Fundamentals of Exercise for Nutrition

By Jennifer Turley and Joan ThompsonBy Jennifer Turley and Joan Thompson

© 2013 Cengage© 2013 Cengage

Presentation Overview• Fuel and Utilization During Exercise• Carbohydrates

– Carbohydrates in the Body and Diet

– Carbohydrate Management for Enhanced Exercise Performance

– Recovery Nutrition after Exercise

• Proteins– Proteins in the Body and Diet

– Protein Management for Enhanced Exercise Performance

• Fats– Fats in the Body and Diet

– Fat Management for Enhanced Exercise Performance

• Thermal Regulation and Hydration– Understanding and Controlling Body Temperature

– Dehydration to Hydration

Fuel Utilization During Exercise• ATP production is primarily from carbohydrate and

fat

• As the intensity of the exercise increases, the percent of carbohydrates used to produce ATP increases

• Nutrition supplies the substrate or fuel (carbohydrate, fat and protein) and the essential structural components of enzymes (cofactors) needed to drive chemical reactions to generate ATP through: – Glycolysis

– The citric acid cycle

– The electron transport chain.

ATP energy production through glycolysis, the citric acid cycle, and the electron transport chain

Carbohydrates

• The objectives of dietary carbohydrate management is to maintain blood sugar and replete muscle glycogen

• Carbohydrate as fuel supports high intensity exercise

• Carbohydrate are limited in the body

Carbohydrates in the Body and Diet

• Blood Glucose– 4.5 grams of glucose total– Constantly used by RBC and CNS

• Liver Glycogen– 75 (to 100) grams when repleted– Used to maintain blood glucose

• Muscle Glycogen– Amount of exercise and dietary

carbohydrate intake determines the amount– Used to produce ATP in the muscle during

exercise

Carbohydrate Management for Enhanced Exercise Performance• Diet and exercise influence glycogen stores in

the muscle.– High carbohydrate intake (7-10 gm/Kg/day)

– 60-65% of Calories from carbohydrate

• The timing of the carbohydrate intake in relation to exercise is important:– Prior to the Exercise (4 hours before or 2 hours

before and 5-10 minutes before)

– During the Exercise (about every 15 or 20 minutes)

– After the Exercise (immediately after and again 2-6 hours later)

The timing of carbohydrate intake for exhaustive athletic performance

Timing and Amount of Intake

68 Kg Exchange List Pattern 68 Kg Food and Beverage Options for Exchange List Patterns

4 hours prior4 gm/kg1.82 gm/lb

10 starch5 fruit3 other carbohydrate

2 cups pasta (90 g)1 bagel (60 g)1 cup juice (45 g)1 cup fat-free frozen yogurt (45 g)1 large banana (30 g)(270 g total)

2 hours prior2 gm/kg0.91 gm/lb

6 starch3 fruitexchanges

1.33 cups pasta (60 g)2 slices of bread (30 g)1 cup juice (45 g)(135 g total)

5-10 minutes prior0.5-1 gm/kg0.23-0.45 gm/lb

2-4 other carbohydrateExchanges

1-2 low-fat sport bars (2 ounce size) or the equivalent of 2-4 tablespoons of sugar(34-68 g total)

During 60 gm/hr

2-4 other carbohydrateexchanges/hour

A six percent glucose electrolyte replacement solution provides about 15 grams of carbohydrate per cup of fluid (1 tablespoon of sugar and ¼ teaspoon of salt per one cup water, drink 2-4 cups per hour)

Immediately afterCarbs: 1.65 gm/kg or 0.75 gm/lbProtein: 0.55 gm/kg or 0.25 gm/lb

7 starches, 3 meats Or2 milk, 2 fruit, 4 starches, 2 meats Or1 milk, 2 fruit, 4 starches, 3 meat

2 cups low-fat milk (24 g carbs, 16 g protein)2 cup ready-to-eat cereal (60 g carbs, 12 g protein)4 tablespoons raisins (30 g carbs)2 egg whites (14 g protein)(114 grams of carbohydrate and 42 grams of protein total)

2-6 hours afterCarbs: 1.65 gm/kg or 0.75 gm/lbProtein: 0.55 gm/kg or 0.25 gm/lb

5 starches, 2.5 vegetables, 3 meats, 2 fruits or similar to immediately after meal

3 ounces chicken (21 g protein)1 large baked potato (60 g carbs, 12 g protein)1.25 cups cooked broccoli (12 g carbs, 5 g protein)1 small roll (15 g carbs)1 large pear (30 g carbs)(117 grams of carbohydrate and 38 grams of protein)

Recovery Nutrition after Exercise

• Muscle glycogen repletion begins immediately after the exercise and prepares the energy stores for the next workout!

