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Chapter 4
Lecture Slides

2. Dietary Carbohydrates
• One of the most important nutrients in your diet,
from the standpoint of both health and athletic
performance, is dietary carbohydrate.

3. What are the different types of dietary
carbohydrate?
• Carbohydrates
– Carbon, hydrogen and oxygen
• Simple carbohydrates
– Monosaccharides
• Name them
– Disaccharides
• Name them and the monosaccharides for each

4. What are some common foods high in
carbohydrate content?

5. How much carbohydrate do we need in
the diet?
• Recommended Dietary Allowance (RDA)
– 130 grams
• Acceptable Macronutrient Distribution Range
(AMDR)
– 45-65% of energy intake
• Daily Value (DV)
– 60% of daily energy needs
– 300 grams on a 2,000 Calorie diet
– 25 grams of fiber

6. Recommended carbohydrate in the diet
• Sport nutritionists
– Recommend high end of AMDR
– 60-70% or higher
– Diet containing 3,000 Calories
• 450 grams of carbohydrate at 60% level

7. Figure 4.4

8. What happens to the carbohydrate after it
is absorbed into the body?
• Most dietary carbohydrates eventually are converted
to glucose which circulates in the blood
• Carbohydrate foods have different effects on blood
glucose levels
• The glycemic index and glycemic load

9. Fates of blood glucose
• May be used for energy
• May be converted to liver or muscle glycogen
• May be converted to and stored as fat in adipose
tissues
• May be excreted in the urine if in excess

10. Figure 4.6

11. Carbohydrate storage in the body

12. Carbohydrates for Exercise
• Carbohydrate as an energy source during exercise
• Effect of training on carbohydrate metabolism
• Methods of providing carbohydrate
– Before competition
– During competition
– After competition
– During training

13. In what type of activities does the body rely
heavily on carbohydrate as an energy source?
• Carbohydrate contributes about 40% of energy
needs at rest
• Fat is main energy source during low exercise
intensity, such as 40-50% VO2max
• Carbohydrate is major source during
– Very high intensity anaerobic exercise
– High intensity (>65% VO2max) aerobic exercise
– Prolonged aerobic exercise events
– Intermittent high-intensity exercise sports

14. Carbohydrate sources for exercise
• Muscle glycogen is a very important source
• Liver glycogen is converted to blood glucose
• Blood glucose is delivered to muscles

15. Hypoglycemia
• The human body attempts to prevent hypoglycemia
• Hormone activity
– Insulin
– Glucagon

16. Hormones and glucose metabolism
Hormone Gland Stimulus Action
Insulin Pancreas Increase in blood
glucose
Helps transport
glucose into cells;
decreases blood
glucose levels
Glucagon Pancreas Decrease in blood
glucose; exercise
stress
Promotes
gluconeogenesis in
liver; helps increase
blood glucose levels
Epinephrine Adrenal Exercise stress;
decrease in blood
glucose
Promotes glycogen
breakdown and
glucose release
from the liver
Cortisol Adrenal Exercise stress;
decrease in blood
glucose
Promotes
breakdown of
protein; stimulates
gluconeogenesis

17. How is low muscle glycogen related to the
development of fatigue?
• Low muscle glycogen and aerobic exercise
– Muscle glycogen is the primary fuel for endurance
athletes, such as marathon runner
• Studies have shown physical exhaustion to be
associated with very low muscle glycogen levels.
However, other studies have shown fatigue with
some muscle glycogen remaining.

18. Optimal supplementation protocol
• Consume carbohydrates both before and during the
exercise task.

19. When, how much, and in what form should
carbohydrates be consumed before or during exercise?
• Athletes who may benefit from carbohydrate intake
– Endurance exercise
– Intermediate high-intensity exercise
• Fluid replacement is also an important consideration

20. What is the importance of carbohydrate
replenishment after prolonged exercise?
• Rapid restoration of muscle glycogen important for
some athletes
– Repeated bouts of prolonged, intense exercise on the
same day
– Prolonged, intense exercise on consecutive days

21. Carbohydrate-rich diets for athletes
• Sport nutritionists recommend that athletes
consume about 8-10 grams of carbohydrate per
kilogram body weight daily
• For a 70-kg athlete, this would amount to 560 to 700
grams of carbohydrate daily, or the equivalent of
2,240 to 2,800 Calories
• On a 3,500-Calorie daily intake, the carbohydrate
would provide 65-80% of daily energy intake.
• This amount of daily carbohydrate would help
restore muscle glycogen levels

22. Carbohydrates during training
• There is no evidence that low-carbohydrate diets
improve exercise performance
• A diet rich in healthy carbohydrates may help
guarantee optimal energy sources for daily training
• Train high and compete high is the concept of
training and competing with high carbohydrate
intake.

23. Carbohydrate loading
What is carbohydrate, or glycogen, loading?
• Method of increasing muscle glycogen levels
– Also known as muscle glycogen supercompensation

24. What type of athlete would benefit from
carbohydrate loading?
• Athletes who sustain high levels of continuous
energy expenditure for prolonged periods
– Long-distance runners
– Cross-country skiers
– Endurance triathletes
– Tournament play in intermittent high-intensity exercise
sports

25. How do you carbohydrate load?
• Athlete should be fully trained
• Classic procedure not necessary:
– Depletion stage
– Low carbohydrate diet
– Carbohydrate loading
• Have about 3-4 days of high carbohydrate intake, about 8-10 grams/kg
body weight, or more
• Low and high glycemic index carbohydrates are equally effective
• Taper exercise training over the course of a week or longer

26. Carbohydrate loading procedures

27. Will carbohydrate loading increase muscle
glycogen concentration?
• Most studies report increased muscle glycogen levels
following carbohydrate loading procedures
• Both males and females will increase glycogen levels
if adequate energy and carbohydrate are consumed
• Muscle glycogen levels may increase two to three
times above normal
• Experiment with the protocol during training

28. Will carbohydrate loading improve
exercise performance?
• In general, the procedure is not needed for exercise
tasks of short duration
• In general, research supports the use of
carbohydrate loading as a means to enhance
performance in prolonged endurance exercise tasks
– Helps maintain an optimal pace longer
– Extra body water may help during exercise in the heat
• Most appropriate protocol is to use both
carbohydrate loading and consumption of
carbohydrate during the event

29. Carbohydrates: Ergogenic Aspects
• Metabolic by-products
– Pyruvate
– DHAP (Pyruvate and dihydroxyacetone)
– Lactate salts
– Ribose
– Multiple carbohydrate products

30. Soluble and insoluble fiber
• The issue of soluble and insoluble fiber
– Difficult to generalize on different health effects
of soluble and insoluble fiber; health effects are
due to total fiber, but it may be illustrative to
discuss soluble and insoluble fiber effects on
health.