1. CHO and Exercise
Research task
30 minutes

2. The role of CHO in Sport

3. CHO and the Body

4. CHO in Sport & Exercise
Capacity for endurance exercise related to pre-exercise muscle glycogen stores.
A high CHO diet will increase glycogen stores.
After exercise glycogen stores need to be replenished .
For most athletes/ active people 5-10g CHO per kg body weight will maximise muscle glycogen recovery

5. How much CHO? Activity level # 3-5 hours per week 4-5
g CHO/kg body weight/day
3-5 hours per week
4-5
5-7 hours per week
5-6
1-2 hours per day
6-7
2-4 hours per day
7-8
More than 4 hours /day
8-10
#No. of hours of moderate intensity exercise or sport

6. Which type of CHO is best?
‘Simple’ and ‘complex’ based on their chemical structure.
In practice, many foods contain a mixture of both.
Glycaemic Index (G I) describes the effect different foods have on blood sugar levels.

7. Before Exercise
Consuming a low GI meal 2-4 hours before provides slow release energy and delays fatigue.
There is still some controversy over whether to eat high or low GI just before exercise.
High GI foods are more ‘risky’ to performance.

8. During Exercise
First hour of exercise most of your energy comes from muscle glycogen
After an hour fuel comes from blood sugar supplied by liver glycogen as well as some muscle glycogen. 
Glycogen depletion = low blood sugar “hypoglycaemia”
Hypoglycaemia = feelings of tiredness and light-headedness, and your legs begin to feel very heavy “hitting the wall”

9. During Exercise
Consuming CHO can maintain your blood sugar levels so you could exercise for longer
Muscles can take up about 30g to 60g an hour of carbohydrate from the bloodstream (Anita Bean 2003)
It takes 30 minutes for the carbohydrate to reach your bloodstream
To promote quick absorption high to moderate GI CHO’s are the best choices
In practice if you consume about 500ml an hour of an isotonic sports drink containing 7g of carbohydrate per 100ml, then you will consume about 35g of carbohydrate per hour, which will roughly maintain your blood sugar levels.

10. After exercise The length of time it takes to refuel depends upon:
How depleted glycogen stores are
Extent of muscle damage
Amount and timing of CHO eaten
Training experience and fitness levels

11. After exercise
consume CHO quickly –within half an hour and certainly within 2 hours
high GI CHO can be absorbed quickly
Water is needed for storage of CHO
Protein and fats aids absorption of the carbohydrates
More experienced athletes refuel quicker and can store up to 20% more glycogen.
The minimum time for refuelling is 20 hours (Coyle 1991)

12. After exercise
1g high GI CHO per kg bodyweight in the two hours post exercise
It makes no difference whether the CHO is liquid or solid
Once stores are replenished in the 6 hour post ex window CHO intake is still important
Low GI meals eaten regularly maintain a steady supply of CHO into the blood stream and avoid fluctuations in blood sugar.