1. MODULE 5 -
CARBOHYDRATE
METABOLISM IN
EXERCISE
(Anandini)

2. MACRONUTRIENTS AND
EXERCISE

3. Macronutrients
1. Carbohydrates (made up of saccharides/
sugars)
2. Proteins (made up of amino acids)
3. Lipids/ Fats (made up of glycerol + fatty acid)
What do they do?
1. Provide energy
2. Maintain structure
3. Provide functional integrity

4. Pathways by which ATP is produced from
Macronutrients
Carbohydrate to ATP - Glycolysis
Non-Carbohydrate to ATP- Gluconeogenesis

5. Production of ATP from food

6. CLASSIFICATION OF
CARBOHYDRATES

8. About Monosaccharides
1. Glucose - used directly by the cell for energy,
stored as glycogen in the liver & muscles,
converted to fat & stored as energy
2. Fructose - Converted to glucose in the liver
3. Galactose - Forms milk sugar (lactose),
converted to glucose for energy

9. About Disaccharides
Di = Mono + Mono
Sucrose - Glucose + Fructose
Lactose - Glucose + Galactose
Maltose - Glucose + Glucose

10. About Polysaccharides
Formed by glycosidic bonds linking monosaccharides
Classified into
1. Plant polysaccahrides - Starch & Fibre
Starch is known as complex carbohydrate.
Fibre is not digested in the human gut.
2. Animal Polysaccharides - Glycogen

11. Roles of Fibre
1. Retains water - gives bulk to food - SATIETY
2. Binds/ dilutes harmful chemicals
3. Shortens transit time for food residues to pass through the
digestive tract

13. Recommended intake of Carbohydrate
Regular physical activity - 60% of total intake
During intense training - 70% of total intake

14. Glycemic Index
The glycemic index (GI) is a ranking of carbohydrates on a scale
from 0 to 100 according to the extent to which they raise
blood sugar levels after eating.
Foods with a high GI are those which are rapidly digested and
absorbed and result in marked fluctuations in blood sugar
levels.
Low-GI foods, by virtue of their slow digestion and absorption,
produce gradual rises in blood sugar and insulin levels, and
have proven benefits for health.

17. Hyper & Hypo glycaemia
Hypoglycaemia
Hyperglycaemia • Low blood levels
of glucose
• Consuming high • Result in
weakness,
glycaemic load food
hunger, dizziness
• Insulin resistance • Impairs exercise
performance
• Metabolic syndrome • Prolonged - loss
of consciousness
and brain
damage

19. a) CARBOHYDRATE AS AN ENERGY
SUBSTRATE FOR EXERCISE

20. CARBOHYDRATE AS AN ENERGY SOURCE
Carbohydrates - most important source of energy in the form of
ATP (Adenosine Triphosphate)
• Broken down to glucose/ fructose and absorbed in the body
• Glucose/ fructose that is not utilized is stored in the liver as
glycogen
• 1 g of carbohydrate gives 4KCal

21. • Failure to sustain continuous delivery of glucose to working
muscles will cause cessation of high intensity activity.
• Avoiding glucose depletion should be a major nutritional
focus.
• Unlike protein and fat the storage capacity of carbohydrate in
the body is limited.
• Humans can store 350 g of glycogen in the muscles,
90 g in the liver and about 5g of free glucose in the blood
stream.

22. Activity:
Given the amount of carbohydrate stored in different parts of
the body, calculate the number of calories that will be
available from glycogen stores in the liver, muscle and blood
stream.

23. b) EFFECT OF EXERCISE INTENSITY,
DURATION AND TRAINING ON
CARBOHYDRATE NEEDS

24. EFFECT OF EXERCISE INTENSITY &
DURATION OF CARBOHYDRATE
UTILIZATION
High intensity, low duration
• More calories burned in less time
More carbohydrate (glycogen) is utilized when:
1. Type II muscle fibres are utilized - contain high amount of
glycolytic enzymes
2. Increased blood epinephrine - increase muscle glycogen
breakdown, glycolysis and lactate production
3. Increased lactate production - inhibits fat metabolism

25. EFFECT OF EXERCISE INTENSITY &
DURATION OF CARBOHYDRATE
UTILIZATION
• At high intensity of exercise (>70%VO2max) carbohydrate is
used as the energy source.
• When the duration of activity is short, carbohydrate is taken
from glycogen for energy.

