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Review
• What are our major fuel sources?
• What are your energy sources besides already made ATP? (How do you make ATP?)
• In what situations does one fuel source dominate over the other?• Anaerobic?• Aerobic?
Carbo Loading
Fat
• Provides energy for low to moderate intensity exercises
• Aim for a diet containing 20% to 30% of energy from fat.
• Low fat diets can lead to nutrient deficiencies.
• Limit intake of saturated fat
• Healthy sources of fat: fish, nuts, nut oils, seeds, vegetable oil.
Protein
• Lean muscle mass (fat free mass)
• Adult RDA: 0.8 g/kg a day
• Heavy training athletes: 1.2 to 1.4 g/kg a day.• Lance Armstrong might need 2 g/kg
• Athlete consuming 1.4 g/kg of protein synthesize more body protein than someone consuming 0.9 grams• However, study have shown that when intake was
increased to 2.4, there was no increase in protein synthesis.
• Do not need protein powder and supplements• High quality protein food: legumes, low-fat dairy products,
egg whites, lean beef and pork, chicken, turkey, and fish• Vegetarians: grains, nuts, and beans (amount consumed
must be higher)
Protein
Protein Intake
• When is the best time for protein intake?• After exercise (immediately after or within 1
hour)• Protein with CHO helps with glycogen
resynthesis• 1:3 ratio of protein to CHO• Stimulate muscle growth via insulin and growth
hormones
Excessive Protein Intake
• Excess protein is excreted in the urine.
• Dangerous!
• Enhances diuresis• Body excretes excess nitrogen through urine
• Dehydration
• Mineral Deficiencies
Fluids
• Exercise: generate heat => increases heat production => triggers body to sweat (cool the body)
• To prevent body from overheating: blood must flow to skin, sweat can dissipate heat.
• During exercise, demand for blood flow can compete with cardiovascular demand for blood to deliver fuel to muscles.• Important to keep hydrated during heavy exercise.
• Fluid requirements are variable• Intensity of exercise• Climate• Intrinsic sweat rate
Electrolyte Balance
• Sodium and Potassium
• Sweating (loss of water) disrupts electrolyte balance
• Loss of sodium and chloride
• Electrolytes are needed for long duration exercise
• If not replaced through sports drinks, then must be replaced through the diet.
Hydration is key!
• Exercise can decrease thirst, so drink fluid as often as you can.
• Keeping hydrated prevents dehydration and optimizes performance
• ACSM recommends:• 2 to 3 cups of water 2-3 hours before exercise• Maintain fluid balance during exercise (6 to 12 ounces every 15
to 20 mins)
• Activities < 60 min: Water
• Activities > 60 min: Sports drink (CHO and sodium)
• Drinking too much can cause hyponatremia
• Avoid beverages with alcohol or caffeine - diuretics
Michael Phelps’ Diet
B Vitamins
• Essential for energy metabolism
• Usually not a problem if athlete consumes adequate calories and complex CHO, fruits, and vegetables.
• But is a problem if consume few calories and eat mostly refined sugar.
• Vegan athletes need to consume more fortified foods.
Calcium
• Important for bone health, blood coagulation, muscular contraction
• Important for athletes because calcium is lost in the sweat and urine
• Intake is typically lower in females than males
• Individuals who exercise and have high sweat rate may require intake higher than DRI
• Factors that can inhibit Ca absorption• High protein and sodium diets• Phytates and oxalates
Iron• Important for oxygen delivery (hemoglobin) and energy
production.• Oxygen delivery to muscle cells
• Female athletes are at greatest risk of iron deficiency.
• Heavy training athletes may need 30 to 70 percent more iron than nonathletes.
• Sports anemia• Lower concentration of hemoglobin in the blood.• Increased plasma volume.
• Anemia can impair physical activity, but mild iron deficiency has little effect on performance.
• Few athletes are anemic but many have mild iron deficiency.
Energy Drinks
Energy Drinks
• Adolescent and Middle aged population consumption from 2001 to 2008:• Estimated about 24% to 56%
• Conflicting data on impact of energy drink on weight loss
• Ingestion of energy drinks before or during training causes restlessness, raises blood pressure, and can promote dehydration.
• Dependence?
• Study on sprinters showed that Red Bull had no adverse or beneficial effects.
• Combination of energy drink with alcohol is a safety concern.
Energy Drinks
Sports Drinks
• Hydration for athletes
• Electrolytes and Carbohydrates
• Isotonic – salt and sugar concentrations are similar to what’s in the human body.
• Prevents water intoxication
• Recommended for sports > 1 hour
• Hot and humid conditions
Gatorade
• First developed in 1965 by researchers in University of Florida
• Named after the Florida Gators
• Salt, sugar, water
• 1990s and early 2000s, Gatorade was sweetened using high fructose corn syrup
• 2011 – sweetened with sucrose-dextrose
• Lower calories option – PureVia
• Recommended that Gatorade be diluted with water due to sugar content.
Pickle Juice
• Juice that’s leftover from your pickles!
• High in sodium
• Claims• Reduces muscle cramping
• Scientifically proven?
• Pickle juice relieved cramps 45% faster than drinking nothing and 37% faster than water alone
• Vinegar is thought to trigger a reflex in the mind to relax the muscle.
Pickle Juice
Caffeine
• Natural stimulant
• Increase fat break down for energy
• One study showed subjects with high caffeine intake one hour before exercise used less glycogen.
• Lower levels of caffeine intake (5-6 mg/kg) have ergogenic effects and produce urine levels less than IOC limits.
Caffeine
Energy Bars
• Bars that contain cereal and energy
• Provide quick food energy
• Typical energy bar supplies about 200-300 calories
• 20-30 g of carbs, 8-10 g of protein
Carnitine
• Natural compound in food
• Synthesized in liver and kidney from lysine and methionine.
• Transport long-chain fatty acids into the mitochondria.
• Claims:• Increases use of fatty acids for fuel• Decrease body fat• Increase endurance
• Studies have shown that carnitine supplementation does not alter muscle use of fatty acids.
• Exercise increases carnitine excretion in the urine, but supplemental carnitine does not benefit athletes.
Creatine
• Nitrogenous compound found in meats and fish.
• Popular supplement
• Prolong short term energy availability (weightlifting)
• Studies have shown improvements in muscle strength with creatine supplementation.
• May improve explosive power needed for sprinting.
• No benefit for aerobic training.
• Weight gain due to water retention.
Whey Protein
• By product of cheese
• Increases nitrogen retention, promotes positive nitrogen balance.
• Claims:• Greater nitrogen retention• Greater muscular gains
• Increases glutathione level
• Does not appear to increase muscle mass in athletes
Pyruvate
• Enhances endurance
• Animal studies: enhanced aerobic endurance capacity.
• Mechanism is unclear
• Increases blood glucose concentration• Spares muscle glycogen
• In trained athletes, pyruvate has no beneficial effects on anaerobic exercise.
• Associated with GI distress
• More research is necessary.
Ephedra
• Ma Huang – herb used in Chinese medicine for 5,000 years.
• Originally for nasal decongestant and treatment of bronchial asthma.
• Active ingredients:• Ephedrine and pseudoephedrine
• Claims:• Improves athletic performance• Promotes weight loss
• Banned by IOC and NCAA
Resources
• http://www.uhs.wisc.edu/docs/uwhealth_sportsnutrition_176.pdf
• American Dietetic Association• http://www.eatright.org/public/content.aspx?
id=7055