sports nutrition: the power to influence exercise performance · the power to influence exercise...

Sports Nutrition:The Power to Influence Exercise

PerformanceMay 21, 2014

Presenter:

Kristine Clark, PhD, RD, FACSMDirector, Sports Nutrition; Assistant Professor

Penn State UniversityModerator:

James M. Rippe, MD – Leading cardiologist, Founder and Director, Rippe Lifestyle Institute

Approved for 1 CPE (Level 2) by the Commission on Dietetic Registration, credentialing agency for the Academy of Nutrition and Dietetics.

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Today’s Faculty

Kristine Clark, PhD, RD, FACSMDirector, Sports Nutrition; Assistant ProfessorPenn State University

Moderator:James M. Rippe, MD – Leading cardiologist, Founder and Director, Rippe Lifestyle Institute

Learning Objectives

After the webinar the participant will be able to: State why carbohydrate rich foods are optimal for athletic

performance and how they play a role in exercise recovery State how macronutrients are used during low, moderate, and

long duration exercise and what foods to recommend based on how someone exercises

Describe the role protein plays in recovery from exercise and how much protein an exerciser needs

Identify optimal fluids a physically active person could drink before, during, and after exercise

Identify strategies to share sports nutrition messages with exercisers

NUTRI-BITES®

Webinar Series

Kristine Clark, PhD, RD, FACSMDirector of Sports Nutrition

Assistant Professor of Nutritional SciencesIntercollegiate Athletics

Penn State University

Sports Nutrition: The Power to Influence Performance

Objective 1

State why carbohydrate rich foods are optimal for athletic performance and how they play a role in recovery.

Nutrient-Related Fatigue

Fatigue is the inability to maintain a given or expected force or power output.

Blood glucose levels fall.

Level of fatty acids in the blood increases.

Proteins provide an increased contribution to energy.

Exercise capacity progressively decreases.

Presenter

Presentation Notes

The reduced power output level comes directly from the relatively slow rate of aerobic energy release from fat oxidation, which now becomes the primary energy source. Severely lowered levels of liver and muscle glycogen during exercise induce fatigue, despite sufficient oxygen availability to muscles and almost unlimited potential energy from stored fat. Known as “hitting the wall.”

Main fuel sources for muscle

Sources of Carbohydrate during Exercise

Maintaining ATP levels in muscle is necessary for exercise

• Breakdown of 1 mole of ATP via myosin ATPase = 7 calories of free energy

• Muscles need both quick AND sustained energy

• Decrease in muscle ATP = fatigue

• Body has multiple mechanisms to prevent a fall in the level of ATP in muscle

Energy from Carbohydrates (CHO)

• Anaerobic and aerobic metabolism

Glycogen: ~ 1600-1800 calories stored in liver and muscles • Breakdown of 1 mole of

glucose makes 38 ATP (net 36 ATP)– Much less than fat, but

delivery of energy immediate

• Exercisers should start out with a full supply of glycogen – especially if exercise will last awhile

• Within 60 min. of exercise, glycogen in liver is depleted, 50% of glycogen in specifically exercised muscles is also depleted

• Within 2 hr of exercise – all glycogen is depleted – performance declines rapidly, exercise difficult to continue

Presenter

Presentation Notes

As exercise progresses muscle glycogen and liver glycogen stores gradually become depleted and fatty acids become a more significant fuel. During 90 min of strenuous exercise blood glucose could decrease to hypoglycemic levels Dietary carbohydrate and use of carbohydrates supplements during physical activity influence the rate of depletion of glycogen.

Energy from Fat: Aerobic Metabolism

• Triglycerides + 3 H20 = Glycerol and 3 fatty acids

– Beta-oxidation of fatty acid TCA cycle

– Glycerol glycolysis– 460 ATP

• We store 60-100,000 calories worth of fat in the form of triglycerides in adipose cells

Energy from Protein• We store protein as muscle and

organs• Difficult to determine precisely

how many calories to calculate in storage because we typically do not want to use these ‘stores”for energy sources

• Protein can be broken down to amino acids, deaminated, with specific amino acids joining pyruvate, acetyl CoA, or entering the Krebs cycle for formation of ATP

Fatigue Prevention = Carbohydrates

A carbohydrate-deficient diet rapidly depletes muscle and liver glycogen.

