Carbohydrate feeding during exercise

Question 1

Majority of studies show carb feeding during exercise improves performance, what type of exercise is this most shown in?

Answer 1

The magnitude of the effect is greater the longer the performance is (greater effect during prolonged exercise).

Question 2

What are the 3 monosaccharides, and what are the 3 disaccharides made from?

Answer 2

• glucose, galactose, fructose
• lactose (glucose + galactose)
• maltose (glucose + glucose)
• sucrose (glucose + fructose)

Question 3

What do ‘fast’ and ‘slow’ carbs refer to?

Answer 3

“Fast” and “Slow” refers to the speed at which these carbohydrate types are digested, absorbed and made
available to the body for energy provision.

Question 4

What are some examples of ‘fast’ carbs?

Answer 4

glucose
maltose
sucrose
maltodextrin
starches rich in amylopectin

Question 5

What are some examples of ‘slow’ carbs?

Answer 5

fructose (alone)
galactose
isomaltulose
starches rich in amylose

Question 6

What are the classical guidelines for carbohydrate feeding during exercise?

Answer 6

1.0 g/min (60 g/h) during exercise

Question 7

According to the updated guidelines, how many carbs should be consumed between 0-60 mins of exercise?

Answer 7

None

Question 8

According to the updated guidelines, how many carbs should be consumed >60 mins of exercise?

Answer 8

A small amount (glucose, glucose polymers, sucrose) - single or multiple transport carbs

Question 9

According to the updated guidelines, how many carbs should be consumed between 60-120 mins of exercise?

Answer 9

30-60 g/h - single or multiple transport carbs

Question 10

According to the updated guidelines, how many carbs should be consumed >180 mins of exercise?

Answer 10

Up to 90 g/h - Only multiple transportable carbs

Question 11

Besides improving endurance capacity and performance, what other aspects of performance can carb feeding improve?

Answer 11

Motor skills during prolonged sports events
E.g., taking a penalty after doing shuttle runs

Question 12

In a 4-hour exercise bout, the last hour is NOT powered by muscle glycogen, what is it likely powered by?

Answer 12

Blood glucose

Question 13

When we have high glucose ingestion it totally reduces glucose from the liver meaning..?

Answer 13

Spares liver glycogen

Question 14

Name the 3 benefits of carb feeding during exercise.

Answer 14

• Maintains plasma glucose concentration and helps to sustain high rates of carbohydrate oxidation.
• Spares liver glycogen (again, helping to sustain plasma glucose and carbohydrate oxidation).
• May spare muscle glycogen… although not often observed.

Question 15

What does mouth-rinsing do?

Answer 15

Mouth-rinsing activates parts of the brain which detects that energy is coming soon which allows you to maintain higher intensity for longer and prevents decrease motor unit recruitment and power output.

Question 16

How does using multiple carbs lead to greater higher uptake?

Answer 16

Explanation - different carbs use different transporters. If we have large amounts you overwhelm the transporters and it becomes blocked. If you use multiple carbs then we can use multiple transporters and we can get a higher uptake.

Question 17

How does power output change between placebo, glucose, glucose + fructose?

Answer 17

8% faster with glucose+fructose compared to glucose, and 19%
faster compared to water (placebo).

Question 18

What does multiple transportable carbohydrates refer to?

Answer 18

Multiple transportable carbohydrates refers to sugars that are transported across the intestine by stimulating more than one protein transporter (e.g., glucose [via SGLT1] and fructose [via GLUT5]).