1. Exercise physiology

2. Intro
The very basis of exercise is dependent on the body’s ability to take up and utilise oxygen in order to produce energy.
This unit examines the production of energy (ATP) and those factors that influence the uptake and delivery of oxygen to working muscles

3. ATP, ADP and AMP
Energy for muscular contraction comes from the breakdown of ATP (adenosine Tri Phosphate)
The three (tri) phosphate molecules are the key to the release of energy
As a phosphate is split off, energy is released

4. ATP, ADP and AMP
Why is it preferable to break down ATP in the muscle cells?
Because the muscles are the site of action.
It makes sense to break ATP down where it will be used
The body however only has limited stores of ATP. The body needs a mechanism for the creation of a regular supply of ATP for muscular work?
What might this be?
Food break down to provide the fundamental components of ATP

5. Sources of ATP
The nutrients we extract from food are used to produce ATP. These are:
Carbohydrate
Fat
protein

6. 1. Carbohydrates
Carbohydrate is broken down into ________ and stored as _________ in the muscle or liver Carbohydrates are the preferred source of ATP and can be used to produce energy either with or without oxygen present
glucose
glycogen

7. 2. Fats Fats are broken down into _____________ or _____________
Fats are stored in the body as ____________
Fats tend to be used in the chemical production of ATP during very sub-maximal exercise and increasingly during aerobic exercise
triglycerides
free fatty acids
adipose

8. Proteins amino acids tissues
Proteins are broken down into ____________ and are used to create ____________
Proteins are used as a source of ATP in extreme cases only
Why?
tissues
Because it requires breaking down tissue

9. Chemical production of ATP
Production of ATP at rest
At rest ATP is produced in the presence of oxygen (aerobically)
This process is called:
Cellular respiration
This process occurs in muscle fibres in the
Mitochondria
The production of ATP at rest uses a mix of carbohydrates (glucose) and fats (free fatty acids)

10. Why is it preferable to burn mostly fats at rest?
So the carbohydrates are made available in exercise when they are the preferred energy source

11. Muscular contractions
Chemical pathway is:
1/3 glucose
Free fatty acids
ADP + P
TCA or Krebs Cycle
CO2
Energy
Muscular contractions
ATP
Heat
Water

12. Equation
Oxygen
Glucose + free fatty acids CO2 + H2O + Heat + Energy

13. What happens to the CO2 produced? What happens to the water produced?
It is breathed out
What happens to the water produced?
Breathed out as vapour but also lost via sweat
This is a very efficient system for producing ATP. For every molecule of glucose or fat used 38 molecules of ATP are produced
What would this ATP be used for at rest?
Heart beating, breathing, skeletal muscle pumps, gut contracts

14. Production of ATP during exercise
During exercise, production of ATP depends upon the energy system being used. This in turn will be governed by the intensity and duration of the exercise.
ATP-CP system
this system uses the ATP already stored within the muscles. The breakdown of ATP to ADP releases energy for muscular contraction
ATP
Stored Creatine Phosphate
Energy
ADP + P

15. What is the role of creatine phosphate within the muscles?
Used to reform ATP from the broken down components of ATP. A theory is that the more stores of CP the more the ATP-CP, the more ATP-CP system can be used
What might the advantages be of taking the dietary supplement creatine?
To increase the stores of CP in the body, so this process can occur more frequently
This system occurs without the presence of oxygen (anaerobically) and provides energy for intense exercise over sec

16. b. Anaerobic glycolysis (Lactic acid system)
Anaerobic means
In the absence of oxygen
Glycolysis means
Breakdown of glycogen
Anaerobic glycolysis is defined as the breakdown of glycogen in the absence of oxygen for energy production

17. The pathway of energy production
Glycogen
ADP + P
Glucose
Muscular contractions
ATP
Pyruvic acid
Insufficient O2
Lactic acid

18. What are the consequences of the product produced at ‘D’
Causes fatigue and the ‘burn’ associated with high intensity, repetitive exercise
This system provides energy over seconds for high to moderate intensity exercise

19. c. Aerobic glycolysis (aerobic system)
Aerobic means
In the presence of oxygen
Glycolysis means
the breakdown of glycogen in the presence of oxygen
Aerobic glycolysis is defined as the breakdown of glycogen in the presence of oxygen for energy production

20. Muscular contractions
Aerobic Glycolysis pathway
Muscular contractions
Glycogen
Glucose
Pyruvic acid
CO2
Energy
Sufficient O2
TCA or Krebs Cycle
ACETYL COA
Sufficient O2
Heat
Water
Fats
triglycerides
Free fatty acids

21. Continued
Initially this process uses blood glucose, followed by stored glycogen. This process produces 36 molecules of ATP for every molecule of glycogen used.
This is the preferred system during aerobic exercise of moderate intensity, e.g. Running and swimming

22. For sub-maximal exercise such as walking, fats (as free fatty acids) are the main source of fuel for the aerobic system. Explain why.
Because there is plenty of oxygen to break it down. Also it saves the carbohydrates for more intense work
For prolonged exercise such as marathons, the main fuel source once again turns to fats. Why?
Because stores of glycogen are used up
Fats however require more oxygen than carbohydrates to produce the same amounts of ATP. What are the consequences of this for the athlete?
They have to slow down to increase oxygen uptake

23. What happens when an athlete hits the wall?
When an athlete ‘hits the wall’ there is a sudden decrease in the amount of glycogen used and matching rise in fatty acid usage. As a result, there is an increased requirement for oxygen to use fatty acids as a fuel for exercise. If they do not slow down, they will start to produce ATP anaerobically. Lactic acid levels will rise, causing a sudden decrease in performance