Carbohydrates

Question 1

What is the significance of carbohydrate intake in athletic performance?

Answer 1

• Lead to adequate levels of glycogen stores, which is important for the offset symptoms of fatigue and for maintaining high work rate during exercise.

Question 2

What is the reason for avoiding alcohol consumption following exercise?

Answer 2

• It can inhibit glycogen storage.

Question 3

The gut can be trained by increasing the exposure to carbohydrate, which increases the number and activity of sodium/ glucose transporters, resulting in greater absorption and oxidation of carbohydrate, less gut discomfort and improved exercise performance.

TRUE/FALSE

Answer 3

TRUE

Question 4

What are the reasons for adding carbohydrate beverage/gel during exhaustive endurance exercise?

Answer 4

• Suppresses markers of muscle damage 12 to 24 h post exercise.
• Decreases muscular soreness.

Question 5

GLUCONEOGENISIS

Answer 5

When glycogen stores are depleted in both muscle and liver stores, carbohydrates energy production is maintained through GLUCONEOGENESIS (formation of glucoses from non-carbohydrates sources, such as amino acids, lactate and glycerol).

Question 6

What is the main function of liver glycogen?

Answer 6

To maintain blood glucose levels during prolonged exercise and/or starvation (GLYCOGENOLYSIS).

Question 7

GLUCOGENESIS

Answer 7

When blood glucose levels exceeds normal limits (~5 mmol·L-1 or ~90 mg·dL-1), the monosaccharides combine to form this large polysaccharide in the muscles and liver through a process called glucogenesis.

Glycogen’s branched structure, consisting of several reducing ends, allows for a rapid breakdown back into glucose.

Question 8

What is the caloric content of carbohydrate?

(A) 4 kcal/g.
(B) 9 kcal/g.

Answer 8

(A) 4 kcal/g.

Question 9

What is the caloric content of fat?

(A) 4 kcal/g.
(B) 9 kcal/g.

Answer 9

(B) 9 kcal/g.

Question 10

What is the caloric content of protein?

(A) 4 kcal/g.
(B) 9 kcal/g.

Answer 10

(A) 4 kcal/g.

Question 11

What is the main function of muscle glycogen?

Answer 11

Serves as metabolic fuel for the muscles.

Question 12

What is the time frame for glucose to be detectable in the bloodstream after consuming carbohydrates when dealing with hypoglycemia?

(A) 5 minutes.
(B) 10 minutes.
(C) 15 minutes.

Answer 12

(A) 5 minutes.

Question 13

What happens to the body after an overnight fast?

Answer 13

• Liver glycogen content can drop to low levels (<20 g).
• brain use glucose at a rate of about 0.1 g/min in resting conditions.
• Muscle glycogen is unchanged by overnight fasting!

Question 14

Recommended dietary allowance of carbohydrates:

Answer 14

• Based on the amount of glucose needed for the brain.
• 45%-65% of total calories.
• 3-5 g/kg body weight low activities.

Question 15

Recommended dietary allowance of fatty acids:

Answer 15

• 20%-30% of total calories.
• 44-77 g/day (when spending 2000kcal).

Question 16

Replenishment of Muscle Glycogen

Answer 16

• 60% after 10 hours (carbohydrate rich nutrition).
• ~2-5 days for complete recovery depending on timing and amount of carbohydrate ingestion.

Question 17

Replenishment of Muscle Triacylglycerides:

Answer 17

• Starts 2-4 hours after cessation.
• ~12-14 hours depending on timing and amount of carbohydrate ingestion.

Question 18

What is the daily recommended allowance of carbohydrates intake?

Answer 18

• 45-65% of the total caloric intake.
• 3-5 grams per kg.

Question 19

What is the daily recommended allowance of fatty acids intake?

Answer 19

• 20-30% of the total caloric intake.

Question 20

If blood glucose levels are too low, more glucagon is released by the pancreas. ____________ triggers the liver glycogen to convert back to glucose so it can enter the bloodstream (glycogenolysis).

Answer 20

Glucagon

Question 21

Higher carbohydrate intake, reduces the symptoms of overtraining.

Answer 21

TRUE

Question 22

Sparing of glycogen stores occurs at ________ intensities of exercise.

(A) Lower.
(B) Higher.

Answer 22

(A) Lower.

Question 23

How many minutes into vigorous exercise do muscle glycogen stores typically become depleted?

Answer 23

• Depleted after 60 to 120 minutes.
• HIGHLY depleted after 45 to 90 minutes.

Question 24

Which glycogen reserves are rapidly depleted during a period of fasting?

Answer 24

Liver glycogen stores.

Question 25

What is the primary fuel of the brain?

Answer 25

Glucose.

Question 26

At what time post-exercise is it recommended to consume carbohydrates for the replenishment of glycogen stores?

Answer 26

Within 30 minutes after exercise. If you start later, there will be less replenishment.

Question 27

At what intake level (grams/kilogram) does carbohydrate consumption offer minimal additional benefits for glycogen replenishment?

Answer 27

Above 1.2 g/kg intake of CHO.

Question 28

What are the signs of hypoglycaemia (drop below critical level often 3 mmol/L)?

Answer 28

• Dizziness.
• Nausea.
• Cold sweat.
• Reduced mental alertness.
• Reduced ability to concentrate.
• Loss of motor skills.
• Increased heart rate.
• Excessive hunger.
• Disorientation.

Question 29

What is the caloric content of alcohol?

(A) 4 kcal/g.
(B) 9 kcal/g.
(B) 7 kcal/g.

Answer 29

(B) 7 kcal/g.

Question 30

What is the caloric content of protein?

(A) 4 kcal/g.
(B) 9 kcal/g.
(B) 7 kcal/g.

Answer 30

(A) 4 kcal/g.

Question 31

Replenishment of ATP-PCr substrate:
This system is activated during onset of exercise and during intense muscle contraction, and supports rapid ATP demand 5 to 15 seconds.

Answer 31

• 70% in 30 seconds.
• Complete replenishment in 3-5 minutes.

Question 32

What are the major strategies to prevent CHO depletion during prolonged exercise?

Answer 32

• Rely (more) on fatty acid metabolism.
• Improve internal storage of glycogen.
• Gluconeogenesis: Resynthesize glucose by the liver to keep homeostasis of blood sugar levels.
• Re-fuel during exercise (CHO ingestion): 30-60 g/hour during intense prolonged exercise (>1 hour), 20 grams every 20 minutes.

Question 33

Why much carbohydrate should someone ingest during prolonged exercise for refueling?

Answer 33

30-60 grams (>1 hour).
20 grams every 20 minutes.

Question 34

How much time is required to restore glycogen stores if a person consumes a high amount of carbohydrates?

Answer 34

Within 24 to 48 hours.

Question 35

How much time is required to restore glycogen stores if a person consumes a low amount of carbohydrates?

Answer 35

Up to 4-7 days needed for complete restoration!