lecture 13

Question 1

depletion of muscle glycogen can lead to fatigue described as 2 things

Answer 1

1- hitting the wall

2- bonking

Question 2

CHO intake during exercise

Answer 2

1- Spares muscle & liver glycogen because ingested glucose can be used as a fuel for exercise. Also spares protein breakdown!
2- Maintains an optimal blood glucose level that prevents headache, light-headedness, nausea etc.

Question 3

Fluid/CHO mixture and

Answer 3

The absorption of fluid and nutrients by the intestine is greatly affected by the
rate that the stomach empties

Question 4

factors that SLOW gastric emptying

Answer 4

1- high caloric drinks = high concentration of particles in solution (soup)
2- exercise greater than 75% of max ability
3- pH that deviates from 7.0
4- dehydration

Question 5

factors that INCREASE gastric emptying

Answer 5

1- A high fluid volume in the stomach. Athlete should consume 400-600 ml of fluid immediately before exercise and then drink 150-250 ml of fluid every 15 min intervals throughout the exercise.
2- Adding low to moderate levels of glucose + sodium in water have been shown to increase fluid absorption in the intestine.

Question 6

what is the ideal % of CHO in solution

Answer 6

between 5-8%

- This % permits CHO replenishment without adversely affecting gastric emptying rate.

Question 7

How to determine fuel mixture in the body

Answer 7

- muscle biopsies made before and after exercise as well as during 
mixture will consist of: 
1- CHO
2- lipids
3- Protein

Question 8

fuel mixture used during exercise depends on

Answer 8

• intensity of exercise,
• duration of exercise,
• fitness and nutritional status of the individual

Question 9

CHO and exercise

Answer 9

high intensity: 80% overall contribution

mod intensity: CHO and lipids

Question 10

bonking

Answer 10

liver and muscle glycogen becomes severly low

Question 11

glycemic index

Answer 11

rates how quickly CHO is converted into blood sugar in the body.
GI scale ranges from 1 – 100, with 100 being the fastest conversion – i.e. jelly beans.
High GI foods result in the fast release of blood sugar (60-100)
Low GI foods result in the slow release of blood sugar (0-40)

Question 12

GI and hormones

Answer 12

Hormones control the level of circulating blood sugar (watchdogs/policeman)

Question 13

Insulin and CHO (if blood sugar is high)

Answer 13

• During rest, if blood sugar levels are high (i.e. after high GI ingestion), insulin levels increase.
• Insulin carries excess blood sugar to the liver for storage as liver glycogen.
• This can result in initial feelings of increased energy followed by fatigue
• A fall in blood sugar reduces the release of more insulin.

Question 14

Glucagon and CHO- If blood sugar is low

Answer 14

• If blood sugar is low, a hormone called glucagon is released.
• Glucagon encourages stored glycogen in the liver to be released back into the blood as glucose.
  = Glycogenolysis.

Question 15

Rebound hypoglycaemia

Answer 15

High GI drink caused a dramatic rise in blood sugar
= resulted in an excessive release of insulin (insulin surge or overshoot).
- This caused too much blood sugar being stored resulting in a dramatic fall in blood sugar levels

Question 16

avoiding hypoglycaemia

Answer 16

• Consuming low GI CHO 45 – 60 mins prior to exercise allowed for a slow conversion rate of CHO to blood glucose.
• This eliminates the insulin surge and the rebound hypoglycaemia effect.
• Provides a steady supply of ‘slow-release’ glucose throughout the exercise
  = beneficial during prolonged exercise.

Question 17

CHO ingested during exercise

Answer 17

After ~5 – 10 mins of mod to high intensity exercise, hormones known as catecholamines are released

• Insulin release is INHIBITED.
• Ingesting High GI food (jelly beans) during prolonged exercise will supply instant energy and top up depleted glucose stores.

Question 18

CHO ingested after exercise

Answer 18

• Mod-high GI CHO’s ingested AFTER exercise have been shown to replenish glycogen and glucose stores faster than low GI CHOs.
• Ingest b/w 50 – 100 g CHO in the first 1 – 2 hrs after a prolonged event