26. Factors affecting increased reliance on carbohydrate as an
energy source:
1. High intensity activity
2. Long duration activity
3. Exercise in hot and cold temperature extremes
4. Exercise in high altitude
5. Age (higher in young boys than men)
Factors that decrease the relative energy expenditure from
carbohydrate:
1. Endurance training
2. Good aerobic conditioning
3. Temperature adaptation
4. Gender

28. c) CARBOHYDRATE LOADING

29. CARBOHYDRATE LOADING
A strategy involving changes to training and nutrition that can
maximise muscle glycogen (carbohydrate) stores prior to
endurance competition.

30. Carbohydrate loading procedure

31. Cons of Carbohydrate Loading

32. Modified Procedure

33. Gender Differences During Carbohydrate
Loading

34. ACTIVITY:

36. Some common foods and their carbohydrate content:
FOOD Carbohydrate Content (g) Calories (KCal)
Skimmed milk (360mL) 18 125
Peanut Butter (1 tablespoon) 3 94
Honey (1 tbsp) 17 64
Oats (4 tbsp) 23 200
Fig bar (3 inches) 40 198
Raisins (30g) 34 129
Whole wheat bread 25 180
Chicken breast (1/2)/ Salmon (100g) 0 142
Baby carrots (12) 10 48
Thin tomato slices 2 44
Digestive biscuit (1) 8.5 90
Apple 25 95
Brown rice (1.5 cups) 69 328
Yoghurt - fat free (1 cup) 12

37. Activity:
What would be a suitable menu plan for an athlete to
carbohydrate load up to about 70% energy coming from
carbohydrate rich food?

39. Activity:
An athlete weighs 80kg. How much carbohyrdate will be require
3 hours before the competition?
After training daily for a moderate intensity endurance program,
how much carbohydrate will he require for recovery?
Also from the above scenarios, how many calories will the
carbohydrate give the athlete?

40. d) CARBOHYDRATE INTAKE BEFORE,
DURING AND AFTER EXERCISE
e) PRE-GAME AND POST-GAME MEALS

41. Carbohydrates before Exercise
The ideal pre-competition meal should:
• Contain about 150 to 300g of carbohydrate
• Be consumed 3 to 4 hours before the competition
• Be low in fibre
• Be low in fat
• Have low to medium GI

42. CARBOHYDRATE INTAKE - PRE GAME
It is vital that athletes have a sufficient carbohydrate intake prior
to exercise so that the total energy requirement is met.
The following foods are suitable to eat 3-4 hours before exercise:
• crumpets with jam or honey + flavoured milk
• baked potato + cottage cheese filling + glass of milk
• baked beans on toast
• breakfast cereal with milk
• bread roll with cheese/meat filling + banana
• fruit salad with fruit-flavoured yoghurt
• pasta or rice with a sauce based on low-fat ingredients (e.g.
tomato, vegetables, lean meat)

43. The following snacks are suitable to eat 1-2 hours before
exercise:
• liquid meal supplement
• milk shake or fruit smoothie
• sports bars (check labels for carbohydrate and protein
content)
• breakfast cereal with milk
• cereal bars
• fruit-flavoured yoghurt
• fruit

44. The following foods are suitable to eat if there is less than 1 hour
before exercise:
• sports drink
• carbohydrate gel
• cordial
• sports bars
• jelly lollies

45. Carbohydrates during Exercise
• Allows for greater intensity during prolonged activity
• Consuming about 60g of liquid/ solid carbohydrate each hour
will benefit :
1. High intensity, long duration aerobic exercise
2. Repetitive short bouts of near-maximal effort
• Spares muscle glycogen
• Maintains more optimal blood glucose level

47. CARBOHYDRATE INTAKE - DURING THE
ACTIVITY
The carbohydrate stores have to be replenished
during exercise as well. The foods given below
are some of the options:
• Banana
• Nuts
• Dry fruits

48. Carbohydrates after Exercise
• High glycemic carbohydrate - rich foods
• Either a single large meal or small frequent meals will
replenish glycogen stores
• Should be consumed as soon as possible after the activity
• Avoid legumes, fructose and milk products

50. CARBOHYDRATE INTAKE - POST GAME
After exercise the glycogen stores will have
depleted and need to be replenished. These
are some of the food options:
• Fruit
• Yoghurt
• Sandwiches
• Corn flakes with milk

51. Activity

54. Activity
From the examples given, suggest a plan for an
athlete to receive sufficient carbohydrates
before, during and after activity