Low carbohydrate levels profoundly affect both anaerobic capacity and prolonged, high-intensity aerobic exercise.

When carbohydrates are low, exercise intensity decreases to a level determined by how well the body mobilizes and oxidizes fat.

Presenter

Presentation Notes

These observations pertain to both athletes and physically active individuals who modify their diets by reducing carbohydrate intake below recommended levels.

General Diet: Low vs. High-CHO

• Daily exercise need to replenish glycogen stores daily need adequate CHO daily

Timing of dietary CHO: 3-5 Hrs pre-competition/training

• GOAL: Ensure adequate liver glycogen and blood glucose levels

• Overnight fast depletes liver glycogen

• Eat ~700 calories mixed, CHO-rich meal to replenish liver glycogen stores

• Example: 150 g CHO, 80% of calories: 2 C cooked oatmeal with milk, 1 banana, 1 glass of orange juice

Timing of Dietary CHO: 30-60 min prior to exercise

• GOAL: To maintain adequate blood glucose and insulin levels

• Recommendations: drink sport drink, eat sport beans/gels, fruit, graham crackers

• Don’t want to begin exercise hungry but don’t want to eat full meal

Timing of dietary CHO: During exercise

• GOAL: Maintain adequate blood glucose level, spare muscle/liver glycogen and avoid gastric discomfort

• CHO intake during exercise >45 min. improves endurance & timeto exhaustion

Timing of dietary CHO: During exercise• GOAL: Maintain adequate blood glucose level, spare

muscle/liver glycogen and avoid gastric discomfort

• Maintains blood glucose levels and high level of CHO oxidation

• Spares liver glycogen and maybe muscle glycogen (running)

• Promotes glycogen synthesis during exercise (low-intensity)

• Affects motor skills and central nervous system (mental)

Ideal exogenous CHO intake during exercise

• 1.1 g CHO/min is max rate of CHO oxidation, ~70 g CHO/60 min of exercise energy bars, sport gels, sport drinks, sport beans, jelly beans, honey

• Mix of rapidly (glucose) and slowly oxidized CHO (fructose) helps absorb more CHO and water

Liquid vs. Solid CHO sources

Liquid = Sports Drinks• Readily available but not

easy to carry

• Helps hydration status

• Large amounts may cause frequent urination

Solid = Energy bars, gels, beans

• Small, easy to carry

• May have longer release time from stomach

• No fluid

Timing of dietary CHO: After exercise

• GOAL: Restore and replenish muscle and liver glycogen stores

• Glycogen replenishment is dependent on: 1. Timing of CHO intake2. Rate of CHO ingestion3. Type of CHO ingested4. Protein + CHO

Post-exercise recovery: CHO Timing

Post-exercise recovery: Rate CHO ingestion

Post-exercise recovery: CHO type

• The rate of glycogen synthesis from fructose is about 50% the rate achieved from glucose.

• High-GI CHO are more effective at restoring muscle glycogen compared to low-GI CHO.

Post-exercise recovery: Protein + CHO

• CHO + protein after exercise resulted in greater glycogen replenishment as compared to CHO or protein alone.

• Consuming adequate CHO is the most important aspect of glycogen synthesis, but adding protein can enhance the effect.

Post-exercise CHO intake recommendations

• Immediately after exercise (0-4 hours) : 1.0-1.2 g CHO /kg bodyweight / hour, ingested in frequent intervals

• Daily recovery from moderate duration, low-intensity training: 5-7 g CHO / kg bodyweight / day

• Daily recovery from moderate to heavy endurance training: 7-12 g CHO / kg bodyweight / day

• Daily recovery from an extreme exercise program (4-6 h training per day): 10-12+ g CHO / kg bodyweight / day

Before Exercise Carbohydrate Recommendations

• Always eat before any type of exercise to elevate blood glucose

• 3-4 hr prior to a workout eat a meal of 700-800 calories (a regular meal)

