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Sports Nutrition 4481 > Lecture 2 Fuel sources for muscle and exercise metabolism > Flashcards

Lecture 2 Fuel sources for muscle and exercise metabolism Flashcards

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1
Q

Metabolic pathways associated with the three energy systems

Phosphagen
Anaerobic
Aerobic

A

None

Glycolysis

Beta-oxidation (fat)
Glycolysis (carbohydrate)
Deamination (protein)
Citric acid cycle
Electron Transport chain

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2
Q

Explain deamination

A

Removing and amino group from protein. This leaves the carbon skeleton which can be used for energy. (we ideally don’t want to do this).

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3
Q

What is the ATP pool for?

A

the small storage pool of ATP is the source of energy whenever instantaneous energy is needed

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4
Q

T or F

All systems are working together to create ATP, and contribute to the ATP pool

A

T

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5
Q

Energy System Contributions to Activities of Varying Intensity

During SHORT BURSTS of very HIGH INTENSITY activity what system is the main energy system that supplies the ATP pool?

A

Phosphagen system

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6
Q

What substrate does the phosphagen system use?

A

ATP-PC system

phosphocreatine

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7
Q

Example of exercise where you use the phosphagen system?

A

100m

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8
Q

During LONGER-LASTING sprint activities of HIGH-INTENSITY the main supplier is what system? WITH HELP FROM THE PHOSPHAGEN AND AEROBIC SYSTEMS

A

Anaerobic system

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9
Q

What substrates would be longer-lasting sprint activities of high-intensity?

A

ATP-PC (phosphocreatine) + fat + glucose (main substrate)

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10
Q

Example of exercise where you use the anaerobic system with help from the phosphagen and aerobic systems?

A

800m

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11
Q

During LONGER-LASTING activities of MODERATE/HIGH-INTENSITY the main supplier becomes what system? with the help of the anaerobic system

A

aerobic system

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12
Q

Example of exercise where you use the aerobic system with help from the anaerobic system?

A

one mile

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13
Q

What substrates would be for this longer-lasting moderate to high-intensity activity?

A

glucose + fat (main substrate)

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14
Q

During LONGER-LASTING activities of LOW-INTENSITY the main supplier becomes what system? with minimal help from the other systems.

A

aerobic system

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15
Q

What substrates would be for low-intensity longer-lasting activity?

A

fat

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16
Q

T or F the energy systems work together to Meet ATP demand

A

T

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17
Q

T or F

Athletes cannot train to depend more on the aerobic system, so that they don’t only rely on the anaerobic, then run out of energy.

A

F

18
Q

How many ATP molecules do you get from the complete oxidation of glucose to CO2 and H2O

A

38 ATP

19
Q

Carbohydrate depletion

Carbohydrate stores are _____ depleted during exercise (muscle glycogen) or during fasting (liver glycogen)

A

rapidly

20
Q

In very high-intensity exercise the muscle glycogen content falls rapidly but is _____ ______ ______ at the point of fatigue.

A

not completely depleted

21
Q

Where is glycogen stored?

A

liver and muscles

22
Q

Glycogen and Performance

The time that a fixed exercise intensity can be sustained is related to the size of the _________ ______ ________ _________

A

preexercise muscle glycogen store

23
Q

What happened to glycogen resynthesis when carbohydrates are ingested immediately post exercise as compared to carbohydrate ingested 2hrs after exercise?

A

Carbohydrate ingested immediately post exercise, glycogen resynthesis is much higher than if carbohydrates are ingested 2hr after exercise.

24
Q

Fat as fuel for exercise

The principal storage from of fat is a?

Muscles cannot oxidize triglycerides directly, so what has to happen?

A

triglyceride

the triglyceride molecule must first be broken down into its (3) fatty acid and (1) glycerol components by lipolysis. This process is activated during exercise by the actions of catecholamines, glucagon, and cortisol.

25
Q

What do these hormones promote?

Epinepherine
Norepinephrine
Glucagon
Cortisol
Growth Hormone

A

promote the use of fat for energy (promote lipolysis)

26
Q

What does insulin do in relation to using fuel for energy

A

insulin promotes the use of glucose for energy

27
Q

Intramuscular Triacylglycerol (IMTG)

Another source of fatty acids are _________ _____ _____ _____ ______

IMTG stores in the muscle decrease during exercise and are used as ____ ____ ___ ____ _____

A

IMTG stores in the muscle

and important source of energy

28
Q

Endurance exercise training can do what to the IMTG content of a muscle, and what fibre type has a higher content of IMTG

A

increases

Type I

29
Q

Amino Acids as fuel for exercise

After the removal of the amino group, what can be used for energy?

A

the carbon skeletons of amino acids can be used for oxidation

30
Q

How much does AA oxidation contributes to energy expenditure?

A

15% in resting and less than 5% in exercise

31
Q

What is the most important factor contributing to fuel selection

A

Exercise intensity

and substrate availability but mainly exercise intensity

32
Q

Exercise Intensity

Fat can only sustain exercise at _____% VO2 Max

To generate ATP to sustain higher exercise intensities, there in an increasing reliance on ___________ and at ____% of VO2 Max, the oxidation of carbohydrate will be the predominant fuel

A

60%

carbohydrates

85%

33
Q

Why can our body only use carbs at high intensity?

A

the body is NOT able to release fatty acids into the bloodstream for energy. So, even if the body wanted to use fat for energy at high intensity, it would struggle to do so

34
Q

So, basically, at what intesnities would you be relying on fats and carbs?

A

Higher the intensities (greater % of VO2 max) = carbs

lower the intensities (lower % of VO2 Max) = fats

35
Q

Fatigue in High Intensity Exercise

During maximal short-duration exercise, fatigue is primarily caused by:

A

gradual decline in anaerobic ATP production or an increase in ADP and Pi accumulation

36
Q

In high-intensity exercise, the pH is _____ and this decrease the rate at which ______ _____ _____ _______

The environment is becoming more acidic

A

lowered

the muscles can contract

37
Q

At a marathon pace, muscle glycogen stores alone can fuel about ___ __________ of exercise before depletion.

Oxidation of blood glucose (derived from _______ glycogen store) enables ATP production to be maintained and exercise to continue

A

80 minutes

liver

38
Q

Summary

High Intensity =

Moderate-intensity =

Low-intensity =

Short exercise =

Prolonged exercises =

A

Posphagen, anaerobic, carbohydrates

aerobic, mix of carbs and fats

aerobic, fat oxidation

phosphagen, anaerobic, carbohydrates

Aerobic, carbs until they get depleted then fats

39
Q

T or F

At high intensity, not all fat oxidation stops. Just mainly relying on carbohydrates.

At low-intensity, not all carbohydrate metabolism stops. Just mainly relying on fats.

A

T

40
Q

Prolonged exercise

glycogen depletes so body cannot rely on ___________. Must now rely on _____ _________. Therefore, when switching to fat oxidation, you will then switch to _____ _______ exercise, because fats cannot sustain you for prolonged _____ __________exercise, but they can for prolonged ____ ______ exercise.

A

carbs

fat oxidation

low-intensity

high-intensity

low-intensity

Sports Nutrition 4481 (10 decks)

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