• Consuming meals that provide the combination of carbohydrate and protein at a three gram to one gram ratio promotes muscle glycogen repletion

Proteins• Athletes require more protein to stay in

nitrogen balance as compared to individuals who are meeting their DRI for physical activity

• The range is 1.2 to 1.6 grams of protein per kilogram of body weight

• To support lean body mass gains, a strenuous weight-lifting program, 1.6 grams of protein per kilogram of body weight and a positive energy balance of 200 Calories is needed

• High quality or the complement equivalent is needed for 2/3 of the protein consumed

Fats• The dietary fat recommendations made to the

athlete are the same that support health and meet the DRIs

• Consume low-fat foods prior to exercise and a low-fat (20-25% of Calories) diet in general

• Adding MUFAs may be the best choice of fats if weight gain is desired

• MCT have been touted to be useful during exercise, but not proven, however, they are useful for malabsorption syndromes due to their direct absorption into the blood stream

Thermal Regulation and Hydration

• The ability to keep the body cooled during exercise is key to exercise capacity and avoiding injury.

• A lot of heat is generated in the body due to the inefficiencies of energy transfer to make ATP.

• Sweating creates the evaporative cooling system employed during exercise to keep the core body temperature in a functional range.

Understanding and Controlling Body Temperature

• The core body temperature rises during exercise

• If the core body temperature >104oF, exercise capacity diminishes and risk of thermal injury increases

• Fluid, salt, and other components are lost in sweat during exercise – about a liter of fluid per hour of exercise, and 2.6 grams of salt per liter

• Salt (NaCl) is 40% sodium, ½ t salt replaces the sodium lost in 1 hour of vigorous exercise

Dehydration to Hydration

• The fluid lost in sweat comes from the blood stream

• The plasma volume is the fluid reserve for sweat

• This is why there is such large deterioration in aerobic exercise capacity due to dehydration

Dehydration to Hydration

• The sensation of thirst signifies 2% dehydration, cardiovascular and aerobic function is reduced.

• 5% dehydration, serious thermal injury risk.• The body can absorb 1 liter of fluid per hour.• Replacing fluids (cool, dilute, small, and

frequent amounts) during strenuous exercise is important:– 1 cup at 41oF, every 10-15 minutes– Drink without thirst to avoid dehydration

Hydration Happy and Dehydration Demise

Importance of hydration during exercise

Cardiovascular demise during dehydration

Optimize muscle strength Optimize aerobic capacity Prevention of thermal injury

which include dizziness, cramping, fainting, heat exhaustion and heat stroke

Pool of fluid to draw upon for sweat loss is the blood stream.

The cardiovascular system is affected dramatically by fluid losses.

Plasma volume decreases Osmolarity of the blood

increases Blood pressure goes down. Constriction of the blood

vessels Increase in heart rate Decrease in heart filling Decrease in cardiac output Decreased sweating Increase in core body

temperature

Summary• Fuel and hydration management are so

influential on exercise capacity.• As the intensity of the exercise increases, so

does the percent of carbohydrate used to produce ATP.

• Carbohydrate stores in the body are limited.• Dietary carbohydrate intake before, during,

and after exhaustive exercise can enhance exercise performance.

• A combination of carbohydrate and protein (3:1 ratio) consumed after exercise can support muscle glycogen repletion.

Summary

• The protein needs of most competitive athletes range between 1.2 to 1.6 grams of protein per kilogram of body weight per day.

• A low fat diet that provides all of the essential fatty acids in adequate amounts can support most athletic endeavors.

• Adequate hydration from fluid and salt intake is important for aerobic performance and avoiding thermal injury.

References for this presentation are the same as those for this topic found in module 4 of the textbook