Lecture 2 Fuel sources for muscle and exercise metabolism Flashcards
Metabolic pathways associated with the three energy systems
Phosphagen
Anaerobic
Aerobic
None
Glycolysis
Beta-oxidation (fat)
Glycolysis (carbohydrate)
Deamination (protein)
Citric acid cycle
Electron Transport chain
Explain deamination
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).
What is the ATP pool for?
the small storage pool of ATP is the source of energy whenever instantaneous energy is needed
T or F
All systems are working together to create ATP, and contribute to the ATP pool
T
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?
Phosphagen system
What substrate does the phosphagen system use?
ATP-PC system
phosphocreatine
Example of exercise where you use the phosphagen system?
100m
During LONGER-LASTING sprint activities of HIGH-INTENSITY the main supplier is what system? WITH HELP FROM THE PHOSPHAGEN AND AEROBIC SYSTEMS
Anaerobic system
What substrates would be longer-lasting sprint activities of high-intensity?
ATP-PC (phosphocreatine) + fat + glucose (main substrate)
Example of exercise where you use the anaerobic system with help from the phosphagen and aerobic systems?
800m
During LONGER-LASTING activities of MODERATE/HIGH-INTENSITY the main supplier becomes what system? with the help of the anaerobic system
aerobic system
Example of exercise where you use the aerobic system with help from the anaerobic system?
one mile
What substrates would be for this longer-lasting moderate to high-intensity activity?
glucose + fat (main substrate)
During LONGER-LASTING activities of LOW-INTENSITY the main supplier becomes what system? with minimal help from the other systems.
aerobic system
What substrates would be for low-intensity longer-lasting activity?
fat
T or F the energy systems work together to Meet ATP demand
T
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.
F
How many ATP molecules do you get from the complete oxidation of glucose to CO2 and H2O
38 ATP
Carbohydrate depletion
Carbohydrate stores are _____ depleted during exercise (muscle glycogen) or during fasting (liver glycogen)
rapidly
In very high-intensity exercise the muscle glycogen content falls rapidly but is _____ ______ ______ at the point of fatigue.
not completely depleted
Where is glycogen stored?
liver and muscles
Glycogen and Performance
The time that a fixed exercise intensity can be sustained is related to the size of the _________ ______ ________ _________
preexercise muscle glycogen store
What happened to glycogen resynthesis when carbohydrates are ingested immediately post exercise as compared to carbohydrate ingested 2hrs after exercise?
Carbohydrate ingested immediately post exercise, glycogen resynthesis is much higher than if carbohydrates are ingested 2hr after exercise.
Fat as fuel for exercise
The principal storage from of fat is a?
Muscles cannot oxidize triglycerides directly, so what has to happen?
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.
What do these hormones promote?
Epinepherine
Norepinephrine
Glucagon
Cortisol
Growth Hormone
promote the use of fat for energy (promote lipolysis)
What does insulin do in relation to using fuel for energy
insulin promotes the use of glucose for energy
Intramuscular Triacylglycerol (IMTG)
Another source of fatty acids are _________ _____ _____ _____ ______
IMTG stores in the muscle decrease during exercise and are used as ____ ____ ___ ____ _____
IMTG stores in the muscle
and important source of energy
Endurance exercise training can do what to the IMTG content of a muscle, and what fibre type has a higher content of IMTG
increases
Type I
Amino Acids as fuel for exercise
After the removal of the amino group, what can be used for energy?
the carbon skeletons of amino acids can be used for oxidation
How much does AA oxidation contributes to energy expenditure?
15% in resting and less than 5% in exercise
What is the most important factor contributing to fuel selection
Exercise intensity
and substrate availability but mainly exercise intensity
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
60%
carbohydrates
85%
Why can our body only use carbs at high intensity?
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
So, basically, at what intesnities would you be relying on fats and carbs?
Higher the intensities (greater % of VO2 max) = carbs
lower the intensities (lower % of VO2 Max) = fats
Fatigue in High Intensity Exercise
During maximal short-duration exercise, fatigue is primarily caused by:
gradual decline in anaerobic ATP production or an increase in ADP and Pi accumulation
In high-intensity exercise, the pH is _____ and this decrease the rate at which ______ _____ _____ _______
The environment is becoming more acidic
lowered
the muscles can contract
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
80 minutes
liver
Summary
High Intensity =
Moderate-intensity =
Low-intensity =
Short exercise =
Prolonged exercises =
Posphagen, anaerobic, carbohydrates
aerobic, mix of carbs and fats
aerobic, fat oxidation
phosphagen, anaerobic, carbohydrates
Aerobic, carbs until they get depleted then fats
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.
T
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.
carbs
fat oxidation
low-intensity
high-intensity
low-intensity
