Transcript Introduction to Sports Nutrition

Ema Thake
Sports Nutrition Intern
University of Utah
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Strengthens bones and joints
Reduces blood pressure
Improves blood glucose regulation
Increases cardiovascular function
Aids in weight loss/control
Increases muscle mass/strength
Slows aging process
Improves sleep habits
Improves immune function
And the list goes on…
• 150 minutes/week of moderate –intensity or 75 minutes/week
of vigorous-intensity aerobic exercise
• Additional health benefits are gained by engaging in
physical activity beyond this amount
• Perform muscle-strengthening activities that involve all major
muscle groups
• 2 or more days a week
• Aerobic – with oxygen
• Endurance activities
• Anaerobic – without oxygen
• Short duration, high intensity activities
• To consume food and beverages appropriate to delay fatigue
during training and competition
• To consume enough fluid to minimize dehydration during
physical activity
• Use strategies that are known to be beneficial for performance
• Fueling prior to exercise
• Fueling during exercise
• Appropriate combination of energy and nutrients
• Nutrient dense food and beverages
• Provides vitamins and minerals with relatively few calories
• Dietary fiber
• Whole foods are all nutrient dense when prepared without fats and
sugars
• Energy Intake:
• Energy required to maintain energy balance
• Adjustments made to energy intake
• Carbohydrate Intake:
• 6-10 grams/kg/day depending on sport, gender, and training
• Appropriate timing of carbohydrate intake
• Protein Intake:
• 1.2-1.7 grams/kg/day depending on sport, gender, and training
• Appropriate timing of protein intake
• Fat Intake:
• Typically 1.0-2.0 grams/kg/day (25-30% total calories)
• Emphasis on healthy fats
• Vitamins and Mineral Intake:
• Meet the DRI
• Intake of nutrient dense foods
• Fluid Intake:
• Match fluid replacement with fluid loss
• Other:
• Maintain an appropriate body composition
• Practice healthy weight loss practices
• Avoid disordered eating patterns
• ATP
• High energy compound generated via carbohydrate, protein,
and fat catabolism
• Chemical energy
• Used by cells for muscle contractions
• Only small amount is stored in resting cells
• 2-4 seconds worth of work
• Other sources of energy are needed
• Temporary storage of glucose in liver and muscle
• Muscle glycogen
• Used only by that muscle
• Liver glycogen
• Released into bloodstream
• “Bonking” or “Hitting the wall”
• Depleted glycogen
• Three energy systems used in ATP production:
• Creatine Phosphate
• Anaerobic Glycolysis
• Oxidative Phosphorylation
• Each system depends on the intensity and duration of the
activity
• Each systems determines what substrate is used for the activity
(i.e. creatine, carbohydrate, fat or protein)
• Although one system predominates for specific activities, all
three systems are used to some extent at all times.
• Substrate used is creatine
• System lasts approx. 5-10 seconds and is anaerobic
• Short, fast sprints
• 100 m sprint
• Short, powerful bursts of energy
• Shot punt
• Dunking a basketball
• Activities requiring large amounts of force
• Heavy weight lifting
• Substrate is carbohydrate
• Lasts approx. 1-2 minutes and is anaerobic
• Sustained sprints
• 400m
• Repeated high intensity sprints
• Soccer
• Basketball
• Repeated high force activities
• 10-15 reps of lifting weights
• Regular, repeated intervals
• 50-100m swimming intervals
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Can use carbohydrate, fat and protein as substrates
Occurs in the mitochondria
Aerobic
Long lasting energy system
Fatigue associated with glycogen depletion
• Carbohydrate and fat are preferred energy sources
• Protein is the least desirable energy source
• Fat is primary source at rest (85%)
• Carbohydrate is primary source for moderate to hard exercise
• As exercise intensity increases, % energy from fat decreases
• Respiratory exchange ratio (RER) can be used to determine the
proportion of carbohydrate to fat being oxidized.
