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