Nutrition for Sports and Performance Ema ThakeSports Nutrition Intern University of Utah

Benefits of Physical Activity • 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…

2008 Physical Activity Guidelines for Americans • 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

Types of Exercise• Aerobic – with oxygen• Endurance activities

• Anaerobic – without oxygen• Short duration, high intensity activities

Nutritional Goals• 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

Healthful Diet• 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

Basic Guidelines for Sports Nutrition• 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

Basic Guidelines for Sports Nutrition • 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

Energy for Physically Active Bodies • 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

Glycogen • 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

Energy Systems• 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.

Creatine Phosphate System• 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

Anaerobic Glycolysis • 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

Oxidative Phosphorylation • Can use carbohydrate, fat and protein as

substrates• Occurs in the mitochondria• Aerobic • Long lasting energy system • Fatigue associated with glycogen depletion

Substrate Utilization• 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

RER for Carbohydrate

RER for Fat

Carbohydrate, Fat, and Protein Metabolism • 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

Carbohydrate • ~60% of total kcal from carbohydrate• Variety of foods important•Whole grains• Fruits• Vegetables

Carbohydrate and Exercise • Primary fuel for exercise • Stored as glycogen:• Muscle glycogen• Liver glycogen

• 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

Carbohydrate Before Exercise• 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

Pre-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

Carbohydrate During Exercise • 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

Carbohydrate After Exercise • 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

Post-Exercise Snacks • Cottage cheese with fruit• Bagel with peanut butter• Chocolate milk• Crackers and cheese• ½ sandwich with turkey or peanut butter

Carbohydrate Loading • 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

Fat • 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

Fat• 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

Protein• 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

Protein and 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

Protein Intake Post-Exercise• 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 • Cottage cheese with fruit• Bagel with peanut butter• Chocolate milk• Crackers and cheese• ½ sandwich with turkey or peanut butter

Fluids and Electrolytes • 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

Fluid Balance and Imbalance • 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• Body fluid below normal levels • Inadequate intake, excessive loss or both• Cells shrink and function is impaired• Affects thermoregulation --- performance and health

Fluid and Exercise • 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

Electrolytes• 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

Assessing Hydration • Weight loss during exercise• Weigh before and after

• Thirst• Urine color

Symptoms of Dehydration

Fluid Replacement • 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

Sports Drinks • Appropriate for exercise lasting > 60 to 90

minutes• Contains carbohydrate and electrolytes• Sodium• Potassium• Chloride

• Enhances absorption due to sugar and sodium content

Hyponatremia • 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

Vitamins and Minerals • Fat soluble• ADEK• Absorbed into lymph• Stored in liver and adipose • Deficiencies slow to develop, toxicity more likely• Daily intake not critical

• Water soluble• 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

Vitamins and Exercise • 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 and Exercise • 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!

Questions?

Resources• 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.