Lecture 2 Fuel sources for muscle and exercise metabolism

Question 1

Metabolic pathways associated with the three energy systems

Phosphagen
Anaerobic
Aerobic

Answer 1

None

Glycolysis

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

Question 2

Explain deamination

Answer 2

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).

Question 3

What is the ATP pool for?

Answer 3

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

Question 4

T or F

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

Answer 4

T

Question 5

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?

Answer 5

Phosphagen system

Question 6

What substrate does the phosphagen system use?

Answer 6

ATP-PC system

phosphocreatine

Question 7

Example of exercise where you use the phosphagen system?

Answer 7

100m

Question 8

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

Answer 8

Anaerobic system

Question 9

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

Answer 9

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

Question 10

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

Answer 10

800m

Question 11

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

Answer 11

aerobic system

Question 12

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

Answer 12

one mile

Question 13

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

Answer 13

glucose + fat (main substrate)

Question 14

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

Answer 14

aerobic system

Question 15

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

Answer 15

fat

Question 16

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

Answer 16

T

Question 17

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.

Answer 17

F

Question 18

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

Answer 18

38 ATP

Question 19

Carbohydrate depletion

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

Answer 19

rapidly

Question 20

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

Answer 20

not completely depleted

Question 21

Where is glycogen stored?

Answer 21

liver and muscles

Question 22

Glycogen and Performance

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

Answer 22

preexercise muscle glycogen store

Question 23

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

Answer 23

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

Question 24

Fat as fuel for exercise

The principal storage from of fat is a?

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

Answer 24

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.

Question 25

What do these hormones promote? Epinepherine Norepinephrine Glucagon Cortisol Growth Hormone

Answer 25

promote the use of fat for energy (promote lipolysis)

Question 26

What does insulin do in relation to using fuel for energy

Answer 26

insulin promotes the use of glucose for energy

Question 27

Intramuscular Triacylglycerol (IMTG) Another source of fatty acids are _________ _____ _____ _____ ______ IMTG stores in the muscle decrease during exercise and are used as ____ ____ ___ ____ _____

Answer 27

IMTG stores in the muscle and important source of energy

Question 28

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

Answer 28

increases Type I

Question 29

Amino Acids as fuel for exercise After the removal of the amino group, what can be used for energy?

Answer 29

the carbon skeletons of amino acids can be used for oxidation

Question 30

How much does AA oxidation contributes to energy expenditure?

Answer 30

15% in resting and less than 5% in exercise

Question 31

What is the most important factor contributing to fuel selection

Answer 31

Exercise intensity and substrate availability but mainly exercise intensity

Question 32

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

Answer 32

60% carbohydrates 85%

Question 33

Why can our body only use carbs at high intensity?

Answer 33

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

Question 34

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

Answer 34

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

Question 35

Fatigue in High Intensity Exercise During maximal short-duration exercise, fatigue is primarily caused by:

Answer 35

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

Question 36

In high-intensity exercise, the pH is _____ and this decrease the rate at which ______ _____ _____ _______ The environment is becoming more acidic

Answer 36

lowered the muscles can contract

Question 37

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

Answer 37

80 minutes liver

Question 38

Summary High Intensity = Moderate-intensity = Low-intensity = Short exercise = Prolonged exercises =

Answer 38

Posphagen, anaerobic, carbohydrates aerobic, mix of carbs and fats aerobic, fat oxidation phosphagen, anaerobic, carbohydrates Aerobic, carbs until they get depleted then fats

Question 39

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.

Answer 39

T

Question 40

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.

Answer 40

carbs fat oxidation low-intensity high-intensity low-intensity