1. Chapter 23: Nutrition, Body Composition, and Performance
EXERCISE PHYSIOLOGY
Theory and Application to Fitness and Performance, 5th edition
Scott K. Powers & Edward T. Howley
Presentation revised and updated by
TK Koesterer, Ph.D., ATC
Humboldt State University

2. Objectives
Describe the effect of various carbohydrate diets on muscle glycogen and on endurance performance during heavy exercise
Contrast the “classic” method of achieving a supercompensation of muscle glycogen stores with the “modified” method
Describe some potential problems when glucose is ingested immediately prior to exercise
Describe the importance of blood glucose as a fuel in prolonged exercise, and the role of carbohydrate supplementation during the performance

3. Objectives
Contrast the evidence that protein is oxidized at a faster rate during exercise with the evidence that the use of labeled amino acids may be an inappropriate methodology to study this issue
Describe the need for protein during the adaptation to a new, more strenuous exercise level with the protein need when the adaptation is complete
Defend the recommendation that a protein intake that is 12 to 15% of energy intake is sufficient to meet an athlete’s need
Describe the recommended fluid replacement strategies for athletic events of different intensities and duration, citing evidence to support your position

4. Objectives
Describe the salt requirement of the athlete, compared to the sedentary individual, and the recommended means of maintaining sodium balance
List steps leading to iron deficiency anemia and special problem that athletes have in maintaining iron balance
Provide a brief summary of the effects of vitamin supplementation on performance
Characterize the role of the pregame meal on performance and the rationale for limiting fats and proteins

5. Objectives
Describe the various components of the somatotype and what the following rating signify: 171, 711, & 117
Describe what the endomorphic and mesomorphic components in the Heath-Carter method of somatotyping represent in conventional body composition analysis
Explain why one must be careful in recommending specific body fatness values for individual athletes

6. Carbohydrates and Performance
Endurance performance is improved by a diet high in carbohydrates
Increases muscle glycogen
58% of caloric intake as carbohydrates provides for adequate muscle glycogen
Muscle glycogen loading (“supercompensation”)
Goal is to maximize muscle glycogen
Replenishing muscle glycogen
Glucose or glucose polymers better than fructose

7. Supercompensation of Glycogen Stores
Classical method
Prolonged strenuous exercise to deplete glycogen stores
A high fat/protein diet for three days while continuing to train
90% CHO diet for three days with inactivity
Modified plan
Tapering workouts over several days from 90 to 40 minutes while eating 50% CHO diet
Two days of 20 minute workouts while eating 70% CHO diet
Day of rest eating 70% CHO diet before event

8. Effect of Diet on Muscle Glycogen and Time to Exhaustion
Fig 23.1

9. Classical and Modified Methods of Glycogen Super-compensation
Fig 23.2

10. Carbohydrate Intake Before and During Exercise
Improves performance by elevating blood glucose
Does not spare muscle glycogen utilization
Pre-exercise
1-5 grams CHO•kg-1 body weight
1-4 hours before exercise
During exercise
CHO ingestion can maintain plasma glucose even as glycogen is depleted

11. Muscle Glycogen & Blood Glucose Use During Prolonged Exercise
Fig 23.3

12. Protein Requirement for Training
Endurance training
RDA of 0.8 g•kg-1•day-1 is sufficient for light to moderate exercise
g•kg-1•day-1 for high-intensity endurance exercise

13. Protein Requirement for Training
Resistance training
0.9 g•kg-1•day-1 for maintaining strength
g•kg-1•day-1 for increasing strength and lean body mass
Average protein intake is ~1.5 g•kg-1•day-1
Enough to meet requirements for athletes

14. Nitrogen Balance During Exercise
Dependent upon:
Training state of the subject
Quality and quantity of protein consumed
Total calories consumed
The body’s carbohydrate stores
Intensity, duration, and type of exercise

15. Effect of Exercise on Nitrogen Balance
Fig 23.4

16. Effect of Muscle Glycogen Levels on Sweat Urea Nitrogen Excretion
Fig 23.5

17. Water Replacement Before exercise 300-500 ml water
Include g CHO for duration <1 hour
During exercise
Duration less than one hour - Water only
Duration greater than one hour
Water plus Na+, Cl-, and glucose
Cold drinks absorbed faster than warm drinks
Gastric emptying slower at intensities above % VO2max

18. Responses to Exercise With Different Volumes of Fluid Replacement
Fig 23.7

19. Factors Affecting Fluid Absorption From the GI Tract
Fig 23.8

20. Salt and Mineral Replacement
Salt needs are met or exceeded by meals
Iron - Deficiency due to decreased intake or increased loss
Supplementation recommended for female athletes
Vitamins - Supplementation is not necessary on well-balanced diet unless clear deficiency is known

21. Pregame Meal Purposes Provide adequate hydration
Provide carbohydrates to “top off” liver stores
Avoid the sensation of hunger
Minimize GI tract problems
Content
500-1,000 kcals
Mostly complex carbohydrates

22. Somatotypes Endomorphy
Relative predominance of soft roundness and large digestive viscera
Mesomorphy
Relative predominance of muscle, bone, and connective tissue
Ectomorphy
Relative predominance of linearity and fragility
Fig 23.10

23. Contrast of Somatotypes Between College Students and Athletes
Fig 23.11

24. Body Fatness and Performance
Optimal body fatness for health
Males: 10-25%
Females: 15-25%
Optimal body fatness for performance differs between men and women and varies within gender and sport
It is natural for some athletes to have higher body fatness than others in order to perform optimally