• Ratio of O2 consumed to CO2 produced
• In fed state:
• Glucose is used for immediate energy
• Extra glucose is stored as glycogen for future use
• Fat is stored for future use
• Non-fed state:
• Glycogen from the liver is broken down to provide glucose
• Fat is released from storage and used as energy source
• ~60% of total kcal from carbohydrate
• Variety of foods important
• Whole grains
• Fruits
• Vegetables
• Primary fuel for exercise
• Stored as glycogen:
• Muscle glycogen
• Liver glycogen
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Amount of stored glycogen is dependent on diet and training
Stores must be replenished daily
Glycogen depletion leads to muscle fatigue
> 5 gm of carbohydrate/kg body weight
• Minimum amount needed to replenish stores
• Aerobic and endurance athletes
• 7-10 gm carbohydrates/kg body weight
• Pre-exercise meal should be low in fat and fiber, high in
carbohydrate, moderate in protein
• 1 gram/kg/hour prior to exercise
• Ex: 2 hours before exercise, eat 2 grams/kg of carbohydrate
• Recommended to consume carbohydrate AT LEAST 3-5 hours
before exercise
• Always recommended if no access to CHO during exercise
• Snacks (1-2 hrs prior):
• Jelly on whole wheat
bread
• Milk and cereal
• Yogurt with fruit
• Meals (3-5 hrs prior):
• Pasta with marinara sauce,
green beans and low fat
milk
• A muffin and fruit smoothie
• Turkey sandwich with
whole wheat bread and
orange juice
• Beneficial for endurance activities lasting > 60 minutes
• Delays fatigue and time to exhaustion by sparing and
maintaining adequate glycogen stores
• Recommended 45-60 grams CHO per hour after the first hour
of exercise
• Can be in the form of food or sports drinks
• Ideal environment for restoring glycogen
• Greatest amount of resynthesis occurs in the first hour after
exercise
• Recommendations:
• Consume 50-70 grams of CHO as soon as possible after exercise
• Small, frequent CHO containing meals
• Addition of protein
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Cottage cheese with fruit
Bagel with peanut butter
Chocolate milk
Crackers and cheese
½ sandwich with turkey or peanut butter
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Not beneficial in events < 60-90 minutes
Can postpone fatigue by 20%
Goal is to maximize glycogen stores
Tapering of exercise while increasing carbohydrate intake
• Provides energy at rest and during low intensity exercise
• More energy dense than carbohydrate or protein
• 9 kcal/gram
• ~35% of total kcal is appropriate for general population
• Diet should be rich in monounsaturated and polyunsaturated
fats
• Avocado
• Olive oil
• Nuts
• Limit saturated fats
• Lard
• Butter and cream
• Coconut oil
• Limit trans fat
• Grilling and steaming are preparation methods that do not
require additional fat
• Tissue growth, hormones, enzyme, and immune system response
• Found in both plant and animal foods
• Animal proteins = complete protein
• Plant proteins = incomplete proteins
• Exception is quinoa
• Needs are easily met by a normal diet
• Protein supplements are not necessary
• Excessive protein has not been shown to be beneficial
• NOT preferred energy source during exercise
• Prolonged endurance exercise results in catabolism of some
protein for energy
• Recommend 0.8 - 1.7 gm protein/kg body weight
• Up to 2.0 gm/km body weight for athletes beginning strength training
• Take advantage of the “anabolic window”
• 10-20 grams within 30-60 minutes of completing exercise
• Post-exercise snacks should also include 50-70 grams of
carbohydrate
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Cottage cheese with fruit
Bagel with peanut butter
Chocolate milk
Crackers and cheese
½ sandwich with turkey or peanut butter
• Water is an essential nutrient
• Excessive water loss could be detrimental to performance and
health
• Important to maintain body water
• Average 42 L for males
• Average 30 L for females
• Tissues containing body water:
• Muscle – 75.6% water
• Liver – 68.3% water
• Euhydration
• Under normal conditions, water balance maintained
• Hyperhydration
• Kidneys respond by increasing urine output
• Drinking large amounts
• Cause cells to swell and function is impaired
• Hypohydration
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Body fluid below normal levels
Inadequate intake, excessive loss or both
Cells shrink and function is impaired
Affects thermoregulation --- performance and health
• Fluid balance easily regulated under normal conditions
• Exercise disrupts fluid balance
• Increases body temperature
• Increases fluid loss via sweating
• Becomes difficult to match fluid intake with fluid loss
• Fluid replacement during exercise can be difficult
• Dehydration due to inaccurate thirst mechanism
• Rate of absorption is limited
• Performance suffers when fluid losses equal 2% body weight
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Important for maintaining hydration
Balance regulated by the renal system
Lost in large amounts via sweat during exercise
Sodium increases voluntary fluid intake and increases fluid
absorption
• Sources:
• Food
• Beverages
• Salt tablets – insufficient evidence regarding exercise
• Weight loss during exercise
• Weigh before and after
• Thirst
• Urine color
• Prior to Exercise:
• Adequate hydration
• 5-7 ml/kg at least 4 hours prior to exercise if adequately hydrated
• During Exercise:
• Goal is to replace fluid lost and maintain fluid balance
• After Exercise:
• 150-200%
• 2-3 cups for every pound lost
• 1.5 L for each kg body weight lost
• Appropriate for exercise lasting > 60 to 90 minutes
• Contains carbohydrate and electrolytes
• Sodium
• Potassium
• Chloride
• Enhances absorption due to sugar and sodium content
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Extremely low plasma sodium concentrations (<135 mmol/L)
Symptoms similar to dehydration
Confusion, seizures, coma, death
Prevention:
• Avoid overconsuming water during exercise
• Replace sodium that is lost in sweat
• Fat soluble
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ADEK
Absorbed into lymph
Stored in liver and adipose
Deficiencies slow to develop, toxicity more likely
Daily intake not critical
• Water soluble
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B vitamins and vitamin C
Dissolve in water
Absorbed into bloodstream
Excess excreted in the urine
Deficiencies rapid to develop, toxicity less likley
Daily intake important
• Factors that increase needs:
• Increased loss in sweat or urine
• Decreased absorption
• Increased enzymes used in protein synthesis
• Factors that decrease needs:
• Decreased urine excretion
• More effective recycling (vitamin C)
• Vitamins are essential for biochemical pathways in the body
• Athletes can easily reach DRI by consuming whole foods
• Supplementation not necessary unless deficiency is present
Thank you!
• Dunford M and J. Andrew Doyle. Nutrition for Sport and
Exercise.
• Gordon M. Wardlaw, Anne M. Smith, Angela L. Collene.
Contemporary Nutrition: A Functional Approach. Third Edition.