• Select primarily carbohydrate rich foods• 30-60 min. prior to exercise eat 100-200

carbohydrate calories• 15 min. before exercise: sport drinks, sport

gels, sport jelly beans

General Recommendations for CHO Intake for an Exercising Individual

• 5-12 g CHO/kg body weight per day• Have CHO-rich sports drink within an hour after

exercise• Post-exercise recovery meal should contain

nutrient-rich, high-glycemic index CHO sources + protein

• Exercise sessions <8 hours apart, begin CHO intake as soon as possible after 1st session

• Exercise sessions >24 hours, consume a CHO- and nutrient-rich diet

• Ensure adequate caloric intake

Take home messages from Objective 1

• The muscle cells preferred energy source is carbohydrate in the form of glycogen

• Carbohydrate delivers energy both anaerobically and aerobically, unlike fat and protein

• Carbohydrate can produce ATP at the faster rate compared to Fat and protein

• When glycogen stores are low, fatigue occurs

Objective 2

State how macronutrients are used during low, moderate, and long duration exercise and what foods to recommend based on how someone exercises.

Intensity is related to the amount of oxygen that can reach the muscles

• Cardiovascular and respiratory systems function to bring in oxygen to the body through the lungs and transport it to all the cells of the body

• Fitness levels are dependent upon the ability to deliver adequate amounts of oxygen to active muscles

• More intense exercise = Less oxygen to muscles

Fuel mix relative to exercise intensity

How duration of exercise affects which fuel is utilized

Fuel mix changes over time at 70% VO2 Max (med-high intensity)

Fatigue from Endurance (aerobic) Exercise

• Prolonged exercise lasting 90-180 minutes

• Glycogen stores determine duration of exercise before fatigue (at a constant intensity) – store only 1800 cal

• Fat oxidation maintains activity at a lower intensity

• Carbohydrate content of diet affects time to fatigue

Food recommendations for various exercises

• Walking: eat balanced meals, eat small amount of carb rich food 30-60 min. before

• Jogging or other aerobic exercise: eat balanced meals, drink and eat carb rich snack prior to exercise. Duration matters: drink every 20 min., if longer than 60 min. eat carb snack during exercise

• Soccer, basketball, lacrosse: high intensity, short burst activities: eat balanced meal 2 hr before, eat carb snack 1 hr before game/practice, drink carb beverage during game breaks

• Marathon, triathlon, long hike/bike: Eat a high carb dinner the night before, eat a meal 2 hr prior to event, carry carb snacks to eat every 60 min., drink carb beverages every 20 min. during exercise

Take home message from objective 2:

• The intensity and duration of physical activity influences which substrate predominates as a fuel source

• Short duration, low intensity physical activity uses more glycogen and some fat

• With increasing intensity, glycogen becomes primary fuel source

• With increasing duration fat becomes primary fuel source

Objective 3:


Protein and Exercise• Amino Acids are oxidized in small amounts during physical activity• Increased protein synthesis must be balanced with protein

breakdown• Regular and modest amounts of physical activity require very small

– if any increase in protein needs

• Evidence: Only endurance types of exercise require more protein– Endurance exercise: increased oxidation of BCAA– When carbohydrate intake is suboptimal, protein can contribute up to

10% of energy expenditure during exercise– Leucine appears (in some studies) to be the BCAA that is oxidized at

the greatest rate

Presenter

Presentation Notes

Scientists recognize that protein plays a significant role in muscle tissue synthesis after exercise ends. But there remains controversy among protein researchers regarding whether or not protein needs increase with exercise. Evidence has been found for both arguments. For those scientists who believe more protein is relevant the rationale is that amino acids are oxidized during physical activity In the case of endurance exercise, such as a marathon, there appears to be increased breakdown of Branched chain amino acids, isoleucine, leucine, and valine. Because these amino acids aren’t synthesized endogenously the implication is that they come fro increased breakdown of protein. Therefore, dietary proteins increase. Several studies using nitrogen balance techniques confirm that dietary protein increases with prolonged exercise. But, Protein as a fuel is not critical fuel however carbohydrate and fat are the two fuel sources for prolonged exercise that matters more.

