protein
 Avoid fatty, fried foods
 Blended or liquid meal recommended for
meals eaten 1-2 hours prior
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Recovery Meal
 Carbohydrate-rich
meal within 2
hours after endurance event
– Glycogen synthesis is the greatest
– 1-2 gm CHO/kg body weight
 Choose
high glycemic index foods
 Aim for 3:1 carbohydrate-to-protein
 Fluid and electrolyte replacement
Replenishing Muscle Glycogen
Availability of adequate carbohydrate
 Ingestion of carbohydrate soon after
exercise
 Selection of high-glycemic-load
carbohydrate
 Combination of carbohydrate and protein
foods
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Nutrition: Fitness/Sports Summary
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Aerobic zone for Fat burning, 120-130 BPM
– Brisk walking, jogging, dancing, warrior yoga,
– Stationary bike, treadmill, elliptical, (talk test)
~60% carbohydrate diet if athlete
 Eat simple sugar before workout (fruit, drink etc.)
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– Maximizes fat metabolism
More PROTEIN: Athletes req. 1.0-1.7 g/kg/bdy wt. /day
 Vit C and E beneficial (oxidative stress)
 Weightlifting: focus on the eccentrics. . . Best stimuli
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Challenge Question>
What is an ergogenic aid?
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And what are some examples?
Ergogenic Aids
Ergogenic Aids
Steroid Hormones
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Among the synthetic anabolic steroids are:
H3 C CH3
OH
H3 C
H3 C
H3 C
O
OH
CH3
O
Me th an di en on e
Me th en ol on e
Why are these hormones of interest?
Do steroids really work? i.e. improve
muscle mass
and performance? . . .
H3 C O
H3 C
O
4-An droste n e-3,17-di on e
H3 C OH
A resounding Yes . . .
H3 C
H3 C
O
H3 C
HO
Testosteron e
And rosterone
Hydroxycut recall
MAY 2009
The FDA has received 23 reports of serious liver injuries,
including a death, linked to Hydroxycut products.
SUSPECTED CULPRIT  hydroxycitric acid (HCA)
1 medical study shows associated liver toxicity
Laboratory and animal studies of HCA
have produced results that indicate a potential
for modulation of lipid metabolism
hydroxycitric acid
Shara et al., 2003, Mol. Cell. Biochem. 254 (1-2): 339–46
Nutrition: Fitness/Sports Controversies
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Any Additional Ergogenic aids????
Best natural/safe muscle building: Creatine
– Add to estab. resistance training routine, not an anabolic!
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Hydroxycut recall
Acai?
5 hour energy drinks?
Rely on your own case study?
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Little scientific data to back up claims. . .
Try out a scientific lit. search??? Folklore/Fad  Added Fitness???
Use at own risk, < upper limit
Maybe toxic, maybe ok?
Try for min. 6 weeks?, evaluate