Carbohydrate training and precompetition diets (lecture eight)

Question 1

What is the crossover concept?

Answer 1

The point of intensity where CHO becomes the primary fuel source and FATS become less and less.

Maximal intensity= virtually CHO only.

Question 2

Where is glycogen stored?

Answer 2

Muscle - used for fuel in intense exercise.

Liver- maintains blood glucose to supply the organs, mainly the brain.

Question 3

How much glycogen in the muscles?

Answer 3

300-400grams

Question 4

approximately when at 60% vo2max does glyocogen deplete?

Answer 4

90mins has gone from 100%-35%

Question 5

Where abouts does the liver maintain blood glucose?

Answer 5

4-6mmol/L

Question 6

How is blood glucose determined?

Answer 6

Exogenous intake

and endogenous production

Question 7

What is a muscle punch biopsy useful for?

Answer 7

Determine accurately the glycogen content of muscles.

Question 8

Why is lactate useful?

Answer 8

Muscles use it as A CHO fuel source
Liver makes glucose from it.
Other organs use it as a fuel source

Question 9

What is the process of glycogen breakdown in the liver called?

Answer 9

Glycogenolysis

Question 10

How much glycogen is stored in the liver?

Answer 10

80-100g

Question 11

what is the process of glucose production called and where does it occur?

Answer 11

Gluconeogenesis and in the liver.

Question 12

If glucose production does not match uptake what results?

Answer 12

hypoglycemia

Question 13

What transporters does the muscles use to uptake glucose?

Answer 13

GLUT4

Question 14

When is CHO loading done?

Answer 14

Days before the event to top up muscle glycogen and on the day to top up liver gylcogen

Question 15

What can CHO loading result in?

Answer 15

CHO supercompensation

Question 16

How is supercompensation achieved?

Answer 16

week before event. Start decreasing the exercise levels from ~90mins and start increasing CHO intake. up to 70% (average diet CHO 50%)

Question 17

what are the disadvantages of supercompensation?

Answer 17

Tend to become hypoglyceamic during the low CHO period..
• GI problems
• Hard to train through the low-CHO period
• Poor recovery (due to low CHO)
• Hard to retrain from training before competition and is not an optimal
peaking strategy
• Irritability.

Question 18

what are the benefits of CHO loading?

Answer 18

Benefits of CHO loading
• Increases time to exhaustion by about 20%
• Improves time trial performance by 2-3%
• Improves skill in team sports that require repeated high-intensity efforts
(e.g. soccer & rugby)

Question 19

What are the limitations of CHO loading?

Answer 19

Limitations of CHO loading
• Exercise seems to need to be at least 90 min for benefit to accrue.
• For short high-intensity exercise it does not seem to have a benefit.

Question 20

What is the benefit of a high CHO diet?

Answer 20

Over a weeks training your muscle glycogen levels remain highish. While in a moderate diet they deplete.

Question 21

What is GI?

Answer 21

Glycemic index is: The elevation in blood glucose from 50g intake.

i.e low GI slow releasing

Question 22

What is better low of high GI foods?

Answer 22

Low GI foods as high GI foods can lead to lower blood glucose levels

Question 23

what type of GI foods should an athlete consume?

Answer 23

Slow GI foods, except during exercise where high GI foods may be of benefit.

Question 24

What are the serious implications of high GI foods?

Answer 24

Cause large insulin release which inhibits lipolysis and causes rapid glucose uptake into the liver, this can leave no glucose supply to the muscles.