Endurance vs Resistance Exercise• The intensity and duration of these exercises influences protein synthesis

after exercise (recovery)

After endurance exercise: increase in mitochondrial protein synthesisAfter strength training: increase in myofibrillar

• Low-moderate intensity exercises do not impact muscle protein turnover

• To maintain nitrogen balance:Endurance athletes: 1.2-1.4 gr/kg/dStrength athletes: 1.6-2.0 gr/kg/d

• Training has a protein–sparing effect

Presenter

Presentation Notes

Training can have profound effects on muscle morphology and function. Different types of training has distinct effects. Strength training results in hypertrophy of muscle – increased muscle mass. Endurance training has no effect on muscle mass hypertrophy but does increase the mitochondrial density inside muscle fibers. But, The better trained a person is(which may be a combination of strength and endurance training) the less dependent on protein oxidation they become and protein breakdown is decreased. Both types of exercise stimulate a rise in protein synthesis. Whole foods should easily be able to accomplished these small suggested increases in protein intake.

Timing of Protein Intake“The window of anabolic opportunity”• 20-30 grams of protein after exercise • Eat both carbohydrates and proteins as soon

after exercise as possible (within a 2 hr frame)• After strength training – muscle protein

synthesis remains high up to 48 hr post exercise

• Eating regular meals with 20-30 g protein in all meals (B, L, D) – spreading it out

• High quality protein: EAA

Presenter

Presentation Notes

The timing of protein intake after exercise is important to the balance between protein breakdown and synthesis. Studies have looked at protein intake immediately after exercise, delayed by 1-3 hr, or ingested before exercise. Studies have shown that 20-30 gr of protein after exercise stimulate muscle protein synthesis helping to provide a.a. to offset muscle protein breakdown(window of anabolic opportunity)

Foods to Eat after workouts

Carbohydrates

• Juice or sport drinks• Fruit• Bread, bagels, crackers• Pretzels• Granola bars, energy bars• muffins

Proteins

• Milk• Yogurt• Peanut butter• Hard boiled egg• Beef jerky, any meat• Protein bars

Recovery Drinks

Milk/chocolate milk: recovery drinks

• Contributes carbohydrate and protein• Addition of protein may suppress breakdown

and enhance synthetic rate of muscle tissue• Sodium & potassium content of milk is higher

than sport drinks : rehydrates more effectively

Presenter

Presentation Notes

Recovery is about restoring carbohydrates for glycogen synthesis, eating adequate protein to promote muscle tissue synthesis and reduce protein breakdown, but also restore fluids. Studies have shown that drinking milk with both carbs and protein after exercise compared to a carb only beverage suppressed muscle tissue breakdown during recovery and after endurance exercise. The higher concentration of sodium and potassium has shown to be more effective in replacing sweat losses due to exercise induced fluid losses (over plain water and sport drinks). The amount of fluid consumed as well as the composition of the fluid influence rehydration. Drink volume needs to exceed sweat losses. But adequate sodium enhances rehydration (extracellular electrolyte). Potassium is the major intracellular cation and has the potential to aid restoration of fluid balance through the retention of water in the intracellular spaces. It is now accepted that for the rehydration process to be optimised it is important to replace not only the fluid but also the electrolytes lost in sweat.

Protein needs easily met with foodBreakfast: Dinner• 2 eggs = 14 gr 4 oz chicken=20 gr• 8 oz milk = 8 gr 8 oz milk = 8 gr• 2 slices toast = 6 gr 2 c rice = 8 gr

Snack: 1 cup yogurt = 16 gr

124 gr/day

Lunch• 1 can of tuna = 28 grams of protein• 16 oz milk = 16 grams of protein

Making a high protein salad

• Meat or fish• Cheese• Beans• Nuts or seeds

Objective 4

• Identify optimal fluids a physically active person could drink before, during, and after exercise

