Overview: Carbohydrates
! Importance of carb storage
! Muscle & liver
! How many carbs are right
for you?
! What to eat before, during
and after exercise to
enhance performance.
Carbs - Most Important
Energy Source for Exercise
! Only fuel that provides the muscle with
energy with or without oxygen.
! The higher the intensity, the greater the
reliance on carbs (glucose and glycogen).
! Assists in the use of fat as fuel.
! Stored in muscle so it is a rapid source of
fuel for working muscle.
Glycogen
! The way the body stores glucose
! Limited storage
! Stored in muscle & liver
! Important to have adequate stores
because glucose is used for:
! Fuel in the anaerobic and aerobic system
! Fat burning; glucose must be available to use
fat to make ATP in the aerobic system
Glucose Stored in 3 Locations
! Muscle glycogen
! Major source of glucose for the muscle
! Provides 1200-1600 calories
! Liver glycogen
! Provides 300-400 calories
! Glucose in blood
! Provides 100 calories
Glycogen Depletion
! Occurs during prolonged
endurance exercise
! Can occur during intermittent
sports and strength training
! Can be gradual, occurring over
repeated days of training.
Glycogen decreases each day
! Workouts become difficult and
fatigue is common.
Decline in Glycogen Stores
Progressive decline due to inadequate carbs (< 50%
of total calories) pg. 82 LAM book
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Glycogen Stores & Endurance
! Strong connection between muscle
glycogen and length of time to exhaustion.
! Study: 3 groups of runners eating different
diets for 3 days.
•  High fat diet – < 5% calories from carbs
•  Mixed diet – 50% calories from carbs (typical
American diet)
•  High carb diet – 82% calories from carbs
Diet & Time to Exhaustion
Why did runners have more
endurance on high carb diet?
! Increases glycogen stores
! 3 days of high carb dietplenty of glucose stored as
glycogen.
! Adequate glycogen
storage before exercise
! Delays fatigue
! Contributes to endurance
Challenge Question
Studies show that runners who eat a typical
mixed diet (50% carbs, 25% fat, 25%
protein), can exercise for approximately
______ minutes until exhaustion.
a) 
b) 
c) 
d) 
90 minutes (1 ½ hours)
120 minutes (2 hours)
150 minutes (2 ½ hours)
180 minutes (3 hours)
How many carbs do you need?
! Determined by weight
and exercise
! For endurance &
strength training
! 5-10 grams carbs per kg
of body weight
! Weight (lb.) ÷ 2.2 = kg
How many carbs do you need?
! New guidelines from International
Olympic Committee (IOC):
! Determined by duration or intensity of
exercise:
• 
• 
• 
• 
Low intensity: 4-5 g/kg/daily
Moderate intensity (1 hour): 5-7 g/kg
High intensity (1-3 hours): 6-10 g/kg
Very High intensity: 8-12 g/kg
Soccer Player
How many grams of carbs needed to
maintain glycogen stores?
1.  Determine weight in kilograms
•  172 lbs. ÷ 2.2 = 78 kilograms
2.  Determine exercise duration or intensity
•  2 hours of high intensity = 8 g per kg of body weight
3.  Multiply the numbers
•  78 kg x 8 g. of carbs = 624 grams carbs each day
How many carbs do YOU need?
1.  Determine your weight in kilograms
•  Weight ÷ by 2.2 = kg
2.  Determine your exercise duration or intensity
• 
• 
• 
• 
Low intensity: 4-5 g/kg/daily
Moderate intensity (1 hour): 5-7 g/kg
High intensity (1-3 hours): 6-10 g/kg
Very High intensity: 8-12 g/kg
3.  Multiply the numbers
•  kg x grams of carbs = total grams carbs each day
4.  Experiment with consuming this amount.
Carbs: Grams vs. % Calories
! 4-10 g/kg/day takes into account body wt.
! More accurate & practical to consume a
specific amount of grams from carbs
rather than a % of calories
! 60 kg endurance athlete eats < 2000
calories per day, a diet of 60% calories
from carbs (4-5 g/kg) will not maintain
optimal glycogen stores.
Eating Before Exercise
! High carb diet on a daily basis helps maintain
adequate glycogen storage
! With adequate glycogen, exercise lasting <90
minutes (moderate, intermittent or high
intensity), no benefit for carbs prior to event.
! High carbohydrate meal the night before event
helps maximize glycogen stores
! Choose a familiar food
Eating Before Exercise, cont.
! Morning practice or event:
! Exercise >60-90 minutes: may want to eat small high
carb meal at least 1 hour prior (limit fat, protein, fiber)
! Afternoon practice or event:
! Best to eat lunch 3-4 hours prior
! Eating within 2 hours of exercise, limit fat, protein, fiber
! Important not to be digesting food during exercise.
! Experiment with pre-exercise meals to determine
what works best.
Carbs During Exercise
! Important if exercise
lasts > 1 hour
! Helps maintain blood
glucose & spare glycogen
! Ability to absorb carbs
limits intake. The body
can absorb:
! 0.5-1 gram carb/minute
! 30—60 g. of carbs/hour
Carbs During Exercise
! The body can absorb &
burn carbs at rate of:
! 0.5-1 gram carb/minute
! 30—60 g. of carbs/hour
! Carb amounts above this
my cause nausea,
cramping or diarrhea.
! Can obtain 30-60 g. from
food (fig bars, gels, energy
bars) or sports drinks.
Sports Drinks During Exercise
! Sports drinks provide carbs and fluids
! Best because they provide 4-8% carbohydrate
! Gatorade is 14 grams of carbs per 8 ounces
! Do not drink juice
! Juice is 27 grams carbs per 8 ounces
! Contributes to cramping, nausea and diarrhea
! The body can absorb 30-60 grams/hour
! Gradually drink approx. 24 ounces (3 c.) per hour
! Ex. Gatorade: 24 ounces per hour = 42 grams
Post Exercise Recovery
! Adequate glycogen storage is critical for
continual optimal performance.
! Replacing glycogen after strenuous
training (1-2 hrs) helps minimize fatigue.
! Within 2 hours, glycogen is restored at
8%/hr. Afterwards, it drops to 5%/hr.
! It takes 20-22 hours to replace glycogen.
Post Exercise Recovery
! Within 30 minutes after exercise:
! Best to consume carb drink - chocolate milk
or sports drink
! Sucrose and glucose are better at restoring
glycogen than fructose from fruit
! Within 2 hours after exercise:
! Consume high carb meal – pasta, bread, rice
! Must consume 5-10 grams carbs per kg
body weight every day during training.