Optimal fluid intake: prevent dehydration

Sport drinks vs Water

• Provide energy • Rapid absorption• Elevates blood sugar quickly • Spares glycogen• Replaces electrolytes lost in sweat• Flavored beverages consumed in greater

volume – forcing hydration

• 2-3 hours prior- ~16-24 oz (500 mL)(avoid excess and take small sips)– Avoid excess due to urination need– Avoid gastric distension

• 10 to 20 minutes prior4-8 oz

Fluid Recommendations Before Exercise

Copyright Dr. Peter Horvath 2010

– drink fluids early and regularly throughout: replace fluids as they’re lost, don’t wait to drink

– 4 oz every 10-20 min of exercise– Water or sports drinks

• Duration of exercise should determine choice

Fluid Recommendations During Exercise

Fluid Recommendations After Exercise

– drink to rehydrate immediately

–About 15-23 oz/ lb lost

–Water/ sport drinks/milk

–high water foods (fruits)

• To keep track of hydration:– Urine color

Hydration and urine color

Copyright Dr. Peter Horvath 2010

Coconut Water: “Mother Nature’s sport drink”

• Clear liquid in the center of a coconut

• Contains less carbohydrate and less sodium than traditional sport drink

(5.4 kcal/oz compared to 6.2 kcal/oz in sport drink)• High in potassium • Fat and cholesterol free

Objective 5

• Identify strategies to share sports nutrition messages with exercisers

Reaching exercisers with sports nutrition messages

1. Health clubs, fitness centers, YMCA: presentations, written materials, newsletters, private clients

2. Local newspapers: fitness columns, weekly Q and A

3. Local grocery stores: sports nutrition shopping, cooking classes, newsletter or shopping guide

4. High schools – contacting coaches who could use assistance with team nutrition

5. Parent organizations: helping parents feed their athletes

Nutrition is a training tool

Recommended Reading and Resources for RD’s/RDN’s

1. Deutz , N & Wolfe, R Is there a maximal anabolic response to protein intake with a meal, Clinical Nutrition, Nov. 2012

2. Lunn, W, et al Chocolate milk and endurance exercise recovery: protein balance, glycogen and performance, Med Sci in Sp and Ex. 2012.

3. Shirreffs, S et al Milk as an effective post-exercise rehydration drink. British J of Nutr, 98,2007.4. Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports

Medicine: Sports Nutrition, March, ‘09, 109:3, p 509-526 (online and full text, is currently being updated)5. Buell, J. et al, National Athletic Trainer’s Association Position Statement: Evaluation of Dietary

Supplements for Performance Nutrition, Journal of Athletic Therapy, Feb. ‘13, 48(1):124-136. (online, full text)

6. Sammarone, P. et al, National Athletic Trainer’s Association Position Statement: Safe weight loss and maintenance practices in sport and exercise, Journal of Athletic Therapy, ‘11, 46(3):322-336. (online and full text)

7. Sports Nutrition Care Manual – eatright.org, written by a variety of Certified Specialists in Sports Dietetics. Covers all topics of sports nutrition

8. Krieder, RB et al, International Society of Sports Nutrition Review: Research and Recommendations, Journal of the International Society of Sports Nutrition, ‘10, 7:7. (online and full text)

Summary 1. Carbohydrate rich foods provide optimal energy source for

physical activity and prevent exercise fatigue2. Protein and carbohydrate rich foods eaten as a snack or meal after

exercise replace energy stores and aid in optimal recovery3. Eat before exercise to optimize energy levels, eat during exercise if

exercise is long lasting4. Eating as soon after exercise is a strategy for rapid recovery (2 hr

anabolic window)5. Depending on how long exercise will last should determine how

much you need to eat before and after exercise6. Drink early and often during exercise, don’t wait until thirsty,

replace lost body water as it’s lost

Questions?

Based on this webinar, learners should be able to: State why carbohydrate rich foods are optimal for athletic

performance and how they play a role in exercise recovery State how macronutrients are used during low, moderate, and

long duration exercise and what foods to recommend based on how someone exercises


Identify optimal fluids a physically active person could drink before, during, and after exercise

Identify strategies to share sports nutrition messages with exercisers

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